Merge branch 'develop' into detail-helpers

Resolve the conflicts with #5781 (iterative binary writers) and the
BJData ND-array change by taking develop's code, then name its exception
ids and use invalid_byte() for the moved _ArrayType_ check.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

README.md

@@ -494,7 +494,7 @@ bool key(string_t& val);
 bool parse_error(std::size_t position, const std::string& last_token, const detail::exception& ex);
 ```
 
-The return value of each function determines whether parsing should proceed. For `parse_error`, returning `true` [recovers from the error](https://json.nlohmann.me/features/parsing/error_recovery/): the parser repairs the input and continues.
+The return value of each function determines whether parsing should proceed.
 
 To implement your own SAX handler, proceed as follows:
 
@@ -502,7 +502,7 @@ To implement your own SAX handler, proceed as follows:
 2. Create an object of your SAX interface class, e.g. `my_sax`.
 3. Call `bool json::sax_parse(input, &my_sax)`; where the first parameter can be any input like a string or an input stream and the second parameter is a pointer to your SAX interface.
 
-Note the `sax_parse` function only returns a `bool` indicating whether the input was parsed without errors and no SAX event returned `false`. It does not return a  `json` value - it is up to you to decide what to do with the SAX events. Furthermore, no exceptions are thrown in case of a parse error -- it is up to you what to do with the exception object passed to your `parse_error` implementation. Internally, the SAX interface is used for the DOM parser (class `json_sax_dom_parser`) as well as the acceptor (`json_sax_acceptor`), see file [`json_sax.hpp`](https://github.com/nlohmann/json/blob/develop/include/nlohmann/detail/input/json_sax.hpp).
+Note the `sax_parse` function only returns a `bool` indicating the result of the last executed SAX event. It does not return a  `json` value - it is up to you to decide what to do with the SAX events. Furthermore, no exceptions are thrown in case of a parse error -- it is up to you what to do with the exception object passed to your `parse_error` implementation. Internally, the SAX interface is used for the DOM parser (class `json_sax_dom_parser`) as well as the acceptor (`json_sax_acceptor`), see file [`json_sax.hpp`](https://github.com/nlohmann/json/blob/develop/include/nlohmann/detail/input/json_sax.hpp).
 
 ### STL-like access
 

docs/mkdocs/docs/api/basic_json/sax_parse.md

@@ -96,9 +96,7 @@ The SAX event lister must follow the interface of [`json_sax`](../json_sax/index
 
 ## Return value
 
-`#!cpp true` if the input was parsed without errors and no SAX event returned `#!cpp false`; `#!cpp false` otherwise.
-In particular, the result is `#!cpp false` for input with errors, even if the SAX parser recovered from all of them
-(see [error recovery](../../features/parsing/error_recovery.md)).
+return value of the last processed SAX event
 
 ## Exception safety
 
@@ -147,7 +145,6 @@ A UTF-8 byte order mark is silently ignored.
 - Added `ignore_trailing_commas` in version 3.13.0.
 - Added `tag_handler` in version 3.13.0.
 - Extended container support (1) to include types with lvalue-only ADL `begin`/`end` (matching `std::begin`/`std::end` semantics) in version 3.13.0.
-- Recovering from parse errors (see [`parse_error`](../json_sax/parse_error.md)) added in version 3.13.0.
 - Extended overload (2) to accept heterogeneous iterator+sentinel pairs (C++20 ranges support) in version 3.13.0.
 - `JSON_PRECISE_STREAM_POSITION` added in version 3.13.0 to optionally leave a `#!cpp std::istream` positioned right
   after the parsed value when `strict` is `#!cpp false`.

docs/mkdocs/docs/api/json_sax/index.md

@@ -7,8 +7,7 @@ struct json_sax;
 
 This class describes the SAX interface used by [sax_parse](../basic_json/sax_parse.md). Each function is called in
 different situations while the input is parsed. The boolean return value informs the parser whether to continue
-processing the input; for [`parse_error`](parse_error.md), it decides whether to
-[recover from the error](../../features/parsing/error_recovery.md).
+processing the input.
 
 For instance, parsing the JSON text `{"a": [1, true]}` triggers the following callbacks, in order:
 

docs/mkdocs/docs/api/json_sax/parse_error.md

@@ -21,18 +21,11 @@ A parse error occurred.
 
 ## Return value
 
-Whether to recover from the error:
-
-- `#!cpp false` stops parsing.
-- `#!cpp true` recovers from the error: the error is repaired and parsing continues. If that is not possible, which
-  happens in the binary formats when the end of the item with the error is unknown, the value read so far is completed
-  and parsing stops. See [error recovery](../../features/parsing/error_recovery.md) for how errors are repaired.
-
-Either way, [`sax_parse`](../basic_json/sax_parse.md) returns `#!cpp false`.
+Whether parsing should proceed (**must return `#!cpp false`**).
 
 ## Examples
 
-??? example "Example: (1) the SAX interface"
+??? example
 
     The example below shows how the SAX interface is used.
 
@@ -46,29 +39,12 @@ Either way, [`sax_parse`](../basic_json/sax_parse.md) returns `#!cpp false`.
     --8<-- "examples/sax_parse.output"
     ```
 
-??? example "Example: (2) recovering from errors"
-
-    The example below shows how a SAX parser recovers from errors.
-
-    ```cpp
-    --8<-- "examples/sax_parse__error_recovery.cpp"
-    ```
-    
-    Output:
-    
-    ```
-    --8<-- "examples/sax_parse__error_recovery.output"
-    ```
-
 ## See also
 
 - [sax_parse](../basic_json/sax_parse.md) - SAX parser
 - [Parsing and Exceptions](../../features/parsing/parse_exceptions.md) - the article on handling parse errors without
   exceptions
-- [Error Recovery](../../features/parsing/error_recovery.md) - the article on recovering from parse errors
 
 ## Version history
 
 - Added in version 3.2.0.
-- Returning `#!cpp true` recovers from the error since version 3.13.0; before, parsing stopped, but the result of
-  [`sax_parse`](../basic_json/sax_parse.md) could be wrong.

docs/mkdocs/docs/examples/sax_parse__error_recovery.cpp

@@ -1,43 +0,0 @@
-#include <iostream>
-#include <iomanip>
-#include <nlohmann/json.hpp>
-
-using json = nlohmann::json;
-
-// a SAX parser that creates a JSON value like json::parse does, but that
-// recovers from parse errors instead of stopping at the first one
-class recovering_parser : public nlohmann::detail::json_sax_dom_parser<json>
-{
-  public:
-    explicit recovering_parser(json& result)
-        : nlohmann::detail::json_sax_dom_parser<json>(result, false)
-    {}
-
-    bool parse_error(std::size_t position,
-                     const std::string& /*last_token*/,
-                     const json::exception& ex)
-    {
-        std::cout << "byte " << position << ": " << ex.what() << '\n';
-
-        // repair the input and continue
-        return true;
-    }
-};
-
-int main()
-{
-    // JSON text with several mistakes that ends too early
-    const std::string text = R"({
-    "name": "Hello World",
-    "tags": ["a" "b",],
-    "valid": tru,
-    "size": 1.,
-    "nested": {"x": 1)";
-
-    json result;
-    recovering_parser sax(result);
-    const bool valid = json::sax_parse(text, &sax);
-
-    std::cout << "\nvalid JSON: " << std::boolalpha << valid << '\n'
-              << std::setw(4) << result << std::endl;
-}

docs/mkdocs/docs/examples/sax_parse__error_recovery.output

@@ -1,19 +0,0 @@
-byte 49: [json.exception.parse_error.101] parse error at line 3, column 20: syntax error while parsing array - unexpected string literal; expected ']'
-byte 51: [json.exception.parse_error.101] parse error at line 3, column 22: syntax error while parsing value - unexpected ']'; expected '[', '{', or a literal
-byte 70: [json.exception.parse_error.101] parse error at line 4, column 17: syntax error while parsing value - invalid literal; last read: '"valid": tru,'
-byte 86: [json.exception.parse_error.101] parse error at line 5, column 15: syntax error while parsing value - invalid number; expected digit after '.'; last read: '1.,'
-byte 109: [json.exception.parse_error.101] parse error at line 6, column 22: syntax error while parsing object - unexpected end of input; expected '}'
-
-valid JSON: false
-{
-    "name": "Hello World",
-    "nested": {
-        "x": 1
-    },
-    "size": 1,
-    "tags": [
-        "a",
-        "b"
-    ],
-    "valid": null
-}

docs/mkdocs/docs/features/parsing/error_recovery.md

@@ -1,122 +0,0 @@
-# Error Recovery
-
-By default, parsing stops at the first error. With the [SAX interface](sax_interface.md), you can instead ask the
-parser to *recover*: to repair the error and continue, so that you get as much as possible out of malformed input, for
-instance a file that was cut off, JSON edited by hand, or the output of a language model.
-
-## Recovering from errors
-
-The SAX parser's [`parse_error`](../../api/json_sax/parse_error.md) function is called for every error. Its return value
-decides what happens next:
-
-- `#!cpp false` stops parsing. This is what the SAX parsers of the library do, so [`parse`](../../api/basic_json/parse.md)
-  and [`accept`](../../api/basic_json/accept.md) never recover.
-- `#!cpp true` repairs the error and continues parsing.
-
-When recovering, the SAX parser still receives well-formed events: every `start_object` or `start_array` is followed by
-the matching `end_object` or `end_array`, and every `key` is followed by exactly one value. A SAX parser that creates a
-JSON value, such as the one in the example below, therefore gets a complete value. Parsing always ends, and
-[`sax_parse`](../../api/basic_json/sax_parse.md) returns `#!cpp false` for input that is not valid JSON, even if every
-error was repaired. Each token is reported at most once, and the SAX parser can stop at any error by returning
-`#!cpp false`.
-
-!!! example
-
-    The example below derives a SAX parser from the library's parser for `json` values (`json_sax_dom_parser`),
-    and recovers from all errors.
-
-    ```cpp
-    --8<-- "examples/sax_parse__error_recovery.cpp"
-    ```
-    
-    Output:
-    
-    ```
-    --8<-- "examples/sax_parse__error_recovery.output"
-    ```
-
-## How errors are repaired
-
-Each error is repaired with the smallest local edit: a missing separator is inserted, a stray token is removed, what can
-be read of a broken string or number is kept, and a value that cannot be read at all becomes `#!json null`.
-
-| Mistake                   | Repair                                                                         | Example                                  | Result                     |
-|---------------------------|--------------------------------------------------------------------------------|------------------------------------------|----------------------------|
-| missing `,` or `:`        | inserted                                                                       | `#!json [1 2]`, `#!json {"a" 1}`         | `[1,2]`, `{"a":1}`         |
-| missing value             | `#!json null` for an object key or between commas in an array                  | `#!json {"a":}`, `#!json [1,,2]`         | `{"a":null}`, `[1,null,2]` |
-| trailing comma            | removed                                                                        | `#!json [1,2,]`                          | `[1,2]`                    |
-| broken string             | invalid escapes and bytes are replaced (see below); a line break ends the string | `#!json ["a\qb"]`                        | `["aqb"]`                  |
-| broken number             | the longest valid beginning is kept                                            | `#!json [1., 2e+]`                       | `[1,2]`                    |
-| unreadable value          | `#!json null`                                                                  | `#!json [1, NaN, tru]`                   | `[1,null,null]`            |
-| number too large          | passed as infinity, together with its text                                     | `#!json [1e999]`                         | infinity (see below)       |
-| stray `:`                 | removed                                                                        | `#!json ["a":1]`                         | `["a",1]`                  |
-| member without a key      | skipped up to the next `,` or `}`                                              | `#!json {1:2, "b":3}`                    | `{"b":3}`                  |
-| wrong closing bracket     | closes the innermost array or object                                           | `#!json {"a":[1,2}, "b":3}`              | `{"a":[1,2],"b":3}`        |
-| input ends too early      | all open arrays and objects are closed                                         | `#!json {"a":[1,2`                       | `{"a":[1,2]}`              |
-| text before the value     | skipped                                                                        | `#!json )]}'{"a":1}`                     | `{"a":1}`                  |
-
-In a string, an unknown escape like `\q` stands for the escaped character (`q`), as in JavaScript. An invalid `\u`
-escape, a lone surrogate, and ill-formed UTF-8 are each replaced by U+FFFD (REPLACEMENT CHARACTER), and control
-characters are kept. A string without its closing quote ends at the next line break or at the end of the input.
-
-The input after the top-level value is not repaired: as without recovery, it is reported as an error, and parsing stops.
-
-## Binary formats
-
-The binary formats ([BJData](../binary_formats/bjdata.md), [BON8](../binary_formats/bon8.md),
-[BSON](../binary_formats/bson.md), [CBOR](../binary_formats/cbor.md), [MessagePack](../binary_formats/messagepack.md),
-and [UBJSON](../binary_formats/ubjson.md)) have no delimiters to find the next value by. So what can be repaired depends
-on whether the end of the item with the error is known, a distinction that
-[RFC 8949, Section 5.3](https://www.rfc-editor.org/rfc/rfc8949.html#section-5.3) makes for CBOR, too.
-
-If the item is complete, but cannot be passed on as it is, it is replaced, and parsing continues after it:
-
-| Mistake                                                             | Formats                 | Repair                                                                  |
-|---------------------------------------------------------------------|-------------------------|-------------------------------------------------------------------------|
-| tag, if `tag_handler` is `cbor_tag_handler_t::error` (the default)  | CBOR                    | ignored                                                                 |
-| simple value other than `false`, `true`, and `null`, like undefined | CBOR                    | `#!json null`                                                           |
-| number too large for a custom `number_float_t`, like `float`        | all                     | infinity                                                                |
-| character (`C`) that is not ASCII                                   | BJData, UBJSON          | U+FFFD                                                                  |
-| invalid high-precision number (`H`)                                 | BJData, UBJSON          | the longest valid beginning is kept, as for JSON text, or `#!json null` |
-| high-precision number too large                                     | BJData, UBJSON          | passed as infinity, together with its text                              |
-| object key that is not a string                                     | BON8, CBOR, MessagePack | the member is skipped                                                   |
-| element of a type the library does not read, like ObjectId or date  | BSON                    | `#!json null`                                                           |
-| string without its terminator                                       | BSON                    | kept                                                                    |
-| document whose size does not match its content                      | BSON                    | kept                                                                    |
-
-CBOR tags and simple values are repaired as [RFC 8949, Section 6.1](https://www.rfc-editor.org/rfc/rfc8949.html#section-6.1)
-suggests for converting CBOR to JSON. By default, [`sax_parse`](../../api/basic_json/sax_parse.md) reports every tag as
-an error; when recovering, tags are then ignored like with
-[`cbor_tag_handler_t::ignore`](../../api/basic_json/cbor_tag_handler_t.md). Strings that are not valid UTF-8 are no
-error: like [`from_cbor`](../../api/basic_json/from_cbor.md) and the other functions by default, `sax_parse` passes
-them on as they are.
-
-After any other error, the end of the item is unknown: the input ended, a byte is not a valid type marker, or a size
-cannot be right. Parsing then stops, and the value read so far is completed: a key that waits for its value gets
-`#!json null`, and all open arrays and objects are closed. This keeps everything before the error of an input that was
-cut off. The exception is BSON, which stores the size of every document: an element whose end is unknown gets
-`#!json null`, the rest of its document is skipped, and parsing continues after the document.
-
-## Limitations
-
-- A repair is a guess. For example, `#!json {"a" "b": 1}` could be meant as `#!json {"a": "b"}` or as
-  `#!json {"a": null, "b": 1}`; it is repaired to the former. Treat recovered values as a best effort, and check the
-  reported errors.
-- A closing bracket always closes the innermost array or object. If a bracket is missing rather than wrong, the
-  repair differs from the intention: `#!json {"a": {"b": [1, 2}, "c": 3}` is repaired to
-  `#!json {"a": {"b": [1, 2], "c": 3}}`, although `#!json {"a": {"b": [1, 2]}, "c": 3}` may have been meant.
-- Keys without quotes, and strings in single quotes, are not supported; such members are skipped.
-- In the binary formats, a member that is skipped because its key is not a string is lost, and so are the elements of a
-  BSON document after one whose end is unknown.
-- A number that is too large for `number_float_t` is passed as positive or negative infinity. The SAX parser's
-  `number_float` also gets the number's text, but a JSON value cannot store it, and
-  [`dump`](../../api/basic_json/dump.md) serializes infinity as `#!json null`.
-- When parsing is not strict (see [`sax_parse`](../../api/basic_json/sax_parse.md)), a repair may read parts of the
-  input after the value, for instance of the next value in a stream of concatenated values.
-
-## See also
-
-- [SAX interface](sax_interface.md) - implement a custom SAX handler
-- [`parse_error`](../../api/json_sax/parse_error.md) - the SAX event for parse errors
-- [`sax_parse`](../../api/basic_json/sax_parse.md) - generate SAX events
-- [parsing and exceptions](parse_exceptions.md) - control error handling

docs/mkdocs/docs/features/parsing/index.md

@@ -75,7 +75,7 @@ You can influence a DOM parse without switching to the SAX interface by passing
 When the input is not valid JSON, the `parse` function throws an exception by default. If exceptions are undesired or
 unavailable, the parser can instead return a discarded value, or [`accept`](../../api/basic_json/accept.md) can be used
 to only check whether an input is valid JSON. See [parsing and exceptions](parse_exceptions.md) for the available
-options. To get as much as possible out of malformed input, a SAX parser can [recover from errors](error_recovery.md).
+options.
 
 ## See also
 
@@ -86,5 +86,4 @@ options. To get as much as possible out of malformed input, a SAX parser can [re
 - [parser callbacks](parser_callbacks.md) - influence the parsing by a callback function
 - [SAX interface](sax_interface.md) - implement a custom SAX handler
 - [parsing and exceptions](parse_exceptions.md) - control error handling
-- [error recovery](error_recovery.md) - get as much as possible out of malformed input
 - [parsing untrusted input](untrusted_input.md) - what to consider when parsing input from untrusted sources

docs/mkdocs/docs/features/parsing/parse_exceptions.md

@@ -64,8 +64,7 @@ bool parse_error(std::size_t position,
                  const json::exception& ex);
 ```
 
-The return value decides whether to stop parsing (`#!cpp false`) or to repair the error and continue
-(`#!cpp true`); see [error recovery](error_recovery.md) for the latter.
+The return value indicates whether the parsing should continue, so the function should usually return `#!cpp false`.
 
 ??? example "Example: report parse errors without exceptions"
 

docs/mkdocs/docs/features/parsing/sax_interface.md

@@ -60,8 +60,7 @@ bool key(string_t& val);
 bool parse_error(std::size_t position, const std::string& last_token, const json::exception& ex);
 ```
 
-The return value of each function determines whether parsing should proceed. For `parse_error`, returning
-`#!cpp true` [recovers from the error](error_recovery.md).
+The return value of each function determines whether parsing should proceed.
 
 To implement your own SAX handler, proceed as follows:
 
@@ -69,7 +68,7 @@ To implement your own SAX handler, proceed as follows:
 2. Create an object of your SAX interface class, e.g. `my_sax`.
 3. Call `#!cpp bool json::sax_parse(input, &my_sax);` where the first parameter can be any input like a string or an input stream and the second parameter is a pointer to your SAX interface.
 
-Note the `sax_parse` function only returns a `#!cpp bool` indicating whether the input was parsed without errors and no SAX event returned `#!cpp false`. It does not return `json` value - it is up to you to decide what to do with the SAX events. Furthermore, no exceptions are thrown in case of a parse error - it is up to you what to do with the exception object passed to your `parse_error` implementation. Internally, the SAX interface is used for the DOM parser (class `json_sax_dom_parser`) as well as the acceptor (`json_sax_acceptor`), see file `json_sax.hpp`.
+Note the `sax_parse` function only returns a `#!cpp bool` indicating the result of the last executed SAX event. It does not return `json` value - it is up to you to decide what to do with the SAX events. Furthermore, no exceptions are thrown in case of a parse error - it is up to you what to do with the exception object passed to your `parse_error` implementation. Internally, the SAX interface is used for the DOM parser (class `json_sax_dom_parser`) as well as the acceptor (`json_sax_acceptor`), see file `json_sax.hpp`.
 
 ## See also
 

docs/mkdocs/mkdocs.yml

@@ -88,7 +88,6 @@ nav:
       - features/performance.md
       - Parsing:
           - features/parsing/index.md
-          - features/parsing/error_recovery.md
           - features/parsing/json_lines.md
           - features/parsing/parse_exceptions.md
           - features/parsing/parser_callbacks.md

include/nlohmann/detail/conversions/from_json.hpp

@@ -48,7 +48,7 @@ inline void from_json(const BasicJsonType& j, typename std::nullptr_t& n)
 {
     if (JSON_HEDLEY_UNLIKELY(!j.is_null()))
     {
-        JSON_THROW(type_error::create(302, concat("type must be null, but is ", j.type_name()), &j));
+        throw_type_must_be("null", j);
     }
     n = nullptr;
 }
@@ -102,7 +102,7 @@ void get_arithmetic_value(const BasicJsonType& j, ArithmeticType& val)
         case value_t::binary:
         case value_t::discarded:
         default:
-            JSON_THROW(type_error::create(302, concat("type must be number, but is ", j.type_name()), &j));
+            throw_type_must_be("number", j);
     }
 }
 
@@ -111,7 +111,7 @@ inline void from_json(const BasicJsonType& j, typename BasicJsonType::boolean_t&
 {
     if (JSON_HEDLEY_UNLIKELY(!j.is_boolean()))
     {
-        JSON_THROW(type_error::create(302, concat("type must be boolean, but is ", j.type_name()), &j));
+        throw_type_must_be("boolean", j);
     }
     b = *j.template get_ptr<const typename BasicJsonType::boolean_t*>();
 }
@@ -121,7 +121,7 @@ inline void from_json(const BasicJsonType& j, typename BasicJsonType::string_t&
 {
     if (JSON_HEDLEY_UNLIKELY(!j.is_string()))
     {
-        JSON_THROW(type_error::create(302, concat("type must be string, but is ", j.type_name()), &j));
+        throw_type_must_be("string", j);
     }
     s = *j.template get_ptr<const typename BasicJsonType::string_t*>();
 }
@@ -137,7 +137,7 @@ inline void from_json(const BasicJsonType& j, StringType& s)
 {
     if (JSON_HEDLEY_UNLIKELY(!j.is_string()))
     {
-        JSON_THROW(type_error::create(302, concat("type must be string, but is ", j.type_name()), &j));
+        throw_type_must_be("string", j);
     }
 
     s = *j.template get_ptr<const typename BasicJsonType::string_t*>();
@@ -183,7 +183,7 @@ inline void from_json(const BasicJsonType& j, std::forward_list<T, Allocator>& l
 {
     if (JSON_HEDLEY_UNLIKELY(!j.is_array()))
     {
-        JSON_THROW(type_error::create(302, concat("type must be array, but is ", j.type_name()), &j));
+        throw_type_must_be("array", j);
     }
     l.clear();
     std::transform(j.rbegin(), j.rend(),
@@ -200,7 +200,7 @@ inline void from_json(const BasicJsonType& j, std::valarray<T>& l)
 {
     if (JSON_HEDLEY_UNLIKELY(!j.is_array()))
     {
-        JSON_THROW(type_error::create(302, concat("type must be array, but is ", j.type_name()), &j));
+        throw_type_must_be("array", j);
     }
     l.resize(j.size());
     std::transform(j.begin(), j.end(), std::begin(l),
@@ -305,7 +305,7 @@ void())
 {
     if (JSON_HEDLEY_UNLIKELY(!j.is_array()))
     {
-        JSON_THROW(type_error::create(302, concat("type must be array, but is ", j.type_name()), &j));
+        throw_type_must_be("array", j);
     }
 
     from_json_array_impl(j, arr, priority_tag<3> {});
@@ -324,7 +324,7 @@ auto from_json(const BasicJsonType& j, identity_tag<std::array<T, N>> tag)
 {
     if (JSON_HEDLEY_UNLIKELY(!j.is_array()))
     {
-        JSON_THROW(type_error::create(302, concat("type must be array, but is ", j.type_name()), &j));
+        throw_type_must_be("array", j);
     }
 
     return from_json_inplace_array_impl(j, tag, make_index_sequence<N> {});
@@ -335,7 +335,7 @@ inline void from_json(const BasicJsonType& j, typename BasicJsonType::binary_t&
 {
     if (JSON_HEDLEY_UNLIKELY(!j.is_binary()))
     {
-        JSON_THROW(type_error::create(302, concat("type must be binary, but is ", j.type_name()), &j));
+        throw_type_must_be("binary", j);
     }
 
     bin = *j.template get_ptr<const typename BasicJsonType::binary_t*>();
@@ -356,7 +356,7 @@ inline void from_json(const BasicJsonType& j, CompatibleArrayType& bin)
     }
     else
     {
-        JSON_THROW(type_error::create(302, concat("type must be binary or array, but is ", j.type_name()), &j));
+        throw_type_must_be("binary or array", j);
     }
 }
 
@@ -377,7 +377,7 @@ inline void from_json(const BasicJsonType& j, ConstructibleObjectType& obj)
 {
     if (JSON_HEDLEY_UNLIKELY(!j.is_object()))
     {
-        JSON_THROW(type_error::create(302, concat("type must be object, but is ", j.type_name()), &j));
+        throw_type_must_be("object", j);
     }
 
     ConstructibleObjectType ret;
@@ -432,7 +432,7 @@ inline void from_json(const BasicJsonType& j, ArithmeticType& val)
         case value_t::binary:
         case value_t::discarded:
         default:
-            JSON_THROW(type_error::create(302, concat("type must be number, but is ", j.type_name()), &j));
+            throw_type_must_be("number", j);
     }
 }
 
@@ -504,7 +504,7 @@ auto from_json(const BasicJsonType& j, TupleRelated&& t)
 {
     if (JSON_HEDLEY_UNLIKELY(!j.is_array()))
     {
-        JSON_THROW(type_error::create(302, concat("type must be array, but is ", j.type_name()), &j));
+        throw_type_must_be("array", j);
     }
 
     return from_json_tuple_impl(j, std::forward<TupleRelated>(t), priority_tag<3> {});
@@ -517,14 +517,14 @@ void from_json_pair_array_to_map(const BasicJsonType& j, MapType& m)
 {
     if (JSON_HEDLEY_UNLIKELY(!j.is_array()))
     {
-        JSON_THROW(type_error::create(302, concat("type must be array, but is ", j.type_name()), &j));
+        throw_type_must_be("array", j);
     }
     m.clear();
     for (const auto& p : j)
     {
         if (JSON_HEDLEY_UNLIKELY(!p.is_array()))
         {
-            JSON_THROW(type_error::create(302, concat("type must be array, but is ", p.type_name()), &p));
+            throw_type_must_be("array", p);
         }
         m.emplace(p.at(0).template get<typename MapType::key_type>(), p.at(1).template get<typename MapType::mapped_type>());
     }
@@ -591,7 +591,7 @@ inline void from_json(const BasicJsonType& j, std_fs::path& p)
 {
     if (JSON_HEDLEY_UNLIKELY(!j.is_string()))
     {
-        JSON_THROW(type_error::create(302, concat("type must be string, but is ", j.type_name()), &j));
+        throw_type_must_be("string", j);
     }
     const auto& s = *j.template get_ptr<const typename BasicJsonType::string_t*>();
     // Checking for C++20 standard or later can be insufficient in case the

include/nlohmann/detail/conversions/to_json.hpp

@@ -414,13 +414,13 @@ inline void to_json(BasicJsonType& j, const EnumKeyedMap& map)
         BasicJsonType key = p.first;
         if (JSON_HEDLEY_UNLIKELY(!key.is_string()))
         {
-            JSON_THROW(type_error::create(302, concat("type must be string, but is ", key.type_name()), &key));
+            throw_type_must_be("string", key);
         }
 
         auto& key_string = *key.template get_ptr<typename BasicJsonType::string_t*>();
         if (JSON_HEDLEY_UNLIKELY(!obj.emplace(key_string, BasicJsonType(p.second)).second))
         {
-            JSON_THROW(type_error::create(318, concat("duplicate object key '", key_string, "'"), &key));
+            JSON_THROW(type_error::create(exception_id::enum_key_duplicate, concat("duplicate object key '", key_string, "'"), &key));
         }
     }
     external_constructor<value_t::object>::construct(j, std::move(obj));

include/nlohmann/detail/exceptions.hpp

@@ -45,6 +45,84 @@ namespace detail
 // exceptions //
 ////////////////
 
+/*!
+@brief the ids of the exceptions thrown by the library
+@note The values are part of the public API: they are the `id` member of the
+      exceptions and appear in their `what()` messages.
+@sa https://json.nlohmann.me/home/exceptions/
+*/
+enum class exception_id : int
+{
+    // parse_error
+    syntax_error = 101, ///< unexpected token or invalid literal while parsing JSON
+    patch_not_an_array = 104, ///< a JSON Patch document is not an array of objects
+    patch_invalid_operation = 105, ///< a JSON Patch operation is malformed
+    pointer_index_leading_zero = 106, ///< a JSON Pointer array index has a leading zero
+    pointer_missing_slash = 107, ///< a JSON Pointer does not start with '/'
+    pointer_invalid_escape = 108, ///< a JSON Pointer contains an escape other than ~0 and ~1
+    pointer_index_not_a_number = 109, ///< a JSON Pointer array index is not a number
+    unexpected_end_of_input = 110, ///< a binary input ends early, or has bytes left at its end
+    unexpected_byte = 112, ///< a binary input contains an unexpected byte or invalid length
+    invalid_string_or_size = 113, ///< a binary input contains an invalid string or size specification
+    bson_unsupported_type = 114, ///< a BSON record type is not supported
+    invalid_high_precision_number = 115, ///< a UBJSON/BJData high-precision number cannot be parsed
+    // invalid_iterator
+    iterators_incompatible = 201, ///< the iterators of a range belong to different values
+    iterator_from_other_value = 202, ///< an iterator does not belong to the value it is used with
+    iterator_range_from_other_value = 203, ///< an iterator range does not belong to the value it is used with
+    iterator_range_out_of_range = 204, ///< an iterator range of a primitive value is not [begin, end)
+    iterator_out_of_range = 205, ///< an iterator of a primitive value is not begin()
+    iterator_range_of_null = 206, ///< an iterator range belongs to a null value
+    iterator_key_not_object = 207, ///< key() is called on an iterator of a non-object
+    iterator_subscript_on_object = 208, ///< operator[] is called on an iterator of an object
+    iterator_arithmetic_on_object = 209, ///< an offset operator is used on an iterator of an object
+    insert_range_incompatible = 210, ///< the iterators of an inserted range belong to different values
+    insert_range_into_itself = 211, ///< an inserted range belongs to the value it is inserted into
+    iterators_compare_different_values = 212, ///< iterators of different values are compared
+    iterator_order_on_object = 213, ///< iterators of an object are compared by order
+    iterator_value_unavailable = 214, ///< an iterator does not refer to a value
+    // type_error
+    object_from_non_pairs = 301, ///< an object is created from an initializer list that is not a list of pairs
+    type_mismatch = 302, ///< a value has the wrong type for a conversion
+    incompatible_reference_type = 303, ///< get_ref() is called with a reference type that does not match the value
+    at_wrong_type = 304, ///< at() is called on a value of the wrong type
+    subscript_wrong_type = 305, ///< operator[] is called on a value of the wrong type
+    value_wrong_type = 306, ///< value() is called on a value of the wrong type
+    erase_wrong_type = 307, ///< erase() is called on a value of the wrong type
+    push_back_wrong_type = 308, ///< push_back() or operator+= is called on a value of the wrong type
+    insert_wrong_type = 309, ///< insert() is called on a value of the wrong type
+    swap_wrong_type = 310, ///< swap() is called on a value of the wrong type
+    emplace_wrong_type = 311, ///< emplace() or emplace_back() is called on a value of the wrong type
+    update_wrong_type = 312, ///< update() is called on a value of the wrong type
+    unflatten_invalid_value = 313, ///< unflatten() finds conflicting paths
+    unflatten_not_object = 314, ///< unflatten() is called on a non-object
+    unflatten_value_not_primitive = 315, ///< unflatten() is called on an object with non-primitive values
+    invalid_utf8 = 316, ///< dump() finds a string that is not valid UTF-8
+    type_not_serializable = 317, ///< a value cannot be serialized to the requested binary format
+    enum_key_duplicate = 318, ///< an enum-keyed map has two keys that serialize to the same string
+    discarded_value_used = 321, ///< a discarded value is used
+    // out_of_range
+    array_index_out_of_range = 401, ///< an array index is out of range
+    pointer_past_the_end_index = 402, ///< a JSON Pointer uses the array index '-'
+    key_not_found = 403, ///< an object key is not found
+    pointer_unresolved = 404, ///< a JSON Pointer reference token cannot be resolved
+    patch_on_root = 405, ///< the root of a value has no parent, e.g. for a JSON Patch 'remove' or 'add' at the root
+    number_overflow = 406, ///< a number cannot be stored without overflowing to NaN or INF
+    integer_too_large = 407, ///< an integer cannot be represented in the binary format
+    container_too_large = 408, ///< the size of a container in a binary input exceeds the maximal capacity
+    bson_key_with_null = 409, ///< a BSON key contains U+0000
+    value_out_of_range = 410, ///< an enum value is undefined, or a JSON Pointer array index exceeds size_type
+    patch_add_parent_not_container = 411, ///< the parent of a JSON Patch 'add' target is not a container
+    length_too_large = 412, ///< a length does not fit into the length field of a binary format
+    patch_remove_parent_not_container = 413, ///< the parent of a JSON Patch 'remove' target is not a container
+    patch_move_into_child = 414, ///< a JSON Patch 'move' moves a value into one of its children
+    subtype_out_of_range = 415, ///< a binary subtype does not fit into one byte
+    // other_error
+    internal_error = 500, ///< unreachable code was reached
+    patch_test_failed = 501, ///< a JSON Patch 'test' operation failed
+    size_marker_required = 502  ///< UBJSON/BJData output with type markers requires size markers
+};
+
 /// @brief general exception of the @ref basic_json class
 /// @sa https://json.nlohmann.me/api/basic_json/exception/
 class exception : public std::exception
@@ -195,6 +273,18 @@ class parse_error : public exception
         return {id_, byte_, w.c_str()};
     }
 
+    template<typename BasicJsonContext, enable_if_t<is_basic_json_context<BasicJsonContext>::value, int> = 0>
+    static parse_error create(exception_id id_, const position_t& pos, const std::string& what_arg, BasicJsonContext context)
+    {
+        return create(static_cast<int>(id_), pos, what_arg, context);
+    }
+
+    template<typename BasicJsonContext, enable_if_t<is_basic_json_context<BasicJsonContext>::value, int> = 0>
+    static parse_error create(exception_id id_, std::size_t byte_, const std::string& what_arg, BasicJsonContext context)
+    {
+        return create(static_cast<int>(id_), byte_, what_arg, context);
+    }
+
     /*!
     @brief byte index of the parse error
 
@@ -229,6 +319,12 @@ class invalid_iterator : public exception
         return {id_, w.c_str()};
     }
 
+    template<typename BasicJsonContext, enable_if_t<is_basic_json_context<BasicJsonContext>::value, int> = 0>
+    static invalid_iterator create(exception_id id_, const std::string& what_arg, BasicJsonContext context)
+    {
+        return create(static_cast<int>(id_), what_arg, context);
+    }
+
   private:
     JSON_HEDLEY_NON_NULL(3)
     invalid_iterator(int id_, const char* what_arg)
@@ -247,6 +343,12 @@ class type_error : public exception
         return {id_, w.c_str()};
     }
 
+    template<typename BasicJsonContext, enable_if_t<is_basic_json_context<BasicJsonContext>::value, int> = 0>
+    static type_error create(exception_id id_, const std::string& what_arg, BasicJsonContext context)
+    {
+        return create(static_cast<int>(id_), what_arg, context);
+    }
+
   private:
     JSON_HEDLEY_NON_NULL(3)
     type_error(int id_, const char* what_arg) : exception(id_, what_arg) {}
@@ -264,6 +366,12 @@ class out_of_range : public exception
         return {id_, w.c_str()};
     }
 
+    template<typename BasicJsonContext, enable_if_t<is_basic_json_context<BasicJsonContext>::value, int> = 0>
+    static out_of_range create(exception_id id_, const std::string& what_arg, BasicJsonContext context)
+    {
+        return create(static_cast<int>(id_), what_arg, context);
+    }
+
   private:
     JSON_HEDLEY_NON_NULL(3)
     out_of_range(int id_, const char* what_arg) : exception(id_, what_arg) {}
@@ -281,6 +389,12 @@ class other_error : public exception
         return {id_, w.c_str()};
     }
 
+    template<typename BasicJsonContext, enable_if_t<is_basic_json_context<BasicJsonContext>::value, int> = 0>
+    static other_error create(exception_id id_, const std::string& what_arg, BasicJsonContext context)
+    {
+        return create(static_cast<int>(id_), what_arg, context);
+    }
+
   private:
     JSON_HEDLEY_NON_NULL(3)
     other_error(int id_, const char* what_arg) : exception(id_, what_arg) {}
@@ -307,6 +421,36 @@ void templated_json_throw(ExceptionType exception)
     (void)exception;
 }
 
+/*!
+@brief throws because @a j does not have the type a conversion expects
+@param[in] expected  the expected type(s), e.g. "array" or "binary or array"
+@param[in] j         the value with the wrong type
+@throw type_error.302 always
+*/
+template<typename BasicJsonType>
+JSON_HEDLEY_NO_RETURN inline void throw_type_must_be(const char* expected, const BasicJsonType& j)
+{
+    static_cast<void>(expected); // unused when JSON_NOEXCEPTION is defined
+    static_cast<void>(j);
+    JSON_THROW(type_error::create(exception_id::type_mismatch, concat("type must be ", expected, ", but is ", j.type_name()), &j));
+}
+
+/*!
+@brief throws because an operation is not supported for the type of @a j
+@param[in] id_        the id of the type_error exception (at_wrong_type..update_wrong_type)
+@param[in] operation  the operation, e.g. "erase()"
+@param[in] j          the value the operation was called on
+@throw type_error always
+*/
+template<typename BasicJsonType>
+JSON_HEDLEY_NO_RETURN inline void throw_cannot_use_with(const exception_id id_, const char* operation, const BasicJsonType& j)
+{
+    static_cast<void>(id_); // unused when JSON_NOEXCEPTION is defined
+    static_cast<void>(operation);
+    static_cast<void>(j);
+    JSON_THROW(type_error::create(id_, concat("cannot use ", operation, " with ", j.type_name()), &j));
+}
+
 }  // namespace detail
 NLOHMANN_JSON_NAMESPACE_END
 

include/nlohmann/detail/input/input_adapters.hpp

@@ -581,7 +581,7 @@ class wide_string_input_adapter
     template<class T>
     JSON_HEDLEY_NO_RETURN std::size_t get_elements(T* /*dest*/, std::size_t /*count*/ = 1)
     {
-        JSON_THROW(parse_error::create(112, 1, "wide string type cannot be interpreted as binary data", nullptr));
+        JSON_THROW(parse_error::create(exception_id::unexpected_byte, 1, "wide string type cannot be interpreted as binary data", nullptr));
     }
 
   private:
@@ -793,7 +793,7 @@ inline file_input_adapter input_adapter(std::FILE* file)
 {
     if (file == nullptr)
     {
-        JSON_THROW(parse_error::create(101, 0, "attempting to parse an empty input; check that your input string or stream contains the expected JSON", nullptr));
+        JSON_THROW(parse_error::create(exception_id::syntax_error, 0, "attempting to parse an empty input; check that your input string or stream contains the expected JSON", nullptr));
     }
     return file_input_adapter(file);
 }
@@ -802,7 +802,7 @@ inline input_stream_adapter input_adapter(std::istream& stream)
 {
     if (stream.rdbuf() == nullptr)
     {
-        JSON_THROW(parse_error::create(101, 0, "attempting to parse an empty input; check that your input string or stream contains the expected JSON", nullptr));
+        JSON_THROW(parse_error::create(exception_id::syntax_error, 0, "attempting to parse an empty input; check that your input string or stream contains the expected JSON", nullptr));
     }
     return input_stream_adapter(stream);
 }
@@ -827,7 +827,7 @@ contiguous_bytes_input_adapter input_adapter(CharT b)
 {
     if (b == nullptr)
     {
-        JSON_THROW(parse_error::create(101, 0, "attempting to parse an empty input; check that your input string or stream contains the expected JSON", nullptr));
+        JSON_THROW(parse_error::create(exception_id::syntax_error, 0, "attempting to parse an empty input; check that your input string or stream contains the expected JSON", nullptr));
     }
     auto length = std::strlen(reinterpret_cast<const char*>(b));
     const auto* ptr = reinterpret_cast<const char*>(b);

include/nlohmann/detail/input/json_sax.hpp

@@ -132,9 +132,7 @@ struct json_sax
     @param[in] position    the position in the input where the error occurs
     @param[in] last_token  the last read token
     @param[in] ex          an exception object describing the error
-    @return whether to recover from the error: false stops parsing; true
-            repairs the error and continues, or, if that is not possible,
-            stops after completing the value read so far
+    @return whether parsing should proceed (must return false)
     */
     virtual bool parse_error(std::size_t position,
                              const std::string& last_token,
@@ -178,6 +176,27 @@ template<typename ArrayType>
 inline void reserve_array(ArrayType& /*arr*/, std::size_t /*len*/, priority_tag<0> /*unused*/)
 {}
 
+/*!
+@brief reports an object or array whose announced size exceeds max_size()
+
+Shared by json_sax_dom_parser and json_sax_dom_callback_parser.
+
+@param[in] sax   the SAX parser to report the error to
+@param[in] len   the number of elements announced by the input, or unknown_size()
+@param[in] kind  "object" or "array"
+@param[in] ref   the object or array that was just created
+@return whether parsing should continue (false after reporting out_of_range.408)
+*/
+template<typename SAX, typename BasicJsonType>
+bool check_container_size(SAX& sax, std::size_t len, const char* kind, BasicJsonType* ref)
+{
+    if (JSON_HEDLEY_UNLIKELY(len != detail::unknown_size() && len > ref->max_size()))
+    {
+        return sax.parse_error(0, "", out_of_range::create(exception_id::container_too_large, concat("excessive ", kind, " size: ", std::to_string(len)), ref));
+    }
+    return true;
+}
+
 #if JSON_DIAGNOSTIC_POSITIONS
 /*!
 @brief set the diagnostic positions of a value the DOM SAX parsers just stored
@@ -187,6 +206,35 @@ befriends this struct, as the position members are private.
 */
 struct diagnostic_positions
 {
+    /*!
+    @param[in,out] v  the object or array whose opening brace or bracket was just read
+    @param[in] lexer  the lexer that read it, or nullptr to leave @a v alone
+    */
+    template<typename BasicJsonType, typename LexerType>
+    static void set_container_start(BasicJsonType& v, LexerType* lexer)
+    {
+        if (lexer)
+        {
+            // Lexer has read the first character of the container, so
+            // subtract 1 from the position to get the correct start position.
+            v.start_position = lexer->get_position() - 1;
+        }
+    }
+
+    /*!
+    @param[in,out] v  the object or array whose closing brace or bracket was just read
+    @param[in] lexer  the lexer that read it, or nullptr to leave @a v alone
+    */
+    template<typename BasicJsonType, typename LexerType>
+    static void set_container_end(BasicJsonType& v, LexerType* lexer)
+    {
+        if (lexer)
+        {
+            // Lexer's position is past the closing brace or bracket, so set that as the end position.
+            v.end_position = lexer->get_position();
+        }
+    }
+
     /*!
     @param[in,out] v  the value that was just parsed
     @param[in] lexer  the lexer that read it, or nullptr to leave @a v alone
@@ -271,12 +319,9 @@ a pointer to the respective array or object for each recursion depth.
 After successful parsing, the value that is passed by reference to the
 constructor contains the parsed value.
 
-@tparam BasicJsonType     the JSON type
-@tparam InputAdapterType  the input adapter of the lexer that can be passed to
-                          the constructor to record diagnostic positions; it
-                          does not matter if no lexer is passed
+@tparam BasicJsonType  the JSON type
 */
-template<typename BasicJsonType, typename InputAdapterType = string_input_adapter_type>
+template<typename BasicJsonType, typename InputAdapterType>
 class json_sax_dom_parser
 {
   public:
@@ -354,22 +399,11 @@ class json_sax_dom_parser
         ref_stack.push_back(handle_value(BasicJsonType::value_t::object));
 
 #if JSON_DIAGNOSTIC_POSITIONS
-        // Manually set the start position of the object here.
         // Ensure this is after the call to handle_value to ensure correct start position.
-        if (m_lexer_ref)
-        {
-            // Lexer has read the first character of the object, so
-            // subtract 1 from the position to get the correct start position.
-            ref_stack.back()->start_position = m_lexer_ref->get_position() - 1;
-        }
+        diagnostic_positions::set_container_start(*ref_stack.back(), m_lexer_ref);
 #endif
 
-        if (JSON_HEDLEY_UNLIKELY(len != detail::unknown_size() && len > ref_stack.back()->max_size()))
-        {
-            return parse_error(0, "", out_of_range::create(408, concat("excessive object size: ", std::to_string(len)), ref_stack.back()));
-        }
-
-        return true;
+        return check_container_size(*this, len, "object", ref_stack.back());
     }
 
     bool key(string_t& val)
@@ -388,11 +422,7 @@ class json_sax_dom_parser
         JSON_ASSERT(ref_stack.back()->is_object());
 
 #if JSON_DIAGNOSTIC_POSITIONS
-        if (m_lexer_ref)
-        {
-            // Lexer's position is past the closing brace, so set that as the end position.
-            ref_stack.back()->end_position = m_lexer_ref->get_position();
-        }
+        diagnostic_positions::set_container_end(*ref_stack.back(), m_lexer_ref);
 #endif
 
         ref_stack.back()->set_parents();
@@ -405,17 +435,13 @@ class json_sax_dom_parser
         ref_stack.push_back(handle_value(BasicJsonType::value_t::array));
 
 #if JSON_DIAGNOSTIC_POSITIONS
-        // Manually set the start position of the array here.
         // Ensure this is after the call to handle_value to ensure correct start position.
-        if (m_lexer_ref)
-        {
-            ref_stack.back()->start_position = m_lexer_ref->get_position() - 1;
-        }
+        diagnostic_positions::set_container_start(*ref_stack.back(), m_lexer_ref);
 #endif
 
-        if (JSON_HEDLEY_UNLIKELY(len != detail::unknown_size() && len > ref_stack.back()->max_size()))
+        if (JSON_HEDLEY_UNLIKELY(!check_container_size(*this, len, "array", ref_stack.back())))
         {
-            return parse_error(0, "", out_of_range::create(408, concat("excessive array size: ", std::to_string(len)), ref_stack.back()));
+            return false;
         }
 
         if (len != detail::unknown_size())
@@ -432,11 +458,7 @@ class json_sax_dom_parser
         JSON_ASSERT(ref_stack.back()->is_array());
 
 #if JSON_DIAGNOSTIC_POSITIONS
-        if (m_lexer_ref)
-        {
-            // Lexer's position is past the closing bracket, so set that as the end position.
-            ref_stack.back()->end_position = m_lexer_ref->get_position();
-        }
+        diagnostic_positions::set_container_end(*ref_stack.back(), m_lexer_ref);
 #endif
 
         ref_stack.back()->set_parents();
@@ -523,7 +545,7 @@ class json_sax_dom_parser
     lexer_t* m_lexer_ref = nullptr;
 };
 
-template<typename BasicJsonType, typename InputAdapterType = string_input_adapter_type>
+template<typename BasicJsonType, typename InputAdapterType>
 class json_sax_dom_callback_parser
 {
   public:
@@ -616,21 +638,11 @@ class json_sax_dom_callback_parser
         {
 
 #if JSON_DIAGNOSTIC_POSITIONS
-            // Manually set the start position of the object here.
             // Ensure this is after the call to handle_value to ensure correct start position.
-            if (m_lexer_ref)
-            {
-                // Lexer has read the first character of the object, so
-                // subtract 1 from the position to get the correct start position.
-                ref_stack.back()->start_position = m_lexer_ref->get_position() - 1;
-            }
+            diagnostic_positions::set_container_start(*ref_stack.back(), m_lexer_ref);
 #endif
 
-            // check object limit
-            if (JSON_HEDLEY_UNLIKELY(len != detail::unknown_size() && len > ref_stack.back()->max_size()))
-            {
-                return parse_error(0, "", out_of_range::create(408, concat("excessive object size: ", std::to_string(len)), ref_stack.back()));
-            }
+            return check_container_size(*this, len, "object", ref_stack.back());
         }
         return true;
     }
@@ -700,11 +712,7 @@ class json_sax_dom_callback_parser
             {
 
 #if JSON_DIAGNOSTIC_POSITIONS
-                if (m_lexer_ref)
-                {
-                    // Lexer's position is past the closing brace, so set that as the end position.
-                    ref_stack.back()->end_position = m_lexer_ref->get_position();
-                }
+                diagnostic_positions::set_container_end(*ref_stack.back(), m_lexer_ref);
 #endif
 
                 ref_stack.back()->set_parents();
@@ -715,13 +723,7 @@ class json_sax_dom_callback_parser
             }
         }
 
-        JSON_ASSERT(!ref_stack.empty());
-        JSON_ASSERT(!keep_stack.empty());
-        JSON_ASSERT(!container_key_stack.empty());
-        ref_stack.pop_back();
-        keep_stack.pop_back();
-        const string_t object_key = std::move(container_key_stack.back());
-        container_key_stack.pop_back();
+        const string_t object_key = pop_container();
 
         if (!ref_stack.empty() && ref_stack.back() && ref_stack.back()->is_structured())
         {
@@ -747,20 +749,13 @@ class json_sax_dom_callback_parser
         {
 
 #if JSON_DIAGNOSTIC_POSITIONS
-            // Manually set the start position of the array here.
             // Ensure this is after the call to handle_value to ensure correct start position.
-            if (m_lexer_ref)
-            {
-                // Lexer has read the first character of the array, so
-                // subtract 1 from the position to get the correct start position.
-                ref_stack.back()->start_position = m_lexer_ref->get_position() - 1;
-            }
+            diagnostic_positions::set_container_start(*ref_stack.back(), m_lexer_ref);
 #endif
 
-            // check array limit
-            if (JSON_HEDLEY_UNLIKELY(len != detail::unknown_size() && len > ref_stack.back()->max_size()))
+            if (JSON_HEDLEY_UNLIKELY(!check_container_size(*this, len, "array", ref_stack.back())))
             {
-                return parse_error(0, "", out_of_range::create(408, concat("excessive array size: ", std::to_string(len)), ref_stack.back()));
+                return false;
             }
 
             if (len != detail::unknown_size())
@@ -784,11 +779,7 @@ class json_sax_dom_callback_parser
             {
 
 #if JSON_DIAGNOSTIC_POSITIONS
-                if (m_lexer_ref)
-                {
-                    // Lexer's position is past the closing bracket, so set that as the end position.
-                    ref_stack.back()->end_position = m_lexer_ref->get_position();
-                }
+                diagnostic_positions::set_container_end(*ref_stack.back(), m_lexer_ref);
 #endif
 
                 ref_stack.back()->set_parents();
@@ -814,13 +805,7 @@ class json_sax_dom_callback_parser
             }
         }
 
-        JSON_ASSERT(!ref_stack.empty());
-        JSON_ASSERT(!keep_stack.empty());
-        JSON_ASSERT(!container_key_stack.empty());
-        ref_stack.pop_back();
-        keep_stack.pop_back();
-        const string_t object_key = std::move(container_key_stack.back());
-        container_key_stack.pop_back();
+        const string_t object_key = pop_container();
 
         // remove discarded value
         if (!ref_stack.empty() && ref_stack.back())
@@ -907,6 +892,23 @@ class json_sax_dom_callback_parser
         return string_t{};
     }
 
+    /*!
+    @brief leave the object or array that end_object()/end_array() just closed
+    @return the key the container is stored under in its parent (see
+            container_key_stack)
+    */
+    string_t pop_container()
+    {
+        JSON_ASSERT(!ref_stack.empty());
+        JSON_ASSERT(!keep_stack.empty());
+        JSON_ASSERT(!container_key_stack.empty());
+        ref_stack.pop_back();
+        keep_stack.pop_back();
+        string_t object_key = std::move(container_key_stack.back());
+        container_key_stack.pop_back();
+        return object_key;
+    }
+
     /*!
     @brief remove the discarded value the callback rejected from its parent,
     unless it is a duplicate key's slot with a stashed previous value, in

include/nlohmann/detail/input/lexer.hpp

@@ -10,7 +10,7 @@
 
 #include <array> // array
 #include <cstddef> // size_t
-#include <cstdint> // uint8_t, uint32_t
+#include <cstdint> // uint32_t
 #include <cstdio> // snprintf
 #include <initializer_list> // initializer_list
 #include <string> // char_traits, string
@@ -439,16 +439,8 @@ class lexer : public lexer_base<BasicJsonType>
                             if (0xD800 <= codepoint1 && codepoint1 <= 0xDBFF)
                             {
                                 // expect next \uxxxx entry
-                                if (JSON_HEDLEY_LIKELY(get() == '\\'))
+                                if (JSON_HEDLEY_LIKELY(get() == '\\' && get() == 'u'))
                                 {
-                                    if (JSON_HEDLEY_UNLIKELY(get() != 'u'))
-                                    {
-                                        // current is the character escaped by the backslash
-                                        error_message = "invalid string: surrogate U+D800..U+DBFF must be followed by U+DC00..U+DFFF";
-                                        string_error_resume = resume_kind::escaped_character;
-                                        return token_type::parse_error;
-                                    }
-
                                     const int codepoint2 = get_codepoint();
 
                                     if (JSON_HEDLEY_UNLIKELY(codepoint2 == -1))
@@ -473,11 +465,7 @@ class lexer : public lexer_base<BasicJsonType>
                                     }
                                     else
                                     {
-                                        // the second escape was read completely and is a
-                                        // code point of its own
                                         error_message = "invalid string: surrogate U+D800..U+DBFF must be followed by U+DC00..U+DFFF";
-                                        string_error_resume = resume_kind::after_escape;
-                                        string_error_codepoint = codepoint2;
                                         return token_type::parse_error;
                                     }
                                 }
@@ -491,9 +479,7 @@ class lexer : public lexer_base<BasicJsonType>
                             {
                                 if (JSON_HEDLEY_UNLIKELY(0xDC00 <= codepoint1 && codepoint1 <= 0xDFFF))
                                 {
-                                    // the escape was read completely
                                     error_message = "invalid string: surrogate U+DC00..U+DFFF must follow U+D800..U+DBFF";
-                                    string_error_resume = resume_kind::after_escape;
                                     return token_type::parse_error;
                                 }
                             }
@@ -2147,574 +2133,6 @@ scan_number_done:
         }
     }
 
-  public:
-    /////////////////////
-    // error recovery
-    /////////////////////
-
-    /*!
-    @brief make the best of the token that scan() rejected
-
-    Called by the parser after scan() returned token_type::parse_error and the
-    SAX parser asked to recover from the error (see #3989). Keeps what can be
-    read of the token and skips the rest:
-
-    - A string keeps its characters. An unknown escape stands for the escaped
-      character itself (as in JavaScript), an invalid Unicode escape and ill-formed
-      UTF-8 become U+FFFD, and a control character is kept. A line break or the
-      end of the input ends a string that lacks its closing quote.
-    - A number keeps its longest valid prefix, e.g. `1` for `1.` or `1e+`.
-    - A block comment that is not closed runs to the end of the input.
-    - Anything else is skipped.
-
-    The rest of an invalid token is skipped up to the next delimiter
-    (whitespace, a structural character, or a quote). A delimiter that the
-    invalid token consumed is returned to the input, so that the next scan()
-    reads it.
-
-    @return token_type::value_string or a number token type if a string or a
-            number could be read, token_type::end_of_input for a block comment
-            that is not closed, token_type::uninitialized otherwise
-    */
-    token_type recover_token()
-    {
-        const resume_kind resume = string_error_resume;
-        const int codepoint = string_error_codepoint;
-        string_error_resume = resume_kind::character;
-        string_error_codepoint = -1;
-
-        if (error_message_starts_with("invalid string"))
-        {
-            return recover_string(resume, codepoint);
-        }
-
-        if (error_message_starts_with("invalid number"))
-        {
-            return recover_number();
-        }
-
-        if (error_message_starts_with("invalid comment; missing"))
-        {
-            // the comment runs to the end of the input
-            return token_type::end_of_input;
-        }
-
-        skip_to_delimiter();
-        return token_type::uninitialized;
-    }
-
-    /*!
-    @brief return the token that scan() read last to the input, so that the
-           next scan() reads it again
-
-    Called by the parser when recovering from an error. The token must be a
-    single character (',', ':', '[', ']', '{', or '}') or the end of the
-    input, and scan() must have read it last.
-    */
-    void unget_token()
-    {
-        JSON_ASSERT(!next_unget);
-        unget();
-    }
-
-    /*!
-    @brief let the token string for the next error begin at the current character
-
-    The token string of an error reaches back to the beginning of the last
-    string or number. After an error, the parser calls this function so that
-    the next error does not report (and, with many errors, copy) everything
-    read since then.
-    */
-    void restart_token_string()
-    {
-        restart_token_string_impl(std::integral_constant<bool, lazy_token_string> {});
-    }
-
-  private:
-    /// how recover_string() continues after the error scan_string() reported
-    enum class resume_kind : std::uint8_t
-    {
-        /// current is the next character of the string (or the end of input)
-        character,
-        /// current is the character escaped by the preceding backslash
-        escaped_character,
-        /// current is the last character of a complete escape
-        after_escape
-    };
-
-    /// whether error_message begins with @a prefix
-    bool error_message_starts_with(const char* prefix) const noexcept
-    {
-        const char* message = error_message;
-        while (*prefix != '\0')
-        {
-            if (*message++ != *prefix++)
-            {
-                return false;
-            }
-        }
-        return true;
-    }
-
-    /// whether current ends an invalid token (see recover_token())
-    bool current_is_delimiter() const noexcept
-    {
-        switch (current)
-        {
-            case ' ':
-            case '\t':
-            case '\n':
-            case '\r':
-            case '[':
-            case ']':
-            case '{':
-            case '}':
-            case ',':
-            case ':':
-            case '\"':
-#if !JSON_STRICT_NUL_HANDLING
-            case '\0':
-#endif
-            case char_traits<char_type>::eof():
-                return true;
-
-            case '/':
-                return ignore_comments;
-
-            default:
-                return false;
-        }
-    }
-
-    /// skip the rest of an invalid token and return its delimiter to the input
-    void skip_to_delimiter()
-    {
-        while (!current_is_delimiter())
-        {
-            get();
-        }
-
-        if (current != char_traits<char_type>::eof())
-        {
-            unget();
-        }
-    }
-
-    /// append U+FFFD REPLACEMENT CHARACTER to token_buffer
-    void add_replacement_character()
-    {
-        add(0xEF);
-        add(0xBF);
-        add(0xBD);
-    }
-
-    /// append the UTF-8 encoding of @a codepoint (not a surrogate) to token_buffer
-    void add_codepoint(const int codepoint)
-    {
-        JSON_ASSERT(0x00 <= codepoint && codepoint <= 0x10FFFF);
-        const auto cp = static_cast<unsigned int>(codepoint);
-        if (cp < 0x80)
-        {
-            add(static_cast<char_int_type>(cp));
-        }
-        else if (cp <= 0x7FF)
-        {
-            add(static_cast<char_int_type>(0xC0u | (cp >> 6u)));
-            add(static_cast<char_int_type>(0x80u | (cp & 0x3Fu)));
-        }
-        else if (cp <= 0xFFFF)
-        {
-            add(static_cast<char_int_type>(0xE0u | (cp >> 12u)));
-            add(static_cast<char_int_type>(0x80u | ((cp >> 6u) & 0x3Fu)));
-            add(static_cast<char_int_type>(0x80u | (cp & 0x3Fu)));
-        }
-        else
-        {
-            add(static_cast<char_int_type>(0xF0u | (cp >> 18u)));
-            add(static_cast<char_int_type>(0x80u | ((cp >> 12u) & 0x3Fu)));
-            add(static_cast<char_int_type>(0x80u | ((cp >> 6u) & 0x3Fu)));
-            add(static_cast<char_int_type>(0x80u | (cp & 0x3Fu)));
-        }
-    }
-
-    /// append a code point read from a Unicode escape; a surrogate becomes U+FFFD
-    void add_escaped_codepoint(const int codepoint)
-    {
-        if (0xD800 <= codepoint && codepoint <= 0xDFFF)
-        {
-            add_replacement_character();
-        }
-        else
-        {
-            add_codepoint(codepoint);
-        }
-    }
-
-    /*!
-    @brief remove an incomplete UTF-8 sequence from the end of token_buffer
-
-    next_byte_in_range() adds the bytes of a sequence as it checks them, so
-    when it rejects a byte, the beginning of the sequence is already in
-    token_buffer, which otherwise holds only complete sequences.
-
-    @return whether an incomplete sequence was removed
-    */
-    bool remove_incomplete_utf8_sequence()
-    {
-        std::size_t lead = token_buffer.size();
-        std::size_t continuation_bytes = 0;
-        while (lead > 0 && continuation_bytes < 3
-                && (static_cast<unsigned char>(token_buffer[lead - 1]) & 0xC0u) == 0x80u)
-        {
-            --lead;
-            ++continuation_bytes;
-        }
-        if (lead == 0)
-        {
-            return false;
-        }
-
-        const auto lead_byte = static_cast<unsigned char>(token_buffer[lead - 1]);
-        std::size_t expected = 0;
-        if (lead_byte >= 0xF0)
-        {
-            expected = 3;
-        }
-        else if (lead_byte >= 0xE0)
-        {
-            expected = 2;
-        }
-        else if (lead_byte >= 0xC0)
-        {
-            expected = 1;
-        }
-        if (continuation_bytes >= expected)
-        {
-            return false;
-        }
-
-        token_buffer.resize(lead - 1);
-        return true;
-    }
-
-    /*!
-    @brief read the UTF-8 sequence that begins with current, which is not ASCII
-    @return whether the next character must be read; false if current still
-            needs to be handled, because it does not belong to the sequence
-    */
-    bool recover_utf8_sequence()
-    {
-        // the number of continuation bytes and the range of the first one;
-        // see the ranges in scan_string()
-        std::size_t count = 0;
-        char_int_type low = 0x80;
-        char_int_type high = 0xBF;
-        if (current >= 0xC2 && current <= 0xDF)
-        {
-            count = 1;
-        }
-        else if (current >= 0xE0 && current <= 0xEF)
-        {
-            count = 2;
-            low = (current == 0xE0) ? 0xA0 : 0x80;
-            high = (current == 0xED) ? 0x9F : 0xBF;
-        }
-        else if (current >= 0xF0 && current <= 0xF4)
-        {
-            count = 3;
-            low = (current == 0xF0) ? 0x90 : 0x80;
-            high = (current == 0xF4) ? 0x8F : 0xBF;
-        }
-        else
-        {
-            // an ill-formed byte
-            add_replacement_character();
-            return true;
-        }
-
-        const std::size_t start = token_buffer.size();
-        add(current);
-        for (std::size_t i = 0; i < count; ++i)
-        {
-            get();
-            if (current < low || current > high)
-            {
-                token_buffer.resize(start);
-                add_replacement_character();
-                return false;
-            }
-            add(current);
-            low = 0x80;
-            high = 0xBF;
-        }
-        return true;
-    }
-
-    /*!
-    @brief read the low surrogate that must follow the high surrogate @a high
-    @return whether the next character must be read; false if current still
-            needs to be handled
-    */
-    bool recover_low_surrogate(int high)
-    {
-        while (true)
-        {
-            if (get() != '\\')
-            {
-                add_replacement_character();
-                return false;
-            }
-            if (get() != 'u')
-            {
-                add_replacement_character();
-                // not 'u', so this does not come back here
-                return recover_escape();
-            }
-
-            const int low = get_codepoint();
-            if (low == -1)
-            {
-                add_replacement_character();
-                return false;
-            }
-            if (0xDC00 <= low && low <= 0xDFFF)
-            {
-                add_codepoint(static_cast<int>((static_cast<unsigned int>(high) << 10u)
-                                               + static_cast<unsigned int>(low) - 0x35FDC00u));
-                return true;
-            }
-
-            // high has no low surrogate
-            add_replacement_character();
-            if (low < 0xD800 || low > 0xDBFF)
-            {
-                add_codepoint(low);
-                return true;
-            }
-            // another high surrogate
-            high = low;
-        }
-    }
-
-    /*!
-    @brief read the escape whose backslash was read; current is the escaped character
-    @return whether the next character must be read; false if current still
-            needs to be handled
-    */
-    bool recover_escape()
-    {
-        switch (current)
-        {
-            case '\"':
-                add('\"');
-                return true;
-            case '\\':
-                add('\\');
-                return true;
-            case '/':
-                add('/');
-                return true;
-            case 'b':
-                add('\b');
-                return true;
-            case 'f':
-                add('\f');
-                return true;
-            case 'n':
-                add('\n');
-                return true;
-            case 'r':
-                add('\r');
-                return true;
-            case 't':
-                add('\t');
-                return true;
-
-            case 'u':
-            {
-                const int codepoint = get_codepoint();
-                if (codepoint == -1)
-                {
-                    add_replacement_character();
-                    return false;
-                }
-                if (0xD800 <= codepoint && codepoint <= 0xDBFF)
-                {
-                    return recover_low_surrogate(codepoint);
-                }
-                add_escaped_codepoint(codepoint);
-                return true;
-            }
-
-            // an unknown escape stands for the escaped character
-            default:
-                return false;
-        }
-    }
-
-    /*!
-    @brief read the rest of a string after scan_string() rejected it
-
-    token_buffer holds what scan_string() read before the error. See
-    recover_token() for how errors are repaired.
-
-    @param[in] resume     how to continue, see resume_kind
-    @param[in] codepoint  for a high surrogate followed by an escape of another
-                          code point: that code point; -1 otherwise
-    */
-    token_type recover_string(const resume_kind resume, const int codepoint)
-    {
-        // whether the next character must be read before it can be handled
-        bool fetch = false;
-
-        if (error_message_starts_with("invalid string: surrogate")
-                || error_message_starts_with("invalid string: '\\u'")
-                || (error_message_starts_with("invalid string: ill-formed UTF-8")
-                    && remove_incomplete_utf8_sequence()))
-        {
-            add_replacement_character();
-        }
-
-        switch (resume)
-        {
-            case resume_kind::escaped_character:
-                fetch = recover_escape();
-                break;
-            case resume_kind::after_escape:
-                if (0xD800 <= codepoint && codepoint <= 0xDBFF)
-                {
-                    fetch = recover_low_surrogate(codepoint);
-                }
-                else
-                {
-                    if (codepoint != -1)
-                    {
-                        add_escaped_codepoint(codepoint);
-                    }
-                    fetch = true;
-                }
-                break;
-            case resume_kind::character:
-            default:
-                break;
-        }
-
-        while (true)
-        {
-            if (fetch)
-            {
-                get();
-            }
-            fetch = true;
-
-            switch (current)
-            {
-                case '\"':
-                // a line break or the end of the input ends a string that
-                // lacks its closing quote
-                case '\n':
-                case '\r':
-                case char_traits<char_type>::eof():
-                    return token_type::value_string;
-
-#if !JSON_STRICT_NUL_HANDLING
-                case '\0':
-                    // the end of the input, see scan()
-                    unget();
-                    return token_type::value_string;
-#endif
-
-                case '\\':
-                    get();
-                    fetch = recover_escape();
-                    break;
-
-                default:
-                    if (current < 0x80)
-                    {
-                        // including control characters
-                        add(current);
-                    }
-                    else
-                    {
-                        fetch = recover_utf8_sequence();
-                    }
-                    break;
-            }
-        }
-    }
-
-    /*!
-    @brief keep the longest valid prefix of a number that scan_number() rejected
-
-    token_buffer holds the characters scan_number() accepted before the error,
-    so the prefix ends at its last digit.
-    */
-    token_type recover_number()
-    {
-        // only size(), operator[], and resize() are used, which every string
-        // type the library supports provides
-        std::size_t length = token_buffer.size();
-        while (length != 0 && (token_buffer[length - 1] < '0' || token_buffer[length - 1] > '9'))
-        {
-            --length;
-        }
-        token_buffer.resize(length);
-
-        if (length == 0)
-        {
-            skip_to_delimiter();
-            return token_type::uninitialized;
-        }
-
-        if (decimal_point_position >= length)
-        {
-            decimal_point_position = std::string::npos;
-        }
-
-        std::size_t exponent = std::string::npos;
-        for (std::size_t i = 0; i < length; ++i)
-        {
-            if (token_buffer[i] == 'e' || token_buffer[i] == 'E')
-            {
-                exponent = i;
-                break;
-            }
-        }
-        const std::size_t mantissa_end = (exponent == std::string::npos) ? length : exponent;
-        token_type number_type = token_type::value_unsigned;
-        if (decimal_point_position != std::string::npos || exponent != std::string::npos)
-        {
-            number_type = token_type::value_float;
-        }
-        else if (token_buffer[0] == '-')
-        {
-            number_type = token_type::value_integer;
-        }
-
-        const token_type result = convert_number(number_type, mantissa_end);
-        skip_to_delimiter();
-        return result;
-    }
-
-    /// seekable adapter: the token string begins at current, which was consumed
-    void restart_token_string_impl(std::true_type /*lazy*/) noexcept
-    {
-        const std::size_t consumed = ia.get_consumed_count();
-        token_string_start = (consumed > 0 && current != char_traits<char_type>::eof()) ? consumed - 1 : consumed;
-    }
-
-    /// streaming adapter: the token string begins at current; a character
-    /// that was put back is copied again when it is read again
-    void restart_token_string_impl(std::false_type /*lazy*/)
-    {
-        token_string.clear();
-        if (!next_unget && current != char_traits<char_type>::eof())
-        {
-            token_string.push_back(char_traits<char_type>::to_char_type(current));
-        }
-    }
-
     /// input adapter
     InputAdapterType ia;
 
@@ -2754,13 +2172,6 @@ scan_number_done:
     /// a description of occurred lexer errors
     const char* error_message = "";
 
-    /// how recover_token() continues a string that scan_string() rejected;
-    /// set only on the error paths that need more than error_message
-    resume_kind string_error_resume = resume_kind::character;
-    /// the code point of the second escape when a high surrogate is followed
-    /// by an escape that is not a low surrogate; -1 otherwise
-    int string_error_codepoint = -1;
-
     // number values
     number_integer_t value_integer = 0;
     number_unsigned_t value_unsigned = 0;

include/nlohmann/detail/input/parser.hpp

@@ -139,59 +139,24 @@ class parser
     bool accept(const bool strict = true)
     {
         json_sax_acceptor<BasicJsonType> sax_acceptor;
-        return sax_parse_impl<false>(&sax_acceptor, strict);
+        return sax_parse(&sax_acceptor, strict);
     }
 
-    /*!
-    @brief public SAX interface
-
-    If the SAX parser's parse_error() returns true, the parser recovers from
-    the error: it repairs the input and continues (see #3989).
-
-    @param[in] sax     the SAX parser
-    @param[in] strict  whether to expect the last token to be EOF
-    @return whether the input was parsed without errors and no SAX event
-            returned false
-    */
     template<typename SAX>
     JSON_HEDLEY_NON_NULL(2)
     bool sax_parse(SAX* sax, const bool strict = true)
-    {
-        return sax_parse_impl<true>(sax, strict);
-    }
-
-  private:
-    /// what sax_parse_internal() does after an object key was expected
-    enum class next_step : std::uint8_t
-    {
-        /// stop parsing
-        stop,
-        /// parse a value that begins with last_token
-        parse_value,
-        /// evaluate the state of the innermost container, which reads
-        /// last_token again
-        evaluate_state
-    };
-
-    template<bool AllowRecovery, typename SAX>
-    JSON_HEDLEY_NON_NULL(2)
-    bool sax_parse_impl(SAX* sax, const bool strict)
     {
         (void)detail::is_sax_static_asserts<SAX, BasicJsonType> {};
-        const bool result = sax_parse_internal<AllowRecovery>(sax);
+        const bool result = sax_parse_internal(sax);
 
         if (result)
         {
             if (strict)
             {
-                // strict mode: next byte must be EOF; after recovering from an
-                // error, the end of the input may already have been read
-                if (last_token != token_type::end_of_input && get_token() != token_type::end_of_input)
+                // strict mode: next byte must be EOF
+                if (get_token() != token_type::end_of_input)
                 {
-                    // the value is complete, so there is nothing to recover
-                    static_cast<void>(report_error(sax, parse_error::create(101, m_lexer.get_position(), exception_message(token_type::end_of_input, "value"), nullptr),
-                                                   std::integral_constant<bool, AllowRecovery> {}));
-                    return false;
+                    return syntax_error(*sax, exception_message(token_type::end_of_input, "value"));
                 }
             }
             else
@@ -202,9 +167,10 @@ class parser
             }
         }
 
-        return result && !error_reported;
+        return result;
     }
 
+  private:
     /*!
     @brief run a DOM SAX parser to completion and position the lexer
 
@@ -222,17 +188,14 @@ class parser
     template<typename DomSax>
     bool parse_dom(DomSax& sdp, const bool strict)
     {
-        sax_parse_internal<false>(&sdp);
+        sax_parse_internal(&sdp);
 
         if (strict)
         {
             // in strict mode, input must be completely read
             if (get_token() != token_type::end_of_input)
             {
-                sdp.parse_error(m_lexer.get_position(),
-                                m_lexer.get_token_string(),
-                                parse_error::create(101, m_lexer.get_position(),
-                                                    exception_message(token_type::end_of_input, "value"), nullptr));
+                syntax_error(sdp, exception_message(token_type::end_of_input, "value"));
             }
         }
         else
@@ -245,20 +208,10 @@ class parser
         return !sdp.is_errored();
     }
 
-    /*!
-    @brief parse a JSON value and pass it to a SAX parser
-
-    @tparam AllowRecovery  whether to recover from an error if the SAX parser's
-                           parse_error() returns true; false for the SAX parsers
-                           of parse() and accept(), which never do, so that no
-                           code for recovering is generated for them
-    */
-    template<bool AllowRecovery, typename SAX>
+    template<typename SAX>
     JSON_HEDLEY_NON_NULL(2)
     bool sax_parse_internal(SAX* sax)
     {
-        const std::integral_constant<bool, AllowRecovery> allow_recovery{};
-
         // stack to remember the hierarchy of structured values we are parsing
         // true = array; false = object
         std::vector<bool> states;
@@ -289,18 +242,10 @@ class parser
                             break;
                         }
 
-                        // remember we are now inside an object
-                        states.push_back(false);
-
-                        // parse key (the steps of parse_key(), which are
-                        // repeated here and below for speed)
+                        // parse key
                         if (JSON_HEDLEY_UNLIKELY(last_token != token_type::value_string))
                         {
-                            if (!continue_after(key_error(sax, allow_recovery, false), skip_to_state_evaluation))
-                            {
-                                return false;
-                            }
-                            continue;
+                            return syntax_error(*sax, exception_message(token_type::value_string, "object key"));
                         }
                         if (JSON_HEDLEY_UNLIKELY(!sax->key(m_lexer.get_string())))
                         {
@@ -310,13 +255,12 @@ class parser
                         // parse separator (:)
                         if (JSON_HEDLEY_UNLIKELY(!get_token_expecting(token_type::name_separator)))
                         {
-                            if (!continue_after(key_error(sax, allow_recovery, true), skip_to_state_evaluation))
-                            {
-                                return false;
-                            }
-                            continue;
+                            return syntax_error(*sax, exception_message(token_type::name_separator, "object separator"));
                         }
 
+                        // remember we are now inside an object
+                        states.push_back(false);
+
                         // parse values
                         get_token();
                         continue;
@@ -352,11 +296,9 @@ class parser
 
                         if (JSON_HEDLEY_UNLIKELY(!std::isfinite(res)))
                         {
-                            if (!overflow_error(sax, res, allow_recovery))
-                            {
-                                return false;
-                            }
-                            break;
+                            return sax->parse_error(m_lexer.get_position(),
+                                                    m_lexer.get_token_string(),
+                                                    out_of_range::create(exception_id::number_overflow, concat("number overflow parsing '", m_lexer.get_token_string(), '\''), nullptr));
                         }
 
                         if (JSON_HEDLEY_UNLIKELY(!sax->number_float(res, m_lexer.get_string())))
@@ -424,63 +366,16 @@ class parser
                     case token_type::parse_error:
                     {
                         // using "uninitialized" to avoid an "expected" message
-                        if (!report_error(sax, parse_error::create(101, m_lexer.get_position(), exception_message(token_type::uninitialized, "value"), nullptr), allow_recovery))
-                        {
-                            return false;
-                        }
-
-                        // recover: keep what can be read of the token
-                        recover_token();
-                        if (last_token != token_type::uninitialized)
-                        {
-                            // a string or a number
-                            continue;
-                        }
-                        if (states.empty())
-                        {
-                            // look for the value after the garbage
-                            if (!skip_to_value())
-                            {
-                                return false;
-                            }
-                            continue;
-                        }
-                        // nothing could be read
-                        if (JSON_HEDLEY_UNLIKELY(!sax->null()))
-                        {
-                            return false;
-                        }
-                        break;
+                        return syntax_error(*sax, exception_message(token_type::uninitialized, "value"));
                     }
                     case token_type::end_of_input:
                     {
                         if (JSON_HEDLEY_UNLIKELY(m_lexer.get_position().chars_read_total == 1))
                         {
-                            // there is nothing to recover
-                            static_cast<void>(report_error(sax, parse_error::create(101, m_lexer.get_position(),
-                                                           "attempting to parse an empty input; check that your input string or stream contains the expected JSON", nullptr), allow_recovery));
-                            return false;
+                            return syntax_error(*sax, "attempting to parse an empty input; check that your input string or stream contains the expected JSON");
                         }
 
-                        if (!report_error(sax, parse_error::create(101, m_lexer.get_position(), exception_message(token_type::literal_or_value, "value"), nullptr), allow_recovery))
-                        {
-                            return false;
-                        }
-
-                        // recover: the input ends where a value is missing
-                        if (states.empty())
-                        {
-                            // there is no value
-                            return false;
-                        }
-                        if (!recover_missing_value(sax, states))
-                        {
-                            return false;
-                        }
-                        // the state evaluation reads the token again
-                        m_lexer.unget_token();
-                        skip_to_state_evaluation = true;
-                        continue;
+                        return syntax_error(*sax, exception_message(token_type::literal_or_value, "value"));
                     }
                     case token_type::uninitialized:
                     case token_type::end_array:
@@ -490,35 +385,7 @@ class parser
                     case token_type::literal_or_value:
                     default: // the last token was unexpected
                     {
-                        if (!report_error(sax, parse_error::create(101, m_lexer.get_position(), exception_message(token_type::literal_or_value, "value"), nullptr), allow_recovery))
-                        {
-                            return false;
-                        }
-
-                        // recover
-                        if (states.empty())
-                        {
-                            // look for the value after the garbage
-                            if (!skip_to_value())
-                            {
-                                return false;
-                            }
-                            continue;
-                        }
-                        if (last_token == token_type::name_separator)
-                        {
-                            // a stray ':'; the value may follow
-                            get_token();
-                            continue;
-                        }
-                        if (!recover_missing_value(sax, states))
-                        {
-                            return false;
-                        }
-                        // the state evaluation reads the token again
-                        m_lexer.unget_token();
-                        skip_to_state_evaluation = true;
-                        continue;
+                        return syntax_error(*sax, exception_message(token_type::literal_or_value, "value"));
                     }
                 }
             }
@@ -569,30 +436,7 @@ class parser
                     continue;
                 }
 
-                if (!report_error(sax, parse_error::create(101, m_lexer.get_position(), exception_message(token_type::end_array, "array"), nullptr), allow_recovery))
-                {
-                    return false;
-                }
-
-                // recover
-                if (last_token == token_type::end_of_input)
-                {
-                    // the input ends inside the array
-                    return close_containers(sax, states);
-                }
-                if (last_token == token_type::end_object)
-                {
-                    // a wrong closing bracket closes the innermost container
-                    if (JSON_HEDLEY_UNLIKELY(!sax->end_array()))
-                    {
-                        return false;
-                    }
-                    states.pop_back();
-                    skip_to_state_evaluation = true;
-                }
-                // otherwise, a missing ',' (or a stray ':', which value
-                // parsing drops): the next value begins here
-                continue;
+                return syntax_error(*sax, exception_message(token_type::end_array, "array"));
             }
 
             // states.back() is false -> object
@@ -609,12 +453,9 @@ class parser
                     // parse key
                     if (JSON_HEDLEY_UNLIKELY(last_token != token_type::value_string))
                     {
-                        if (!continue_after(key_error(sax, allow_recovery, false), skip_to_state_evaluation))
-                        {
-                            return false;
-                        }
-                        continue;
+                        return syntax_error(*sax, exception_message(token_type::value_string, "object key"));
                     }
+
                     if (JSON_HEDLEY_UNLIKELY(!sax->key(m_lexer.get_string())))
                     {
                         return false;
@@ -623,11 +464,7 @@ class parser
                     // parse separator (:)
                     if (JSON_HEDLEY_UNLIKELY(!get_token_expecting(token_type::name_separator)))
                     {
-                        if (!continue_after(key_error(sax, allow_recovery, true), skip_to_state_evaluation))
-                        {
-                            return false;
-                        }
-                        continue;
+                        return syntax_error(*sax, exception_message(token_type::name_separator, "object separator"));
                     }
 
                     // parse values
@@ -655,479 +492,10 @@ class parser
                 continue;
             }
 
-            if (!report_error(sax, parse_error::create(101, m_lexer.get_position(), exception_message(token_type::end_object, "object"), nullptr), allow_recovery))
-            {
-                return false;
-            }
-
-            // recover
-            if (last_token == token_type::end_of_input)
-            {
-                // the input ends inside the object
-                return close_containers(sax, states);
-            }
-            if (last_token == token_type::end_array)
-            {
-                // a wrong closing bracket closes the innermost container
-                if (JSON_HEDLEY_UNLIKELY(!sax->end_object()))
-                {
-                    return false;
-                }
-                states.pop_back();
-                skip_to_state_evaluation = true;
-                continue;
-            }
-            if (!continue_after(recover_member(sax, allow_recovery), skip_to_state_evaluation))
-            {
-                return false;
-            }
+            return syntax_error(*sax, exception_message(token_type::end_object, "object"));
         }
     }
 
-    /*!
-    @brief continue sax_parse_internal() after a recovery
-    @return whether to continue parsing
-    */
-    bool continue_after(const next_step step, bool& skip_to_state_evaluation)
-    {
-        if (step == next_step::evaluate_state)
-        {
-            // the state evaluation reads the token again
-            m_lexer.unget_token();
-            skip_to_state_evaluation = true;
-        }
-        return step != next_step::stop;
-    }
-
-    /// the parser for parse() and accept() never recovers: stop parsing
-    static std::false_type continue_after(std::false_type /*step*/, bool& /*skip_to_state_evaluation*/) noexcept
-    {
-        return {};
-    }
-
-    /*!
-    @brief parse an object key and the name separator (:) after it
-
-    last_token is the token where the key is expected. sax_parse_internal()
-    repeats these steps rather than calling this function, which is used
-    when recovering from an error.
-
-    @return next_step::parse_value if the value follows, with last_token its
-            first token; next_step::evaluate_state if the object's state is
-            to be evaluated after recovering from an error; next_step::stop
-            to stop parsing
-    */
-    template<typename SAX>
-    next_step parse_key(SAX* sax)
-    {
-        const std::true_type allow_recovery{};
-
-        if (JSON_HEDLEY_UNLIKELY(last_token != token_type::value_string))
-        {
-            return key_error(sax, allow_recovery, false);
-        }
-
-        if (JSON_HEDLEY_UNLIKELY(!sax->key(m_lexer.get_string())))
-        {
-            return next_step::stop;
-        }
-
-        // parse separator (:)
-        if (JSON_HEDLEY_UNLIKELY(get_token() != token_type::name_separator))
-        {
-            return key_error(sax, allow_recovery, true);
-        }
-
-        // the value begins with the next token
-        get_token();
-        return next_step::parse_value;
-    }
-
-    /*!
-    @brief report a number that is too large for number_float_t, and recover
-           from the error by passing the value on; the SAX parser gets the
-           number's text as well
-
-    This is a separate function, as reading other numbers is measurably
-    slower if the error is handled where they are read.
-
-    @param[in] sax    the SAX parser
-    @param[in] value  the value that is not finite
-    @return whether to continue parsing
-    */
-    template<typename SAX, typename AllowRecovery>
-    bool overflow_error(SAX* sax, const number_float_t value, AllowRecovery allow_recovery)
-    {
-        if (!report_error(sax, out_of_range::create(406, concat("number overflow parsing '", m_lexer.get_token_string(), '\''), nullptr), allow_recovery))
-        {
-            return false;
-        }
-        return sax->number_float(value, m_lexer.get_string());
-    }
-
-    /*!
-    @brief report a missing key, or a missing name separator (:) after the
-           key; the parser for parse() and accept() never recovers
-
-    @param[in] key_read  whether the key was read, so that the name separator
-                         is missing
-    @return std::false_type, see report_error()
-    */
-    template<typename SAX>
-    std::false_type key_error(SAX* sax, std::false_type allow_recovery, const bool key_read)
-    {
-        return report_error(sax, parse_error::create(101, m_lexer.get_position(), key_read
-                            ? exception_message(token_type::name_separator, "object separator")
-                            : exception_message(token_type::value_string, "object key"), nullptr), allow_recovery);
-    }
-
-    /*!
-    @brief report a missing key, or a missing name separator (:) after the
-           key, and recover from it
-
-    @param[in] key_read  whether the key was read, so that the name separator
-                         is missing
-    */
-    template<typename SAX>
-    next_step key_error(SAX* sax, std::true_type allow_recovery, const bool key_read)
-    {
-        if (!key_read)
-        {
-            if (!report_error(sax, parse_error::create(101, m_lexer.get_position(), exception_message(token_type::value_string, "object key"), nullptr), allow_recovery))
-            {
-                return next_step::stop;
-            }
-            return recover_key(sax);
-        }
-
-        if (!report_error(sax, parse_error::create(101, m_lexer.get_position(), exception_message(token_type::name_separator, "object separator"), nullptr), allow_recovery))
-        {
-            return next_step::stop;
-        }
-        return recover_name_separator(sax);
-    }
-
-    /////////////////////
-    // error recovery
-    /////////////////////
-
-    /*
-    The functions below repair an error after the SAX parser's parse_error()
-    returned true (see #3989). Each mistake is repaired by the smallest local
-    edit: a missing ',' or ':' is inserted, a stray token is removed, what can
-    be read of an invalid string or number is kept (see
-    lexer::recover_token()), a missing value becomes null, a wrong closing
-    bracket closes the innermost container, and the end of the input closes
-    all of them. The events stay balanced, and every key() is followed by
-    exactly one value.
-
-    A repair hands a token to the state evaluation, by returning it to the
-    lexer (lexer::unget_token()) so that the state evaluation reads it again,
-    only if it is ',', ']', '}', or the end of the input. The state evaluation
-    hands a token to value or key parsing only if it is none of them, so a
-    token is never handed back and forth. Every other step reads a token or
-    closes a container, so parsing always ends.
-    */
-
-    /*!
-    @brief report an error to the SAX parser; the parser for parse() and
-           accept() never recovers
-
-    @return std::false_type rather than false: its value is known where the
-            function is called even if the call is not inlined, so the code
-            for recovering is not generated
-    */
-    template<typename SAX, typename Exception>
-    std::false_type report_error(SAX* sax, const Exception& ex, std::false_type /*allow_recovery*/)
-    {
-        error_reported = true;
-        static_cast<void>(sax->parse_error(m_lexer.get_position(), m_lexer.get_token_string(), ex));
-        return {};
-    }
-
-    /*!
-    @brief report an error to the SAX parser
-    @return whether to recover from the error
-    */
-    template<typename SAX, typename Exception>
-    bool report_error(SAX* sax, const Exception& ex, std::true_type /*allow_recovery*/)
-    {
-        const std::size_t position = m_lexer.get_position().chars_read_total;
-        if (error_reported && position == last_error_position && last_token == last_error_token)
-        {
-            // a repair handed on the token of the error it repaired; the
-            // token was reported already, and the SAX parser asked to recover
-            return true;
-        }
-
-        error_reported = true;
-        last_error_position = position;
-        last_error_token = last_token;
-
-        if (!sax->parse_error(m_lexer.get_position(), m_lexer.get_token_string(), ex))
-        {
-            return false;
-        }
-
-        // the token string of the next error begins here
-        m_lexer.restart_token_string();
-        return true;
-    }
-
-    /*!
-    @brief keep what can be read of the token that the lexer rejected
-
-    The error was reported for the rejected token, so it is not reported again
-    for the token it is repaired to (see lexer::recover_token()).
-    */
-    token_type recover_token()
-    {
-        last_token = m_lexer.recover_token();
-        last_error_position = m_lexer.get_position().chars_read_total;
-        last_error_token = last_token;
-        return last_token;
-    }
-
-    /// pass the end events of all open containers
-    template<typename SAX>
-    bool close_containers(SAX* sax, std::vector<bool>& states)
-    {
-        while (!states.empty())
-        {
-            const bool is_array = states.back();
-            states.pop_back();
-            if (JSON_HEDLEY_UNLIKELY(is_array ? !sax->end_array() : !sax->end_object()))
-            {
-                return false;
-            }
-        }
-        return true;
-    }
-
-    /*!
-    @brief read tokens until one begins a value, skipping everything before
-           the top-level value
-    @return whether a value begins with last_token
-    */
-    bool skip_to_value()
-    {
-        while (true)
-        {
-            switch (get_token())
-            {
-                case token_type::begin_array:
-                case token_type::begin_object:
-                case token_type::literal_false:
-                case token_type::literal_null:
-                case token_type::literal_true:
-                case token_type::value_float:
-                case token_type::value_integer:
-                case token_type::value_string:
-                case token_type::value_unsigned:
-                    return true;
-
-                case token_type::end_of_input:
-                    return false;
-
-                case token_type::parse_error:
-                    recover_token();
-                    if (last_token != token_type::uninitialized)
-                    {
-                        return true;
-                    }
-                    break;
-
-                case token_type::uninitialized:
-                case token_type::end_array:
-                case token_type::end_object:
-                case token_type::name_separator:
-                case token_type::value_separator:
-                case token_type::literal_or_value:
-                default:
-                    break;
-            }
-        }
-    }
-
-    /*!
-    @brief skip the rest of an object member that cannot be read
-
-    Reads tokens, beginning with last_token, until a ',', '}', or ']' that is
-    not inside a container that begins in the skipped tokens, or the end of
-    the input.
-    */
-    void skip_member()
-    {
-        std::size_t depth = 0;
-        while (true)
-        {
-            switch (last_token)
-            {
-                case token_type::begin_array:
-                case token_type::begin_object:
-                    ++depth;
-                    break;
-
-                case token_type::end_array:
-                case token_type::end_object:
-                    if (depth == 0)
-                    {
-                        return;
-                    }
-                    --depth;
-                    break;
-
-                case token_type::value_separator:
-                    if (depth == 0)
-                    {
-                        return;
-                    }
-                    break;
-
-                case token_type::end_of_input:
-                    return;
-
-                case token_type::parse_error:
-                    recover_token();
-                    break;
-
-                case token_type::uninitialized:
-                case token_type::literal_true:
-                case token_type::literal_false:
-                case token_type::literal_null:
-                case token_type::value_string:
-                case token_type::value_unsigned:
-                case token_type::value_integer:
-                case token_type::value_float:
-                case token_type::name_separator:
-                case token_type::literal_or_value:
-                default:
-                    break;
-            }
-            get_token();
-        }
-    }
-
-    /*!
-    @brief pass a value where it is missing
-
-    last_token is ',', ']', '}', or the end of the input, where a value was
-    expected. In an object, the key gets null; in an array, a ',' where a
-    value is missing stands for null (as in JavaScript), while an array that
-    ends there just ends.
-    */
-    template<typename SAX>
-    bool recover_missing_value(SAX* sax, const std::vector<bool>& states)
-    {
-        JSON_ASSERT(!states.empty());
-        if (!states.back() || last_token == token_type::value_separator)
-        {
-            return sax->null();
-        }
-        return true;
-    }
-
-    /// recover from a missing key; last_token is where it was expected
-    template<typename SAX>
-    next_step recover_key(SAX* sax)
-    {
-        switch (last_token)
-        {
-            case token_type::value_separator:
-            case token_type::end_object:
-            case token_type::end_array:
-            case token_type::end_of_input:
-                // no member: the object's state handles the token
-                return next_step::evaluate_state;
-
-            case token_type::parse_error:
-                recover_token();
-                if (last_token == token_type::value_string)
-                {
-                    // a key that could be repaired
-                    return parse_key(sax);
-                }
-                skip_member();
-                return next_step::evaluate_state;
-
-            case token_type::uninitialized:
-            case token_type::literal_true:
-            case token_type::literal_false:
-            case token_type::literal_null:
-            case token_type::value_string:
-            case token_type::value_unsigned:
-            case token_type::value_integer:
-            case token_type::value_float:
-            case token_type::begin_array:
-            case token_type::begin_object:
-            case token_type::name_separator:
-            case token_type::literal_or_value:
-            default:
-                // a member without a key
-                skip_member();
-                return next_step::evaluate_state;
-        }
-    }
-
-    /// recover from a missing name separator (:) after the key; last_token
-    /// is where it was expected
-    template<typename SAX>
-    next_step recover_name_separator(SAX* sax)
-    {
-        switch (last_token)
-        {
-            case token_type::value_separator:
-            case token_type::end_object:
-            case token_type::end_array:
-            case token_type::end_of_input:
-                // the value is missing as well
-                return sax->null() ? next_step::evaluate_state : next_step::stop;
-
-            case token_type::uninitialized:
-            case token_type::literal_true:
-            case token_type::literal_false:
-            case token_type::literal_null:
-            case token_type::value_string:
-            case token_type::value_unsigned:
-            case token_type::value_integer:
-            case token_type::value_float:
-            case token_type::begin_array:
-            case token_type::begin_object:
-            case token_type::name_separator:
-            case token_type::parse_error:
-            case token_type::literal_or_value:
-            default:
-                // a missing ':'; the value begins here
-                return next_step::parse_value;
-        }
-    }
-
-    /// recover from a token after an object member that is neither ',' nor
-    /// '}' (nor ']' or the end of the input, which the caller handles)
-    template<typename SAX>
-    next_step recover_member(SAX* sax, std::true_type /*allow_recovery*/)
-    {
-        if (last_token == token_type::parse_error)
-        {
-            recover_token();
-        }
-        if (last_token == token_type::value_string)
-        {
-            // a missing ','; the next key begins here
-            return parse_key(sax);
-        }
-        skip_member();
-        return next_step::evaluate_state;
-    }
-
-    /// the parser for parse() and accept() never recovers (and does not come
-    /// here, as report_error() returned false)
-    template<typename SAX>
-    std::false_type recover_member(SAX* /*sax*/, std::false_type /*allow_recovery*/) const noexcept
-    {
-        return {};
-    }
-
     /// get next token from lexer
     token_type get_token()
     {
@@ -1141,6 +509,19 @@ class parser
         return (last_token = m_lexer.scan_expecting(expected_type)) == expected_type;
     }
 
+    /*!
+    @brief reports a syntax error at the current token (parse_error.101)
+    @param[in] sax      the SAX parser to report the error to
+    @param[in] message  the error message
+    @return the result of the SAX parser's parse_error()
+    */
+    template<typename SAX>
+    bool syntax_error(SAX& sax, const std::string& message)
+    {
+        return sax.parse_error(m_lexer.get_position(), m_lexer.get_token_string(),
+                               parse_error::create(exception_id::syntax_error, m_lexer.get_position(), message, nullptr));
+    }
+
     std::string exception_message(const token_type expected, const std::string& context)
     {
         std::string error_msg = "syntax error ";
@@ -1181,12 +562,6 @@ class parser
     const bool allow_exceptions = true;
     /// whether trailing commas in objects and arrays should be ignored (true) or signaled as errors (false)
     const bool ignore_trailing_commas = false;
-    /// whether an error was reported to the SAX parser
-    bool error_reported = false;
-    /// the position of the last reported error
-    std::size_t last_error_position = 0;
-    /// the token of the last reported error
-    token_type last_error_token = token_type::uninitialized;
 };
 
 }  // namespace detail

include/nlohmann/detail/iterators/iter_impl.hpp

@@ -279,6 +279,12 @@ class iter_impl // NOLINT(cppcoreguidelines-special-member-functions,hicpp-speci
         }
     }
 
+    /// @throw invalid_iterator.214 always
+    JSON_HEDLEY_NO_RETURN void throw_cannot_get_value() const
+    {
+        JSON_THROW(invalid_iterator::create(exception_id::iterator_value_unavailable, "cannot get value", m_object));
+    }
+
   public:
     /*!
     @brief return a reference to the value pointed to by the iterator
@@ -303,7 +309,7 @@ class iter_impl // NOLINT(cppcoreguidelines-special-member-functions,hicpp-speci
             }
 
             case value_t::null:
-                JSON_THROW(invalid_iterator::create(214, "cannot get value", m_object));
+                throw_cannot_get_value();
 
             case value_t::string:
             case value_t::boolean:
@@ -319,7 +325,7 @@ class iter_impl // NOLINT(cppcoreguidelines-special-member-functions,hicpp-speci
                     return *m_object;
                 }
 
-                JSON_THROW(invalid_iterator::create(214, "cannot get value", m_object));
+                throw_cannot_get_value();
             }
         }
     }
@@ -361,7 +367,7 @@ class iter_impl // NOLINT(cppcoreguidelines-special-member-functions,hicpp-speci
                     return m_object;
                 }
 
-                JSON_THROW(invalid_iterator::create(214, "cannot get value", m_object));
+                throw_cannot_get_value();
             }
         }
     }
@@ -478,7 +484,7 @@ class iter_impl // NOLINT(cppcoreguidelines-special-member-functions,hicpp-speci
         // if objects are not the same, the comparison is undefined
         if (JSON_HEDLEY_UNLIKELY(m_object != other.m_object))
         {
-            JSON_THROW(invalid_iterator::create(212, "cannot compare iterators of different containers", m_object));
+            JSON_THROW(invalid_iterator::create(exception_id::iterators_compare_different_values, "cannot compare iterators of different containers", m_object));
         }
 
         // value-initialized forward iterators can be compared, and must compare equal to other value-initialized iterators of the same type #4493
@@ -527,7 +533,7 @@ class iter_impl // NOLINT(cppcoreguidelines-special-member-functions,hicpp-speci
         // if objects are not the same, the comparison is undefined
         if (JSON_HEDLEY_UNLIKELY(m_object != other.m_object))
         {
-            JSON_THROW(invalid_iterator::create(212, "cannot compare iterators of different containers", m_object));
+            JSON_THROW(invalid_iterator::create(exception_id::iterators_compare_different_values, "cannot compare iterators of different containers", m_object));
         }
 
         // value-initialized forward iterators can be compared, and must compare equal to other value-initialized iterators of the same type #4493
@@ -540,7 +546,7 @@ class iter_impl // NOLINT(cppcoreguidelines-special-member-functions,hicpp-speci
         switch (m_object->m_data.m_type)
         {
             case value_t::object:
-                JSON_THROW(invalid_iterator::create(213, "cannot compare order of object iterators", m_object));
+                JSON_THROW(invalid_iterator::create(exception_id::iterator_order_on_object, "cannot compare order of object iterators", m_object));
 
             case value_t::array:
                 return (m_it.array_iterator < other.m_it.array_iterator);
@@ -596,7 +602,7 @@ class iter_impl // NOLINT(cppcoreguidelines-special-member-functions,hicpp-speci
         switch (m_object->m_data.m_type)
         {
             case value_t::object:
-                JSON_THROW(invalid_iterator::create(209, "cannot use offsets with object iterators", m_object));
+                JSON_THROW(invalid_iterator::create(exception_id::iterator_arithmetic_on_object, "cannot use offsets with object iterators", m_object));
 
             case value_t::array:
             {
@@ -675,7 +681,7 @@ class iter_impl // NOLINT(cppcoreguidelines-special-member-functions,hicpp-speci
         switch (m_object->m_data.m_type)
         {
             case value_t::object:
-                JSON_THROW(invalid_iterator::create(209, "cannot use offsets with object iterators", m_object));
+                JSON_THROW(invalid_iterator::create(exception_id::iterator_arithmetic_on_object, "cannot use offsets with object iterators", m_object));
 
             case value_t::array:
                 return m_it.array_iterator - other.m_it.array_iterator;
@@ -704,13 +710,13 @@ class iter_impl // NOLINT(cppcoreguidelines-special-member-functions,hicpp-speci
         switch (m_object->m_data.m_type)
         {
             case value_t::object:
-                JSON_THROW(invalid_iterator::create(208, "cannot use operator[] for object iterators", m_object));
+                JSON_THROW(invalid_iterator::create(exception_id::iterator_subscript_on_object, "cannot use operator[] for object iterators", m_object));
 
             case value_t::array:
                 return *std::next(m_it.array_iterator, n);
 
             case value_t::null:
-                JSON_THROW(invalid_iterator::create(214, "cannot get value", m_object));
+                throw_cannot_get_value();
 
             case value_t::string:
             case value_t::boolean:
@@ -726,7 +732,7 @@ class iter_impl // NOLINT(cppcoreguidelines-special-member-functions,hicpp-speci
                     return *m_object;
                 }
 
-                JSON_THROW(invalid_iterator::create(214, "cannot get value", m_object));
+                throw_cannot_get_value();
             }
         }
     }
@@ -744,7 +750,7 @@ class iter_impl // NOLINT(cppcoreguidelines-special-member-functions,hicpp-speci
             return m_it.object_iterator->first;
         }
 
-        JSON_THROW(invalid_iterator::create(207, "cannot use key() for non-object iterators", m_object));
+        JSON_THROW(invalid_iterator::create(exception_id::iterator_key_not_object, "cannot use key() for non-object iterators", m_object));
     }
 
     /*!

include/nlohmann/detail/json_pointer.hpp

@@ -166,7 +166,7 @@ class json_pointer
     {
         if (JSON_HEDLEY_UNLIKELY(empty()))
         {
-            JSON_THROW(detail::out_of_range::create(405, "JSON pointer has no parent", nullptr));
+            throw_no_parent();
         }
 
         reference_tokens.erase(reference_tokens.begin());
@@ -178,7 +178,7 @@ class json_pointer
     {
         if (JSON_HEDLEY_UNLIKELY(empty()))
         {
-            JSON_THROW(detail::out_of_range::create(405, "JSON pointer has no parent", nullptr));
+            throw_no_parent();
         }
 
         return reference_tokens.front();
@@ -204,7 +204,7 @@ class json_pointer
     {
         if (JSON_HEDLEY_UNLIKELY(empty()))
         {
-            JSON_THROW(detail::out_of_range::create(405, "JSON pointer has no parent", nullptr));
+            throw_no_parent();
         }
 
         reference_tokens.pop_back();
@@ -216,7 +216,7 @@ class json_pointer
     {
         if (JSON_HEDLEY_UNLIKELY(empty()))
         {
-            JSON_THROW(detail::out_of_range::create(405, "JSON pointer has no parent", nullptr));
+            throw_no_parent();
         }
 
         return reference_tokens.back();
@@ -244,6 +244,21 @@ class json_pointer
     }
 
   private:
+    /// @throw out_of_range.405 always
+    JSON_HEDLEY_NO_RETURN static void throw_no_parent()
+    {
+        JSON_THROW(detail::out_of_range::create(detail::exception_id::patch_on_root, "JSON pointer has no parent", nullptr));
+    }
+
+    /// @throw out_of_range.404 always
+    template<typename BasicJsonContext>
+    JSON_HEDLEY_NO_RETURN static void throw_unresolved(const string_t& reference_token, BasicJsonContext context)
+    {
+        static_cast<void>(reference_token); // unused when JSON_NOEXCEPTION is defined
+        static_cast<void>(context);
+        JSON_THROW(detail::out_of_range::create(detail::exception_id::pointer_unresolved, detail::concat("unresolved reference token '", reference_token, "'"), context));
+    }
+
     /*!
     @brief result of @ref parse_array_index
 
@@ -329,13 +344,13 @@ class json_pointer
             // the branches differ in their messages, not after JSON_THROW's expansion
             // NOLINTNEXTLINE(bugprone-branch-clone)
             case array_index_status::leading_zero:
-                JSON_THROW(detail::parse_error::create(106, 0, detail::concat("array index '", s, "' must not begin with '0'"), nullptr));
+                JSON_THROW(detail::parse_error::create(detail::exception_id::pointer_index_leading_zero, 0, detail::concat("array index '", s, "' must not begin with '0'"), nullptr));
             case array_index_status::not_a_number:
-                JSON_THROW(detail::parse_error::create(109, 0, detail::concat("array index '", s, "' is not a number"), nullptr));
+                JSON_THROW(detail::parse_error::create(detail::exception_id::pointer_index_not_a_number, 0, detail::concat("array index '", s, "' is not a number"), nullptr));
             case array_index_status::unresolved:
-                JSON_THROW(detail::out_of_range::create(404, detail::concat("unresolved reference token '", s, "'"), nullptr));
+                throw_unresolved(s, nullptr);
             case array_index_status::exceeds_size_type:
-                JSON_THROW(detail::out_of_range::create(410, detail::concat("array index ", s, " exceeds size_type"), nullptr));
+                JSON_THROW(detail::out_of_range::create(detail::exception_id::value_out_of_range, detail::concat("array index ", s, " exceeds size_type"), nullptr));
             case array_index_status::ok:
             default:
                 break;
@@ -349,7 +364,7 @@ class json_pointer
     {
         if (JSON_HEDLEY_UNLIKELY(empty()))
         {
-            JSON_THROW(detail::out_of_range::create(405, "JSON pointer has no parent", nullptr));
+            throw_no_parent();
         }
 
         json_pointer result = *this;
@@ -437,7 +452,7 @@ class json_pointer
                 case detail::value_t::binary:
                 case detail::value_t::discarded:
                 default:
-                    JSON_THROW(detail::type_error::create(313, "invalid value to unflatten", &j));
+                    JSON_THROW(detail::type_error::create(detail::exception_id::unflatten_invalid_value, "invalid value to unflatten", &j));
             }
 
             prefix.push_back(reference_token);
@@ -520,7 +535,7 @@ class json_pointer
                 case detail::value_t::binary:
                 case detail::value_t::discarded:
                 default:
-                    JSON_THROW(detail::out_of_range::create(404, detail::concat("unresolved reference token '", reference_token, "'"), ptr));
+                    throw_unresolved(reference_token, ptr);
             }
         }
 
@@ -552,7 +567,7 @@ class json_pointer
                     if (JSON_HEDLEY_UNLIKELY(reference_token == "-"))
                     {
                         // "-" always fails the range check
-                        JSON_THROW(detail::out_of_range::create(402, detail::concat(
+                        JSON_THROW(detail::out_of_range::create(detail::exception_id::pointer_past_the_end_index, detail::concat(
                                 "array index '-' (", std::to_string(ptr->m_data.m_value.array->size()),
                                 ") is out of range"), ptr));
                     }
@@ -561,7 +576,7 @@ class json_pointer
                     // Bounds check before access to avoid exception with JSON_NOEXCEPTION
                     if (JSON_HEDLEY_UNLIKELY(idx >= ptr->m_data.m_value.array->size()))
                     {
-                        JSON_THROW(detail::out_of_range::create(401, detail::concat(
+                        JSON_THROW(detail::out_of_range::create(detail::exception_id::array_index_out_of_range, detail::concat(
                                 "array index ", std::to_string(idx), " is out of range"), ptr));
                     }
                     ptr = &ptr->operator[](idx);
@@ -577,7 +592,7 @@ class json_pointer
                 case detail::value_t::binary:
                 case detail::value_t::discarded:
                 default:
-                    JSON_THROW(detail::out_of_range::create(404, detail::concat("unresolved reference token '", reference_token, "'"), ptr));
+                    throw_unresolved(reference_token, ptr);
             }
         }
 
@@ -621,7 +636,7 @@ class json_pointer
                     if (JSON_HEDLEY_UNLIKELY(reference_token == "-"))
                     {
                         // "-" cannot be used for const access
-                        JSON_THROW(detail::out_of_range::create(402, detail::concat("array index '-' (", std::to_string(ptr->m_data.m_value.array->size()), ") is out of range"), ptr));
+                        JSON_THROW(detail::out_of_range::create(detail::exception_id::pointer_past_the_end_index, detail::concat("array index '-' (", std::to_string(ptr->m_data.m_value.array->size()), ") is out of range"), ptr));
                     }
 
                     // use unchecked array access; the const operator[]
@@ -639,7 +654,7 @@ class json_pointer
                 case detail::value_t::binary:
                 case detail::value_t::discarded:
                 default:
-                    JSON_THROW(detail::out_of_range::create(404, detail::concat("unresolved reference token '", reference_token, "'"), ptr));
+                    throw_unresolved(reference_token, ptr);
             }
         }
 
@@ -694,9 +709,9 @@ class json_pointer
                         // the branches differ in their messages, not after JSON_THROW's expansion
                         // NOLINTNEXTLINE(bugprone-branch-clone)
                         case array_index_status::leading_zero:
-                            JSON_THROW(detail::parse_error::create(106, 0, detail::concat("array index '", reference_token, "' must not begin with '0'"), nullptr));
+                            JSON_THROW(detail::parse_error::create(detail::exception_id::pointer_index_leading_zero, 0, detail::concat("array index '", reference_token, "' must not begin with '0'"), nullptr));
                         case array_index_status::not_a_number:
-                            JSON_THROW(detail::parse_error::create(109, 0, detail::concat("array index '", reference_token, "' is not a number"), nullptr));
+                            JSON_THROW(detail::parse_error::create(detail::exception_id::pointer_index_not_a_number, 0, detail::concat("array index '", reference_token, "' is not a number"), nullptr));
                         case array_index_status::unresolved:
                         case array_index_status::exceeds_size_type:
                             return nullptr;
@@ -823,7 +838,7 @@ class json_pointer
         // check if a nonempty reference string begins with slash
         if (JSON_HEDLEY_UNLIKELY(reference_string[0] != '/'))
         {
-            JSON_THROW(detail::parse_error::create(107, 1, detail::concat("JSON pointer must be empty or begin with '/' - was: '", reference_string, "'"), nullptr));
+            JSON_THROW(detail::parse_error::create(detail::exception_id::pointer_missing_slash, 1, detail::concat("JSON pointer must be empty or begin with '/' - was: '", reference_string, "'"), nullptr));
         }
 
         // extract the reference tokens:
@@ -859,7 +874,7 @@ class json_pointer
                                          (reference_token[pos + 1] != '0' &&
                                           reference_token[pos + 1] != '1')))
                 {
-                    JSON_THROW(detail::parse_error::create(108, 0, "escape character '~' must be followed with '0' or '1'", nullptr));
+                    JSON_THROW(detail::parse_error::create(detail::exception_id::pointer_invalid_escape, 0, "escape character '~' must be followed with '0' or '1'", nullptr));
                 }
             }
 
@@ -956,7 +971,7 @@ class json_pointer
     {
         if (JSON_HEDLEY_UNLIKELY(!value.is_object()))
         {
-            JSON_THROW(detail::type_error::create(314, "only objects can be unflattened", &value));
+            JSON_THROW(detail::type_error::create(detail::exception_id::unflatten_not_object, "only objects can be unflattened", &value));
         }
 
         BasicJsonType result;
@@ -984,7 +999,7 @@ class json_pointer
         {
             if (JSON_HEDLEY_UNLIKELY(!element.second.is_primitive()))
             {
-                JSON_THROW(detail::type_error::create(315, "values in object must be primitive", &element.second));
+                JSON_THROW(detail::type_error::create(detail::exception_id::unflatten_value_not_primitive, "values in object must be primitive", &element.second));
             }
 
             // Assign the value to the reference pointed to by JSON pointer. Note

include/nlohmann/detail/macro_scope.hpp

@@ -312,7 +312,7 @@
             return ej_pair.first == e;                                                          \
         });                                                                                     \
         if (it != std::end(m)) j = it->second;                                                  \
-        else ::nlohmann::detail::templated_json_throw<nlohmann::detail::out_of_range>(nlohmann::detail::out_of_range::create(410,"enum value out of range for " #ENUM_TYPE, nullptr)); \
+        else ::nlohmann::detail::templated_json_throw<nlohmann::detail::out_of_range>(nlohmann::detail::out_of_range::create(nlohmann::detail::exception_id::value_out_of_range,"enum value out of range for " #ENUM_TYPE, nullptr)); \
     }                                                                                           \
     template<typename BasicJsonType>                                                            \
     inline void from_json(const BasicJsonType& j, ENUM_TYPE& e)                                 \
@@ -327,7 +327,7 @@
             return ej_pair.second == j;                                                         \
         });                                                                                     \
         if (it != std::end(m)) e = it->first;                                                   \
-        else ::nlohmann::detail::templated_json_throw<nlohmann::detail::out_of_range>(nlohmann::detail::out_of_range::create(410, nlohmann::detail::concat("enum value out of range for " #ENUM_TYPE ": ", j.dump(-1, ' ', false, nlohmann::detail::error_handler_t::replace)), &j)); \
+        else ::nlohmann::detail::templated_json_throw<nlohmann::detail::out_of_range>(nlohmann::detail::out_of_range::create(nlohmann::detail::exception_id::value_out_of_range, nlohmann::detail::concat("enum value out of range for " #ENUM_TYPE ": ", j.dump(-1, ' ', false, nlohmann::detail::error_handler_t::replace)), &j)); \
     }
 
 // Ugly macros to avoid uglier copy-paste when specializing basic_json. They

include/nlohmann/detail/output/binary_writer.hpp

@@ -151,7 +151,7 @@ class binary_writer
             case value_t::discarded:
             default:
             {
-                JSON_THROW(type_error::create(317, concat("to serialize to BSON, top-level type must be object, but is ", j.type_name()), &j));
+                JSON_THROW(type_error::create(exception_id::type_not_serializable, concat("to serialize to BSON, top-level type must be object, but is ", j.type_name()), &j));
             }
         }
     }
@@ -354,7 +354,7 @@ class binary_writer
     {
         if (JSON_HEDLEY_UNLIKELY(!value_in_range_of<std::uint32_t>(length)))
         {
-            JSON_THROW(out_of_range::create(412, concat("MessagePack length ", std::to_string(length), " exceeds maximum of ", std::to_string((std::numeric_limits<std::uint32_t>::max)())), &j));
+            JSON_THROW(out_of_range::create(exception_id::length_too_large, concat("MessagePack length ", std::to_string(length), " exceeds maximum of ", std::to_string((std::numeric_limits<std::uint32_t>::max)())), &j));
         }
 
         static_cast<void>(j);
@@ -613,7 +613,7 @@ class binary_writer
                 {
                     if (JSON_HEDLEY_UNLIKELY(j.m_data.m_value.binary->subtype() > (std::numeric_limits<std::uint8_t>::max)()))
                     {
-                        JSON_THROW(out_of_range::create(415, concat("subtype ", std::to_string(j.m_data.m_value.binary->subtype()), " is too large for the MessagePack ext type (max 255)"), &j));
+                        JSON_THROW(out_of_range::create(exception_id::subtype_out_of_range, concat("subtype ", std::to_string(j.m_data.m_value.binary->subtype()), " is too large for the MessagePack ext type (max 255)"), &j));
                     }
 
                     write_number(static_cast<std::int8_t>(j.m_data.m_value.binary->subtype()));
@@ -767,7 +767,7 @@ class binary_writer
                 {
                     if (!use_count)
                     {
-                        JSON_THROW(other_error::create(502, "use_type requires use_size = true", &j));
+                        JSON_THROW(other_error::create(exception_id::size_marker_required, "use_type requires use_size = true", &j));
                     }
                     oa.write_character(to_char_type('$'));
                     oa.write_character(bjdata_draft3 ? 'B' : 'U');
@@ -866,7 +866,7 @@ class binary_writer
     {
         static_cast<void>(j); // unused when JSON_NOEXCEPTION is defined
         static_cast<void>(format_name);
-        JSON_THROW(type_error::create(321, concat("cannot serialize discarded value to ", format_name), &j));
+        JSON_THROW(type_error::create(exception_id::discarded_value_used, concat("cannot serialize discarded value to ", format_name), &j));
     }
 
     void write_msgpack_array_prefix(const std::size_t N, const BasicJsonType& j)
@@ -1132,7 +1132,7 @@ class binary_writer
         {
             if (!use_count)
             {
-                JSON_THROW(other_error::create(502, "use_type requires use_size = true", &j));
+                JSON_THROW(other_error::create(exception_id::size_marker_required, "use_type requires use_size = true", &j));
             }
             const CharType first_prefix = ubjson_prefix(j.front(), use_bjdata);
             const bool same_prefix = std::all_of(j.begin() + 1, j.end(),
@@ -1182,7 +1182,7 @@ class binary_writer
         {
             if (!use_count)
             {
-                JSON_THROW(other_error::create(502, "use_type requires use_size = true", &j));
+                JSON_THROW(other_error::create(exception_id::size_marker_required, "use_type requires use_size = true", &j));
             }
             const CharType first_prefix = ubjson_prefix(j.front(), use_bjdata);
             const bool same_prefix = std::all_of(j.begin(), j.end(),
@@ -1397,7 +1397,7 @@ class binary_writer
         const auto it = name.find(static_cast<typename string_t::value_type>(0));
         if (JSON_HEDLEY_UNLIKELY(it != BasicJsonType::string_t::npos))
         {
-            JSON_THROW(out_of_range::create(409, concat("BSON key cannot contain code point U+0000 (at byte ", std::to_string(it), ")"), &j));
+            JSON_THROW(out_of_range::create(exception_id::bson_key_with_null, concat("BSON key cannot contain code point U+0000 (at byte ", std::to_string(it), ")"), &j));
         }
 
         string_t storage;
@@ -1415,7 +1415,7 @@ class binary_writer
     {
         if (JSON_HEDLEY_UNLIKELY(!value_in_range_of<std::int32_t>(size)))
         {
-            JSON_THROW(out_of_range::create(412, concat("BSON length ", std::to_string(size), " exceeds maximum of ", std::to_string((std::numeric_limits<std::int32_t>::max)())), nullptr));
+            JSON_THROW(out_of_range::create(exception_id::length_too_large, concat("BSON length ", std::to_string(size), " exceeds maximum of ", std::to_string((std::numeric_limits<std::int32_t>::max)())), nullptr));
         }
 
         return static_cast<std::int32_t>(size);
@@ -1601,7 +1601,7 @@ class binary_writer
 
         if (value.has_subtype() && JSON_HEDLEY_UNLIKELY(value.subtype() > (std::numeric_limits<std::uint8_t>::max)()))
         {
-            JSON_THROW(out_of_range::create(415, concat("subtype ", std::to_string(value.subtype()), " is too large for the BSON binary subtype (max 255)"), &j));
+            JSON_THROW(out_of_range::create(exception_id::subtype_out_of_range, concat("subtype ", std::to_string(value.subtype()), " is too large for the BSON binary subtype (max 255)"), &j));
         }
 
         return sizeof(std::int32_t) + value.size() + 1ul;
@@ -2551,7 +2551,7 @@ class binary_writer
             {
                 if (j.m_data.m_value.number_unsigned > static_cast<typename BasicJsonType::number_unsigned_t>((std::numeric_limits<std::int64_t>::max)()))
                 {
-                    JSON_THROW(out_of_range::create(407, concat("integer number ", std::to_string(j.m_data.m_value.number_unsigned), " cannot be represented by BON8 as it does not fit int64"), &j));
+                    JSON_THROW(out_of_range::create(exception_id::integer_too_large, concat("integer number ", std::to_string(j.m_data.m_value.number_unsigned), " cannot be represented by BON8 as it does not fit int64"), &j));
                 }
                 write_bon8_integer(static_cast<std::int64_t>(j.m_data.m_value.number_unsigned));
                 string_open = false;
@@ -2704,7 +2704,7 @@ class binary_writer
         const std::size_t valid = valid_utf8_prefix(data, s.size());
         if (JSON_HEDLEY_UNLIKELY(valid != s.size()))
         {
-            JSON_THROW(type_error::create(316, concat("invalid UTF-8 byte at index ", std::to_string(valid), ": 0x", detail::hex_byte(data[valid])), &context));
+            JSON_THROW(type_error::create(exception_id::invalid_utf8, concat("invalid UTF-8 byte at index ", std::to_string(valid), ": 0x", detail::hex_byte(data[valid])), &context));
         }
     }
 

include/nlohmann/detail/output/serializer.hpp

@@ -888,7 +888,7 @@ class serializer
                     {
                         case error_handler_t::strict:
                         {
-                            JSON_THROW(type_error::create(316, concat("invalid UTF-8 byte at index ", std::to_string(i), ": 0x", detail::hex_byte(byte)), nullptr));
+                            JSON_THROW(type_error::create(exception_id::invalid_utf8, concat("invalid UTF-8 byte at index ", std::to_string(i), ": 0x", detail::hex_byte(byte)), nullptr));
                         }
 
                         case error_handler_t::ignore:
@@ -1021,7 +1021,7 @@ class serializer
             {
                 case error_handler_t::strict:
                 {
-                    JSON_THROW(type_error::create(316, concat("incomplete UTF-8 string; last byte: 0x", detail::hex_byte(static_cast<std::uint8_t>(s[s.size() - 1]))), nullptr));
+                    JSON_THROW(type_error::create(exception_id::invalid_utf8, concat("incomplete UTF-8 string; last byte: 0x", detail::hex_byte(static_cast<std::uint8_t>(s[s.size() - 1]))), nullptr));
                 }
 
                 case error_handler_t::ignore:

include/nlohmann/detail/string_utils.hpp

@@ -13,7 +13,6 @@
 #include <cstddef> // size_t
 #include <cstdint> // uint8_t, uint32_t
 #include <string> // string, to_string
-#include <utility> // move
 
 #include <nlohmann/detail/abi_macros.hpp>
 #include <nlohmann/detail/macro_scope.hpp>

include/nlohmann/json.hpp

@@ -149,7 +149,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     friend class ::nlohmann::detail::iter_impl;
     template<typename BasicJsonType, typename CharType, typename OutputSinkType>
     friend class ::nlohmann::detail::binary_writer;
-    template<typename BasicJsonType, typename InputType, typename SAX, bool AllowRecovery>
+    template<typename BasicJsonType, typename InputType, typename SAX>
     friend class ::nlohmann::detail::binary_reader;
     template<typename BasicJsonType, typename InputAdapterType>
     friend class ::nlohmann::detail::json_sax_dom_parser;
@@ -639,7 +639,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
                     object = nullptr;  // silence warning, see #821
                     if (JSON_HEDLEY_UNLIKELY(t == value_t::null))
                     {
-                        JSON_THROW(other_error::create(500, "961c151d2e87f2686a955a9be24d316f1362bf21 3.12.0", nullptr)); // LCOV_EXCL_LINE
+                        JSON_THROW(other_error::create(detail::exception_id::internal_error, "961c151d2e87f2686a955a9be24d316f1362bf21 3.12.0", nullptr)); // LCOV_EXCL_LINE
                     }
                     break;
                 }
@@ -2287,7 +2287,7 @@ public:
             // if an object is wanted but impossible, throw an exception
             if (JSON_HEDLEY_UNLIKELY(manual_type == value_t::object && !is_an_object))
             {
-                JSON_THROW(type_error::create(301, "cannot create object from initializer list", nullptr));
+                JSON_THROW(type_error::create(detail::exception_id::object_from_non_pairs, "cannot create object from initializer list", nullptr));
             }
         }
 
@@ -2407,7 +2407,7 @@ public:
         // make sure the iterator fits the current value
         if (JSON_HEDLEY_UNLIKELY(first.m_object != last.m_object))
         {
-            JSON_THROW(invalid_iterator::create(201, "iterators are not compatible", nullptr));
+            JSON_THROW(invalid_iterator::create(detail::exception_id::iterators_incompatible, "iterators are not compatible", nullptr));
         }
 
         // copy type from the first iterator
@@ -2426,7 +2426,7 @@ public:
                 if (JSON_HEDLEY_UNLIKELY(!first.m_it.primitive_iterator.is_begin()
                                          || !last.m_it.primitive_iterator.is_end()))
                 {
-                    JSON_THROW(invalid_iterator::create(204, "iterators out of range", first.m_object));
+                    JSON_THROW(invalid_iterator::create(detail::exception_id::iterator_range_out_of_range, "iterators out of range", first.m_object));
                 }
                 break;
             }
@@ -2494,7 +2494,7 @@ public:
             case value_t::null:
             case value_t::discarded:
             default:
-                JSON_THROW(invalid_iterator::create(206, detail::concat("cannot construct with iterators from ", first.m_object->type_name()), first.m_object));
+                JSON_THROW(invalid_iterator::create(detail::exception_id::iterator_range_of_null, detail::concat("cannot construct with iterators from ", first.m_object->type_name()), first.m_object));
         }
 
         set_parents();
@@ -2882,7 +2882,7 @@ public:
             return *ptr;
         }
 
-        JSON_THROW(type_error::create(303, detail::concat("incompatible ReferenceType for get_ref, actual type is ", obj.type_name()), &obj));
+        JSON_THROW(type_error::create(detail::exception_id::incompatible_reference_type, detail::concat("incompatible ReferenceType for get_ref, actual type is ", obj.type_name()), &obj));
     }
 
   public:
@@ -3266,7 +3266,7 @@ public:
     {
         if (!is_binary())
         {
-            JSON_THROW(type_error::create(302, detail::concat("type must be binary, but is ", type_name()), this));
+            detail::throw_type_must_be("binary", *this);
         }
 
         return *get_ptr<binary_t*>();
@@ -3278,7 +3278,7 @@ public:
     {
         if (!is_binary())
         {
-            JSON_THROW(type_error::create(302, detail::concat("type must be binary, but is ", type_name()), this));
+            detail::throw_type_must_be("binary", *this);
         }
 
         return *get_ptr<const binary_t*>();
@@ -3320,7 +3320,7 @@ public:
         // at only works for objects
         if (JSON_HEDLEY_UNLIKELY(!j.is_object()))
         {
-            JSON_THROW(type_error::create(304, detail::concat("cannot use at() with ", j.type_name()), &j));
+            detail::throw_cannot_use_with(detail::exception_id::at_wrong_type, "at()", j);
         }
 
         auto it = object_lookup(j, std::forward<KeyType>(key));
@@ -3330,7 +3330,7 @@ public:
             // std::map or ordered_map) never moves from its argument, so key is still
             // valid here regardless of whether KeyType was deduced as an rvalue reference
             // NOLINTNEXTLINE(bugprone-use-after-move,hicpp-invalid-access-moved)
-            JSON_THROW(out_of_range::create(403, detail::concat("key '", string_t(key), "' not found"), &j));
+            JSON_THROW(out_of_range::create(detail::exception_id::key_not_found, detail::concat("key '", string_t(key), "' not found"), &j));
         }
         return it->second;
     }
@@ -3345,12 +3345,12 @@ public:
         // at only works for arrays
         if (JSON_HEDLEY_UNLIKELY(!j.is_array()))
         {
-            JSON_THROW(type_error::create(304, detail::concat("cannot use at() with ", j.type_name()), &j));
+            detail::throw_cannot_use_with(detail::exception_id::at_wrong_type, "at()", j);
         }
 
         if (JSON_HEDLEY_UNLIKELY(idx >= j.m_data.m_value.array->size()))
         {
-            JSON_THROW(out_of_range::create(401, detail::concat("array index ", std::to_string(idx), " is out of range"), &j));
+            JSON_THROW(out_of_range::create(detail::exception_id::array_index_out_of_range, detail::concat("array index ", std::to_string(idx), " is out of range"), &j));
         }
 
         return (*j.m_data.m_value.array)[idx];
@@ -3383,6 +3383,15 @@ public:
         m_data.m_type = value_t::object;
     }
 
+    /// @brief throws because operator[] is not supported for the type of this value
+    /// @param[in] argument  the kind of the operator's argument, "numeric" or "string"
+    /// @throw type_error.305 always
+    JSON_HEDLEY_NO_RETURN void throw_subscript_wrong_type(const char* argument) const
+    {
+        detail::throw_cannot_use_with(detail::exception_id::subscript_wrong_type,
+                                      detail::concat("operator[] with a ", argument, " argument").c_str(), *this);
+    }
+
   public:
     ////////////////////
     // element access //
@@ -3487,7 +3496,7 @@ public:
             return m_data.m_value.array->operator[](idx);
         }
 
-        JSON_THROW(type_error::create(305, detail::concat("cannot use operator[] with a numeric argument with ", type_name()), this));
+        throw_subscript_wrong_type("numeric");
     }
 
     /// @brief access specified array element
@@ -3501,7 +3510,7 @@ public:
             return m_data.m_value.array->operator[](idx);
         }
 
-        JSON_THROW(type_error::create(305, detail::concat("cannot use operator[] with a numeric argument with ", type_name()), this));
+        throw_subscript_wrong_type("numeric");
     }
 
     /// @brief access specified object element
@@ -3521,7 +3530,7 @@ public:
             return set_parent(result.first->second);
         }
 
-        JSON_THROW(type_error::create(305, detail::concat("cannot use operator[] with a string argument with ", type_name()), this));
+        throw_subscript_wrong_type("string");
     }
 
     /// @brief access specified object element
@@ -3536,7 +3545,7 @@ public:
             return it->second;
         }
 
-        JSON_THROW(type_error::create(305, detail::concat("cannot use operator[] with a string argument with ", type_name()), this));
+        throw_subscript_wrong_type("string");
     }
 
     // these two functions resolve a (const) char * ambiguity affecting Clang and MSVC
@@ -3572,7 +3581,7 @@ public:
             return set_parent(result.first->second);
         }
 
-        JSON_THROW(type_error::create(305, detail::concat("cannot use operator[] with a string argument with ", type_name()), this));
+        throw_subscript_wrong_type("string");
     }
 
     /// @brief access specified object element
@@ -3589,7 +3598,7 @@ public:
             return it->second;
         }
 
-        JSON_THROW(type_error::create(305, detail::concat("cannot use operator[] with a string argument with ", type_name()), this));
+        throw_subscript_wrong_type("string");
     }
 
   private:
@@ -3613,7 +3622,7 @@ public:
         // value only works for objects
         if (JSON_HEDLEY_UNLIKELY(!is_object()))
         {
-            JSON_THROW(type_error::create(306, detail::concat("cannot use value() with ", type_name()), this));
+            detail::throw_cannot_use_with(detail::exception_id::value_wrong_type, "value()", *this);
         }
 
         const auto it = find(std::forward<KeyType>(key));
@@ -3628,7 +3637,7 @@ public:
         // value only works for arrays and objects
         if (JSON_HEDLEY_UNLIKELY(!is_structured()))
         {
-            JSON_THROW(type_error::create(306, detail::concat("cannot use value() with ", type_name()), this));
+            detail::throw_cannot_use_with(detail::exception_id::value_wrong_type, "value()", *this);
         }
 
         return ptr.get_checked_or_null(this);
@@ -3795,7 +3804,7 @@ public:
         // make sure the iterator fits the current value
         if (JSON_HEDLEY_UNLIKELY(this != pos.m_object))
         {
-            JSON_THROW(invalid_iterator::create(202, "iterator does not fit current value", this));
+            JSON_THROW(invalid_iterator::create(detail::exception_id::iterator_from_other_value, "iterator does not fit current value", this));
         }
 
         IteratorType result = end();
@@ -3811,7 +3820,7 @@ public:
             {
                 if (JSON_HEDLEY_UNLIKELY(!pos.m_it.primitive_iterator.is_begin()))
                 {
-                    JSON_THROW(invalid_iterator::create(205, "iterator out of range", this));
+                    JSON_THROW(invalid_iterator::create(detail::exception_id::iterator_out_of_range, "iterator out of range", this));
                 }
 
                 m_data.m_value.destroy(m_data.m_type);
@@ -3837,7 +3846,7 @@ public:
             case value_t::null:
             case value_t::discarded:
             default:
-                JSON_THROW(type_error::create(307, detail::concat("cannot use erase() with ", type_name()), this));
+                detail::throw_cannot_use_with(detail::exception_id::erase_wrong_type, "erase()", *this);
         }
 
         return result;
@@ -3853,7 +3862,7 @@ public:
         // make sure the iterator fits the current value
         if (JSON_HEDLEY_UNLIKELY(this != first.m_object || this != last.m_object))
         {
-            JSON_THROW(invalid_iterator::create(203, "iterators do not fit current value", this));
+            JSON_THROW(invalid_iterator::create(detail::exception_id::iterator_range_from_other_value, "iterators do not fit current value", this));
         }
 
         IteratorType result = end();
@@ -3870,7 +3879,7 @@ public:
                 if (JSON_HEDLEY_UNLIKELY(!first.m_it.primitive_iterator.is_begin()
                                          || !last.m_it.primitive_iterator.is_end()))
                 {
-                    JSON_THROW(invalid_iterator::create(204, "iterators out of range", this));
+                    JSON_THROW(invalid_iterator::create(detail::exception_id::iterator_range_out_of_range, "iterators out of range", this));
                 }
 
                 m_data.m_value.destroy(m_data.m_type);
@@ -3898,7 +3907,7 @@ public:
             case value_t::null:
             case value_t::discarded:
             default:
-                JSON_THROW(type_error::create(307, detail::concat("cannot use erase() with ", type_name()), this));
+                detail::throw_cannot_use_with(detail::exception_id::erase_wrong_type, "erase()", *this);
         }
 
         return result;
@@ -3912,7 +3921,7 @@ public:
         // this erase only works for objects
         if (JSON_HEDLEY_UNLIKELY(!is_object()))
         {
-            JSON_THROW(type_error::create(307, detail::concat("cannot use erase() with ", type_name()), this));
+            detail::throw_cannot_use_with(detail::exception_id::erase_wrong_type, "erase()", *this);
         }
 
         const auto erased = m_data.m_value.object->erase(std::forward<KeyType>(key));
@@ -3927,7 +3936,7 @@ public:
         // this erase only works for objects
         if (JSON_HEDLEY_UNLIKELY(!is_object()))
         {
-            JSON_THROW(type_error::create(307, detail::concat("cannot use erase() with ", type_name()), this));
+            detail::throw_cannot_use_with(detail::exception_id::erase_wrong_type, "erase()", *this);
         }
 
         const auto it = object_lookup(*this, std::forward<KeyType>(key));
@@ -3969,14 +3978,14 @@ public:
         {
             if (JSON_HEDLEY_UNLIKELY(idx >= size()))
             {
-                JSON_THROW(out_of_range::create(401, detail::concat("array index ", std::to_string(idx), " is out of range"), this));
+                JSON_THROW(out_of_range::create(detail::exception_id::array_index_out_of_range, detail::concat("array index ", std::to_string(idx), " is out of range"), this));
             }
 
             m_data.m_value.array->erase(m_data.m_value.array->begin() + static_cast<difference_type>(idx));
         }
         else
         {
-            JSON_THROW(type_error::create(307, detail::concat("cannot use erase() with ", type_name()), this));
+            detail::throw_cannot_use_with(detail::exception_id::erase_wrong_type, "erase()", *this);
         }
     }
 
@@ -4465,7 +4474,7 @@ public:
         // push_back only works for null objects or arrays
         if (JSON_HEDLEY_UNLIKELY(!(is_null() || is_array())))
         {
-            JSON_THROW(type_error::create(308, detail::concat("cannot use push_back() with ", type_name()), this));
+            detail::throw_cannot_use_with(detail::exception_id::push_back_wrong_type, "push_back()", *this);
         }
 
         // transform a null object into an array
@@ -4496,7 +4505,7 @@ public:
         // push_back only works for null objects or arrays
         if (JSON_HEDLEY_UNLIKELY(!(is_null() || is_array())))
         {
-            JSON_THROW(type_error::create(308, detail::concat("cannot use push_back() with ", type_name()), this));
+            detail::throw_cannot_use_with(detail::exception_id::push_back_wrong_type, "push_back()", *this);
         }
 
         // transform a null object into an array
@@ -4526,7 +4535,7 @@ public:
         // push_back only works for null objects or objects
         if (JSON_HEDLEY_UNLIKELY(!(is_null() || is_object())))
         {
-            JSON_THROW(type_error::create(308, detail::concat("cannot use push_back() with ", type_name()), this));
+            detail::throw_cannot_use_with(detail::exception_id::push_back_wrong_type, "push_back()", *this);
         }
 
         // transform a null object into an object
@@ -4580,7 +4589,7 @@ public:
         // emplace_back only works for null objects or arrays
         if (JSON_HEDLEY_UNLIKELY(!(is_null() || is_array())))
         {
-            JSON_THROW(type_error::create(311, detail::concat("cannot use emplace_back() with ", type_name()), this));
+            detail::throw_cannot_use_with(detail::exception_id::emplace_wrong_type, "emplace_back()", *this);
         }
 
         // transform a null object into an array
@@ -4603,7 +4612,7 @@ public:
         // emplace only works for null objects or arrays
         if (JSON_HEDLEY_UNLIKELY(!(is_null() || is_object())))
         {
-            JSON_THROW(type_error::create(311, detail::concat("cannot use emplace() with ", type_name()), this));
+            detail::throw_cannot_use_with(detail::exception_id::emplace_wrong_type, "emplace()", *this);
         }
 
         // transform a null object into an object
@@ -4655,14 +4664,14 @@ public:
             // check if iterator pos fits to this JSON value
             if (JSON_HEDLEY_UNLIKELY(pos.m_object != this))
             {
-                JSON_THROW(invalid_iterator::create(202, "iterator does not fit current value", this));
+                JSON_THROW(invalid_iterator::create(detail::exception_id::iterator_from_other_value, "iterator does not fit current value", this));
             }
 
             // insert to array and return iterator
             return insert_iterator(pos, val);
         }
 
-        JSON_THROW(type_error::create(309, detail::concat("cannot use insert() with ", type_name()), this));
+        detail::throw_cannot_use_with(detail::exception_id::insert_wrong_type, "insert()", *this);
     }
 
     /// @brief inserts element into array
@@ -4675,7 +4684,7 @@ public:
             // check if iterator pos fits to this JSON value
             if (JSON_HEDLEY_UNLIKELY(pos.m_object != this))
             {
-                JSON_THROW(invalid_iterator::create(202, "iterator does not fit current value", this));
+                JSON_THROW(invalid_iterator::create(detail::exception_id::iterator_from_other_value, "iterator does not fit current value", this));
             }
 
             // moving into a local first keeps this safe even if val aliases
@@ -4684,7 +4693,7 @@ public:
             return insert_iterator(pos, std::move(tmp));
         }
 
-        JSON_THROW(type_error::create(309, detail::concat("cannot use insert() with ", type_name()), this));
+        detail::throw_cannot_use_with(detail::exception_id::insert_wrong_type, "insert()", *this);
     }
 
     /// @brief inserts copies of element into array
@@ -4697,14 +4706,14 @@ public:
             // check if iterator pos fits to this JSON value
             if (JSON_HEDLEY_UNLIKELY(pos.m_object != this))
             {
-                JSON_THROW(invalid_iterator::create(202, "iterator does not fit current value", this));
+                JSON_THROW(invalid_iterator::create(detail::exception_id::iterator_from_other_value, "iterator does not fit current value", this));
             }
 
             // insert to array and return iterator
             return insert_iterator(pos, cnt, val);
         }
 
-        JSON_THROW(type_error::create(309, detail::concat("cannot use insert() with ", type_name()), this));
+        detail::throw_cannot_use_with(detail::exception_id::insert_wrong_type, "insert()", *this);
     }
 
     /// @brief inserts range of elements into array
@@ -4714,30 +4723,30 @@ public:
         // insert only works for arrays
         if (JSON_HEDLEY_UNLIKELY(!is_array()))
         {
-            JSON_THROW(type_error::create(309, detail::concat("cannot use insert() with ", type_name()), this));
+            detail::throw_cannot_use_with(detail::exception_id::insert_wrong_type, "insert()", *this);
         }
 
         // check if iterator pos fits to this JSON value
         if (JSON_HEDLEY_UNLIKELY(pos.m_object != this))
         {
-            JSON_THROW(invalid_iterator::create(202, "iterator does not fit current value", this));
+            JSON_THROW(invalid_iterator::create(detail::exception_id::iterator_from_other_value, "iterator does not fit current value", this));
         }
 
         // check if range iterators belong to the same JSON object
         if (JSON_HEDLEY_UNLIKELY(first.m_object != last.m_object))
         {
-            JSON_THROW(invalid_iterator::create(210, "iterators do not fit", this));
+            JSON_THROW(invalid_iterator::create(detail::exception_id::insert_range_incompatible, "iterators do not fit", this));
         }
 
         if (JSON_HEDLEY_UNLIKELY(first.m_object == this))
         {
-            JSON_THROW(invalid_iterator::create(211, "passed iterators may not belong to container", this));
+            JSON_THROW(invalid_iterator::create(detail::exception_id::insert_range_into_itself, "passed iterators may not belong to container", this));
         }
 
         // passed iterators must belong to arrays
         if (JSON_HEDLEY_UNLIKELY(!first.m_object->is_array()))
         {
-            JSON_THROW(invalid_iterator::create(202, "iterators first and last must point to arrays", this));
+            JSON_THROW(invalid_iterator::create(detail::exception_id::iterator_from_other_value, "iterators first and last must point to arrays", this));
         }
 
         // insert to array and return iterator
@@ -4751,13 +4760,13 @@ public:
         // insert only works for arrays
         if (JSON_HEDLEY_UNLIKELY(!is_array()))
         {
-            JSON_THROW(type_error::create(309, detail::concat("cannot use insert() with ", type_name()), this));
+            detail::throw_cannot_use_with(detail::exception_id::insert_wrong_type, "insert()", *this);
         }
 
         // check if iterator pos fits to this JSON value
         if (JSON_HEDLEY_UNLIKELY(pos.m_object != this))
         {
-            JSON_THROW(invalid_iterator::create(202, "iterator does not fit current value", this));
+            JSON_THROW(invalid_iterator::create(detail::exception_id::iterator_from_other_value, "iterator does not fit current value", this));
         }
 
         // copy the values first: ilist may refer to elements of this array
@@ -4779,19 +4788,19 @@ public:
         // insert only works for objects
         if (JSON_HEDLEY_UNLIKELY(!is_object()))
         {
-            JSON_THROW(type_error::create(309, detail::concat("cannot use insert() with ", type_name()), this));
+            detail::throw_cannot_use_with(detail::exception_id::insert_wrong_type, "insert()", *this);
         }
 
         // check if range iterators belong to the same JSON object
         if (JSON_HEDLEY_UNLIKELY(first.m_object != last.m_object))
         {
-            JSON_THROW(invalid_iterator::create(210, "iterators do not fit", this));
+            JSON_THROW(invalid_iterator::create(detail::exception_id::insert_range_incompatible, "iterators do not fit", this));
         }
 
         // passed iterators must belong to objects
         if (JSON_HEDLEY_UNLIKELY(!first.m_object->is_object()))
         {
-            JSON_THROW(invalid_iterator::create(202, "iterators first and last must point to objects", this));
+            JSON_THROW(invalid_iterator::create(detail::exception_id::iterator_from_other_value, "iterators first and last must point to objects", this));
         }
 
         m_data.m_value.object->insert(first.m_it.object_iterator, last.m_it.object_iterator);
@@ -4808,7 +4817,7 @@ public:
         // j, not the copy made below)
         if (JSON_HEDLEY_UNLIKELY(!j.is_object()))
         {
-            JSON_THROW(type_error::create(312, detail::concat("cannot use update() with ", j.type_name()), &j));
+            detail::throw_cannot_use_with(detail::exception_id::update_wrong_type, "update()", j);
         }
 
         // copy first: j may be *this or one of its descendants, and is
@@ -4826,13 +4835,13 @@ public:
         // check if range iterators belong to the same JSON object
         if (JSON_HEDLEY_UNLIKELY(first.m_object != last.m_object))
         {
-            JSON_THROW(invalid_iterator::create(210, "iterators do not fit", this));
+            JSON_THROW(invalid_iterator::create(detail::exception_id::insert_range_incompatible, "iterators do not fit", this));
         }
 
         // passed iterators must belong to objects
         if (JSON_HEDLEY_UNLIKELY(!first.m_object->is_object()))
         {
-            JSON_THROW(type_error::create(312, detail::concat("cannot use update() with ", first.m_object->type_name()), first.m_object));
+            detail::throw_cannot_use_with(detail::exception_id::update_wrong_type, "update()", *first.m_object);
         }
 
         // copy first: the range may belong to *this or one of its
@@ -4868,7 +4877,7 @@ public:
 
         if (JSON_HEDLEY_UNLIKELY(!is_object()))
         {
-            JSON_THROW(type_error::create(312, detail::concat("cannot use update() with ", type_name()), this));
+            detail::throw_cannot_use_with(detail::exception_id::update_wrong_type, "update()", *this);
         }
     }
 
@@ -5031,7 +5040,7 @@ public:
         }
         else
         {
-            JSON_THROW(type_error::create(310, detail::concat("cannot use swap(array_t&) with ", type_name()), this));
+            detail::throw_cannot_use_with(detail::exception_id::swap_wrong_type, "swap(array_t&)", *this);
         }
     }
 
@@ -5048,7 +5057,7 @@ public:
         }
         else
         {
-            JSON_THROW(type_error::create(310, detail::concat("cannot use swap(object_t&) with ", type_name()), this));
+            detail::throw_cannot_use_with(detail::exception_id::swap_wrong_type, "swap(object_t&)", *this);
         }
     }
 
@@ -5064,7 +5073,7 @@ public:
         }
         else
         {
-            JSON_THROW(type_error::create(310, detail::concat("cannot use swap(string_t&) with ", type_name()), this));
+            detail::throw_cannot_use_with(detail::exception_id::swap_wrong_type, "swap(string_t&)", *this);
         }
     }
 
@@ -5080,7 +5089,7 @@ public:
         }
         else
         {
-            JSON_THROW(type_error::create(310, detail::concat("cannot use swap(binary_t&) with ", type_name()), this));
+            detail::throw_cannot_use_with(detail::exception_id::swap_wrong_type, "swap(binary_t&)", *this);
         }
     }
 
@@ -5096,7 +5105,7 @@ public:
         }
         else
         {
-            JSON_THROW(type_error::create(310, detail::concat("cannot use swap(binary_t::container_type&) with ", type_name()), this));
+            detail::throw_cannot_use_with(detail::exception_id::swap_wrong_type, "swap(binary_t::container_type&)", *this);
         }
     }
 
@@ -5689,7 +5698,7 @@ public:
         auto ia = detail::input_adapter(std::forward<InputType>(i));
         return format == input_format_t::json
                ? parser(std::move(ia), nullptr, true, ignore_comments, ignore_trailing_commas).sax_parse(sax, strict)
-               : detail::binary_reader<basic_json, decltype(ia), SAX, true>(std::move(ia), format).sax_parse(sax, strict, tag_handler);
+               : detail::binary_reader<basic_json, decltype(ia), SAX>(std::move(ia), format).sax_parse(sax, strict, tag_handler);
     }
 
     /// @brief generate SAX events (iterator pair, or iterator+sentinel pair for C++20 ranges support)
@@ -5707,7 +5716,7 @@ public:
         auto ia = detail::input_adapter(std::move(first), std::move(last));
         return format == input_format_t::json
                ? parser(std::move(ia), nullptr, true, ignore_comments, ignore_trailing_commas).sax_parse(sax, strict)
-               : detail::binary_reader<basic_json, decltype(ia), SAX, true>(std::move(ia), format).sax_parse(sax, strict, tag_handler);
+               : detail::binary_reader<basic_json, decltype(ia), SAX>(std::move(ia), format).sax_parse(sax, strict, tag_handler);
     }
 
     /// @brief generate SAX events
@@ -5746,7 +5755,7 @@ public:
                // NOLINTNEXTLINE(hicpp-move-const-arg,performance-move-const-arg)
                ? parser(std::move(ia), nullptr, true, ignore_comments, ignore_trailing_commas).sax_parse(sax, strict)
                // NOLINTNEXTLINE(hicpp-move-const-arg,performance-move-const-arg)
-               : detail::binary_reader<basic_json, decltype(ia), SAX, true>(std::move(ia), format).sax_parse(sax, strict, tag_handler);
+               : detail::binary_reader<basic_json, decltype(ia), SAX>(std::move(ia), format).sax_parse(sax, strict, tag_handler);
     }
 #endif
 #if defined(__clang__)
@@ -6558,7 +6567,7 @@ public:
                         if (JSON_HEDLEY_UNLIKELY(idx > parent.size()))
                         {
                             // avoid undefined behavior
-                            JSON_THROW(out_of_range::create(401, detail::concat("array index ", std::to_string(idx), " is out of range"), &parent));
+                            JSON_THROW(out_of_range::create(detail::exception_id::array_index_out_of_range, detail::concat("array index ", std::to_string(idx), " is out of range"), &parent));
                         }
 
                         // default case: insert add offset
@@ -6577,7 +6586,7 @@ public:
                 case value_t::binary:
                 case value_t::discarded:
                 default:
-                    JSON_THROW(out_of_range::create(411, detail::concat("cannot add value: the JSON Patch 'add' target's parent is of type ", parent.type_name(), ", but must be an object or array"), &parent));
+                    JSON_THROW(out_of_range::create(detail::exception_id::patch_add_parent_not_container, detail::concat("cannot add value: the JSON Patch 'add' target's parent is of type ", parent.type_name(), ", but must be an object or array"), &parent));
             }
         };
 
@@ -6600,7 +6609,7 @@ public:
                 }
                 else
                 {
-                    JSON_THROW(out_of_range::create(403, detail::concat("key '", last_path, "' not found"), this));
+                    JSON_THROW(out_of_range::create(detail::exception_id::key_not_found, detail::concat("key '", last_path, "' not found"), this));
                 }
             }
             else if (parent.is_array())
@@ -6612,7 +6621,7 @@ public:
             {
                 // the parent of a "remove" target must be an object or array
                 // (see #5396)
-                JSON_THROW(out_of_range::create(413, detail::concat("cannot remove value: the JSON Patch 'remove' target's parent is of type ", parent.type_name(), ", but must be an object or array"), &parent));
+                JSON_THROW(out_of_range::create(detail::exception_id::patch_remove_parent_not_container, detail::concat("cannot remove value: the JSON Patch 'remove' target's parent is of type ", parent.type_name(), ", but must be an object or array"), &parent));
             }
         };
 
@@ -6643,7 +6652,7 @@ public:
         // type check: top level value must be an array
         if (JSON_HEDLEY_UNLIKELY(!json_patch.is_array()))
         {
-            JSON_THROW(parse_error::create(104, 0, "JSON patch must be an array of objects", &json_patch));
+            JSON_THROW(parse_error::create(detail::exception_id::patch_not_an_array, 0, "JSON patch must be an array of objects", &json_patch));
         }
 
         // iterate and apply the operations
@@ -6664,14 +6673,14 @@ public:
                 if (JSON_HEDLEY_UNLIKELY(it == val.m_data.m_value.object->end()))
                 {
                     // NOLINTNEXTLINE(performance-inefficient-string-concatenation)
-                    JSON_THROW(parse_error::create(105, 0, detail::concat(error_msg, " must have member '", member, "'"), &val));
+                    JSON_THROW(parse_error::create(detail::exception_id::patch_invalid_operation, 0, detail::concat(error_msg, " must have member '", member, "'"), &val));
                 }
 
                 // check if the result is of type string
                 if (JSON_HEDLEY_UNLIKELY(string_type && !it->second.is_string()))
                 {
                     // NOLINTNEXTLINE(performance-inefficient-string-concatenation)
-                    JSON_THROW(parse_error::create(105, 0, detail::concat(error_msg, " must have string member '", member, "'"), &val));
+                    JSON_THROW(parse_error::create(detail::exception_id::patch_invalid_operation, 0, detail::concat(error_msg, " must have string member '", member, "'"), &val));
                 }
 
                 // no error: return value
@@ -6681,7 +6690,7 @@ public:
             // type check: every element of the array must be an object
             if (JSON_HEDLEY_UNLIKELY(!val.is_object()))
             {
-                JSON_THROW(parse_error::create(104, 0, "JSON patch must be an array of objects", &val));
+                JSON_THROW(parse_error::create(detail::exception_id::patch_not_an_array, 0, "JSON patch must be an array of objects", &val));
             }
 
             // collect mandatory members
@@ -6717,7 +6726,7 @@ public:
 
                     if (JSON_HEDLEY_UNLIKELY(is_proper_prefix(from_ptr, ptr)))
                     {
-                        JSON_THROW(out_of_range::create(414, detail::concat("cannot move value: 'from' path '", from_path, "' is a proper prefix of 'path' '", path, "'"), &result));
+                        JSON_THROW(out_of_range::create(detail::exception_id::patch_move_into_child, detail::concat("cannot move value: 'from' path '", from_path, "' is a proper prefix of 'path' '", path, "'"), &result));
                     }
 
                     // the "from" location must exist - use at()
@@ -6764,7 +6773,7 @@ public:
                     // throw an exception if the test fails
                     if (JSON_HEDLEY_UNLIKELY(!success))
                     {
-                        JSON_THROW(other_error::create(501, detail::concat("unsuccessful: ", val.dump()), &val));
+                        JSON_THROW(other_error::create(detail::exception_id::patch_test_failed, detail::concat("unsuccessful: ", val.dump()), &val));
                     }
 
                     break;
@@ -6775,7 +6784,7 @@ public:
                 {
                     // op must be "add", "remove", "replace", "move", "copy", or
                     // "test"
-                    JSON_THROW(parse_error::create(105, 0, detail::concat("operation value '", op, "' is invalid"), &val));
+                    JSON_THROW(parse_error::create(detail::exception_id::patch_invalid_operation, 0, detail::concat("operation value '", op, "' is invalid"), &val));
                 }
             }
         }

include/nlohmann/ordered_map.hpp

@@ -90,6 +90,19 @@ private:
         return self.end();
     }
 
+    /// @brief shared implementation of the const and non-const at() overloads
+    /// @throw std::out_of_range if @a key is not found
+    template<typename Self, typename KeyType>
+    static auto at_impl(Self& self, const KeyType& key) -> decltype((self.begin()->second))
+    {
+        const auto it = find_impl(self, key);
+        if (it == self.end())
+        {
+            JSON_THROW(std::out_of_range("key not found"));
+        }
+        return it->second;
+    }
+
     /// @brief remove the entry @a it points to, preserving order
     /// @note keys are not movable, so the tail is destroyed and re-constructed in place
     void erase_at(iterator it)
@@ -156,46 +169,26 @@ public:
 
     T& at(const key_type& key)
     {
-        const auto it = find_impl(*this, key);
-        if (it == this->end())
-        {
-            JSON_THROW(std::out_of_range("key not found"));
-        }
-        return it->second;
+        return at_impl(*this, key);
     }
 
     template<class KeyType, detail::enable_if_t<
                  detail::is_usable_as_key_type<key_compare, key_type, KeyType>::value, int> = 0>
     T & at(KeyType && key) // NOLINT(cppcoreguidelines-missing-std-forward)
     {
-        const auto it = find_impl(*this, key);
-        if (it == this->end())
-        {
-            JSON_THROW(std::out_of_range("key not found"));
-        }
-        return it->second;
+        return at_impl(*this, key);
     }
 
     const T& at(const key_type& key) const
     {
-        const auto it = find_impl(*this, key);
-        if (it == this->end())
-        {
-            JSON_THROW(std::out_of_range("key not found"));
-        }
-        return it->second;
+        return at_impl(*this, key);
     }
 
     template<class KeyType, detail::enable_if_t<
                  detail::is_usable_as_key_type<key_compare, key_type, KeyType>::value, int> = 0>
     const T & at(KeyType && key) const // NOLINT(cppcoreguidelines-missing-std-forward)
     {
-        const auto it = find_impl(*this, key);
-        if (it == this->end())
-        {
-            JSON_THROW(std::out_of_range("key not found"));
-        }
-        return it->second;
+        return at_impl(*this, key);
     }
 
     size_type erase(const key_type& key)

src/modules/json.cppm

@@ -47,7 +47,6 @@ inline namespace json_literals
 namespace detail
 {
     using NLOHMANN_JSON_NAMESPACE::detail::json_sax_dom_callback_parser;
-    using NLOHMANN_JSON_NAMESPACE::detail::json_sax_dom_parser;
     using NLOHMANN_JSON_NAMESPACE::detail::unknown_size;
 } // namespace detail
 

tests/src/fuzzer-parse_bjdata.cpp

@@ -47,32 +47,11 @@ dumps is stable under exactly the same values that break operator==.
 The unit tests run the same checks on a fixed corpus (see the "BJData round-trip
 invariants" test case), so keep both in sync.
 
-Furthermore, it reads data with a SAX parser that recovers from every error
-and checks that the events are balanced, that reading ends, and that it
-reports an error exactly when from_bjdata() fails (see #3989).
-
 The provided function `LLVMFuzzerTestOneInput` can be used in different fuzzer
 drivers.
 */
 
-#include <cassert>
-#include <nlohmann/json.hpp>
-
-// the round-trip checks below are assertions; NDEBUG would compile them away
-#ifdef NDEBUG
-    #error "the fuzzer drivers must be built without NDEBUG"
-#endif
-
-#include "fuzzer-recovering_checker.hpp"
-
-using json = nlohmann::json;
-
-// compares dumps rather than values, because NaN != NaN; keep writes strings
-// byte for byte, so ill-formed UTF-8 that a binary reader accepts cannot throw
-static bool same_value(const json& lhs, const json& rhs)
-{
-    return lhs.dump(-1, ' ', false, json::error_handler_t::keep) == rhs.dump(-1, ' ', false, json::error_handler_t::keep);
-}
+#include "fuzzer_common.hpp"
 
 // value-stable comparison for the round-trip checks below; see the note
 // above on why this compares dump()s rather than the json values directly
@@ -84,28 +63,11 @@ static bool is_value_stable(const json& lhs, const json& rhs)
 // see http://llvm.org/docs/LibFuzzer.html
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
 {
-    // recover from all errors, reading from memory and from a stream
-    const bool recovered_without_errors = check_recovering_parse(data, size, json::input_format_t::bjdata).errors == 0;
-
     std::vector<uint8_t> const vec1(data, data + size);
 
-    // step 0: parse input without exceptions; a parse error must then be
-    // reported as a discarded value, never thrown
-    json j_noexcept;
+    // step 0: parse input without exceptions
     bool noexcept_threw = false;
-    try
-    {
-        j_noexcept = json::from_bjdata(vec1, true, false);
-    }
-    catch (const json::parse_error&)
-    {
-        assert(false);
-    }
-    catch (const json::exception&)
-    {
-        // type and out-of-range errors are not parse errors and still throw
-        noexcept_threw = true;
-    }
+    json const j_noexcept = parse_without_exceptions([&] { return json::from_bjdata(vec1, true, false); }, noexcept_threw);
     // whether step 1 succeeded; if not, the catch blocks below check that
     // step 0 failed, too
     bool parsed = false;
@@ -119,9 +81,6 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
         // without exceptions, the same input must give the same value
         assert(!noexcept_threw && !j_noexcept.is_discarded() && same_value(j_noexcept, j1));
 
-        // the recovering parser must not have reported an error either
-        assert(recovered_without_errors);
-
         try
         {
             // step 2.1: round trip without adding size annotations to container types
@@ -155,7 +114,6 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
     {
         // parse errors are ok, because input may be random bytes
         assert(parsed || noexcept_threw || j_noexcept.is_discarded());
-        assert(parsed || !recovered_without_errors);
     }
     catch (const json::type_error&)
     {
@@ -166,7 +124,6 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
     {
         // out of range errors may happen if provided sizes are excessive
         assert(parsed || noexcept_threw || j_noexcept.is_discarded());
-        assert(parsed || !recovered_without_errors);
     }
 
     // return 0 - non-zero return values are reserved for future use

tests/src/fuzzer-parse_bon8.cpp

@@ -21,33 +21,12 @@ It also checks that reading the data from a stream, which reads strings byte by
 byte, gives the same value or error as reading it from contiguous memory, which
 copies strings in bulk.
 
-Furthermore, it reads data with a SAX parser that recovers from every error
-and checks that the events are balanced, that reading ends, and that it
-reports an error exactly when from_bon8() fails (see #3989).
-
 The provided function `LLVMFuzzerTestOneInput` can be used in different fuzzer
 drivers.
 */
 
-#include <cassert>
 #include <sstream>
-#include <nlohmann/json.hpp>
-
-// the round-trip checks below are assertions; NDEBUG would compile them away
-#ifdef NDEBUG
-    #error "the fuzzer drivers must be built without NDEBUG"
-#endif
-
-#include "fuzzer-recovering_checker.hpp"
-
-using json = nlohmann::json;
-
-// compares dumps rather than values, because NaN != NaN; keep writes strings
-// byte for byte, so ill-formed UTF-8 that a binary reader accepts cannot throw
-static bool same_value(const json& lhs, const json& rhs)
-{
-    return lhs.dump(-1, ' ', false, json::error_handler_t::keep) == rhs.dump(-1, ' ', false, json::error_handler_t::keep);
-}
+#include "fuzzer_common.hpp"
 
 namespace
 {
@@ -70,9 +49,6 @@ std::string read_bon8(InputType&& input)
 // see http://llvm.org/docs/LibFuzzer.html
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
 {
-    // recover from all errors, reading from memory and from a stream
-    const bool recovered_without_errors = check_recovering_parse(data, size, json::input_format_t::bon8).errors == 0;
-
     // contiguous and stream input must be read alike
     {
         std::istringstream stream(std::string(reinterpret_cast<const char*>(data), size));
@@ -81,23 +57,9 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
 
     std::vector<uint8_t> const vec1(data, data + size);
 
-    // step 0: parse input without exceptions; a parse error must then be
-    // reported as a discarded value, never thrown
-    json j_noexcept;
+    // step 0: parse input without exceptions
     bool noexcept_threw = false;
-    try
-    {
-        j_noexcept = json::from_bon8(vec1, true, false);
-    }
-    catch (const json::parse_error&)
-    {
-        assert(false);
-    }
-    catch (const json::exception&)
-    {
-        // type and out-of-range errors are not parse errors and still throw
-        noexcept_threw = true;
-    }
+    json const j_noexcept = parse_without_exceptions([&] { return json::from_bon8(vec1, true, false); }, noexcept_threw);
     // whether step 1 succeeded; if not, the catch blocks below check that
     // step 0 failed, too
     bool parsed = false;
@@ -111,9 +73,6 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
         // without exceptions, the same input must give the same value
         assert(!noexcept_threw && !j_noexcept.is_discarded() && same_value(j_noexcept, j1));
 
-        // the recovering parser must not have reported an error either
-        assert(recovered_without_errors);
-
         try
         {
             // step 2: round trip
@@ -135,7 +94,6 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
     {
         // parse errors are ok, because input may be random bytes
         assert(parsed || noexcept_threw || j_noexcept.is_discarded());
-        assert(parsed || !recovered_without_errors);
     }
     catch (const json::type_error&)
     {
@@ -146,7 +104,6 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
     {
         // out of range errors may happen if provided sizes are excessive
         assert(parsed || noexcept_threw || j_noexcept.is_discarded());
-        assert(parsed || !recovered_without_errors);
     }
 
     // return 0 - non-zero return values are reserved for future use

tests/src/fuzzer-parse_bson.cpp

@@ -17,58 +17,20 @@ array data, it performs the following steps:
 - j2 = from_bson(vec)
 - assert(to_bson(j2) == vec)
 
-Furthermore, it reads data with a SAX parser that recovers from every error
-and checks that the events are balanced, that reading ends, and that it
-reports an error exactly when from_bson() fails (see #3989).
-
 The provided function `LLVMFuzzerTestOneInput` can be used in different fuzzer
 drivers.
 */
 
-#include <cassert>
-#include <nlohmann/json.hpp>
-
-// the round-trip checks below are assertions; NDEBUG would compile them away
-#ifdef NDEBUG
-    #error "the fuzzer drivers must be built without NDEBUG"
-#endif
-
-#include "fuzzer-recovering_checker.hpp"
-
-using json = nlohmann::json;
-
-// compares dumps rather than values, because NaN != NaN; keep writes strings
-// byte for byte, so ill-formed UTF-8 that a binary reader accepts cannot throw
-static bool same_value(const json& lhs, const json& rhs)
-{
-    return lhs.dump(-1, ' ', false, json::error_handler_t::keep) == rhs.dump(-1, ' ', false, json::error_handler_t::keep);
-}
+#include "fuzzer_common.hpp"
 
 // see http://llvm.org/docs/LibFuzzer.html
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
 {
-    // recover from all errors, reading from memory and from a stream
-    const bool recovered_without_errors = check_recovering_parse(data, size, json::input_format_t::bson).errors == 0;
-
     std::vector<uint8_t> const vec1(data, data + size);
 
-    // step 0: parse input without exceptions; a parse error must then be
-    // reported as a discarded value, never thrown
-    json j_noexcept;
+    // step 0: parse input without exceptions
     bool noexcept_threw = false;
-    try
-    {
-        j_noexcept = json::from_bson(vec1, true, false);
-    }
-    catch (const json::parse_error&)
-    {
-        assert(false);
-    }
-    catch (const json::exception&)
-    {
-        // type and out-of-range errors are not parse errors and still throw
-        noexcept_threw = true;
-    }
+    json const j_noexcept = parse_without_exceptions([&] { return json::from_bson(vec1, true, false); }, noexcept_threw);
     // whether step 1 succeeded; if not, the catch blocks below check that
     // step 0 failed, too
     bool parsed = false;
@@ -82,9 +44,6 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
         // without exceptions, the same input must give the same value
         assert(!noexcept_threw && !j_noexcept.is_discarded() && same_value(j_noexcept, j1));
 
-        // the recovering parser must not have reported an error either
-        assert(recovered_without_errors);
-
         try
         {
             // step 2: round trip
@@ -106,7 +65,6 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
     {
         // parse errors are ok, because input may be random bytes
         assert(parsed || noexcept_threw || j_noexcept.is_discarded());
-        assert(parsed || !recovered_without_errors);
     }
     catch (const json::type_error&)
     {
@@ -117,7 +75,6 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
     {
         // out of range errors can occur during parsing, too
         assert(parsed || noexcept_threw || j_noexcept.is_discarded());
-        assert(parsed || !recovered_without_errors);
     }
 
     // return 0 - non-zero return values are reserved for future use

tests/src/fuzzer-parse_cbor.cpp

@@ -17,58 +17,20 @@ array data, it performs the following steps:
 - j2 = from_cbor(vec)
 - assert(to_cbor(j2) == vec)
 
-Furthermore, it reads data with a SAX parser that recovers from every error
-and checks that the events are balanced, that reading ends, and that it
-reports an error exactly when from_cbor() fails (see #3989).
-
 The provided function `LLVMFuzzerTestOneInput` can be used in different fuzzer
 drivers.
 */
 
-#include <cassert>
-#include <nlohmann/json.hpp>
-
-// the round-trip checks below are assertions; NDEBUG would compile them away
-#ifdef NDEBUG
-    #error "the fuzzer drivers must be built without NDEBUG"
-#endif
-
-#include "fuzzer-recovering_checker.hpp"
-
-using json = nlohmann::json;
-
-// compares dumps rather than values, because NaN != NaN; keep writes strings
-// byte for byte, so ill-formed UTF-8 that a binary reader accepts cannot throw
-static bool same_value(const json& lhs, const json& rhs)
-{
-    return lhs.dump(-1, ' ', false, json::error_handler_t::keep) == rhs.dump(-1, ' ', false, json::error_handler_t::keep);
-}
+#include "fuzzer_common.hpp"
 
 // see http://llvm.org/docs/LibFuzzer.html
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
 {
-    // recover from all errors, reading from memory and from a stream
-    const bool recovered_without_errors = check_recovering_parse(data, size, json::input_format_t::cbor).errors == 0;
-
     std::vector<uint8_t> const vec1(data, data + size);
 
-    // step 0: parse input without exceptions; a parse error must then be
-    // reported as a discarded value, never thrown
-    json j_noexcept;
+    // step 0: parse input without exceptions
     bool noexcept_threw = false;
-    try
-    {
-        j_noexcept = json::from_cbor(vec1, true, false);
-    }
-    catch (const json::parse_error&)
-    {
-        assert(false);
-    }
-    catch (const json::exception&)
-    {
-        // type and out-of-range errors are not parse errors and still throw
-        noexcept_threw = true;
-    }
+    json const j_noexcept = parse_without_exceptions([&] { return json::from_cbor(vec1, true, false); }, noexcept_threw);
     // whether step 1 succeeded; if not, the catch blocks below check that
     // step 0 failed, too
     bool parsed = false;
@@ -82,9 +44,6 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
         // without exceptions, the same input must give the same value
         assert(!noexcept_threw && !j_noexcept.is_discarded() && same_value(j_noexcept, j1));
 
-        // the recovering parser must not have reported an error either
-        assert(recovered_without_errors);
-
         try
         {
             // step 2: round trip
@@ -106,7 +65,6 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
     {
         // parse errors are ok, because input may be random bytes
         assert(parsed || noexcept_threw || j_noexcept.is_discarded());
-        assert(parsed || !recovered_without_errors);
     }
     catch (const json::type_error&)
     {
@@ -117,7 +75,6 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
     {
         // out of range errors can occur during parsing, too
         assert(parsed || noexcept_threw || j_noexcept.is_discarded());
-        assert(parsed || !recovered_without_errors);
     }
 
     // return 0 - non-zero return values are reserved for future use

tests/src/fuzzer-parse_json.cpp

@@ -18,60 +18,18 @@ array data, it performs the following steps:
 - s2 = serialize(j2)
 - assert(s1 == s2)
 
-Furthermore, it parses data with a SAX parser that recovers from every error
-and checks that the events are balanced, that parsing ends, and that valid
-input is parsed without errors (see #3989).
-
 The provided function `LLVMFuzzerTestOneInput` can be used in different fuzzer
 drivers.
 */
 
-#include <cassert>
-#include <nlohmann/json.hpp>
-
-// the round-trip checks below are assertions; NDEBUG would compile them away
-#ifdef NDEBUG
-    #error "the fuzzer drivers must be built without NDEBUG"
-#endif
-
-#include "fuzzer-recovering_checker.hpp"
-
-using json = nlohmann::json;
-
-// compares dumps rather than values, because NaN != NaN; keep writes strings
-// byte for byte, so ill-formed UTF-8 that a binary reader accepts cannot throw
-static bool same_value(const json& lhs, const json& rhs)
-{
-    return lhs.dump(-1, ' ', false, json::error_handler_t::keep) == rhs.dump(-1, ' ', false, json::error_handler_t::keep);
-}
+#include "fuzzer_common.hpp"
 
 // see http://llvm.org/docs/LibFuzzer.html
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
 {
-    // recover from all errors, reading from memory and from a stream
-    {
-        const auto checker = check_recovering_parse(data, size, json::input_format_t::json);
-        assert(checker.events <= (4 * size) + 4);
-        assert((checker.errors == 0) == json::accept(data, data + size));
-    }
-
-    // step 0: parse input without exceptions; a parse error must then be
-    // reported as a discarded value, never thrown
-    json j_noexcept;
+    // step 0: parse input without exceptions
     bool noexcept_threw = false;
-    try
-    {
-        j_noexcept = json::parse(data, data + size, nullptr, false);
-    }
-    catch (const json::parse_error&)
-    {
-        assert(false);
-    }
-    catch (const json::exception&)
-    {
-        // type and out-of-range errors are not parse errors and still throw
-        noexcept_threw = true;
-    }
+    json const j_noexcept = parse_without_exceptions([&] { return json::parse(data, data + size, nullptr, false); }, noexcept_threw);
     // whether step 1 succeeded; if not, the catch blocks below check that
     // step 0 failed, too
     bool parsed = false;

tests/src/fuzzer-parse_msgpack.cpp

@@ -17,58 +17,20 @@ array data, it performs the following steps:
 - j2 = from_msgpack(vec)
 - assert(to_msgpack(j2) == vec)
 
-Furthermore, it reads data with a SAX parser that recovers from every error
-and checks that the events are balanced, that reading ends, and that it
-reports an error exactly when from_msgpack() fails (see #3989).
-
 The provided function `LLVMFuzzerTestOneInput` can be used in different fuzzer
 drivers.
 */
 
-#include <cassert>
-#include <nlohmann/json.hpp>
-
-// the round-trip checks below are assertions; NDEBUG would compile them away
-#ifdef NDEBUG
-    #error "the fuzzer drivers must be built without NDEBUG"
-#endif
-
-#include "fuzzer-recovering_checker.hpp"
-
-using json = nlohmann::json;
-
-// compares dumps rather than values, because NaN != NaN; keep writes strings
-// byte for byte, so ill-formed UTF-8 that a binary reader accepts cannot throw
-static bool same_value(const json& lhs, const json& rhs)
-{
-    return lhs.dump(-1, ' ', false, json::error_handler_t::keep) == rhs.dump(-1, ' ', false, json::error_handler_t::keep);
-}
+#include "fuzzer_common.hpp"
 
 // see http://llvm.org/docs/LibFuzzer.html
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
 {
-    // recover from all errors, reading from memory and from a stream
-    const bool recovered_without_errors = check_recovering_parse(data, size, json::input_format_t::msgpack).errors == 0;
-
     std::vector<uint8_t> const vec1(data, data + size);
 
-    // step 0: parse input without exceptions; a parse error must then be
-    // reported as a discarded value, never thrown
-    json j_noexcept;
+    // step 0: parse input without exceptions
     bool noexcept_threw = false;
-    try
-    {
-        j_noexcept = json::from_msgpack(vec1, true, false);
-    }
-    catch (const json::parse_error&)
-    {
-        assert(false);
-    }
-    catch (const json::exception&)
-    {
-        // type and out-of-range errors are not parse errors and still throw
-        noexcept_threw = true;
-    }
+    json const j_noexcept = parse_without_exceptions([&] { return json::from_msgpack(vec1, true, false); }, noexcept_threw);
     // whether step 1 succeeded; if not, the catch blocks below check that
     // step 0 failed, too
     bool parsed = false;
@@ -82,9 +44,6 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
         // without exceptions, the same input must give the same value
         assert(!noexcept_threw && !j_noexcept.is_discarded() && same_value(j_noexcept, j1));
 
-        // the recovering parser must not have reported an error either
-        assert(recovered_without_errors);
-
         try
         {
             // step 2: round trip
@@ -106,7 +65,6 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
     {
         // parse errors are ok, because input may be random bytes
         assert(parsed || noexcept_threw || j_noexcept.is_discarded());
-        assert(parsed || !recovered_without_errors);
     }
     catch (const json::type_error&)
     {
@@ -117,7 +75,6 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
     {
         // out of range errors may happen if provided sizes are excessive
         assert(parsed || noexcept_threw || j_noexcept.is_discarded());
-        assert(parsed || !recovered_without_errors);
     }
 
     // return 0 - non-zero return values are reserved for future use

tests/src/fuzzer-parse_ubjson.cpp

@@ -26,58 +26,20 @@ array data, it performs the following steps:
 The unit tests run the same checks on a fixed corpus (see the "UBJSON round-trip
 invariants" test case), so keep both in sync.
 
-Furthermore, it reads data with a SAX parser that recovers from every error
-and checks that the events are balanced, that reading ends, and that it
-reports an error exactly when from_ubjson() fails (see #3989).
-
 The provided function `LLVMFuzzerTestOneInput` can be used in different fuzzer
 drivers.
 */
 
-#include <cassert>
-#include <nlohmann/json.hpp>
-
-// the round-trip checks below are assertions; NDEBUG would compile them away
-#ifdef NDEBUG
-    #error "the fuzzer drivers must be built without NDEBUG"
-#endif
-
-#include "fuzzer-recovering_checker.hpp"
-
-using json = nlohmann::json;
-
-// compares dumps rather than values, because NaN != NaN; keep writes strings
-// byte for byte, so ill-formed UTF-8 that a binary reader accepts cannot throw
-static bool same_value(const json& lhs, const json& rhs)
-{
-    return lhs.dump(-1, ' ', false, json::error_handler_t::keep) == rhs.dump(-1, ' ', false, json::error_handler_t::keep);
-}
+#include "fuzzer_common.hpp"
 
 // see http://llvm.org/docs/LibFuzzer.html
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
 {
-    // recover from all errors, reading from memory and from a stream
-    const bool recovered_without_errors = check_recovering_parse(data, size, json::input_format_t::ubjson).errors == 0;
-
     std::vector<uint8_t> const vec1(data, data + size);
 
-    // step 0: parse input without exceptions; a parse error must then be
-    // reported as a discarded value, never thrown
-    json j_noexcept;
+    // step 0: parse input without exceptions
     bool noexcept_threw = false;
-    try
-    {
-        j_noexcept = json::from_ubjson(vec1, true, false);
-    }
-    catch (const json::parse_error&)
-    {
-        assert(false);
-    }
-    catch (const json::exception&)
-    {
-        // type and out-of-range errors are not parse errors and still throw
-        noexcept_threw = true;
-    }
+    json const j_noexcept = parse_without_exceptions([&] { return json::from_ubjson(vec1, true, false); }, noexcept_threw);
     // whether step 1 succeeded; if not, the catch blocks below check that
     // step 0 failed, too
     bool parsed = false;
@@ -91,9 +53,6 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
         // without exceptions, the same input must give the same value
         assert(!noexcept_threw && !j_noexcept.is_discarded() && same_value(j_noexcept, j1));
 
-        // the recovering parser must not have reported an error either
-        assert(recovered_without_errors);
-
         try
         {
             // step 2.1: round trip without adding size annotations to container types
@@ -125,7 +84,6 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
     {
         // parse errors are ok, because input may be random bytes
         assert(parsed || noexcept_threw || j_noexcept.is_discarded());
-        assert(parsed || !recovered_without_errors);
     }
     catch (const json::type_error&)
     {
@@ -136,7 +94,6 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size)
     {
         // out of range errors may happen if provided sizes are excessive
         assert(parsed || noexcept_threw || j_noexcept.is_discarded());
-        assert(parsed || !recovered_without_errors);
     }
 
     // return 0 - non-zero return values are reserved for future use

tests/src/fuzzer-recovering_checker.hpp

@@ -1,154 +0,0 @@
-//     __ _____ _____ _____
-//  __|  |   __|     |   | |  JSON for Modern C++ (supporting code)
-// |  |  |__   |  |  | | | |  version 3.12.0
-// |_____|_____|_____|_|___|  https://github.com/nlohmann/json
-//
-// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
-// SPDX-License-Identifier: MIT
-
-#pragma once
-
-#include <cassert>
-#include <cstddef>
-#include <cstdint>
-#include <sstream>
-#include <string>
-#include <vector>
-#include <nlohmann/json.hpp>
-
-namespace
-{
-// a SAX parser that recovers from every error and checks that the events are
-// balanced and that every key is followed by exactly one value
-class recovering_checker : public nlohmann::json_sax<nlohmann::json>
-{
-  public:
-    bool null() override
-    {
-        return value();
-    }
-
-    bool boolean(bool /*val*/) override
-    {
-        return value();
-    }
-
-    bool number_integer(number_integer_t /*val*/) override
-    {
-        return value();
-    }
-
-    bool number_unsigned(number_unsigned_t /*val*/) override
-    {
-        return value();
-    }
-
-    bool number_float(number_float_t /*val*/, const string_t& /*s*/) override
-    {
-        return value();
-    }
-
-    bool string(string_t& /*val*/) override
-    {
-        return value();
-    }
-
-    bool binary(binary_t& /*val*/) override
-    {
-        return value();
-    }
-
-    bool start_object(std::size_t /*elements*/) override
-    {
-        value();
-        stack.push_back('o');
-        return true;
-    }
-
-    bool key(string_t& /*val*/) override
-    {
-        ++events;
-        assert(!stack.empty() && stack.back() == 'o');
-        stack.back() = 'v';
-        return true;
-    }
-
-    bool end_object() override
-    {
-        ++events;
-        assert(!stack.empty() && stack.back() == 'o');
-        stack.pop_back();
-        return true;
-    }
-
-    bool start_array(std::size_t /*elements*/) override
-    {
-        value();
-        stack.push_back('a');
-        return true;
-    }
-
-    bool end_array() override
-    {
-        ++events;
-        assert(!stack.empty() && stack.back() == 'a');
-        stack.pop_back();
-        return true;
-    }
-
-    bool parse_error(std::size_t /*position*/, const std::string& /*last_token*/, const nlohmann::detail::exception& /*ex*/) override
-    {
-        ++errors;
-        return true;
-    }
-
-    bool complete() const
-    {
-        return stack.empty();
-    }
-
-    std::size_t events = 0;
-    std::size_t errors = 0;
-
-  private:
-    bool value()
-    {
-        ++events;
-        if (!stack.empty())
-        {
-            // an array element, or the value of a key
-            assert(stack.back() != 'o');
-            if (stack.back() == 'v')
-            {
-                stack.back() = 'o';
-            }
-        }
-        return true;
-    }
-
-    // 'a' for an array, 'o' for an object that expects a key, 'v' for an
-    // object that expects the value of a key
-    std::vector<char> stack {}; // NOLINT(readability-redundant-member-init)
-};
-
-/// parses @a data with a recovering_checker from memory and from a stream,
-/// checks that both see the same, that the events are balanced, and that the
-/// number of errors is bounded, and returns the checker (see #3989)
-inline recovering_checker check_recovering_parse(const std::uint8_t* data, const std::size_t size, const nlohmann::json::input_format_t format)
-{
-    recovering_checker checker;
-    const bool ok = nlohmann::json::sax_parse(data, data + size, &checker, format);
-    assert(checker.complete());
-    assert(checker.errors <= size + 1);
-    assert(ok == (checker.errors == 0));
-
-    std::istringstream stream(std::string(reinterpret_cast<const char*>(data), size));
-    recovering_checker stream_checker;
-    assert(nlohmann::json::sax_parse(stream, &stream_checker, format) == ok);
-    assert(stream_checker.complete());
-    assert(stream_checker.events == checker.events);
-    assert(stream_checker.errors == checker.errors);
-
-    return checker;
-}
-} // namespace

tests/src/fuzzer_common.hpp

@@ -0,0 +1,51 @@
+//     __ _____ _____ _____
+//  __|  |   __|     |   | |  JSON for Modern C++ (supporting code)
+// |  |  |__   |  |  | | | |  version 3.12.0
+// |_____|_____|_____|_|___|  https://github.com/nlohmann/json
+//
+// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
+// SPDX-License-Identifier: MIT
+
+// code shared by the fuzzer drivers tests/src/fuzzer-parse_*.cpp
+
+#pragma once
+
+#include <cassert> // assert
+#include <nlohmann/json.hpp>
+
+using nlohmann::json; // NOLINT(google-global-names-in-headers): shared by all fuzzer drivers
+
+// the round-trip checks of the drivers are assertions; NDEBUG would compile them away
+#ifdef NDEBUG
+    #error "the fuzzer drivers must be built without NDEBUG"
+#endif
+
+// compares dumps rather than values, because NaN != NaN; keep writes strings
+// byte for byte, so ill-formed UTF-8 that a binary reader accepts cannot throw
+inline bool same_value(const json& lhs, const json& rhs)
+{
+    return lhs.dump(-1, ' ', false, json::error_handler_t::keep) == rhs.dump(-1, ' ', false, json::error_handler_t::keep);
+}
+
+// step 0 of each driver: parse the input without exceptions; a parse error
+// must then be reported as a discarded value, never thrown. Type and
+// out-of-range errors are not parse errors and still throw; then @a threw is
+// set and null is returned.
+template<typename Parse>
+json parse_without_exceptions(Parse parse, bool& threw)
+{
+    threw = false;
+    try
+    {
+        return parse();
+    }
+    catch (const json::parse_error&)
+    {
+        assert(false);
+    }
+    catch (const json::exception&)
+    {
+        threw = true;
+    }
+    return {};
+}

tests/src/sax_event_loggers.hpp

@@ -0,0 +1,174 @@
+//     __ _____ _____ _____
+//  __|  |   __|     |   | |  JSON for Modern C++ (supporting code)
+// |  |  |__   |  |  | | | |  version 3.12.0
+// |_____|_____|_____|_|___|  https://github.com/nlohmann/json
+//
+// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
+// SPDX-License-Identifier: MIT
+
+#pragma once
+
+#include <cstddef> // size_t
+#include <cstdint> // uint8_t (via json::binary_t)
+#include <limits> // numeric_limits
+#include <string> // string, to_string
+#include <vector> // vector
+
+#include <nlohmann/json.hpp>
+
+namespace utils
+{
+/// a SAX event consumer that records every event it receives as a
+/// human-readable string, used by the deserialization tests to check the
+/// exact sequence of SAX events a parse run produces
+struct SaxEventLogger : public nlohmann::json_sax<nlohmann::json>
+{
+    using json = nlohmann::json;
+
+    bool null() override
+    {
+        events.emplace_back("null()");
+        return true;
+    }
+
+    bool boolean(bool val) override
+    {
+        events.emplace_back(val ? "boolean(true)" : "boolean(false)");
+        return true;
+    }
+
+    bool number_integer(json::number_integer_t val) override
+    {
+        events.push_back("number_integer(" + std::to_string(val) + ")");
+        return true;
+    }
+
+    bool number_unsigned(json::number_unsigned_t val) override
+    {
+        events.push_back("number_unsigned(" + std::to_string(val) + ")");
+        return true;
+    }
+
+    bool number_float(json::number_float_t /*val*/, const std::string& s) override
+    {
+        events.push_back("number_float(" + s + ")");
+        return true;
+    }
+
+    bool string(std::string& val) override
+    {
+        events.push_back("string(" + val + ")");
+        return true;
+    }
+
+    bool binary(json::binary_t& val) override
+    {
+        std::string binary_contents = "binary(";
+        std::string comma_space;
+        for (const auto b : val)
+        {
+            binary_contents.append(comma_space);
+            binary_contents.append(std::to_string(static_cast<int>(b)));
+            comma_space = ", ";
+        }
+        binary_contents.append(")");
+        events.push_back(binary_contents);
+        return true;
+    }
+
+    bool start_object(std::size_t elements) override
+    {
+        if (elements == (std::numeric_limits<std::size_t>::max)())
+        {
+            events.emplace_back("start_object()");
+        }
+        else
+        {
+            events.push_back("start_object(" + std::to_string(elements) + ")");
+        }
+        return true;
+    }
+
+    bool key(std::string& val) override
+    {
+        events.push_back("key(" + val + ")");
+        return true;
+    }
+
+    bool end_object() override
+    {
+        events.emplace_back("end_object()");
+        return true;
+    }
+
+    bool start_array(std::size_t elements) override
+    {
+        if (elements == (std::numeric_limits<std::size_t>::max)())
+        {
+            events.emplace_back("start_array()");
+        }
+        else
+        {
+            events.push_back("start_array(" + std::to_string(elements) + ")");
+        }
+        return true;
+    }
+
+    bool end_array() override
+    {
+        events.emplace_back("end_array()");
+        return true;
+    }
+
+    bool parse_error(std::size_t position, const std::string& /*last_token*/, const json::exception& /*ex*/) override
+    {
+        errored = true;
+        events.push_back("parse_error(" + std::to_string(position) + ")");
+        return false;
+    }
+
+    std::vector<std::string> events {}; // NOLINT(readability-redundant-member-init)
+    bool errored = false;
+};
+
+struct SaxEventLoggerExitAfterStartObject : public SaxEventLogger
+{
+    bool start_object(std::size_t elements) override
+    {
+        if (elements == (std::numeric_limits<std::size_t>::max)())
+        {
+            events.emplace_back("start_object()");
+        }
+        else
+        {
+            events.push_back("start_object(" + std::to_string(elements) + ")");
+        }
+        return false;
+    }
+};
+
+struct SaxEventLoggerExitAfterKey : public SaxEventLogger
+{
+    bool key(std::string& val) override
+    {
+        events.push_back("key(" + val + ")");
+        return false;
+    }
+};
+
+struct SaxEventLoggerExitAfterStartArray : public SaxEventLogger
+{
+    bool start_array(std::size_t elements) override
+    {
+        if (elements == (std::numeric_limits<std::size_t>::max)())
+        {
+            events.emplace_back("start_array()");
+        }
+        else
+        {
+            events.push_back("start_array(" + std::to_string(elements) + ")");
+        }
+        return false;
+    }
+};
+} // namespace utils

tests/src/unit-alt-string.cpp

@@ -415,46 +415,6 @@ TEST_CASE("alternative string type")
         CHECK(j2.dump() == R"({"/foo/0":"bar","/foo/1":"baz"})");
     }
 
-    SECTION("error recovery")
-    {
-        // a SAX parser that recovers from every error (see #3989)
-        struct recovering_parser : nlohmann::detail::json_sax_dom_parser<alt_json>
-        {
-            explicit recovering_parser(alt_json& j)
-                : nlohmann::detail::json_sax_dom_parser<alt_json>(j, false)
-            {}
-
-            // sax_parse() calls the SAX parser's own parse_error(), so hiding
-            // the one of the base class is what recovering takes
-            // NOLINTNEXTLINE(bugprone-derived-method-shadowing-base-method)
-            bool parse_error(std::size_t /*unused*/, const std::string& /*unused*/, const nlohmann::detail::exception& /*unused*/)
-            {
-                ++errors;
-                return true;
-            }
-
-            std::size_t errors = 0;
-        };
-
-        alt_json j;
-        recovering_parser sax(j);
-        // not inside CHECK(): MSVC reads the escape in a stringized raw string
-        const std::string input = R"([1., "a\qb", tru, {"k" 2}])";
-        CHECK(!alt_json::sax_parse(input, &sax));
-        CHECK(sax.errors == 4);
-        CHECK(j.dump() == R"([1,"aqb",null,{"k":2}])");
-
-        // a UBJSON high-precision number, a CBOR key that is not a string
-        alt_json u;
-        recovering_parser ubjson_sax(u);
-        CHECK(!alt_json::sax_parse(std::vector<std::uint8_t> {'[', 'H', 'i', 2, '1', '.', ']'}, &ubjson_sax, alt_json::input_format_t::ubjson));
-        CHECK(u.dump() == "[1]");
-        alt_json c;
-        recovering_parser cbor_sax(c);
-        CHECK(!alt_json::sax_parse(std::vector<std::uint8_t> {0xA2, 0x01, 0x02, 0x61, 'a', 0x03}, &cbor_sax, alt_json::input_format_t::cbor));
-        CHECK(c.dump() == R"({"a":3})");
-    }
-
     SECTION("conversion between basic_json specializations (#2649)")
     {
         // explicit conversions are always possible

tests/src/unit-class_parser.cpp

@@ -37,196 +37,15 @@ using nlohmann::json;
 #include <utility>
 #include <vector>
 
+#include "sax_countdown.hpp"
+#include "sax_event_loggers.hpp"
 #include "test_utils.hpp"
 
+using utils::SaxCountdown;
+using utils::SaxEventLogger;
+
 namespace
 {
-class SaxEventLogger
-{
-  public:
-    bool null()
-    {
-        events.emplace_back("null()");
-        return true;
-    }
-
-    bool boolean(bool val)
-    {
-        events.emplace_back(val ? "boolean(true)" : "boolean(false)");
-        return true;
-    }
-
-    bool number_integer(json::number_integer_t val)
-    {
-        events.push_back("number_integer(" + std::to_string(val) + ")");
-        return true;
-    }
-
-    bool number_unsigned(json::number_unsigned_t val)
-    {
-        events.push_back("number_unsigned(" + std::to_string(val) + ")");
-        return true;
-    }
-
-    bool number_float(json::number_float_t /*unused*/, const std::string& s)
-    {
-        events.push_back("number_float(" + s + ")");
-        return true;
-    }
-
-    bool string(std::string& val)
-    {
-        events.push_back("string(" + val + ")");
-        return true;
-    }
-
-    bool binary(json::binary_t& val)
-    {
-        std::string binary_contents = "binary(";
-        std::string comma_space;
-        for (auto b : val)
-        {
-            binary_contents.append(comma_space);
-            binary_contents.append(std::to_string(static_cast<int>(b)));
-            comma_space = ", ";
-        }
-        binary_contents.append(")");
-        events.push_back(binary_contents);
-        return true;
-    }
-
-    bool start_object(std::size_t elements)
-    {
-        if (elements == (std::numeric_limits<std::size_t>::max)())
-        {
-            events.emplace_back("start_object()");
-        }
-        else
-        {
-            events.push_back("start_object(" + std::to_string(elements) + ")");
-        }
-        return true;
-    }
-
-    bool key(std::string& val)
-    {
-        events.push_back("key(" + val + ")");
-        return true;
-    }
-
-    bool end_object()
-    {
-        events.emplace_back("end_object()");
-        return true;
-    }
-
-    bool start_array(std::size_t elements)
-    {
-        if (elements == (std::numeric_limits<std::size_t>::max)())
-        {
-            events.emplace_back("start_array()");
-        }
-        else
-        {
-            events.push_back("start_array(" + std::to_string(elements) + ")");
-        }
-        return true;
-    }
-
-    bool end_array()
-    {
-        events.emplace_back("end_array()");
-        return true;
-    }
-
-    bool parse_error(std::size_t position, const std::string& /*unused*/, const json::exception& /*unused*/)
-    {
-        errored = true;
-        events.push_back("parse_error(" + std::to_string(position) + ")");
-        return recover;
-    }
-
-    std::vector<std::string> events {}; // NOLINT(readability-redundant-member-init)
-    bool errored = false;
-    /// whether parse_error() asks the parser to recover from the error (see #3989)
-    bool recover = false;
-};
-
-class SaxCountdown : public nlohmann::json::json_sax_t
-{
-  public:
-    explicit SaxCountdown(const int count) : events_left(count)
-    {}
-
-    bool null() override
-    {
-        return events_left-- > 0;
-    }
-
-    bool boolean(bool /*val*/) override
-    {
-        return events_left-- > 0;
-    }
-
-    bool number_integer(json::number_integer_t /*val*/) override
-    {
-        return events_left-- > 0;
-    }
-
-    bool number_unsigned(json::number_unsigned_t /*val*/) override
-    {
-        return events_left-- > 0;
-    }
-
-    bool number_float(json::number_float_t /*val*/, const std::string& /*s*/) override
-    {
-        return events_left-- > 0;
-    }
-
-    bool string(std::string& /*val*/) override
-    {
-        return events_left-- > 0;
-    }
-
-    bool binary(json::binary_t& /*val*/) override
-    {
-        return events_left-- > 0;
-    }
-
-    bool start_object(std::size_t /*elements*/) override
-    {
-        return events_left-- > 0;
-    }
-
-    bool key(std::string& /*val*/) override
-    {
-        return events_left-- > 0;
-    }
-
-    bool end_object() override
-    {
-        return events_left-- > 0;
-    }
-
-    bool start_array(std::size_t /*elements*/) override
-    {
-        return events_left-- > 0;
-    }
-
-    bool end_array() override
-    {
-        return events_left-- > 0;
-    }
-
-    bool parse_error(std::size_t /*position*/, const std::string& /*last_token*/, const json::exception& /*ex*/) override
-    {
-        return false;
-    }
-
-  private:
-    int events_left = 0;
-};
-
 json parser_helper(const std::string& s);
 bool accept_helper(const std::string& s);
 void comments_helper(const std::string& s);
@@ -3028,583 +2847,3 @@ TEST_CASE("diagnostic positions: value lifetime, input adapters, and SAX")
     }
 }
 #endif
-
-namespace
-{
-/// builds a value like json::parse(), but asks the parser to recover from
-/// errors (see #3989), and checks that the events it receives are balanced
-class RecoveringDomParser
-{
-  public:
-    explicit RecoveringDomParser(json& j, std::size_t max_errors_ = static_cast<std::size_t>(-1))
-        : dom(j, false)
-        , max_errors(max_errors_)
-    {}
-
-    bool null()
-    {
-        value();
-        return dom.null();
-    }
-
-    bool boolean(bool val)
-    {
-        value();
-        return dom.boolean(val);
-    }
-
-    bool number_integer(json::number_integer_t val)
-    {
-        value();
-        return dom.number_integer(val);
-    }
-
-    bool number_unsigned(json::number_unsigned_t val)
-    {
-        value();
-        return dom.number_unsigned(val);
-    }
-
-    bool number_float(json::number_float_t val, const std::string& s)
-    {
-        value();
-        return dom.number_float(val, s);
-    }
-
-    bool string(std::string& val)
-    {
-        value();
-        return dom.string(val);
-    }
-
-    bool binary(json::binary_t& val)
-    {
-        value();
-        return dom.binary(val);
-    }
-
-    bool start_object(std::size_t elements)
-    {
-        value();
-        stack.push_back('o');
-        return dom.start_object(elements);
-    }
-
-    bool key(std::string& val)
-    {
-        ++events;
-        if (stack.empty() || stack.back() != 'o')
-        {
-            well_formed = false;
-            return false;
-        }
-        stack.back() = 'v';
-        return dom.key(val);
-    }
-
-    bool end_object()
-    {
-        ++events;
-        if (stack.empty() || stack.back() != 'o')
-        {
-            well_formed = false;
-            return false;
-        }
-        stack.pop_back();
-        return dom.end_object();
-    }
-
-    bool start_array(std::size_t elements)
-    {
-        value();
-        stack.push_back('a');
-        return dom.start_array(elements);
-    }
-
-    bool end_array()
-    {
-        ++events;
-        if (stack.empty() || stack.back() != 'a')
-        {
-            well_formed = false;
-            return false;
-        }
-        stack.pop_back();
-        return dom.end_array();
-    }
-
-    bool parse_error(std::size_t /*unused*/, const std::string& /*unused*/, const json::exception& ex)
-    {
-        errors.emplace_back(ex.what());
-        return errors.size() < max_errors;
-    }
-
-    /// whether the events were balanced and every key was followed by a value
-    bool balanced() const
-    {
-        return well_formed && stack.empty();
-    }
-
-    /// builds the value
-    nlohmann::detail::json_sax_dom_parser<json> dom;
-    std::vector<std::string> errors {}; // NOLINT(readability-redundant-member-init)
-    std::size_t events = 0;
-    /// the open containers: 'a' for an array, 'o' for an object that expects
-    /// a key, 'v' for an object that expects the value of a key
-    std::vector<char> stack {}; // NOLINT(readability-redundant-member-init)
-    bool well_formed = true;
-    std::size_t max_errors;
-
-  private:
-    /// a value is passed: it is an array element, or the value of a key
-    void value()
-    {
-        ++events;
-        if (!stack.empty())
-        {
-            if (stack.back() == 'v')
-            {
-                stack.back() = 'o';
-            }
-            else if (stack.back() == 'o')
-            {
-                // a value without a key
-                well_formed = false;
-            }
-        }
-    }
-
-};
-
-struct RecoveryResult
-{
-    json value;
-    std::vector<std::string> errors;
-    std::size_t events;
-    bool ok;
-    bool balanced;
-};
-
-template<typename InputType>
-RecoveryResult parse_recovering(InputType&& input, const bool strict = true,
-                                const bool ignore_comments = false, const bool ignore_trailing_commas = false)
-{
-    json j;
-    RecoveringDomParser sax(j);
-    const bool ok = json::sax_parse(std::forward<InputType>(input), &sax, json::input_format_t::json,
-                                    strict, ignore_comments, ignore_trailing_commas);
-    return {j, sax.errors, sax.events, ok, sax.balanced()};
-}
-
-/// stops after a number of events, but recovers from errors
-class RecoveringCountdown : public SaxCountdown
-{
-  public:
-    using SaxCountdown::SaxCountdown;
-
-    bool parse_error(std::size_t /*position*/, const std::string& /*last_token*/, const json::exception& /*ex*/) override
-    {
-        return true;
-    }
-};
-
-/// a repaired input: the value it is repaired to, and the number of errors
-struct Repair
-{
-    const char* input;
-    const char* expected;
-    std::size_t errors;
-};
-} // namespace
-
-TEST_CASE("parser error recovery (#3989)")
-{
-    SECTION("repairs")
-    {
-        const std::vector<Repair> repairs =
-        {
-            // a missing separator is inserted
-            {"[1 2]", "[1,2]", 1},
-            {R"({"a":1 "b":2})", R"({"a":1,"b":2})", 1},
-            {R"({"a" 1})", R"({"a":1})", 1},
-            {"[1 tru 2]", "[1,null,2]", 2},
-            {R"({"a" "b": 1})", R"({"a":"b"})", 2},
-
-            // a missing value is null in an object; in an array, a ',' stands
-            // for null, while an array that ends there just ends
-            {R"({"a":})", R"({"a":null})", 1},
-            {R"({"a"})", R"({"a":null})", 1},
-            {R"({"a","b":1})", R"({"a":null,"b":1})", 1},
-            {"[1,,2]", "[1,null,2]", 1},
-            {"[,1]", "[null,1]", 1},
-            {"[1,]", "[1]", 1},
-            {"[1,2,3,]", "[1,2,3]", 1},
-            {R"({"a":1,})", R"({"a":1})", 1},
-
-            // a broken string keeps what can be read
-            {R"(["a\qb"])", R"(["aqb"])", 1},
-            {R"({"na\me":1})", R"({"name":1})", 1},
-            {"[\"\xFF\"]", R"(["\uFFFD"])", 1},
-            {"[\"a\xC3(\"]", R"(["a\uFFFD("])", 1},
-            {"[\"\xE2\x82\"]", R"(["\uFFFD"])", 1},
-            {"[\"\xC3\\\\\", 1]", R"(["\uFFFD\\",1])", 1},
-            {R"(["\u12"])", R"(["\uFFFD"])", 1},
-            {R"(["\u12G4"])", R"(["\uFFFDG4"])", 1},
-            {R"(["\uDC00x"])", R"(["\uFFFDx"])", 1},
-            {R"(["\uD800x"])", R"(["\uFFFDx"])", 1},
-            {R"(["\uD800\u0041"])", R"(["\uFFFDA"])", 1},
-            {R"(["\uD800\uD800\uDC00"])", R"(["\uFFFD\uD800\uDC00"])", 1},
-            {R"(["\uD800\uD800\uD800x"])", R"(["\uFFFD\uFFFD\uFFFDx"])", 1},
-            {
-                R"(["\uD800\"x", 1])", R"(["\uFFFD\"x",1])", 1
-            },
-            {R"(["\uD800\q"])", R"(["\uFFFDq"])", 1},
-            {"[\"a\tb\"]", R"(["a\tb"])", 1},
-            {R"(["a\qb\u0041\x"])", R"(["aqbAx"])", 1},
-
-            // a broken number keeps its longest valid prefix
-            {"[1.]", "[1]", 1},
-            {"[-2.]", "[-2]", 1},
-            {"[1.5e]", "[1.5]", 1},
-            {"[1e+]", "[1]", 1},
-            {"[1.x2, 3]", "[1,3]", 1},
-
-            // what cannot be read at all is null
-            {"[1,NaN,3]", "[1,null,3]", 1},
-            {"[tru]", "[null]", 1},
-            {"[-]", "[null]", 1},
-            {R"({"a":Infinity})", R"({"a":null})", 1},
-
-            // a stray token is dropped
-            {"[:1]", "[1]", 1},
-            {R"(["a":1])", R"(["a",1])", 1},
-            {R"({"a"::1})", R"({"a":1})", 1},
-
-            // a member that cannot be read is skipped
-            {R"({1:2,"b":3})", R"({"b":3})", 1},
-            {R"({"a":1 2})", R"({"a":1})", 1},
-            {R"({,"a":1})", R"({"a":1})", 1},
-            {R"({"a":1,,"b":2})", R"({"a":1,"b":2})", 1},
-            {"{a:1}", "{}", 1},
-            {R"({"a":1 [1,{"b":2}], "c":3})", R"({"a":1,"c":3})", 1},
-            {R"([{1}, "a"])", R"([{},"a"])", 1},
-
-            // a wrong closing bracket closes the innermost container
-            {R"({"a":[1,2}, "b":3})", R"({"a":[1,2],"b":3})", 1},
-            {R"([{"a":1], 2])", R"([{"a":1},2])", 1},
-            {"{]", "{}", 1},
-            {"[}", "[]", 1},
-
-            // the end of the input closes all containers
-            {R"({"a":[1,2)", R"({"a":[1,2]})", 1},
-            {"[", "[]", 1},
-            {"{", "{}", 1},
-            {R"({"a")", R"({"a":null})", 1},
-            {R"({"a":)", R"({"a":null})", 1},
-            {"[1,", "[1]", 1},
-            {"[[[1", "[[[1]]]", 1},
-            {
-                R"(["abc)", R"(["abc"])", 2
-            },
-            {"[1,tr", "[1,null]", 2},
-            {"\"abc", "\"abc\"", 1},
-            {"[\"ab\ncd\"]", R"(["ab",null,"]"])", 4},
-
-            // what comes before the top-level value is skipped
-            {")]}'\n{\"a\":1}", R"({"a":1})", 1},
-            {R"(data: {"a":1})", R"({"a":1})", 1},
-            {"\xEF\xBB[1]", "[1]", 1},
-
-            // what comes after it is an error that ends parsing
-            {R"({"a":1}})", R"({"a":1})", 1},
-            {"[1}]", "[1]", 2},
-            {"[1] [2]", "[1]", 1},
-        };
-
-        for (const auto& repair : repairs)
-        {
-            CAPTURE(repair.input)
-            const auto result = parse_recovering(std::string(repair.input));
-            CHECK(!result.ok);
-            CHECK(result.balanced);
-            CHECK(result.value == json::parse(repair.expected));
-            CHECK(result.errors.size() == repair.errors);
-        }
-    }
-
-    SECTION("number overflow")
-    {
-        const auto result = parse_recovering(std::string("[1e999,-1e999]"));
-        CHECK(!result.ok);
-        CHECK(result.balanced);
-        CHECK(result.errors.size() == 2);
-        CHECK(result.errors[0] == "[json.exception.out_of_range.406] number overflow parsing '1e999'");
-        REQUIRE(result.value.size() == 2);
-        CHECK(result.value[0].is_number_float());
-        CHECK(result.value[0].get<double>() == std::numeric_limits<double>::infinity());
-        CHECK(result.value[1].get<double>() == -std::numeric_limits<double>::infinity());
-
-        // the SAX parser gets the number's text
-        SaxEventLogger logger;
-        logger.recover = true;
-        CHECK(!json::sax_parse("1e999", &logger));
-        CHECK(logger.events == std::vector<std::string>({"parse_error(5)", "number_float(1e999)"}));
-    }
-
-    SECTION("nothing to recover")
-    {
-        for (const std::string s :
-                {
-                    "", "   ", "]", "tru", "NaN", ",:", "/* comment"
-                })
-        {
-            CAPTURE(s)
-            const auto result = parse_recovering(s, true, true);
-            CHECK(!result.ok);
-            CHECK(result.balanced);
-            CHECK(result.events == 0);
-            CHECK(result.value == nullptr);
-            CHECK(result.errors.size() == 1);
-        }
-    }
-
-    SECTION("error messages")
-    {
-        // the first error is reported as without recovery
-        for (const std::string s :
-                {
-                    "[1 2]", R"({"a":1 "b":2})", R"({"a" 1})", R"({"a":})", "[1,]", "[1.]",
-                    R"(["a\qb"])", "[1e999]", "{1:2}", R"({"a":[1,2}})", "[1,", "[1] [2]", "{a:1}"
-                })
-        {
-            CAPTURE(s)
-            const auto result = parse_recovering(s);
-            REQUIRE(!result.errors.empty());
-            json _;
-            CHECK_THROWS_WITH_STD_STR(_ = json::parse(s), result.errors.front());
-        }
-
-        // the token of an error begins where the previous error was
-        const auto result = parse_recovering(std::string("[tru, fals, nul]"));
-        CHECK(result.errors == std::vector<std::string>(
-        {
-            "[json.exception.parse_error.101] parse error at line 1, column 5: syntax error while parsing value - invalid literal; last read: '[tru,'",
-            "[json.exception.parse_error.101] parse error at line 1, column 11: syntax error while parsing value - invalid literal; last read: ', fals,'",
-            "[json.exception.parse_error.101] parse error at line 1, column 16: syntax error while parsing value - invalid literal; last read: ', nul]'"
-        }));
-        CHECK(result.value == json::parse("[null,null,null]"));
-    }
-
-    SECTION("events")
-    {
-        // see #4522
-        SaxEventLogger logger;
-        logger.recover = true;
-        CHECK(!json::sax_parse(R"([{1}, "a"])", &logger));
-        CHECK(logger.events == std::vector<std::string>(
-        {
-            "start_array()", "start_object()", "parse_error(3)", "end_object()", "string(a)", "end_array()"
-        }));
-    }
-
-    SECTION("options")
-    {
-        SECTION("strict")
-        {
-            const auto result = parse_recovering(std::string("[1 2] [3]"), false);
-            CHECK(!result.ok);
-            CHECK(result.value == json::parse("[1,2]"));
-            CHECK(result.errors.size() == 1);
-        }
-
-        SECTION("ignore_trailing_commas")
-        {
-            for (const std::string s :
-                    {
-                        "[1,]", R"({"a":1,})", "[[1,],]"
-                    })
-            {
-                CAPTURE(s)
-                const auto result = parse_recovering(s, true, false, true);
-                CHECK(result.ok);
-                CHECK(result.errors.empty());
-            }
-
-            auto result = parse_recovering(std::string("[1,,]"), true, false, true);
-            CHECK(result.value == json::parse("[1,null]"));
-            CHECK(result.errors.size() == 1);
-
-            result = parse_recovering(std::string(R"({"a":1,,})"), true, false, true);
-            CHECK(result.value == json::parse(R"({"a":1})"));
-            CHECK(result.errors.size() == 1);
-        }
-
-        SECTION("ignore_comments")
-        {
-            auto result = parse_recovering(std::string("[1 /* one */ 2]"), true, true);
-            CHECK(result.value == json::parse("[1,2]"));
-            CHECK(result.errors.size() == 1);
-
-            // a comment that is not closed runs to the end of the input, which
-            // is not reported again
-            result = parse_recovering(std::string("[1, 2 /* unterminated"), true, true);
-            CHECK(result.balanced);
-            CHECK(result.value == json::parse("[1,2]"));
-            CHECK(result.errors.size() == 1);
-
-            // a '/' that does not begin a comment is garbage
-            result = parse_recovering(std::string("[1, /x, 2]"), true, true);
-            CHECK(result.balanced);
-            CHECK(result.value == json::parse("[1,null,2]"));
-            CHECK(result.errors.size() == 1);
-        }
-    }
-
-    SECTION("null bytes")
-    {
-        // a null byte ends the input, unless JSON_STRICT_NUL_HANDLING is set
-        const auto result = parse_recovering(std::string("[1,\0x", 5));
-        CHECK(result.balanced);
-        CHECK(!result.ok);
-#ifdef JSON_TEST_STRICT_NUL_HANDLING_ENABLED
-        CHECK(result.value == json::parse("[1,null]"));
-#else
-        CHECK(result.value == json::parse("[1]"));
-        CHECK(result.errors.size() == 1);
-#endif
-
-        const auto in_string = parse_recovering(std::string("[\"a\0b\"]", 7));
-        CHECK(in_string.balanced);
-#ifdef JSON_TEST_STRICT_NUL_HANDLING_ENABLED
-        CHECK(in_string.value == json::array({std::string("a\0b", 3)}));
-#else
-        CHECK(in_string.value == json::parse(R"(["a"])"));
-#endif
-    }
-
-    SECTION("the SAX parser stops recovering")
-    {
-        json j;
-        RecoveringDomParser sax(j, 2);
-        CHECK(!json::sax_parse("[1 2 3 4 5]", &sax));
-        CHECK(sax.errors.size() == 2);
-
-        // an error at a delimiter that an invalid token consumed is reported
-        // to the SAX parser, too
-        json j2;
-        RecoveringDomParser sax2(j2, 2);
-        CHECK(!json::sax_parse("[tru}, 1]", &sax2));
-        CHECK(sax2.errors.size() == 2);
-    }
-
-    SECTION("an event stops parsing during a repair")
-    {
-        // start_object() and key() are passed, then null() for the missing
-        // value returns false
-        RecoveringCountdown countdown(2);
-        CHECK(!json::sax_parse(R"({"a":})", &countdown));
-
-        // the end of the input: end_array() for the second array returns false
-        RecoveringCountdown countdown2(4);
-        CHECK(!json::sax_parse("[[1", &countdown2));
-    }
-
-    SECTION("input adapters")
-    {
-        // the lexer reads contiguous and streaming input differently, and it
-        // puts back a character that ended an invalid token
-        for (const std::string s :
-                {
-                    "[1 2]", "[tru}, 1]", R"({"a" "b\q", "c":[1.x, 2}})", "[\"\xFF\xC3(\", -, 1e+]", "{a:1,\"b\":2", ")]}' [1]"
-                })
-        {
-            CAPTURE(s)
-            const auto reference = parse_recovering(s);
-            CHECK(reference.balanced);
-
-            const auto from_c_string = parse_recovering(s.c_str());
-            CHECK(from_c_string.value == reference.value);
-            CHECK(from_c_string.errors == reference.errors);
-
-            const std::list<char> l(s.begin(), s.end());
-            json j;
-            RecoveringDomParser sax(j);
-            CHECK(!json::sax_parse(l.begin(), l.end(), &sax));
-            CHECK(j == reference.value);
-            CHECK(sax.errors == reference.errors);
-
-            std::istringstream ss(s);
-            const auto from_stream = parse_recovering(ss);
-            CHECK(from_stream.value == reference.value);
-            CHECK(from_stream.errors == reference.errors);
-        }
-    }
-
-    SECTION("long runs of errors")
-    {
-        // no error may copy all the input read before it
-        const auto closing = parse_recovering("[" + std::string(100000, '}'));
-        CHECK(closing.balanced);
-        CHECK(closing.value == json::array());
-
-        const auto garbage = parse_recovering("[" + std::string(100000, 'x') + "]");
-        CHECK(garbage.balanced);
-        CHECK(garbage.errors.size() == 1);
-
-        const auto commas = parse_recovering("{" + std::string(100000, ',') + "}");
-        CHECK(commas.balanced);
-        CHECK(commas.value == json::object());
-    }
-
-    SECTION("mutations of valid input")
-    {
-        // whatever the input, the events are balanced, every error is reported
-        // at most once, and valid input is parsed as usual
-        const std::vector<std::string> documents =
-        {
-            R"({"name": "value", "list": [1, -2.5, true, null, {"x": [[]]}], "e": "\u00e9"})",
-            R"([{"a": [1, 2, {"b": "c"}]}, [], {}, "\ud83d\ude00", 1e10])",
-            "{\"\xC3\xA9\": \"\xF0\x9F\x98\x80\"}",
-            R"(  {"k" : [ "v" , 0 ] }  )",
-        };
-        // each character that can be inserted, including a null byte
-        const std::string insertions("[]{},:\"x\\\0\xFF", 11);
-
-        std::vector<std::string> inputs;
-        for (const auto& doc : documents)
-        {
-            for (std::size_t i = 0; i <= doc.size(); ++i)
-            {
-                inputs.push_back(doc.substr(0, i));
-                if (i < doc.size())
-                {
-                    inputs.push_back(doc.substr(0, i) + doc.substr(i + 1));
-                }
-                for (const char c : insertions)
-                {
-                    inputs.push_back(doc.substr(0, i) + c + doc.substr(i));
-                }
-            }
-        }
-
-        for (const auto& s : inputs)
-        {
-            CAPTURE(s)
-            const auto result = parse_recovering(s);
-            CHECK(result.balanced);
-            CHECK(result.errors.size() <= s.size() + 1);
-            CHECK(result.events <= (4 * s.size()) + 4);
-            if (json::accept(s))
-            {
-                CHECK(result.ok);
-                CHECK(result.errors.empty());
-                CHECK(result.value == json::parse(s));
-            }
-            else
-            {
-                CHECK(!result.ok);
-                CHECK(!result.errors.empty());
-            }
-        }
-    }
-}

tests/src/unit-deserialization.cpp

@@ -36,155 +36,15 @@ using nlohmann::json;
 #include <string>
 #include <valarray>
 
+#include "sax_event_loggers.hpp"
+
+using utils::SaxEventLogger;
+using utils::SaxEventLoggerExitAfterKey;
+using utils::SaxEventLoggerExitAfterStartArray;
+using utils::SaxEventLoggerExitAfterStartObject;
+
 namespace
 {
-struct SaxEventLogger : public nlohmann::json_sax<json>
-{
-    bool null() override
-    {
-        events.emplace_back("null()");
-        return true;
-    }
-
-    bool boolean(bool val) override
-    {
-        events.emplace_back(val ? "boolean(true)" : "boolean(false)");
-        return true;
-    }
-
-    bool number_integer(json::number_integer_t val) override
-    {
-        events.push_back("number_integer(" + std::to_string(val) + ")");
-        return true;
-    }
-
-    bool number_unsigned(json::number_unsigned_t val) override
-    {
-        events.push_back("number_unsigned(" + std::to_string(val) + ")");
-        return true;
-    }
-
-    bool number_float(json::number_float_t /*val*/, const std::string& s) override
-    {
-        events.push_back("number_float(" + s + ")");
-        return true;
-    }
-
-    bool string(std::string& val) override
-    {
-        events.push_back("string(" + val + ")");
-        return true;
-    }
-
-    bool binary(json::binary_t& val) override
-    {
-        std::string binary_contents = "binary(";
-        std::string comma_space;
-        for (auto b : val)
-        {
-            binary_contents.append(comma_space);
-            binary_contents.append(std::to_string(static_cast<int>(b)));
-            comma_space = ", ";
-        }
-        binary_contents.append(")");
-        events.push_back(binary_contents);
-        return true;
-    }
-
-    bool start_object(std::size_t elements) override
-    {
-        if (elements == (std::numeric_limits<std::size_t>::max)())
-        {
-            events.emplace_back("start_object()");
-        }
-        else
-        {
-            events.push_back("start_object(" + std::to_string(elements) + ")");
-        }
-        return true;
-    }
-
-    bool key(std::string& val) override
-    {
-        events.push_back("key(" + val + ")");
-        return true;
-    }
-
-    bool end_object() override
-    {
-        events.emplace_back("end_object()");
-        return true;
-    }
-
-    bool start_array(std::size_t elements) override
-    {
-        if (elements == (std::numeric_limits<std::size_t>::max)())
-        {
-            events.emplace_back("start_array()");
-        }
-        else
-        {
-            events.push_back("start_array(" + std::to_string(elements) + ")");
-        }
-        return true;
-    }
-
-    bool end_array() override
-    {
-        events.emplace_back("end_array()");
-        return true;
-    }
-
-    bool parse_error(std::size_t position, const std::string& /*last_token*/, const json::exception& /*ex*/) override
-    {
-        events.push_back("parse_error(" + std::to_string(position) + ")");
-        return false;
-    }
-
-    std::vector<std::string> events {}; // NOLINT(readability-redundant-member-init)
-};
-
-struct SaxEventLoggerExitAfterStartObject : public SaxEventLogger
-{
-    bool start_object(std::size_t elements) override
-    {
-        if (elements == (std::numeric_limits<std::size_t>::max)())
-        {
-            events.emplace_back("start_object()");
-        }
-        else
-        {
-            events.push_back("start_object(" + std::to_string(elements) + ")");
-        }
-        return false;
-    }
-};
-
-struct SaxEventLoggerExitAfterKey : public SaxEventLogger
-{
-    bool key(std::string& val) override
-    {
-        events.push_back("key(" + val + ")");
-        return false;
-    }
-};
-
-struct SaxEventLoggerExitAfterStartArray : public SaxEventLogger
-{
-    bool start_array(std::size_t elements) override
-    {
-        if (elements == (std::numeric_limits<std::size_t>::max)())
-        {
-            events.emplace_back("start_array()");
-        }
-        else
-        {
-            events.push_back("start_array(" + std::to_string(elements) + ")");
-        }
-        return false;
-    }
-};
-
 template <typename T>
 class proxy_iterator
 {

tests/src/unit-regression2.cpp

@@ -1029,605 +1029,6 @@ TEST_CASE("regression test - excessive binary container size honors allow_except
     CHECK(json::from_cbor(std::vector<std::uint8_t> {0x9b, 0, 0, 0, 0, 0, 0, 0, 0x02}, true, false).is_discarded());
 }
 
-namespace
-{
-/// builds a value from SAX events, asks the parser to recover from its first
-/// 100 errors, and checks that the events are balanced (see #3989)
-template<typename BasicJsonType>
-class BasicRecoveringParser
-{
-  public:
-    explicit BasicRecoveringParser(BasicJsonType& j)
-        : dom(j, false)
-    {}
-
-    bool null()
-    {
-        value();
-        return dom.null();
-    }
-
-    bool boolean(bool val)
-    {
-        value();
-        return dom.boolean(val);
-    }
-
-    bool number_integer(typename BasicJsonType::number_integer_t val)
-    {
-        value();
-        return dom.number_integer(val);
-    }
-
-    bool number_unsigned(typename BasicJsonType::number_unsigned_t val)
-    {
-        value();
-        return dom.number_unsigned(val);
-    }
-
-    bool number_float(typename BasicJsonType::number_float_t val, const std::string& s)
-    {
-        value();
-        return dom.number_float(val, s);
-    }
-
-    bool string(std::string& val)
-    {
-        value();
-        return dom.string(val);
-    }
-
-    bool binary(typename BasicJsonType::binary_t& val)
-    {
-        value();
-        return dom.binary(val);
-    }
-
-    bool start_object(std::size_t elements)
-    {
-        value();
-        stack.push_back('o');
-        return dom.start_object(elements);
-    }
-
-    bool key(std::string& val)
-    {
-        if (stack.empty() || stack.back() != 'o')
-        {
-            well_formed = false;
-            return false;
-        }
-        stack.back() = 'v';
-        return dom.key(val);
-    }
-
-    bool end_object()
-    {
-        if (stack.empty() || stack.back() != 'o')
-        {
-            well_formed = false;
-            return false;
-        }
-        stack.pop_back();
-        return dom.end_object();
-    }
-
-    bool start_array(std::size_t elements)
-    {
-        value();
-        stack.push_back('a');
-        return dom.start_array(elements);
-    }
-
-    bool end_array()
-    {
-        if (stack.empty() || stack.back() != 'a')
-        {
-            well_formed = false;
-            return false;
-        }
-        stack.pop_back();
-        return dom.end_array();
-    }
-
-    bool parse_error(std::size_t /*unused*/, const std::string& /*unused*/, const json::exception& ex)
-    {
-        messages.emplace_back(ex.what());
-        // a limit, so that a reader that does not stop fails the test
-        // instead of making it hang
-        return ++errors < 100;
-    }
-
-    /// whether the events were balanced and every key was followed by a value
-    bool balanced() const
-    {
-        return well_formed && stack.empty();
-    }
-
-    /// builds the value
-    nlohmann::detail::json_sax_dom_parser<BasicJsonType> dom;
-    std::size_t errors = 0;
-    std::vector<std::string> messages {}; // NOLINT(readability-redundant-member-init)
-    std::vector<char> stack {}; // NOLINT(readability-redundant-member-init)
-    bool well_formed = true;
-
-  private:
-    void value()
-    {
-        if (!stack.empty())
-        {
-            if (stack.back() == 'v')
-            {
-                stack.back() = 'o';
-            }
-            else if (stack.back() == 'o')
-            {
-                well_formed = false;
-            }
-        }
-    }
-
-};
-
-using RecoveringParser = BasicRecoveringParser<json>;
-
-struct BinaryParseResult
-{
-    json value;
-    std::size_t errors;
-    std::vector<std::string> messages;
-    bool ok;
-    bool balanced;
-};
-
-BinaryParseResult parse_binary_recovering(const std::vector<std::uint8_t>& input, const json::input_format_t format)
-{
-    json j;
-    RecoveringParser sax(j);
-    const bool ok = json::sax_parse(input, &sax, format);
-    return {j, sax.errors, sax.messages, ok, sax.balanced()};
-}
-
-#if !defined(JSON_NOEXCEPTION)
-/// the message of the exception that reading @a input into a JSON value
-/// throws, or an empty string if reading succeeds
-std::string binary_error_message(const std::vector<std::uint8_t>& input, const json::input_format_t format)
-{
-    try
-    {
-        json _;
-        switch (format)
-        {
-            case json::input_format_t::cbor:
-                _ = json::from_cbor(input);
-                break;
-            case json::input_format_t::msgpack:
-                _ = json::from_msgpack(input);
-                break;
-            case json::input_format_t::ubjson:
-                _ = json::from_ubjson(input);
-                break;
-            case json::input_format_t::bjdata:
-                _ = json::from_bjdata(input);
-                break;
-            case json::input_format_t::bson:
-                _ = json::from_bson(input);
-                break;
-            case json::input_format_t::bon8:
-                _ = json::from_bon8(input);
-                break;
-            case json::input_format_t::json:
-            default:
-                break;
-        }
-    }
-    catch (const json::exception& e)
-    {
-        return e.what();
-    }
-    return "";
-}
-#endif
-
-/// a BSON element: its type, its name, and its value
-std::vector<std::uint8_t> bson_element(const std::uint8_t type, const std::string& name, const std::vector<std::uint8_t>& value)
-{
-    std::vector<std::uint8_t> result = {type};
-    result.insert(result.end(), name.begin(), name.end());
-    result.push_back(0x00);
-    result.insert(result.end(), value.begin(), value.end());
-    return result;
-}
-
-/// a BSON document of the given elements; @a size_offset is added to the
-/// size it declares
-std::vector<std::uint8_t> bson_document(const std::vector<std::vector<std::uint8_t>>& elements, const int size_offset = 0)
-{
-    std::vector<std::uint8_t> body;
-    for (const auto& element : elements)
-    {
-        body.insert(body.end(), element.begin(), element.end());
-    }
-    const auto size = static_cast<std::uint32_t>(static_cast<int>(body.size()) + 5 + size_offset);
-    std::vector<std::uint8_t> result = {static_cast<std::uint8_t>(size & 0xFFu), static_cast<std::uint8_t>((size >> 8u) & 0xFFu),
-                                        static_cast<std::uint8_t>((size >> 16u) & 0xFFu), static_cast<std::uint8_t>((size >> 24u) & 0xFFu)
-                                       };
-    result.insert(result.end(), body.begin(), body.end());
-    result.push_back(0x00);
-    return result;
-}
-
-/// a BSON int32 value
-std::vector<std::uint8_t> bson_int32(const std::int32_t value)
-{
-    const auto u = static_cast<std::uint32_t>(value);
-    return {static_cast<std::uint8_t>(u & 0xFFu), static_cast<std::uint8_t>((u >> 8u) & 0xFFu),
-            static_cast<std::uint8_t>((u >> 16u) & 0xFFu), static_cast<std::uint8_t>((u >> 24u) & 0xFFu)};
-}
-
-/// a BSON string value, whose length is @a length_offset off
-std::vector<std::uint8_t> bson_string(const std::string& value, const std::int32_t length_offset = 0)
-{
-    auto result = bson_int32(static_cast<std::int32_t>(value.size() + 1) + length_offset);
-    result.insert(result.end(), value.begin(), value.end());
-    result.push_back(0x00);
-    return result;
-}
-
-/// @a count bytes of value 0xAB
-std::vector<std::uint8_t> bytes(const std::size_t count)
-{
-    return std::vector<std::uint8_t>(count, 0xAB);
-}
-
-template<typename... Parts>
-std::vector<std::uint8_t> concatenated(const std::vector<std::uint8_t>& first, const Parts& ... rest)
-{
-    std::vector<std::uint8_t> result = first;
-    for (const auto& part : std::initializer_list<std::vector<std::uint8_t>> {rest...})
-    {
-        result.insert(result.end(), part.begin(), part.end());
-    }
-    return result;
-}
-
-/// U+FFFD REPLACEMENT CHARACTER
-std::string replacement_character()
-{
-    return "\xEF\xBF\xBD";
-}
-}  // namespace
-
-TEST_CASE("regression test - #3989 SAX parse_error() returning true")
-{
-    SECTION("binary formats complete what was read before the input ends")
-    {
-        const json j = {{"a", {1, -2, {{"b", "c"}}, json::array()}}, {"d", {{"e", nullptr}, {"f", true}}}, {"g", 1.5}, {"h", json::binary({1, 2, 3})}};
-
-        const std::vector<std::pair<json::input_format_t, std::vector<std::uint8_t>>> encodings =
-        {
-            {json::input_format_t::cbor, json::to_cbor(j)},
-            {json::input_format_t::msgpack, json::to_msgpack(j)},
-            {json::input_format_t::ubjson, json::to_ubjson(j)},
-            {json::input_format_t::ubjson, json::to_ubjson(j, true, true)},
-            {json::input_format_t::bjdata, json::to_bjdata(j)},
-            {json::input_format_t::bjdata, json::to_bjdata(j, true, true)},
-            {json::input_format_t::bson, json::to_bson(j)},
-            {json::input_format_t::bon8, json::to_bon8(j)},
-        };
-
-        for (const auto& encoding : encodings)
-        {
-            const auto format = encoding.first;
-            const auto& bytes = encoding.second;
-            CAPTURE(format)
-
-            // every prefix is truncated input
-            for (std::size_t length = 0; length < bytes.size(); ++length)
-            {
-                CAPTURE(length)
-                const auto result = parse_binary_recovering(std::vector<std::uint8_t>(bytes.begin(), bytes.begin() + static_cast<std::ptrdiff_t>(length)), format);
-                CHECK(!result.ok);
-                CHECK(result.errors == 1);
-                CHECK(result.balanced);
-            }
-
-            // the complete input is read as usual (binary values do not
-            // round-trip through every format, so compare with a plain parse)
-            json expected;
-            nlohmann::detail::json_sax_dom_parser<json> dom(expected);
-            CHECK(json::sax_parse(bytes, &dom, format));
-            const auto complete = parse_binary_recovering(bytes, format);
-            CHECK(complete.ok);
-            CHECK(complete.errors == 0);
-            CHECK(complete.value == expected);
-
-            // a byte after the value
-            auto trailing_bytes = bytes;
-            trailing_bytes.push_back(0x01);
-            const auto trailing = parse_binary_recovering(trailing_bytes, format);
-            CHECK(!trailing.ok);
-            CHECK(trailing.errors == 1);
-            CHECK(trailing.value == expected);
-        }
-    }
-
-    SECTION("containers without an end")
-    {
-        // these made the readers loop, or read on, after the error
-        const auto cbor_array = parse_binary_recovering({0x9F}, json::input_format_t::cbor);
-        CHECK(cbor_array.errors == 1);
-        CHECK(cbor_array.value == json::array());
-
-        const auto cbor_map = parse_binary_recovering({0xBF, 0x61, 'a'}, json::input_format_t::cbor);
-        CHECK(cbor_map.errors == 1);
-        CHECK(cbor_map.value == json({{"a", nullptr}}));
-
-        const auto msgpack_array = parse_binary_recovering({0xDD, 0xFF, 0xFF, 0xFF, 0xFF}, json::input_format_t::msgpack);
-        CHECK(msgpack_array.errors == 1);
-        CHECK(msgpack_array.value == json::array());
-
-        const auto msgpack_map = parse_binary_recovering({0x81, 0xA1, 'a', 0x92, 0x01}, json::input_format_t::msgpack);
-        CHECK(msgpack_map.errors == 1);
-        CHECK(msgpack_map.value == json({{"a", {1}}}));
-    }
-
-    SECTION("BJData ndarray")
-    {
-        // a 2x3 int8 array with two of its six elements; the annotated array
-        // format opens an object and two arrays of its own
-        const auto result = parse_binary_recovering({'[', '$', 'i', '#', '[', '$', 'i', '#', 'i', 2, 2, 3, 1, 2}, json::input_format_t::bjdata);
-        CHECK(result.errors == 1);
-        CHECK(result.balanced);
-        CHECK(result.value == json({{"_ArrayType_", "int8"}, {"_ArraySize_", {2, 3}}, {"_ArrayData_", {1, 2}}}));
-    }
-
-    SECTION("binary formats repair items whose end is known")
-    {
-        struct Repair
-        {
-            json::input_format_t format;
-            std::vector<std::uint8_t> input;
-            json expected;
-            std::size_t errors;
-        };
-
-        const std::vector<Repair> repairs =
-        {
-            // CBOR: tags are ignored (here tag 1 and the self-describe tag 55799)
-            {json::input_format_t::cbor, {0x82, 0xC1, 0x05, 0xD9, 0xD9, 0xF7, 0x06}, {5, 6}, 2},
-            // CBOR: undefined and other simple values become null
-            {json::input_format_t::cbor, {0x84, 0xF7, 0xE0, 0xF8, 0x20, 0x01}, {nullptr, nullptr, nullptr, 1}, 3},
-            // CBOR: members whose key is not a string are skipped, whatever their key and value
-            {json::input_format_t::cbor, {0xA4, 0x01, 0x02, 0x82, 0x01, 0x02, 0xA1, 0x61, 'x', 0x9F, 0xFF, 0xC1, 0x01, 0x5F, 0x41, 0x00, 0xFF, 0x61, 'a', 0x03}, {{"a", 3}}, 3},
-            {json::input_format_t::cbor, {0xBF, 0xF5, 0xBF, 0x61, 'x', 0x7F, 0x61, 'y', 0xFF, 0xFF, 0x61, 'a', 0x03, 0xFF}, {{"a", 3}}, 1},
-            // MessagePack: members whose key is not a string are skipped
-            {json::input_format_t::msgpack, {0x84, 0x01, 0x02, 0x81, 0xA1, 'x', 0x01, 0x92, 0x01, 0x02, 0xD4, 0x01, 0x02, 0xC0, 0xA1, 'a', 0x04}, {{"a", 4}}, 3},
-            // UBJSON: a char that is not ASCII becomes U+FFFD
-            {json::input_format_t::ubjson, {'[', 'C', 0x80, 'C', 'A', ']'}, {replacement_character(), "A"}, 1},
-            // UBJSON: the longest beginning of a high-precision number is kept
-            {json::input_format_t::ubjson, {'[', 'H', 'i', 5, '1', '2', 'a', 'b', 'c', 'H', 'i', 2, '1', '.', 'H', 'i', 3, 'a', 'b', 'c', 'H', 'i', 3, '4', '.', '5', ']'}, {12, 1, nullptr, 4.5}, 3},
-            // BJData, too
-            {json::input_format_t::bjdata, {'[', 'C', 0xFF, 'H', 'i', 2, '-', '1', 'H', 'i', 2, '-', 'x', ']'}, {replacement_character(), -1, nullptr}, 2},
-            // a NUL ends a high-precision number, as it ends JSON text
-            {json::input_format_t::ubjson, {'[', 'H', 'i', 4, '1', '2', 0, '9', 'H', 'i', 2, 0, '1', 'i', 3, ']'}, {12, nullptr, 3}, 2},
-            // BON8: members whose key is not a string are skipped
-            {json::input_format_t::bon8, {0x89, 0x91, 0x92, 0xC9, 0x40, 0x82, 0x91, 0x92, 0x61, 0x93}, {{"a", 3}}, 2},
-            {json::input_format_t::bon8, {0x8B, 0x91, 0x85, 0x91, 0xFE, 0xFA, 0x8B, 'x', 0x91, 0xFE, 0x61, 0x93, 0xFE}, {{"a", 3}}, 2},
-            // BSON: elements of types the library does not read become null
-            {
-                json::input_format_t::bson, bson_document(
-                {
-                    bson_element(0x07, "_id", bytes(12)),                         // ObjectId
-                    bson_element(0x09, "date", bytes(8)),                         // UTC datetime
-                    bson_element(0x13, "decimal", bytes(16)),                     // 128-bit decimal
-                    bson_element(0x0B, "regex", {'a', '+', 0, 'i', 0}),           // regular expression
-                    bson_element(0x0D, "code", bson_string("f()")),               // JavaScript code
-                    bson_element(0x0E, "symbol", bson_string("s")),               // symbol
-                    bson_element(0x0C, "pointer", concatenated(bson_string("c"), bytes(12))), // DBPointer
-                    bson_element(0x0F, "scope", concatenated(bson_int32(15), bson_string("g"), bson_document({}))), // code with scope
-                    bson_element(0x06, "undefined", {}),                          // undefined
-                    bson_element(0xFF, "min", {}),                                // min key
-                    bson_element(0x7F, "max", {}),                                // max key
-                    bson_element(0x10, "z", bson_int32(7)),
-                }),
-                {{"_id", nullptr}, {"date", nullptr}, {"decimal", nullptr}, {"regex", nullptr}, {"code", nullptr}, {"symbol", nullptr}, {"pointer", nullptr}, {"scope", nullptr}, {"undefined", nullptr}, {"min", nullptr}, {"max", nullptr}, {"z", 7}},
-                11
-            },
-            // BSON: an element of an unknown type becomes null, and the rest of its document is skipped
-            {
-                json::input_format_t::bson, bson_document(
-                {
-                    bson_element(0x03, "inner", bson_document({bson_element(0x10, "a", bson_int32(1)), bson_element(0x42, "x", bytes(3)), bson_element(0x10, "b", bson_int32(2))})),
-                    bson_element(0x04, "array", bson_document({bson_element(0x10, "0", bson_int32(1)), bson_element(0x42, "1", bytes(3))})),
-                    bson_element(0x10, "after", bson_int32(3)),
-                }),
-                {{"inner", {{"a", 1}, {"x", nullptr}}}, {"array", {1, nullptr}}, {"after", 3}},
-                2
-            },
-            // BSON: so does a string or byte array whose length cannot be right
-            {
-                json::input_format_t::bson, bson_document(
-                {
-                    bson_element(0x03, "inner", bson_document({bson_element(0x02, "s", bson_string("abc", -10)), bson_element(0x10, "b", bson_int32(2))})),
-                    bson_element(0x03, "bin", bson_document({bson_element(0x05, "b", concatenated(bson_int32(-1), bytes(1))), bson_element(0x10, "b", bson_int32(2))})),
-                    bson_element(0x10, "after", bson_int32(3)),
-                }),
-                {{"inner", {{"s", nullptr}}}, {"bin", {{"b", nullptr}}}, {"after", 3}},
-                2
-            },
-            // BSON: a string without its terminator, and a document whose size does not match, are kept
-            {
-                json::input_format_t::bson, bson_document(
-                {
-                    bson_element(0x02, "s", {2, 0, 0, 0, 'a', 'X'}),
-                    bson_element(0x03, "inner", bson_document({bson_element(0x10, "a", bson_int32(1))}, 1)),
-                }),
-                {{"s", "a"}, {"inner", {{"a", 1}}}},
-                2
-            },
-        };
-
-        for (const auto& repair : repairs)
-        {
-            CAPTURE(repair.format)
-            CAPTURE(repair.input)
-            const auto result = parse_binary_recovering(repair.input, repair.format);
-            CHECK(!result.ok);
-            CHECK(result.balanced);
-            CHECK(result.errors == repair.errors);
-            CHECK(result.value == repair.expected);
-            REQUIRE(!result.messages.empty());
-#if !defined(JSON_NOEXCEPTION)
-            // the first error is the one reported without recovering; under
-            // JSON_NOEXCEPTION, reading without recovering aborts instead of
-            // throwing, so there is no message to compare with
-            CHECK(result.messages.front() == binary_error_message(repair.input, repair.format));
-#endif
-        }
-    }
-
-    SECTION("binary formats repair numbers that are out of range")
-    {
-        // CBOR: a double too large for a float number_float_t
-        float_json cbor;
-        BasicRecoveringParser<float_json> sax(cbor);
-        const std::vector<std::uint8_t> cbor_input = {0x82, 0xFB, 0x7E, 0x37, 0xE4, 0x3C, 0x88, 0x00, 0x75, 0x9C, 0x01}; // [1e300, 1]
-        CHECK(!float_json::sax_parse(cbor_input, &sax, float_json::input_format_t::cbor));
-        CHECK(sax.errors == 1);
-        CHECK(sax.messages.front() == "[json.exception.out_of_range.406] syntax error while parsing CBOR value: number overflow");
-        REQUIRE(cbor.size() == 2);
-        CHECK(std::isinf(cbor[0].get<float>()));
-        CHECK(cbor[1] == 1);
-
-        // UBJSON: a high-precision number too large for number_float_t
-        const auto ubjson = parse_binary_recovering({'H', 'i', 5, '1', 'e', '9', '9', '9'}, json::input_format_t::ubjson);
-        CHECK(ubjson.errors == 1);
-        CHECK(ubjson.value.is_number_float());
-        CHECK(std::isinf(ubjson.value.get<double>()));
-    }
-
-    SECTION("binary formats stop where the end of an item is not known")
-    {
-        // a byte that begins no item
-        const auto cbor = parse_binary_recovering({0x82, 0x01, 0x1C, 0x02}, json::input_format_t::cbor);
-        CHECK(cbor.errors == 1);
-        CHECK(cbor.value == json({1}));
-
-        // a key that is no item: the unused MessagePack byte, a CBOR break
-        // in a map of known size, and the end of a BON8 container
-        const auto msgpack = parse_binary_recovering({0x82, 0xA1, 'a', 0x01, 0xC1, 0x02}, json::input_format_t::msgpack);
-        CHECK(msgpack.errors == 1);
-        CHECK(msgpack.value == json({{"a", 1}}));
-        const auto cbor_break = parse_binary_recovering({0xA2, 0x61, 'a', 0x01, 0xFF, 0x02}, json::input_format_t::cbor);
-        CHECK(cbor_break.errors == 1);
-        CHECK(cbor_break.value == json({{"a", 1}}));
-        const auto bon8 = parse_binary_recovering({0x88, 0x61, 0x91, 0xFE}, json::input_format_t::bon8);
-        CHECK(bon8.errors == 1);
-        CHECK(bon8.value == json({{"a", 1}}));
-
-        // an indefinite-length string inside an indefinite-length string
-        const auto nested = parse_binary_recovering({0x82, 0x01, 0x7F, 0x7F, 0x61, 'a', 0xFF, 0xFF}, json::input_format_t::cbor);
-        CHECK(nested.errors == 1);
-        CHECK(nested.value == json({1}));
-
-        // a BJData ndarray whose element type has no name: the object that
-        // holds the ndarray was already begun
-        const auto ndarray = parse_binary_recovering({'[', '$', 0x01, '#', '[', '$', 'i', '#', 'i', 2, 2, 3}, json::input_format_t::bjdata);
-        CHECK(ndarray.errors == 1);
-        CHECK(ndarray.balanced);
-        CHECK(ndarray.value == json::object());
-
-        // a skipped member that the input ends in
-        const auto truncated = parse_binary_recovering({0xA2, 0x01, 0x82, 0x01}, json::input_format_t::cbor);
-        CHECK(truncated.errors == 2);
-        CHECK(truncated.balanced);
-        CHECK(truncated.value == json::object());
-
-        // a BSON element of an unknown type in a document whose size cannot be right
-        const auto bson = parse_binary_recovering(bson_document({bson_element(0x10, "a", bson_int32(1)), bson_element(0x42, "x", bytes(3))}, -10), json::input_format_t::bson);
-        CHECK(bson.errors == 1);
-        CHECK(bson.value == json({{"a", 1}, {"x", nullptr}}));
-    }
-
-    SECTION("changed bytes in binary input")
-    {
-        const json j = {{"a", {1, -2, {{"b", "c"}}, json::array()}}, {"d", {{"e", nullptr}, {"f", true}}}, {"g", 1.5}, {"h", json::binary({1, 2, 3})}, {"i", "\xC3\xA4"}};
-
-        const std::vector<std::pair<json::input_format_t, std::vector<std::uint8_t>>> encodings =
-        {
-            {json::input_format_t::cbor, json::to_cbor(j)},
-            {json::input_format_t::msgpack, json::to_msgpack(j)},
-            {json::input_format_t::ubjson, json::to_ubjson(j)},
-            {json::input_format_t::ubjson, json::to_ubjson(j, true, true)},
-            {json::input_format_t::bjdata, json::to_bjdata(j)},
-            {json::input_format_t::bjdata, json::to_bjdata(j, true, true)},
-            {json::input_format_t::bson, json::to_bson(j)},
-            {json::input_format_t::bon8, json::to_bon8(j)},
-        };
-        const std::vector<std::uint8_t> replacements = {0x00, 0x01, 0x7F, 0x80, 0xC1, 0xD9, 0xE0, 0xF7, 0xFE, 0xFF};
-
-        for (const auto& encoding : encodings)
-        {
-            const auto format = encoding.first;
-            const auto& original = encoding.second;
-            CAPTURE(format)
-
-            std::vector<std::vector<std::uint8_t>> inputs;
-            for (std::size_t position = 0; position < original.size(); ++position)
-            {
-                for (const auto replacement : replacements)
-                {
-                    auto changed = original;
-                    changed[position] = replacement;
-                    inputs.push_back(changed);
-                }
-                auto removed = original;
-                removed.erase(removed.begin() + static_cast<std::ptrdiff_t>(position));
-                inputs.push_back(removed);
-            }
-
-            for (const auto& input : inputs)
-            {
-                CAPTURE(input)
-                const auto result = parse_binary_recovering(input, format);
-                CHECK(result.balanced);
-                CHECK(result.errors <= input.size() + 1);
-#if !defined(JSON_NOEXCEPTION)
-                // an error is reported exactly if reading into a JSON value
-                // fails, and the first one is the same (under JSON_NOEXCEPTION,
-                // that reading aborts instead of throwing)
-                const auto message = binary_error_message(input, format);
-                CHECK(result.ok == message.empty());
-                if (!result.ok && result.errors < 100)
-                {
-                    CHECK(result.messages.front() == message);
-                }
-#endif
-            }
-        }
-    }
-
-    SECTION("JSON text")
-    {
-        // the parser stopped, but reported success
-        json j;
-        RecoveringParser sax(j);
-        CHECK(!json::sax_parse("[1,2,3,]", &sax));
-        CHECK(sax.errors == 1);
-        CHECK(j == json({1, 2, 3}));
-    }
-
-    SECTION("the SAX parsers of the library stop")
-    {
-        json _;
-        CHECK(json::from_cbor(std::vector<std::uint8_t> {0x9F}, true, false).is_discarded());
-        CHECK_THROWS_WITH_AS(_ = json::from_cbor(std::vector<std::uint8_t> {0x9F}), "[json.exception.parse_error.110] parse error at byte 2: syntax error while parsing CBOR value: unexpected end of input", json::parse_error&);
-        CHECK(json::parse("[1,2,3,]", nullptr, false).is_discarded());
-        CHECK(!json::accept("[1,2,3,]"));
-    }
-}
-
 #if (defined(__cpp_exceptions) || defined(__EXCEPTIONS) || defined(_CPPUNWIND)) && !defined(JSON_NOEXCEPTION)
 TEST_CASE("regression test #5135 - destructor never allocates, even under memory pressure")
 {