json_view: no save() and load() on big-endian targets

The image format is little-endian only. Instead of throwing
type_error.320 at runtime, save_image(), load_image() and the members
save() and load() do not exist on a big-endian target, so a call fails to
compile, like set() on a read-only document. type_error.320 remains for
saving a discarded document.

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

BUILD.bazel

@@ -90,6 +90,7 @@ cc_library(
         "include/nlohmann/detail/view/simd.hpp",
         "include/nlohmann/detail/view/string_ref.hpp",
         "include/nlohmann/detail/view/value.hpp",
+        "include/nlohmann/detail/view/view_mode.hpp",
         "include/nlohmann/json.hpp",
         "include/nlohmann/json_fwd.hpp",
         "include/nlohmann/json_literals.hpp",

docs/mkdocs/docs/api/basic_json_document/erase.md

@@ -12,7 +12,7 @@ void erase(view_type array, I idx);
 std::size_t erase(const json_pointer& ptr);
 ```
 
-Only an **editable** document (`#!cpp Editable == true`, e.g. [`json_editable_document`](../json_editable_document.md))
+Only an **editable** document (`#!cpp view_mode::editable`, e.g. [`json_editable_document`](../json_editable_document.md))
 has `erase`; calling it on a read-only `basic_json_document` fails to compile (`#!cpp static_assert`).
 
 1. Removes every member of `object` whose key is `key` (see [Notes](#notes) on duplicate keys) and returns how many

docs/mkdocs/docs/api/basic_json_document/index.md

@@ -3,7 +3,7 @@
 <small>Defined in header `<nlohmann/json_view.hpp>`</small>
 
 ```cpp
-template<typename BasicJsonType, bool Editable = false>
+template<typename BasicJsonType, view_mode Mode = view_mode::read_only>
 class basic_json_document;
 ```
 
@@ -20,9 +20,9 @@ is move-only: a copy would duplicate the whole index, the decoded-string buffer,
 enough in every use we know of. The index, the decoded strings, and the owned text live in one heap block that the
 document holds through a `#!cpp std::unique_ptr`; this is also why views survive a move of the document.
 
-With `#!cpp Editable == true`, the document also offers [`set`](set.md), [`push_back`](push_back.md),
+With `#!cpp Mode == view_mode::editable`, the document also offers [`set`](set.md), [`push_back`](push_back.md),
 [`insert`](insert.md), and [`erase`](erase.md) to change values in place, see [Edits](#edits) below. The source text
-itself is never written; a read-only document (`#!cpp Editable == false`, the default) does not carry any of the
+itself is never written; a read-only document (`#!cpp view_mode::read_only`, the default) does not carry any of the
 bookkeeping edits need, and calling any of them on one fails to compile (`#!cpp static_assert`).
 
 ## Template parameters
@@ -32,9 +32,10 @@ bookkeeping edits need, and calling any of them on one fails to compile (`#!cpp
     [`ordered_json`](../ordered_json.md). Only 64-bit `number_integer_t`/`number_unsigned_t` types are supported; this
     is checked with a `static_assert`.
 
-`Editable`
-:   whether the document supports [`set`](set.md), [`push_back`](push_back.md), [`insert`](insert.md), and
-    [`erase`](erase.md) (optional, `#!cpp false` by default). See [Edits](#edits) below.
+`Mode`
+:   a [`view_mode`](../view_mode.md): `#!cpp view_mode::editable` if the document supports [`set`](set.md),
+    [`push_back`](push_back.md), [`insert`](insert.md), and [`erase`](erase.md) (optional, `#!cpp view_mode::read_only`
+    by default). See [Edits](#edits) below.
 
 ## Specializations
 
@@ -47,7 +48,7 @@ bookkeeping edits need, and calling any of them on one fails to compile (`#!cpp
 
 ## Member types
 
-- **view_type** - the type of view returned by [`root()`](root.md) (`#!cpp basic_json_view<BasicJsonType, Editable>`)
+- **view_type** - the type of view returned by [`root()`](root.md) (`#!cpp basic_json_view<BasicJsonType, Mode>`)
 - **value_t** - the JSON type enumeration, see [`basic_json::value_t`](../basic_json/value_t.md)
 - **image_check** - how [`load()`](load.md) validates an image (`full`, `bounds`, `none`), see [`image_check`](load.md#image_check)
 
@@ -80,15 +81,15 @@ bookkeeping edits need, and calling any of them on one fails to compile (`#!cpp
 ### Edits
 
 - [**set**](set.md) - replace a value, or set an object member, an array element, or the value a JSON pointer refers
-  to (`#!cpp Editable` documents only)
-- [**push_back**](push_back.md) - append to an array (`#!cpp Editable` documents only)
-- [**insert**](insert.md) - insert an element into an array before a given position (`#!cpp Editable` documents only)
+  to (editable documents only)
+- [**push_back**](push_back.md) - append to an array (editable documents only)
+- [**insert**](insert.md) - insert an element into an array before a given position (editable documents only)
 - [**erase**](erase.md) - remove an object member, an array element, or the value a JSON pointer refers to
-  (`#!cpp Editable` documents only)
+  (editable documents only)
 
 ## Edits
 
-An editable document (`#!cpp Editable == true`) can be changed after parsing, with [`set`](set.md),
+An editable document (`#!cpp view_mode::editable`) can be changed after parsing, with [`set`](set.md),
 [`push_back`](push_back.md), [`insert`](insert.md), and [`erase`](erase.md);
 [`json_editable_document`](../json_editable_document.md) and
 [`ordered_json_editable_document`](../ordered_json_editable_document.md) are the corresponding specializations. A few

docs/mkdocs/docs/api/basic_json_document/insert.md

@@ -5,7 +5,7 @@ template<typename I, typename V>
 view_type insert(view_type array, I idx, V&& value);
 ```
 
-Only an **editable** document (`#!cpp Editable == true`, e.g. [`json_editable_document`](../json_editable_document.md))
+Only an **editable** document (`#!cpp view_mode::editable`, e.g. [`json_editable_document`](../json_editable_document.md))
 has `insert`; calling it on a read-only `basic_json_document` fails to compile (`#!cpp static_assert`).
 
 Inserts `value` into `array` as a new element before position `idx`, which must not be past the end

docs/mkdocs/docs/api/basic_json_document/load.md

@@ -55,10 +55,7 @@ validate with overload 2 first, if the original vector must survive a failed loa
 
 ## Exceptions
 
-On a big-endian target, throws [`type_error.320`](../../home/exceptions.md#jsonexceptiontype_error320) -- the same
-exception [`save()`](save.md#exceptions) throws there, since the image format is little-endian only.
-
-Otherwise throws [`parse_error.116`](../../home/exceptions.md#jsonexceptionparse_error116) if `image` is not one
+Throws [`parse_error.116`](../../home/exceptions.md#jsonexceptionparse_error116) if `image` is not one
 `save()` could have written, or fails the requested `check`:
 
 | message               | when                                                                                                |
@@ -95,6 +92,9 @@ are checked once, however many nodes refer to it.
 
 ## Notes
 
+**Little-endian targets only.** On a big-endian target, `load()` does not exist, just like
+[`save()`](save.md#notes): the image format is little-endian, so a call fails to compile.
+
 ### `image_check` { #image_check }
 
 ```cpp

docs/mkdocs/docs/api/basic_json_document/push_back.md

@@ -13,7 +13,7 @@ editable, and it does not have to be `array`'s own document -- which is copied s
 source document afterward; a `BasicJsonType` value; or anything `BasicJsonType` can be constructed from (numbers,
 strings, `#!cpp bool`, `#!cpp nullptr`, containers, ...).
 
-Only an **editable** document (`#!cpp Editable == true`, e.g. [`json_editable_document`](../json_editable_document.md))
+Only an **editable** document (`#!cpp view_mode::editable`, e.g. [`json_editable_document`](../json_editable_document.md))
 has `push_back`; calling it on a read-only `basic_json_document` fails to compile (`#!cpp static_assert`).
 
 ## Template parameters

docs/mkdocs/docs/api/basic_json_document/save.md

@@ -12,7 +12,7 @@ An edited document is written in its *current* state, with its values in documen
 parser would have produced them for that JSON text: a member [`set`](set.md) added goes at the end, an
 [`erase`](erase.md)d member leaves no trace, and a float that is not finite (NaN or positive/negative infinity)
 becomes null, the same substitution [`dump()`](../basic_json_view/dump.md) makes. The same document always saves to
-the same bytes -- also across `BasicJsonType` and `#!cpp Editable`, since the image reflects document order and
+the same bytes -- also across `BasicJsonType` and the [`view_mode`](../view_mode.md), since the image reflects document order and
 values only, not which specialization produced them.
 
 ## Return value
@@ -31,9 +31,6 @@ Throws [`type_error.320`](../../home/exceptions.md#jsonexceptiontype_error320) i
 [discarded](is_discarded.md) -- a default-constructed document, or one a failed [`parse()`](parse.md)/
 [`read()`](read.md) with `allow_exceptions == false` left discarded.
 
-On a big-endian target, throws `type_error.320` with a different message instead: the image format is little-endian
-only (see [Notes](#notes)).
-
 Throws [`out_of_range.416`](../../home/exceptions.md#jsonexceptionout_of_range416) if the node count, the text, or
 the decoded strings of the image would individually reach 4 GiB -- the same 32-bit offsets
 [`parse()`](parse.md#exceptions) and, for edits, [`set`](set.md)/[`push_back`](push_back.md) are already limited to.
@@ -44,9 +41,6 @@ the decoded strings of the image would individually reach 4 GiB -- the same 32-b
     [json.exception.type_error.320] cannot save a discarded json_document
     ```
     ```
-    [json.exception.type_error.320] json_document images need a little-endian target
-    ```
-    ```
     [json.exception.out_of_range.416] images of 4 GiB or more are not supported by json_document
     ```
 
@@ -70,9 +64,9 @@ else -- see [`load`'s Exceptions](load.md#exceptions).
     the *same* build on the *same* (little-endian) machine -- not as a long-term storage format. Keep the original
     JSON text if you need to read a saved document back with a future library version.
 
-**Little-endian only.** The image is written as raw little-endian bytes, with no byte-swapping. `save()` (and
-[`load`](load.md)) throw `type_error.320` on a big-endian target rather than silently produce bytes a big-endian
-reader could not interpret correctly.
+**Little-endian targets only.** The image is written as raw little-endian bytes, with no byte-swapping. On a
+big-endian target, `save()` and [`load`](load.md) do not exist: a call fails to compile rather than produce bytes a
+big-endian reader could not interpret correctly.
 
 ## Examples
 

docs/mkdocs/docs/api/basic_json_document/set.md

@@ -18,7 +18,7 @@ template<typename V>
 view_type set(const json_pointer& ptr, V&& value);
 ```
 
-Only an **editable** document (`#!cpp Editable == true`, e.g. [`json_editable_document`](../json_editable_document.md))
+Only an **editable** document (`#!cpp view_mode::editable`, e.g. [`json_editable_document`](../json_editable_document.md))
 has `set`; calling it on a read-only `basic_json_document` fails to compile (`#!cpp static_assert`).
 
 1. Replaces the value `target` refers to with `value`.

docs/mkdocs/docs/api/basic_json_view/index.md

@@ -3,7 +3,7 @@
 <small>Defined in header `<nlohmann/json_view.hpp>`</small>
 
 ```cpp
-template<typename BasicJsonType, bool Editable = false>
+template<typename BasicJsonType, view_mode Mode = view_mode::read_only>
 class basic_json_view;
 ```
 
@@ -37,7 +37,7 @@ Moving the document itself does not invalidate its views: the index is heap-allo
 `#!cpp operator ValueType()`), and no `#!cpp get_ptr()` or `#!cpp get_ref()`; see [`get`](get.md).
 
 `basic_json_view` itself is always read-only -- it never has a `set` or `push_back` of its own. A view of an
-**editable** document (`#!cpp Editable == true`) sees every edit made through
+**editable** document (`#!cpp view_mode::editable`) sees every edit made through
 [`basic_json_document::set`](../basic_json_document/set.md) and
 [`basic_json_document::push_back`](../basic_json_document/push_back.md): once a value is changed, every view that
 still refers to it -- including ones taken before the change -- reads the new value. See
@@ -49,9 +49,10 @@ still refers to it -- including ones taken before the change -- reads the new va
 :   a specialization of [`basic_json`](../basic_json/index.md), matching the
     [`basic_json_document`](../basic_json_document/index.md) the view was taken from.
 
-`Editable`
-:   whether the view is of an editable document, matching the [`basic_json_document`](../basic_json_document/index.md)
-    it was taken from (optional, `#!cpp false` by default). See [Edits](../basic_json_document/index.md#edits).
+`Mode`
+:   a [`view_mode`](../view_mode.md): whether the view is of an editable document, matching the
+    [`basic_json_document`](../basic_json_document/index.md) it was taken from (optional, `#!cpp view_mode::read_only` by
+    default). See [Edits](../basic_json_document/index.md#edits).
 
 ## Specializations
 

docs/mkdocs/docs/api/json_editable_document.md

@@ -3,7 +3,7 @@
 <small>Defined in header `<nlohmann/json_view.hpp>`</small>
 
 ```cpp
-using json_editable_document = basic_json_document<json, true>;
+using json_editable_document = basic_json_document<json, view_mode::editable>;
 ```
 
 This type is an **editable** [`basic_json_document`](basic_json_document/index.md) of the default

docs/mkdocs/docs/api/json_editable_view.md

@@ -3,7 +3,7 @@
 <small>Defined in header `<nlohmann/json_view.hpp>`</small>
 
 ```cpp
-using json_editable_view = basic_json_view<json, true>;
+using json_editable_view = basic_json_view<json, view_mode::editable>;
 ```
 
 This type is a [`basic_json_view`](basic_json_view/index.md) of a value of a

docs/mkdocs/docs/api/ordered_json_editable_document.md

@@ -3,7 +3,7 @@
 <small>Defined in header `<nlohmann/json_view.hpp>`</small>
 
 ```cpp
-using ordered_json_editable_document = basic_json_document<ordered_json, true>;
+using ordered_json_editable_document = basic_json_document<ordered_json, view_mode::editable>;
 ```
 
 This type is an **editable** [`basic_json_document`](basic_json_document/index.md) of the

docs/mkdocs/docs/api/ordered_json_editable_view.md

@@ -3,7 +3,7 @@
 <small>Defined in header `<nlohmann/json_view.hpp>`</small>
 
 ```cpp
-using ordered_json_editable_view = basic_json_view<ordered_json, true>;
+using ordered_json_editable_view = basic_json_view<ordered_json, view_mode::editable>;
 ```
 
 This type is a [`basic_json_view`](basic_json_view/index.md) of a value of an

docs/mkdocs/docs/api/view_mode.md

@@ -0,0 +1,80 @@
+# <small>nlohmann::</small>view_mode
+
+<small>Defined in header `<nlohmann/json_view.hpp>`</small>
+
+```cpp
+enum class view_mode : std::uint8_t
+{
+    read_only,
+    editable
+};
+```
+
+The second template parameter of [`basic_json_document`](basic_json_document/index.md) and
+[`basic_json_view`](basic_json_view/index.md): whether a document can be changed after parsing, and whether a view is
+of such a document.
+
+`read_only`
+:   the default: the document is parsed once and then only read. It carries none of the bookkeeping edits need, and
+    calling [`set`](basic_json_document/set.md), [`push_back`](basic_json_document/push_back.md),
+    [`insert`](basic_json_document/insert.md), or [`erase`](basic_json_document/erase.md) on it fails to compile.
+
+`editable`
+:   the document also offers [`set`](basic_json_document/set.md), [`push_back`](basic_json_document/push_back.md),
+    [`insert`](basic_json_document/insert.md), and [`erase`](basic_json_document/erase.md); its views see every edit,
+    see [Edits](basic_json_document/index.md#edits).
+
+The shortcuts name both modes: [`json_document`](json_document.md) and [`json_view`](json_view.md) are read-only,
+[`json_editable_document`](json_editable_document.md) and [`json_editable_view`](json_editable_view.md) are editable
+(and likewise for `ordered_json`).
+
+## Notes
+
+The mode is part of the view's type, and there is no conversion between the two modes: a read-only view reads a
+container in place, while a view of an editable document follows the links that edits leave behind. A function that
+accepts views therefore names the modes it accepts in its signature:
+
+```cpp
+// views of editable documents only
+template<typename BasicJsonType>
+void f(basic_json_view<BasicJsonType, view_mode::editable> v);
+
+// views of read-only documents only
+template<typename BasicJsonType>
+void f(basic_json_view<BasicJsonType, view_mode::read_only> v);
+
+// either
+template<typename BasicJsonType, view_mode Mode>
+void f(basic_json_view<BasicJsonType, Mode> v);
+```
+
+A function that takes a [`json_view`](json_view.md) accepts neither an [`ordered_json_view`](ordered_json_view.md)
+nor a [`json_editable_view`](json_editable_view.md). Views of the two modes still compare with
+[`operator==`](basic_json_view/operator_eq.md).
+
+## Examples
+
+??? example
+
+    The example below shows a function template that accepts the views of both modes, and one that accepts only
+    views of editable documents.
+
+    ```cpp
+    --8<-- "examples/view_mode.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/view_mode.output"
+    ```
+
+## See also
+
+- [basic_json_document](basic_json_document/index.md) - a parsed JSON text
+- [basic_json_view](basic_json_view/index.md) - a handle to one value of a document
+- [json_editable_document](json_editable_document.md) - an editable document of `json`
+
+## Version history
+
+Added in version 3.13.0.

docs/mkdocs/docs/examples/ordered_json_editable_document.cpp

@@ -5,7 +5,7 @@ using ordered_json_editable_document = nlohmann::ordered_json_editable_document;
 
 int main()
 {
-    // ordered_json_editable_document is basic_json_document<nlohmann::ordered_json, true>
+    // ordered_json_editable_document is basic_json_document<nlohmann::ordered_json, nlohmann::view_mode::editable>
     ordered_json_editable_document doc = ordered_json_editable_document::parse(R"({"z": 1, "a": 2, "m": 3})");
     doc.set(doc.root(), "b", 4); // set() always appends a new member at the end
 

docs/mkdocs/docs/examples/view_mode.cpp

@@ -0,0 +1,29 @@
+#include <iostream>
+#include <nlohmann/json_view.hpp>
+
+using nlohmann::basic_json_view;
+using nlohmann::view_mode;
+
+// accepts the views of read-only and of editable documents, of json and of ordered_json
+template<typename BasicJsonType, view_mode Mode>
+std::size_t count_members(basic_json_view<BasicJsonType, Mode> v)
+{
+    return v.is_object() ? v.size() : 0;
+}
+
+// accepts only the views of editable documents
+template<typename BasicJsonType>
+bool is_edited(basic_json_view<BasicJsonType, view_mode::editable> v)
+{
+    return v.is_string() && v.get_string() == "edited";
+}
+
+int main()
+{
+    const nlohmann::json_document doc = nlohmann::json_document::parse(R"({"a": 1, "b": 2})");
+    nlohmann::json_editable_document edoc = nlohmann::json_editable_document::parse(R"({"a": 1})");
+    edoc.set(edoc.root()["a"], "edited");
+
+    std::cout << count_members(doc.root()) << ' ' << count_members(edoc.root()) << '\n';
+    std::cout << std::boolalpha << is_edited(edoc.root()["a"]) << '\n';
+}

docs/mkdocs/docs/examples/view_mode.output

@@ -0,0 +1,2 @@
+2 1
+true

docs/mkdocs/docs/features/json_view.md

@@ -252,14 +252,14 @@ the stream's `width`/`fill` for indentation.
 ## Editing a document
 
 Everything above is read-only: a `json_document`/`json_view` lets you look at a parsed text without copying it, but
-not change it. [`basic_json_document<BasicJsonType, true>`](../api/basic_json_document/index.md) -- more conveniently
+not change it. [`basic_json_document<BasicJsonType, view_mode::editable>`](../api/basic_json_document/index.md) -- more conveniently
 spelled [`json_editable_document`](../api/json_editable_document.md) or
 [`ordered_json_editable_document`](../api/ordered_json_editable_document.md) -- also lets you
 [`set`](../api/basic_json_document/set.md) a value, [`push_back`](../api/basic_json_document/push_back.md) onto or
 [`insert`](../api/basic_json_document/insert.md) into an array, and [`erase`](../api/basic_json_document/erase.md)
 an object member or an array element, still without ever building a `basic_json` tree for parts you do not touch.
 
-`#!cpp Editable` defaults to `#!cpp false`, so `json_document`/`ordered_json_document` are unaffected -- they carry
+The [mode](../api/view_mode.md) defaults to `#!cpp view_mode::read_only`, so `json_document`/`ordered_json_document` are unaffected -- they carry
 none of the bookkeeping edits need, and calling `set`/`push_back`/`insert`/`erase` on one is a compile error, not a
 runtime one.
 
@@ -354,9 +354,10 @@ validation entirely, for an image trusted as much as the process's own memory. S
 !!! warning "Experimental"
 
     The image format is versioned but not yet stable, and may change in an incompatible way before it is declared
-    stable. It is little-endian only, and tied to the library build that wrote it -- use it to cache a document or to
-    hand one to another process running the *same* build, not as a long-term storage format; keep the original JSON
-    text if a saved document needs to be readable by a future library version.
+    stable. It is little-endian only (on big-endian targets, `save()` and `load()` do not exist), and tied to the
+    library build that wrote it -- use it to cache a document or to hand one to another process running the *same*
+    build, not as a long-term storage format; keep the original JSON text if a saved document needs to be readable by
+    a future library version.
 
 The idea of a document you can read without parsing comes from zero-copy formats such as
 [FlatBuffers](https://github.com/google/flatbuffers) and [YaFF](https://github.com/yandex/yaff); the check

docs/mkdocs/docs/home/exceptions.md

@@ -853,17 +853,12 @@ from JSON text.
 
 [`basic_json_document::save()`](../api/basic_json_document/save.md) cannot write an
 [image](../features/json_view.md#images) of a [discarded](../api/basic_json_document/is_discarded.md) document.
-[`save()`](../api/basic_json_document/save.md) and [`load()`](../api/basic_json_document/load.md) also throw this
-exception on a big-endian target, since the image format is little-endian only.
 
 !!! failure "Example messages"
 
     ```
     [json.exception.type_error.320] cannot save a discarded json_document
     ```
-    ```
-    [json.exception.type_error.320] json_document images need a little-endian target
-    ```
 
 !!! note
 

docs/mkdocs/mkdocs.yml

@@ -407,6 +407,7 @@ nav:
       - 'ordered_json_editable_view': api/ordered_json_editable_view.md
       - 'ordered_json_view': api/ordered_json_view.md
       - 'ordered_map': api/ordered_map.md
+      - 'view_mode': api/view_mode.md
       - macros:
           - 'Overview': api/macros/index.md
           - 'JSON_ASSERT': api/macros/json_assert.md

include/nlohmann/detail/exceptions.hpp

@@ -102,7 +102,7 @@ enum class exception_id : int
     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
     document_binary_value = 319, ///< a binary value is stored in a json_document
-    document_image_unsupported = 320, ///< a json_document image cannot be saved or loaded (discarded document, big-endian target)
+    document_image_unsupported = 320, ///< a discarded json_document cannot be saved as an image
     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

include/nlohmann/detail/view/builder.hpp

@@ -978,7 +978,7 @@ indent_done:
             std::memcpy(reinterpret_cast<unsigned char*>(n), &first, 8);
             std::memcpy(reinterpret_cast<unsigned char*>(n) + 8, &second, 8);
 #else
-            n->kind = static_cast<std::uint8_t>(k);
+            n->kind = static_cast<node_kind>(k);
             n->flags = flags;
             n->extra = extra;
             n->off = static_cast<std::uint32_t>(off);

include/nlohmann/detail/view/document_data.hpp

@@ -232,7 +232,7 @@ struct document_data
     /// following loads.
     static NLOHMANN_VIEW_ALWAYS_INLINE const node* deref(const node* n) noexcept
     {
-        return NLOHMANN_VIEW_LIKELY(n->kind != kind_link) ? n : follow_link(n);
+        return NLOHMANN_VIEW_LIKELY(n->kind != node_kind::link) ? n : follow_link(n);
     }
 
     static NLOHMANN_VIEW_NOINLINE const node* follow_link(const node* n) noexcept

include/nlohmann/detail/view/edit.hpp

@@ -26,12 +26,10 @@
 #include <nlohmann/detail/view/lookup.hpp>
 #include <nlohmann/detail/view/macro_scope.hpp>
 #include <nlohmann/detail/view/node.hpp>
+#include <nlohmann/detail/view/view_mode.hpp>
 
 NLOHMANN_JSON_NAMESPACE_BEGIN
 
-template<typename BasicJsonType, bool Editable>
-class basic_json_view;
-
 namespace detail
 {
 namespace view
@@ -120,13 +118,13 @@ class editor
     View set(const View& object, string_view_t key, V&& value)
     {
         node* const o = own(object);
-        if (o->kind != static_cast<std::uint8_t>(value_t::object) && o->kind != static_cast<std::uint8_t>(value_t::null))
+        if (o->kind != node_kind::object && o->kind != node_kind::null)
         {
             throw_type_error(exception_id::subscript_wrong_type, "cannot use operator[] with a string argument with ", object.type_name());
         }
         check_utf8(key.data(), key.size());
         const encoded e = encode(std::forward<V>(value));
-        if (o->kind == static_cast<std::uint8_t>(value_t::null))
+        if (o->kind == node_kind::null)
         {
             become_empty(o, value_t::object);
         }
@@ -171,7 +169,7 @@ class editor
     View set(const View& array, std::size_t idx, V&& value)
     {
         node* const a = own(array);
-        if (a->kind != static_cast<std::uint8_t>(value_t::array))
+        if (a->kind != node_kind::array)
         {
             throw_type_error(exception_id::subscript_wrong_type, "cannot use operator[] with a numeric argument with ", array.type_name());
         }
@@ -188,12 +186,12 @@ class editor
     View push_back(const View& array, V&& value)
     {
         node* const a = own(array);
-        if (a->kind != static_cast<std::uint8_t>(value_t::array) && a->kind != static_cast<std::uint8_t>(value_t::null))
+        if (a->kind != node_kind::array && a->kind != node_kind::null)
         {
             throw_type_error(exception_id::push_back_wrong_type, "cannot use push_back() with ", array.type_name());
         }
         const encoded e = encode(std::forward<V>(value));
-        if (a->kind == static_cast<std::uint8_t>(value_t::null))
+        if (a->kind == node_kind::null)
         {
             become_empty(a, value_t::array);
         }
@@ -212,7 +210,7 @@ class editor
     View insert(const View& array, std::size_t idx, V&& value)
     {
         node* const a = own(array);
-        if (a->kind != static_cast<std::uint8_t>(value_t::array))
+        if (a->kind != node_kind::array)
         {
             throw_type_error(exception_id::insert_wrong_type, "cannot use insert() with ", array.type_name());
         }
@@ -232,7 +230,7 @@ class editor
     std::size_t erase(const View& object, string_view_t key)
     {
         node* const o = own(object);
-        if (o->kind != static_cast<std::uint8_t>(value_t::object))
+        if (o->kind != node_kind::object)
         {
             throw_type_error(exception_id::erase_wrong_type, "cannot use erase() with ", object.type_name());
         }
@@ -250,7 +248,7 @@ class editor
     void erase(const View& array, std::size_t idx)
     {
         node* const a = own(array);
-        if (a->kind != static_cast<std::uint8_t>(value_t::array))
+        if (a->kind != node_kind::array)
         {
             throw_type_error(exception_id::erase_wrong_type, "cannot use erase() with ", array.type_name());
         }
@@ -328,7 +326,7 @@ class editor
     {
         const std::uint8_t linked = n->flags & node_flags::linked;
         *n = node{};
-        n->kind = static_cast<std::uint8_t>(k);
+        n->kind = static_cast<node_kind>(k);
         n->flags = static_cast<std::uint8_t>(node_flags::is_new | linked);
         n->next = 1;
     }
@@ -405,8 +403,8 @@ class editor
     template<typename T>
     struct is_view : std::false_type {};
 
-    template<typename J, bool E>
-    struct is_view<basic_json_view<J, E>> : std::true_type {};
+    template<typename J, view_mode M>
+    struct is_view<basic_json_view<J, M>> : std::true_type {};
 
     template<typename V>
     encoded encode(V&& v)
@@ -421,8 +419,8 @@ class editor
     }
 
     /// a view of any document (copied; nothing is shared with it)
-    template<typename J, bool E>
-    encoded encode_impl(const basic_json_view<J, E>& v, encode_tag<0> /*view*/)
+    template<typename J, view_mode M>
+    encoded encode_impl(const basic_json_view<J, M>& v, encode_tag<0> /*view*/)
     {
         if (NLOHMANN_VIEW_UNLIKELY(v.m_node == nullptr))
         {
@@ -434,8 +432,8 @@ class editor
             r.scalar = copy_scalar(*v.m_doc, *v.m_node);
             return r;
         }
-        r.region = alloc_nodes(m_doc, count_nodes<E>(*v.m_doc, v.m_node));
-        fill_nodes<E>(*v.m_doc, v.m_node, r.region);
+        r.region = alloc_nodes(m_doc, count_nodes<M == view_mode::editable>(*v.m_doc, v.m_node));
+        fill_nodes<M == view_mode::editable>(*v.m_doc, v.m_node, r.region);
         edit_state_of(m_doc).regions.emplace(r.region, nullptr);
         return r;
     }
@@ -496,7 +494,7 @@ class editor
     static node plain_node(value_t k) noexcept
     {
         node n{};
-        n.kind = static_cast<std::uint8_t>(k);
+        n.kind = static_cast<node_kind>(k);
         n.flags = node_flags::is_new;
         return n;
     }
@@ -681,7 +679,7 @@ class editor
             ++r;
             if (is_container(*n))
             {
-                open.push_back(frame{walk::first(d, n), walk::end(d, n), n->kind == static_cast<std::uint8_t>(value_t::object)});
+                open.push_back(frame{walk::first(d, n), walk::end(d, n), n->kind == node_kind::object});
             }
             // the next value: close finished containers, then step over the key
             for (;;)
@@ -730,7 +728,7 @@ class editor
                 node* const self = out++;
                 *self = plain_node(static_cast<value_t>(n->kind));
                 self->len = n->len;
-                open.push_back(frame{walk::first(d, n), walk::end(d, n), n->kind == static_cast<std::uint8_t>(value_t::object), self});
+                open.push_back(frame{walk::first(d, n), walk::end(d, n), n->kind == node_kind::object, self});
             }
             else
             {

include/nlohmann/detail/view/edit_storage.hpp

@@ -27,7 +27,7 @@
 // live in chunks that never move; strings and number tokens written by edits
 // live in the edit arena. An array/object whose elements change gets
 // node_flags::moved: its elements then live in a separate sequence (a header
-// node, then the entries), whose entries link to the values (kind_link).
+// node, then the entries), whose entries link to the values (node_kind::link).
 
 NLOHMANN_JSON_NAMESPACE_BEGIN
 namespace detail
@@ -185,7 +185,7 @@ inline node* block_of(document_data& d, node* n, std::size_t extra)
         return nh;
     }
     reserve_moved(d); // (so that set_moved() below cannot throw: the links are marked before)
-    const bool object = n->kind == static_cast<std::uint8_t>(value_t::object);
+    const bool object = n->kind == node_kind::object;
     const std::size_t used = 1 + (static_cast<std::size_t>(n->len) * (object ? 2 : 1));
     const std::size_t cap = used + extra;
     node* const h = alloc_nodes(d, cap);
@@ -251,7 +251,7 @@ inline node* find_parent(const document_data& d, const node* target)
         {
             return nullptr; // LCOV_EXCL_LINE (the value is inside c)
         }
-        const bool object = c->kind == static_cast<std::uint8_t>(value_t::object);
+        const bool object = c->kind == node_kind::object;
         const node* down = nullptr;
         for (const node* p = d.first_child_edited(c), *e = d.child_end_edited(c); p != e;)
         {

include/nlohmann/detail/view/image.hpp

@@ -117,7 +117,7 @@ inline void compact_nodes(const document_data& d, std::size_t arena_size, std::v
                 r.off = (v->flags & (node_flags::moved | node_flags::is_new)) != 0 ? 0 : v->off;
                 r.len = 0;  // counted below
                 r.next = 0; // set when the container is complete
-                stack.push_back(frame{d.first_child_edited(v), d.child_end_edited(v), out.size(), 0, v->kind == static_cast<std::uint8_t>(value_t::object)});
+                stack.push_back(frame{d.first_child_edited(v), d.child_end_edited(v), out.size(), 0, v->kind == node_kind::object});
                 break;
             case value_t::string:
                 r = string_node(*v);
@@ -138,7 +138,7 @@ inline void compact_nodes(const document_data& d, std::size_t arena_size, std::v
                     if (t[0] == 'n' || t[0] == 'i' || (v->len > 1 && t[1] == 'i'))
                     {
                         r = node{}; // nan and infinity: null, as dump() writes them
-                        r.kind = static_cast<std::uint8_t>(value_t::null);
+                        r.kind = node_kind::null;
                         break;
                     }
                     r.off = static_cast<std::uint32_t>(d.size + text_tail.size());
@@ -182,12 +182,10 @@ inline void compact_nodes(const document_data& d, std::size_t arena_size, std::v
     }
 }
 
+#if NLOHMANN_VIEW_LITTLE_ENDIAN // (the image format is little-endian: no save() elsewhere)
 /// the document as an image
 inline std::vector<std::uint8_t> save_image(const document_data& d)
 {
-#if !NLOHMANN_VIEW_LITTLE_ENDIAN
-    throw_type_error(exception_id::document_image_unsupported, "json_document images need a little-endian target"); // LCOV_EXCL_LINE
-#endif
     const std::size_t arena_size = d.arena_size;
     std::vector<node> compacted;
     std::string text_tail;
@@ -221,7 +219,7 @@ inline std::vector<std::uint8_t> save_image(const document_data& d)
     // extra of an object, and the same document saves to the same bytes
     for (std::size_t i = 0; i < count; ++i)
     {
-        if (nodes[i].kind == static_cast<std::uint8_t>(value_t::object) && nodes[i].extra != 0)
+        if (nodes[i].kind == node_kind::object && nodes[i].extra != 0)
         {
             std::memset(o + (i * sizeof(node)) + offsetof(node, extra), 0, sizeof(nodes[i].extra));
         }
@@ -243,6 +241,7 @@ inline std::vector<std::uint8_t> save_image(const document_data& d)
     *o = 0;
     return image;
 }
+#endif
 
 /// the parts of a number token that the checks need
 struct number_token
@@ -337,7 +336,7 @@ inline bool float_token_finite(const unsigned char* s, std::size_t len, const nu
     if (static_cast<std::int64_t>(t.int_digits) + t.exponent > 300)
     {
         node n{};
-        n.kind = static_cast<std::uint8_t>(value_t::number_float);
+        n.kind = node_kind::number_float;
         n.len = static_cast<std::uint32_t>(len);
         const auto v = float_value<double>(reinterpret_cast<const char*>(s), n); // NOLINT(cppcoreguidelines-pro-type-reinterpret-cast)
         return v <= (std::numeric_limits<double>::max)() && v >= -(std::numeric_limits<double>::max)();
@@ -358,7 +357,7 @@ inline bool check_integer(const node& n, const unsigned char* text)
     }
     // the token's value is the stored one; number_integer nodes of edits can
     // be non-negative (as basic_json keeps the type of a value)
-    const bool integer = n.kind == static_cast<std::uint8_t>(value_t::number_integer);
+    const bool integer = n.kind == node_kind::number_integer;
     if (t.is_float || t.int_digits > 20 || (t.negative && !integer))
     {
         return false;
@@ -540,7 +539,7 @@ inline bool check_image(const node* nodes, std::size_t count, const unsigned cha
         {
             return false;
         }
-        if (n.kind != static_cast<std::uint8_t>(value_t::number_float))
+        if (n.kind != node_kind::number_float)
         {
             return (n.extra >> 8u) == 0;
         }
@@ -581,7 +580,7 @@ inline bool check_image(const node* nodes, std::size_t count, const unsigned cha
         const node& n = nodes[i];
         if (!stack.empty() && stack.back().object && stack.back().expect_key)
         {
-            if (n.kind != static_cast<std::uint8_t>(value_t::string) || !check_string(n))
+            if (n.kind != node_kind::string || !check_string(n))
             {
                 return false;
             }
@@ -622,7 +621,7 @@ inline bool check_image(const node* nodes, std::size_t count, const unsigned cha
                 {
                     // (the contents of float tokens are checked later; the token of an
                     // integer has at most 256 characters)
-                    if (n.kind == static_cast<std::uint8_t>(value_t::number_float))
+                    if (n.kind == node_kind::number_float)
                     {
                         floats.push_back(float_range{n.off, n.len, n.extra});
                     }
@@ -640,7 +639,7 @@ inline bool check_image(const node* nodes, std::size_t count, const unsigned cha
                 {
                     return false;
                 }
-                stack.push_back(frame{i + n.next, n.len, 0, n.kind == static_cast<std::uint8_t>(value_t::object), true});
+                stack.push_back(frame{i + n.next, n.len, 0, n.kind == node_kind::object, true});
                 complete = false;
                 break;
             }
@@ -663,13 +662,11 @@ inline bool check_image(const node* nodes, std::size_t count, const unsigned cha
     throw_parse_error(exception_id::invalid_document_image, concat("invalid json_document image: ", what));
 }
 
+#if NLOHMANN_VIEW_LITTLE_ENDIAN // (the image format is little-endian: no load() elsewhere)
 /// Read an image into d. The text and the decoded strings stay in the image;
 /// the nodes are copied (so that they are aligned, and edits can change them).
 inline void load_image(document_data& d, const std::uint8_t* image, std::size_t size, image_check check)
 {
-#if !NLOHMANN_VIEW_LITTLE_ENDIAN
-    throw_type_error(exception_id::document_image_unsupported, "json_document images need a little-endian target"); // LCOV_EXCL_LINE
-#endif
     if (image == nullptr || size < sizeof(image_header))
     {
         throw_invalid_image("too short");
@@ -729,7 +726,7 @@ inline void load_image(document_data& d, const std::uint8_t* image, std::size_t
     for (std::size_t i = 0; i < count; ++i)
     {
         const node& n = d.nodes[i];
-        if (n.kind == static_cast<std::uint8_t>(value_t::object) && n.len >= document_data::index_min_members)
+        if (n.kind == node_kind::object && n.len >= document_data::index_min_members)
         {
             d.large_objects.push_back(static_cast<std::uint32_t>(i));
         }
@@ -738,6 +735,7 @@ inline void load_image(document_data& d, const std::uint8_t* image, std::size_t
     std::vector<std::uint32_t>().swap(d.large_objects); // (only needed while building)
     d.discarded = false;
 }
+#endif
 
 }  // namespace view
 }  // namespace detail

include/nlohmann/detail/view/lookup.hpp

@@ -182,7 +182,7 @@ const node* element_at(const document_data& d, const node* array, std::size_t id
 template<bool Editable>
 const node* last_child(const document_data& d, const node* container) noexcept
 {
-    const std::size_t value_offset = container->kind == static_cast<std::uint8_t>(value_t::object) ? 1 : 0;
+    const std::size_t value_offset = container->kind == node_kind::object ? 1 : 0;
     const node* const end = navigation<Editable>::end(d, container);
     const node* last = navigation<Editable>::first(d, container);
     if (value_offset == 0 && container->next == container->len + 1u && (!navigation<Editable>::editable() || (container->flags & node_flags::moved) == 0))

include/nlohmann/detail/view/materialize.hpp

@@ -101,7 +101,7 @@ BasicJsonType materialize(const document_data& d, const node* n)
             case value_t::object:
             case value_t::array:
             {
-                const bool object = n->kind == static_cast<std::uint8_t>(value_t::object);
+                const bool object = n->kind == node_kind::object;
                 if (object)
                 {
                     sax.start_object(n->len);

include/nlohmann/detail/view/node.hpp

@@ -41,9 +41,21 @@ struct node_flags
     static constexpr std::uint8_t linked = 32; ///< an entry of a moved sequence links to this value (editable documents): its extent in the parsed layout no longer matters
 };
 
-/// kind of an entry of an edited sequence that stands for a value stored
-/// elsewhere (the address of the value's node is kept in the len/next bytes)
-constexpr std::uint8_t kind_link = 10;
+/// the kind of a node: the value_t of its value, or link
+enum class node_kind : std::uint8_t
+{
+    null = static_cast<std::uint8_t>(value_t::null),
+    object = static_cast<std::uint8_t>(value_t::object),
+    array = static_cast<std::uint8_t>(value_t::array),
+    string = static_cast<std::uint8_t>(value_t::string),
+    boolean = static_cast<std::uint8_t>(value_t::boolean),
+    number_integer = static_cast<std::uint8_t>(value_t::number_integer),
+    number_unsigned = static_cast<std::uint8_t>(value_t::number_unsigned),
+    number_float = static_cast<std::uint8_t>(value_t::number_float),
+    /// an entry of an edited sequence that stands for a value stored elsewhere
+    /// (the address of the value's node is kept in the len/next bytes)
+    link = static_cast<std::uint8_t>(value_t::discarded) + 1,
+};
 
 /// One entry of the flat index, in document order. An object's members are
 /// stored as key node followed by the value's subtree. Integers keep their
@@ -51,7 +63,7 @@ constexpr std::uint8_t kind_link = 10;
 /// always the next one, and the token length follows from `extra`).
 struct node
 {
-    std::uint8_t kind;   ///< value_t, or kind_link
+    node_kind kind;      ///< value_t, or link
     std::uint8_t flags;  ///< node_flags
     std::uint16_t extra; ///< numbers: integer digits (low byte) and fraction digits (high byte), 255 = "many"; objects: number of the object's key hash index (1-based, 0 = none); otherwise 0
     std::uint32_t off;   ///< source offset (string content, number token, literal, bracket); arena offset if escaped/edited; number of the element sequence if moved
@@ -60,8 +72,9 @@ struct node
 };
 static_assert(sizeof(node) == 16, "node must stay 16 bytes");
 
-// the node kinds are value_t values; the test below (object and array are 1
-// and 2) and those of the number kinds depend on this numbering
+// the node kinds are value_t values, and images store them as bytes; the test
+// below (object and array are 1 and 2) and those of the number kinds depend
+// on this numbering
 static_assert(static_cast<std::uint8_t>(value_t::null) == 0 && static_cast<std::uint8_t>(value_t::object) == 1
               && static_cast<std::uint8_t>(value_t::array) == 2 && static_cast<std::uint8_t>(value_t::string) == 3
               && static_cast<std::uint8_t>(value_t::boolean) == 4 && static_cast<std::uint8_t>(value_t::number_integer) == 5
@@ -86,7 +99,7 @@ inline void make_link(node& n, node* target) noexcept
 {
     target->flags = static_cast<std::uint8_t>(target->flags | node_flags::linked);
     n = node{};
-    n.kind = kind_link;
+    n.kind = node_kind::link;
     std::memcpy(reinterpret_cast<unsigned char*>(&n) + 8, static_cast<const void*>(&target), sizeof(const node*)); // NOLINT(cppcoreguidelines-pro-type-reinterpret-cast)
 }
 
@@ -116,8 +129,8 @@ NLOHMANN_VIEW_ALWAYS_INLINE void set_integer_bits(node& n, std::uint64_t v) noex
 /// token length of a number node
 NLOHMANN_VIEW_ALWAYS_INLINE std::uint32_t number_length(const node& n) noexcept
 {
-    return n.kind == static_cast<std::uint8_t>(value_t::number_float) ? n.len
-           : (n.extra & 0xFFu) + (n.kind == static_cast<std::uint8_t>(value_t::number_integer) ? 1u : 0u);
+    return n.kind == node_kind::number_float ? n.len
+           : (n.extra & 0xFFu) + (n.kind == node_kind::number_integer ? 1u : 0u);
 }
 
 /// estimated number of nodes for an input of `size` bytes (one node per ~12

include/nlohmann/detail/view/number.hpp

@@ -19,7 +19,6 @@
 #include <nlohmann/detail/view/macro_scope.hpp>
 #include <nlohmann/detail/view/node.hpp>
 #include <nlohmann/detail/view/scan.hpp>
-#include <nlohmann/detail/view/simd.hpp>
 
 NLOHMANN_JSON_NAMESPACE_BEGIN
 namespace detail
@@ -104,56 +103,12 @@ NLOHMANN_VIEW_NOINLINE FloatType float_value(const char* first, const node& n)
     return convert_float<FloatType>(first, last, dot, mantissa_end);
 }
 
-#if NLOHMANN_VIEW_VECTOR
-/*!
-@brief the value of the first 16 digits of a run of digits with a point after
-int_digits of them (or none, if int_digits >= 16)
-
-The 17 bytes at p are read at once: the bytes after the point move down by one,
-then pairs, quadruples, and octets of digits are combined by multiplications
-(after simdjson). The bytes [p, p + 32) must be readable. Bytes that are not
-digits (only in a damaged image loaded with image_check::bounds) give a wrong
-value, but no undefined behavior.
-*/
-NLOHMANN_VIEW_ALWAYS_INLINE std::uint64_t sixteen_digits(const unsigned char* p, unsigned int_digits) noexcept
-{
-#if NLOHMANN_VIEW_NEON
-    const uint8x16_t low = vld1q_u8(p);
-    const uint8x16_t index = vcombine_u8(vcreate_u8(0x0706050403020100u), vcreate_u8(0x0F0E0D0C0B0A0908u));
-    const uint8x16_t before_point = vcltq_u8(index, vdupq_n_u8(static_cast<std::uint8_t>(int_digits)));
-    const uint8x16_t digits = vsubq_u8(vbslq_u8(before_point, low, vextq_u8(low, vld1q_u8(p + 16), 1)), vdupq_n_u8('0'));
-    const uint16x8_t twos = vpaddlq_u8(vmulq_u8(digits, vreinterpretq_u8_u16(vdupq_n_u16(0x010A))));
-    const uint32x4_t fours = vpaddlq_u16(vmulq_u16(twos, vreinterpretq_u16_u32(vdupq_n_u32(0x00010064))));
-    const uint64x2_t eights = vpaddlq_u32(vmulq_u32(fours, vreinterpretq_u32_u64(vdupq_n_u64(0x0000000100002710u))));
-    return (vgetq_lane_u64(eights, 0) * 100000000u) + vgetq_lane_u64(eights, 1);
-#else
-    // NOLINTBEGIN(portability-simd-intrinsics)
-    const __m128i low = _mm_loadu_si128(static_cast<const __m128i*>(static_cast<const void*>(p))); // NOLINT(bugprone-casting-through-void)
-    const __m128i high = _mm_loadu_si128(static_cast<const __m128i*>(static_cast<const void*>(p + 16))); // NOLINT(bugprone-casting-through-void)
-    const __m128i before_point = _mm_cmpgt_epi8(_mm_set1_epi8(static_cast<char>(int_digits)), _mm_setr_epi8(0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15));
-    const __m128i moved = _mm_or_si128(_mm_srli_si128(low, 1), _mm_slli_si128(high, 15));
-    const __m128i digits = _mm_sub_epi8(_mm_or_si128(_mm_and_si128(before_point, low), _mm_andnot_si128(before_point, moved)), _mm_set1_epi8('0'));
-    // (16-bit lanes: SSE2 has no multiply-add of bytes)
-    const __m128i tens = _mm_setr_epi16(10, 1, 10, 1, 10, 1, 10, 1);
-    const __m128i twos = _mm_packs_epi32(_mm_madd_epi16(_mm_unpacklo_epi8(digits, _mm_setzero_si128()), tens),
-                                         _mm_madd_epi16(_mm_unpackhi_epi8(digits, _mm_setzero_si128()), tens));
-    const __m128i fours = _mm_madd_epi16(twos, _mm_setr_epi16(100, 1, 100, 1, 100, 1, 100, 1));
-    const __m128i eights = _mm_madd_epi16(_mm_packs_epi32(fours, fours), _mm_setr_epi16(10000, 1, 10000, 1, 10000, 1, 10000, 1));
-    const auto upper = static_cast<std::uint32_t>(_mm_cvtsi128_si32(eights));
-    const auto lower = static_cast<std::uint32_t>(_mm_cvtsi128_si32(_mm_srli_si128(eights, 4)));
-    // NOLINTEND(portability-simd-intrinsics)
-    return (std::uint64_t{upper} * 100000000u) + lower;
-#endif
-}
-#endif
-
 /*!
 @brief the digits of a float token with at most 19 digits, from its layout
 
 The digit layout recorded while parsing says where the integer digits, the
 fraction digits, and the exponent are, so the digits are read eight at a
-time without scanning (with SIMD, a token of 16 to 19 digits sixteen at a
-time).
+time without scanning.
 
 @param[in] p  first character of the token
 @param[in] e  end of the token
@@ -163,34 +118,15 @@ NLOHMANN_VIEW_ALWAYS_INLINE float_significand layout_decimal(const unsigned char
 {
     const bool negative = *p == '-';
     p += negative ? 1 : 0;
-    std::uint64_t w = 0;
+    std::uint64_t w = parse_upto19(p, int_digits, limit);
+    p += int_digits;
     std::int64_t q = 0;
-#if NLOHMANN_VIEW_VECTOR
-    const unsigned count = int_digits + frac_digits;
-    if (count >= 16 && limit - p >= 32)
+    if (frac_digits != 0)
     {
-        // (the point, if any, follows the integer digits; the digits after
-        // the first 16 are at most three)
-        w = sixteen_digits(p, int_digits);
-        for (unsigned i = 16; i < count; ++i)
-        {
-            w = (w * 10) + static_cast<std::uint64_t>(p[i + (i >= int_digits ? 1 : 0)] - '0');
-        }
-        p += count + (frac_digits != 0 ? 1 : 0);
+        w = (w * int_pow10(frac_digits)) + parse_upto19(p + 1, frac_digits, limit);
+        p += 1 + frac_digits;
         q = -static_cast<std::int64_t>(frac_digits);
     }
-    else
-#endif
-    {
-        w = parse_upto19(p, int_digits, limit);
-        p += int_digits;
-        if (frac_digits != 0)
-        {
-            w = (w * int_pow10(frac_digits)) + parse_upto19(p + 1, frac_digits, limit);
-            p += 1 + frac_digits;
-            q = -static_cast<std::int64_t>(frac_digits);
-        }
-    }
     if (p != e)
     {
         // [eE][+-]digits; huge exponents saturate (the parser rejected
@@ -225,22 +161,12 @@ NLOHMANN_VIEW_ALWAYS_INLINE float_significand layout_decimal(const unsigned char
 The result is correctly rounded by the lexer's conversion
 (detail::decimal_to_float(): Clinger's fast path where both operands are
 exact, else the Eisel-Lemire algorithm, which needs no fallback for up to 19
-digits), so it is the value parse() produces. Tokens of 16 or more digits go
-to Eisel-Lemire directly: the fast path takes few of them (none of 17 digits),
-and its check is a branch that data like GeoJSON coordinates mispredicts.
+digits), so it is the value parse() produces.
 */
 template<typename FloatType>
 NLOHMANN_VIEW_ALWAYS_INLINE FloatType layout_float(const unsigned char* p, const unsigned char* e, unsigned int_digits, unsigned frac_digits, const unsigned char* limit) noexcept
 {
-    const float_significand d = layout_decimal(p, e, int_digits, frac_digits, limit);
-    if (int_digits + frac_digits >= 16)
-    {
-        using format = ieee_binary_format<std::numeric_limits<FloatType>::digits>;
-        native_float_t<FloatType> value{};
-        float_from_bits(eisel_lemire<format>(d.exponent, d.w) | (d.negative ? (std::uint64_t{1} << format::sign_bit()) : 0u), value);
-        return value;
-    }
-    return decimal_to_float<FloatType>(d);
+    return decimal_to_float<FloatType>(layout_decimal(p, e, int_digits, frac_digits, limit));
 }
 
 /// the value of a float set by an edit: its token (the shortest round-trip
@@ -259,80 +185,6 @@ NLOHMANN_VIEW_NOINLINE FloatType edited_float(const char* token, const node& n)
     return float_value<FloatType>(token, n);
 }
 
-#if NLOHMANN_VIEW_VECTOR
-/// eisel_lemire() for the token w * 10^q of coordinate_float()
-template<typename Format>
-NLOHMANN_VIEW_ALWAYS_INLINE std::uint64_t coordinate_bits(std::int64_t q, std::uint64_t w, Format /*format*/) noexcept
-{
-    return eisel_lemire<Format>(q, w);
-}
-
-/*!
-@brief (binary64) eisel_lemire() without the cases that tokens of 16 or 17
-digits with 5 or more after the point cannot reach: a value of 0, a
-subnormal, an infinity, or a tie (q < -4)
-*/
-NLOHMANN_VIEW_ALWAYS_INLINE std::uint64_t coordinate_bits(std::int64_t q, std::uint64_t w, ieee_binary_format<53> format) noexcept
-{
-    if (NLOHMANN_VIEW_UNLIKELY(w == 0 || q > -5))
-    {
-        return eisel_lemire<ieee_binary_format<53>>(q, w);
-    }
-    static_cast<void>(format);
-    const int lz = count_leading_zeros(w);
-    const std::uint64_t normalized = w << static_cast<unsigned>(lz);
-    const auto index = static_cast<std::size_t>(2 * (q - pow5_128_smallest_power));
-    const uint128_parts product = full_multiplication(normalized, pow5_128()[index]);
-    std::uint64_t high = product.high;
-    if (NLOHMANN_VIEW_UNLIKELY((high & 0x1FFu) == 0x1FFu))
-    {
-        // (the lower bits may carry into the result)
-        const std::uint64_t second = full_multiplication(normalized, pow5_128()[index + 1]).high;
-        high += product.low + second < product.low ? 1u : 0u;
-    }
-    const auto upperbit = static_cast<unsigned>(high >> 63u);
-    std::uint64_t mantissa = high >> (upperbit + 9);
-    std::uint64_t power2 = static_cast<std::uint64_t>(((217706 * q) >> 16) + 63 + static_cast<std::int64_t>(upperbit) - lz + 1023);
-    mantissa = (mantissa + (mantissa & 1u)) >> 1u;
-    const bool carry = mantissa >= (std::uint64_t{2} << 52u);
-    mantissa = carry ? (std::uint64_t{1} << 52u) : mantissa;
-    power2 += carry ? 1u : 0u;
-    return (mantissa & ~(std::uint64_t{1} << 52u)) | (power2 << 52u);
-}
-
-/*!
-@brief (binary32 and binary64) the value of a float token of the source with
-16 or 17 digits, a point, and no exponent, the shape of most coordinates
-written with full precision; whether the token of n has this shape
-
-These tokens skip the general layout of layout_decimal(): no digits beyond
-the 17th, no exponent (and Eisel-Lemire directly, as in layout_float()).
-*/
-template<typename FloatType>
-NLOHMANN_VIEW_ALWAYS_INLINE bool coordinate_float(const document_data& d, const node& n, FloatType& value) noexcept
-{
-    const unsigned int_digits = n.extra & 0xFFu;
-    const unsigned frac_digits = n.extra >> 8u;
-    const unsigned count = int_digits + frac_digits;
-    const auto* const first = reinterpret_cast<const unsigned char*>(d.src + n.off); // NOLINT(cppcoreguidelines-pro-type-reinterpret-cast)
-    const unsigned negative = first[0] == '-' ? 1u : 0u;
-    if (count - 16u > 1u || frac_digits == 0 || n.len != negative + count + 1 || d.size - n.off < 33)
-    {
-        return false;
-    }
-    const unsigned char* const digits = first + negative;
-    const std::uint64_t w = sixteen_digits(digits, int_digits);
-    // (the 17th digit follows the point)
-    const std::uint64_t w17 = (w * 10) + static_cast<std::uint64_t>(digits[17] - '0');
-    using format = ieee_binary_format<std::numeric_limits<FloatType>::digits>;
-    native_float_t<FloatType> result{};
-    float_from_bits(coordinate_bits(-static_cast<std::int64_t>(frac_digits), count == 17 ? w17 : w, format{}) | (static_cast<std::uint64_t>(negative) << format::sign_bit()), result);
-    value = result;
-    return true;
-}
-
-#endif
-
 /// the value of the float token of a node, as parse() converts it; floats and
 /// doubles with at most 19 digits are converted from the digit layout
 template<typename FloatType>
@@ -348,13 +200,6 @@ FloatType float_value(const document_data& d, const node& n)
 template<typename FloatType>
 FloatType float_value(const document_data& d, const node& n, std::true_type /*binary32 or binary64*/)
 {
-#if NLOHMANN_VIEW_VECTOR
-    FloatType value {};
-    if (coordinate_float(d, n, value))
-    {
-        return value;
-    }
-#endif
     const unsigned int_digits = n.extra & 0xFFu;
     const unsigned frac_digits = n.extra >> 8u;
     if (NLOHMANN_VIEW_LIKELY(int_digits + frac_digits <= 19)) // (255 marks "many")

include/nlohmann/detail/view/serializer.hpp

@@ -14,9 +14,7 @@
 #include <cstddef> // size_t
 #include <cstdint> // uint8_t, uint32_t
 #include <cstring> // memcpy, memset
-#include <functional> // less
 #include <limits> // numeric_limits
-#include <memory> // unique_ptr
 #include <type_traits> // integral_constant
 #include <vector> // vector
 
@@ -386,127 +384,6 @@ struct depth_counter<false>
     }
 };
 
-/*!
-@brief where the double x nearest to a token w * 10^q lies, for 10^15 <= w <
-10^17 and -17 <= q <= -1 (Eisel-Lemire, then a fixed-point position)
-
-dump() writes the shortest decimal in the rounding interval of x (the closest
-one if there are several, see zmij::to_shortest()). Its digits are those of a
-multiple of 10^g of the token's last digit, with g = dec_exp + 1 - q for x's
-decimal exponent dec_exp: the multiple of 10^g nearest to x if it lies in the
-interval (at most one does), else the multiple of 10^(g - 1) nearest to x
-(see token_digits_1() and token_digits_2()). For g <= 0, the token itself is
-in the interval.
-
-The position is exact in a 64-bit fixed-point number with 56 bits after the
-point (of the token's last digit): x / 10^q = 2c * 5^-q / 2^t for x = c * 2^e2
-and t = q + 1 - e2, with at most 56 bits after the point here, and |x / 10^q -
-w| is at most half the spacing of the doubles, below 12 units. So only the low
-64 bits of 2c * 5^-q are needed. c and e2 come from Eisel-Lemire's product
-directly (as eisel_lemire() rounds it: no tie is possible for q < -4, and its
-second product is added where it can carry into the result).
-
-@param[out] offset  x / 10^q - w + 32, with 56 bits after the point
-@param[out] radius  half the spacing of the doubles at x, likewise (+ 1 if
-                    the interval is closed)
-@return g; 3 if the digits are not decided here (a power of two, whose
-        interval is not symmetric, or out of range)
-*/
-NLOHMANN_VIEW_ALWAYS_INLINE int locate_token(std::uint64_t w, int q, std::uint64_t& offset, std::uint64_t& radius) noexcept
-{
-    const int lz = count_leading_zeros(w);
-    const std::uint64_t normalized = w << static_cast<unsigned>(lz);
-    const auto index = static_cast<std::size_t>(2 * (q - pow5_128_smallest_power));
-    const uint128_parts product = full_multiplication(normalized, pow5_128()[index]);
-    std::uint64_t high = product.high;
-    if (NLOHMANN_VIEW_UNLIKELY((high & 0x1FFu) == 0x1FFu))
-    {
-        // (as eisel_lemire(): the lower bits may carry into the result)
-        const std::uint64_t second = full_multiplication(normalized, pow5_128()[index + 1]).high;
-        high += product.low + second < product.low ? 1u : 0u;
-    }
-    const auto upperbit = static_cast<unsigned>(high >> 63u);
-    const std::uint64_t mantissa = high >> (upperbit + 9);
-    const std::uint64_t c = (mantissa + (mantissa & 1u)) >> 1u;
-    // e2 as eisel_lemire() computes the exponent (log2(10) ~ 217706 / 2^16)
-    const int e2 = static_cast<int>((217706 * static_cast<std::int64_t>(q)) >> 16) + 63 + static_cast<int>(upperbit) - lz - 52;
-    const int t = q + 1 - e2;
-    const int g = ((e2 * 315653) >> 20) + 1 - q; // (dec_exp as in zmij::to_shortest(), for a regular x)
-    static const std::array<std::uint64_t, 17> fives = {{1u, 5u, 25u, 125u, 625u, 3125u, 15625u, 78125u, 390625u, 1953125u, 9765625u, 48828125u, 244140625u, 1220703125u, 6103515625u, 30517578125u, 152587890625u}};
-    const std::uint64_t five = fives[static_cast<std::size_t>(-q)]; // 5^-q
-    const unsigned s = static_cast<unsigned>(56 - t) & 63u;
-    offset = ((2 * c * five) << s) - (w << 56u) + (std::uint64_t{32} << 56u);
-    radius = (five << s) + ((c & 1u) == 0 ? 1u : 0u);
-    // (c = 2^52: a power of two; c = 2^53: rounded up to one. With 8 to 16
-    // fraction digits, as the batch's tokens have, t is in [15, 40] and g at
-    // most 2. x lies halfway between two candidates only if its distance from
-    // the token is a whole unit (g == 2) or a half (g == 1): such tokens are
-    // left to the full conversion)
-    const bool decided = c - ((std::uint64_t{1} << 52u) + 1) < (std::uint64_t{1} << 52u) - 1
-                         && (offset & ((std::uint64_t{1} << 55u) - 1)) != 0;
-    return decided ? g : 3;
-}
-
-/// the distance of a position (see locate_token()) from the biased point 32
-NLOHMANN_VIEW_ALWAYS_INLINE std::uint64_t biased_distance(std::uint64_t position) noexcept
-{
-    constexpr std::uint64_t center = std::uint64_t{32} << 56u;
-    return position >= center ? position - center : center - position;
-}
-
-/*!
-@brief (g == 1) the digits dump() writes for a token, from the position of its
-double (see locate_token()): the multiple of 10 nearest to x if it is in the
-interval, else w rounded to x (an exact tie between two candidates, like
-754570942.33984373, whose double is 754570942.33984375, is excluded by
-locate_token())
-
-With |x - w| at most the radius, which is below half the spacing of the
-candidates, the multiple of 10 nearest to x is w - r10 or the one above it.
-*/
-NLOHMANN_VIEW_ALWAYS_INLINE std::uint64_t token_digits_1(std::uint64_t w, std::uint64_t offset, std::uint64_t radius, std::uint64_t r10) noexcept
-{
-    constexpr std::uint64_t one = std::uint64_t{1} << 56u;
-    const std::uint64_t from = offset + (r10 * one); // x - (w - r10) (+ 32)
-    const bool up = from > 37 * one;                  // (nearer to the multiple above)
-    const bool shorter = biased_distance(from - (up ? 10 * one : 0)) < radius;
-    const std::uint64_t a = w - r10 + (up ? 10u : 0u);
-    const std::uint64_t b = w + ((offset + (one / 2)) >> 56u) - 32;                // w rounded to x
-    return shorter ? a : b;
-}
-
-/*!
-@brief (g == 2) the digits dump() writes for a token, as token_digits_1(): the
-multiple of 100 nearest to x if it is in the interval, else the multiple of 10
-nearest to x
-*/
-NLOHMANN_VIEW_ALWAYS_INLINE std::uint64_t token_digits_2(std::uint64_t w, std::uint64_t offset, std::uint64_t radius, std::uint64_t r10, std::uint64_t r100) noexcept
-{
-    constexpr std::uint64_t one = std::uint64_t{1} << 56u;
-    const std::uint64_t from = offset + (r100 * one);
-    const bool up = from > 82 * one;
-    const bool shorter = biased_distance(from - (up ? 100 * one : 0)) < radius;
-    const std::uint64_t a = w - r100 + (up ? 100u : 0u);
-    // x - (w - r10), in [-12, 21]: the multiple of 10 nearest to x is that one,
-    // or one or two above, or one below
-    const std::uint64_t y = offset + (r10 * one);
-    const std::uint64_t steps = (y > 37 * one ? 1u : 0u) + (y > 47 * one ? 1u : 0u);
-    const bool down = y < 27 * one;
-    const std::uint64_t b = w - r10 + (10 * steps) - (down ? 10u : 0u);
-    return shorter ? a : b;
-}
-
-/// the four ASCII digits of x < 10^4, the first in the lowest byte (as
-/// little-endian memory holds them)
-NLOHMANN_VIEW_ALWAYS_INLINE std::uint32_t four_digit_text(std::uint32_t x) noexcept
-{
-    const std::uint32_t ab = (x * 5243u) >> 19u; // x / 100
-    std::uint32_t v = ab | ((x - (ab * 100u)) << 16u);
-    const std::uint32_t a = ((v * 103u) >> 10u) & 0x000F000Fu; // / 10 per 16-bit lane
-    v = a | ((v - (a * 10u)) << 8u);
-    return v + 0x30303030u;
-}
-
 /// how the view's dump() writes a value
 struct dump_style
 {
@@ -834,7 +711,6 @@ class view_serializer
         std::array<frame, 32> buffer; // NOLINT(cppcoreguidelines-pro-type-member-init,hicpp-member-init): written before read
         std::vector<frame> heap;
         small_stack<frame> stack(buffer.data(), buffer.size(), heap);
-        float_batch batch;
         const char* const src = m_doc.src;
         const char* const src_end = src + m_doc.size;
         char* w = m_out.cursor();
@@ -974,7 +850,7 @@ class view_serializer
                     else if (enabled(fast_double::value))
                     {
                         room(64);
-                        w = write_double_ahead(w, src, n, batch);
+                        w = write_double_at(w, *n);
                     }
                     else
                     {
@@ -998,21 +874,7 @@ class view_serializer
                 case value_t::object:
                 case value_t::array:
                 {
-                    const bool object = n->kind == static_cast<std::uint8_t>(value_t::object);
-                    // (read-only documents, compact output) a pair of floats,
-                    // like the coordinates of GeoJSON, without a frame
-                    if (enabled(!Editable && !Pretty && !SourceNumbers && fast_double::value) && n->next == 3 && n->len == 2
-                            && n[1].kind == static_cast<std::uint8_t>(value_t::number_float) && n[2].kind == static_cast<std::uint8_t>(value_t::number_float))
-                    {
-                        room(2 * 64);
-                        *w++ = '[';
-                        w = write_double_ahead(w, src, n + 1, batch);
-                        *w++ = ',';
-                        w = write_double_ahead(w, src, n + 2, batch);
-                        *w++ = ']';
-                        n += 2; // (the element before the next node)
-                        break;
-                    }
+                    const bool object = n->kind == node_kind::object;
                     room(8);
                     if (n->len == 0)
                     {
@@ -1122,247 +984,6 @@ class view_serializer
         }
     }
 
-    /// (float_batch) the mark of digits whose rounding carried beyond the
-    /// token's last four (see mark())
-    static constexpr std::uint64_t carried() noexcept
-    {
-        return std::uint64_t{1} << 63u;
-    }
-
-    /// floats of 16 or 17 digits ahead of the walk, converted together (see
-    /// convert_ahead()), with their digits as mark() keeps them
-    struct float_batch
-    {
-        static constexpr std::size_t capacity() noexcept
-        {
-            return 256;
-        }
-        /// (on the heap, allocated by the first conversion: a frame of more
-        /// than a page made every dump of a small document slower)
-        struct entries
-        {
-            std::array<const node*, 256> at; // NOLINT(cppcoreguidelines-pro-type-member-init,hicpp-member-init): written before read
-            std::array<std::uint64_t, 256> digits; // NOLINT(cppcoreguidelines-pro-type-member-init,hicpp-member-init): written before read
-        };
-        std::unique_ptr<entries> storage{};
-        const node** at = nullptr;
-        std::uint64_t* digits = nullptr;
-        std::size_t count = 0;
-        std::size_t next = 0;
-        const node* scanned = nullptr; ///< where the last scan of the node array ended
-    };
-
-    /// (doubles) the float at n as dump() writes it, at w (64 bytes of room):
-    /// from the batch if it holds n
-    NLOHMANN_VIEW_ALWAYS_INLINE char* write_double_ahead(char* w, const char* src, const node* n, float_batch& batch)
-    {
-#if NLOHMANN_VIEW_VECTOR && NLOHMANN_VIEW_LITTLE_ENDIAN
-        // (digits 0: not written by the batch; carried(): rounding carried
-        // beyond the last four digits)
-        if (batch.next != batch.count && batch.at[batch.next] == n && batch.digits[batch.next] - 1 < carried() - 1)
-        {
-            return write_token_digits(w, src, *n, batch.digits[batch.next++]);
-        }
-        return write_double_beside(w, n, batch);
-#else
-        static_cast<void>(src);
-        static_cast<void>(batch);
-        return write_double_at(w, *n);
-#endif
-    }
-
-#if NLOHMANN_VIEW_VECTOR && NLOHMANN_VIEW_LITTLE_ENDIAN
-    /// write_double_ahead() for a float that is not the batch's next one (out
-    /// of line: the walk is faster with less code in its loop)
-    NLOHMANN_VIEW_NOINLINE char* write_double_beside(char* w, const node* n, float_batch& batch)
-    {
-        // (an editable document's walk can skip nodes of the array)
-        const std::less<const node*> before;
-        while (batch.next != batch.count && before(batch.at[batch.next], n))
-        {
-            ++batch.next;
-        }
-        if ((batch.next != batch.count && batch.at[batch.next] == n) || convert_ahead(n, batch))
-        {
-            const std::uint64_t digits = batch.digits[batch.next++];
-            if ((digits & carried()) != 0)
-            {
-                return write_carried_digits(w, *n, digits & ~carried());
-            }
-            if (digits != 0)
-            {
-                return write_token_digits(w, m_doc.src, *n, digits);
-            }
-        }
-        return write_double_at(w, *n);
-    }
-
-    /*!
-    @brief convert the floats of 16 or 17 digits among the next nodes of the
-    array at once; whether n is the first of them
-
-    Such tokens (like the coordinates of GeoJSON, written with 17 digits) are
-    written as the token with its last four digits replaced
-    (write_token_digits()). Each step (the digits, locate_token(),
-    token_digits_1/2()) is a long chain of dependent operations; one loop per
-    step over many floats lets the processor overlap the floats, which it does
-    not across the steps of one float (on Apple M1, one loop for the digits and
-    locate_token() made the dump of canada.json 12 % slower). Each node of the array
-    is scanned once; a node that the walk does not reach in order (in an
-    editable document) is written without the batch.
-    */
-    NLOHMANN_VIEW_NOINLINE bool convert_ahead(const node* n, float_batch& batch)
-    {
-        const std::less<const node*> before;
-        const node* const last = m_doc.nodes + m_doc.node_count;
-        if (before(n, batch.scanned) || before(n, m_doc.nodes) || !before(n, last))
-        {
-            return false;
-        }
-        const char* const src = m_doc.src;
-        const char* const src_end = src + m_doc.size;
-        const node* const stop = last - n > 1024 ? n + 1024 : last;
-        batch.count = 0;
-        batch.next = 0;
-        // the digits of each token (and its last four from the text)
-        std::array<std::uint64_t, 256> digits;     // NOLINT(cppcoreguidelines-pro-type-member-init,hicpp-member-init): written before read
-        std::array<int, 256> exponent;             // NOLINT(cppcoreguidelines-pro-type-member-init,hicpp-member-init): written before read
-        std::array<std::uint32_t, 256> last_four;  // NOLINT(cppcoreguidelines-pro-type-member-init,hicpp-member-init): written before read
-        const node* p = n;
-        if (!batch.storage)
-        {
-            batch.storage.reset(new typename float_batch::entries); // NOLINT(cppcoreguidelines-owning-memory,modernize-make-unique): C++11
-            batch.at = batch.storage->at.data();
-            batch.digits = batch.storage->digits.data();
-        }
-        for (; p != stop && batch.count != float_batch::capacity(); ++p)
-        {
-            // a token of the source: 16 or 17 digits, at least 8 after the
-            // point, no exponent, 32 bytes to read
-            const unsigned frac_digits = p->extra >> 8u;
-            const unsigned int_digits = p->extra & 0xFFu;
-            const unsigned count = int_digits + frac_digits;
-            if (p->kind == static_cast<std::uint8_t>(value_t::number_float) && (p->flags & node_flags::storage) == 0
-                    && count - 16u <= 1u && frac_digits >= 8 && src_end - (src + p->off) >= 33)
-            {
-                const auto* const token = reinterpret_cast<const unsigned char*>(src + p->off); // NOLINT(cppcoreguidelines-pro-type-reinterpret-cast)
-                const unsigned sign = token[0] == '-' ? 1 : 0;
-                const unsigned char* const first = token + sign;
-                const std::uint64_t w = sixteen_digits(first, int_digits);
-                // (the 17th digit follows the point; a token with an exponent
-                // gets digits outside the range of locate_token(), and is not
-                // written by the batch. A token 0.xxx with 16 significant
-                // digits is: its double is written as "0." and its digits too)
-                const std::uint64_t w17 = (w * 10) + static_cast<std::uint64_t>(first[17] - '0');
-                const std::size_t i = batch.count++;
-                batch.at[i] = p;
-                digits[i] = p->len != sign + count + 1 ? 0 : (count == 17 ? w17 : w);
-                exponent[i] = -static_cast<int>(frac_digits);
-                // (byte 0: the last digit, byte 1: the last two, bits 16-29: the last four)
-                std::uint32_t four = 0;
-                std::memcpy(&four, token + p->len - 4, 4);
-                four -= 0x30303030u;
-                const std::uint32_t pairs = ((four & 0x0F0F0F0Fu) * 2561u) >> 8u; // (byte 0, 2: the pairs)
-                last_four[i] = (four >> 24u) | ((pairs >> 16u & 0xFFu) << 8u) | ((((pairs & 0x00FF00FFu) * 6553601u) >> 16u) << 16u);
-            }
-        }
-        batch.scanned = p;
-        // the position of each double, and the floats of either kind
-        std::array<std::uint64_t, 256> offset; // NOLINT(cppcoreguidelines-pro-type-member-init,hicpp-member-init): written before read
-        std::array<std::uint64_t, 256> radius; // NOLINT(cppcoreguidelines-pro-type-member-init,hicpp-member-init): written before read
-        std::array<std::uint8_t, 256> kind_1;  // NOLINT(cppcoreguidelines-pro-type-member-init,hicpp-member-init): written before read
-        std::array<std::uint8_t, 256> kind_2;  // NOLINT(cppcoreguidelines-pro-type-member-init,hicpp-member-init): written before read
-        std::size_t count_1 = 0;
-        std::size_t count_2 = 0;
-        for (std::size_t i = 0; i != batch.count; ++i)
-        {
-            const std::uint64_t w = digits[i];
-            // (the range excludes the values of bytes that are not digits, only
-            // in a damaged image loaded with image_check::bounds)
-            const int g = w - 1000000000000000u < 99000000000000000u ? locate_token(w, exponent[i], offset[i], radius[i]) : 3;
-            batch.digits[i] = g <= 0 ? (last_four[i] >> 16u) + 1 : 0;
-            kind_1[count_1] = static_cast<std::uint8_t>(i);
-            count_1 += g == 1 ? 1 : 0;
-            kind_2[count_2] = static_cast<std::uint8_t>(i);
-            count_2 += g == 2 ? 1 : 0;
-        }
-        // the digits to write, in one loop per kind (see mark())
-        for (std::size_t k = 0; k != count_1; ++k)
-        {
-            const std::size_t i = kind_1[k];
-            const std::uint64_t s = token_digits_1(digits[i], offset[i], radius[i], last_four[i] & 0xFFu);
-            batch.digits[i] = mark(digits[i], s, last_four[i] >> 16u);
-        }
-        for (std::size_t k = 0; k != count_2; ++k)
-        {
-            const std::size_t i = kind_2[k];
-            const std::uint64_t s = token_digits_2(digits[i], offset[i], radius[i], last_four[i] & 0xFFu, (last_four[i] >> 8u) & 0xFFu);
-            batch.digits[i] = mark(digits[i], s, last_four[i] >> 16u);
-        }
-        return batch.count != 0 && batch.at[0] == n;
-    }
-
-    /*!
-    @brief a float token of 16 or 17 digits as dump() writes it, at w (64 bytes
-    of room), from the digits of its double (see locate_token()) whose
-    rounding carried beyond the token's last four digits
-
-    (like 43.42027299999999 -> 43.420273): the digits go to the writer of
-    Zmij's results as its 15 or 16 leading digits and one more, which omits
-    the trailing zeros.
-    */
-    NLOHMANN_VIEW_NOINLINE char* write_carried_digits(char* w, const node& n, std::uint64_t digits) const noexcept
-    {
-        const int exponent = -(n.extra >> 8u);
-        const std::uint64_t leading = digits / 10;
-        const auto last = static_cast<unsigned char>(digits - (leading * 10));
-        const bool seventeen = digits >= 10000000000000000u;
-        *w = '-';
-        w += m_doc.src[n.off] == '-' ? 1 : 0;
-        return ::nlohmann::detail::dtoa_impl::write_shortest(w, seventeen ? ::nlohmann::detail::zmij::shortest_decimal{leading, exponent, last, last != 0}
-                : ::nlohmann::detail::zmij::shortest_decimal{digits, exponent - 1, 0, false});
-    }
-
-    /// the digits s of a token with the digits w and the last four digits
-    /// r4, as the batch keeps them: the new last four digits + 1 (only those
-    /// are written over the token's), or s marked if it differs from w beyond
-    /// them (0 stays for a float the batch does not write)
-    static std::uint64_t mark(std::uint64_t w, std::uint64_t s, std::uint64_t r4) noexcept
-    {
-        const std::uint64_t last = s - (w - r4);
-        return last < 10000 ? last + 1 : s | carried();
-    }
-
-    /*!
-    @brief a float token of 16 or 17 digits as dump() writes it, at w (64 bytes
-    of room): the token with its last four digits replaced by digits - 1 (see
-    mark(); the others are the token's), and without trailing zeros after the
-    point, but one
-    */
-    char* write_token_digits(char* w, const char* src, const node& n, std::uint64_t digits)
-    {
-        const char* const token = src + n.off;
-        std::memcpy(w, token, 32);
-        char* const end = w + n.len;
-        const std::uint32_t last = four_digit_text(static_cast<std::uint32_t>(digits - 1));
-        std::memcpy(end - 4, &last, 4);
-        // (the token's text before the new digits, from the source: reading
-        // the output back would wait for the stores)
-        std::uint64_t before = 0;
-        std::memcpy(&before, token + n.len - 12, 8);
-        const std::uint32_t last_zeros = last ^ 0x30303030u;
-        const std::uint64_t before_zeros = before ^ 0x3030303030303030u;
-        if (NLOHMANN_VIEW_UNLIKELY(last_zeros == 0 && before_zeros == 0))
-        {
-            return write_double_at(w, n); // (twelve or more trailing zeros)
-        }
-        const unsigned zeros = last_zeros != 0 ? static_cast<unsigned>(count_leading_zeros(last_zeros)) / 8 - 4
-                               : 4 + (static_cast<unsigned>(count_leading_zeros(before_zeros)) / 8);
-        const unsigned frac_digits = n.extra >> 8u;
-        return end - (zeros < frac_digits ? zeros : frac_digits - 1);
-    }
-#endif
-
     /// a float node as dump() writes it
     void write_float_node(const node& n)
     {

include/nlohmann/detail/view/view_mode.hpp

@@ -0,0 +1,27 @@
+//     __ _____ _____ _____
+//  __|  |   __|     |   | |  JSON for Modern C++
+// |  |  |__   |  |  | | | |  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 <cstdint> // uint8_t
+
+#include <nlohmann/json.hpp>
+
+NLOHMANN_JSON_NAMESPACE_BEGIN
+
+/// whether a basic_json_document and its views can be edited
+enum class view_mode : std::uint8_t
+{
+    read_only, ///< parsed once, then only read (the default)
+    editable,  ///< also has set(), push_back(), insert(), and erase()
+};
+
+template<typename BasicJsonType, view_mode Mode>
+class basic_json_view;
+
+NLOHMANN_JSON_NAMESPACE_END

include/nlohmann/json_view.hpp

@@ -84,6 +84,7 @@
 #include <nlohmann/detail/view/serializer.hpp>
 #include <nlohmann/detail/view/string_ref.hpp>
 #include <nlohmann/detail/view/value.hpp>
+#include <nlohmann/detail/view/view_mode.hpp>
 
 NLOHMANN_JSON_NAMESPACE_BEGIN
 
@@ -93,13 +94,16 @@ NLOHMANN_JSON_NAMESPACE_BEGIN
 Trivially copyable (two pointers). Valid as long as the document is alive and
 has not been re-parsed, and as long as a borrowed source text is alive.
 */
-template<typename BasicJsonType, bool Editable = false>
+template<typename BasicJsonType, view_mode Mode = view_mode::read_only>
 class basic_json_view
 {
+    /// whether this is a view of an editable document
+    static constexpr bool is_editable = Mode == view_mode::editable;
+
     using node = detail::view::node;
     using document_data = detail::view::document_data;
     /// how the index is walked (with edits only for editable documents)
-    using navigation = detail::view::navigation<Editable>;
+    using navigation = detail::view::navigation<is_editable>;
 
   public:
     using value_t = detail::value_t;
@@ -446,7 +450,7 @@ class basic_json_view
         if (is_structured() && m_node->len != 0)
         {
             return unedited() ? basic_json_view(m_doc, detail::view::last_child<false>(*m_doc, m_node) + (is_object() ? 1 : 0))
-                   : basic_json_view(m_doc, navigation::value(detail::view::last_child<Editable>(*m_doc, m_node) + (is_object() ? 1 : 0)));
+                   : basic_json_view(m_doc, navigation::value(detail::view::last_child<is_editable>(*m_doc, m_node) + (is_object() ? 1 : 0)));
         }
         return front();
     }
@@ -504,7 +508,7 @@ class basic_json_view
     /// more than once); 0 if this is not an object
     size_type count(string_view_t key) const
     {
-        return is_object() ? detail::view::count_members<Editable>(*m_doc, m_node, key.data(), key.size()) : 0;
+        return is_object() ? detail::view::count_members<is_editable>(*m_doc, m_node, key.data(), key.size()) : 0;
     }
 
     size_type count(const char* key) const
@@ -646,7 +650,7 @@ class basic_json_view
         }
         else
         {
-            detail::view::view_serializer<BasicJsonType, Editable>(*m_doc, out, estimate, style).dump(m_node);
+            detail::view::view_serializer<BasicJsonType, is_editable>(*m_doc, out, estimate, style).dump(m_node);
         }
         return out;
     }
@@ -682,14 +686,14 @@ class basic_json_view
     }
 
     /// a view of an editable document compares with one of a read-only document
-    template < bool E, typename std::enable_if < E != Editable, int >::type = 0 >
-    friend bool operator==(const basic_json_view& a, const basic_json_view<BasicJsonType, E>& b)
+    template < view_mode M, typename std::enable_if < M != Mode, int >::type = 0 >
+    friend bool operator==(const basic_json_view& a, const basic_json_view<BasicJsonType, M>& b)
     {
-        return detail::view::equal<BasicJsonType>(side(a), detail::view::view_side<BasicJsonType, basic_json_view<BasicJsonType, E>>(b));
+        return detail::view::equal<BasicJsonType>(side(a), detail::view::view_side<BasicJsonType, basic_json_view<BasicJsonType, M>>(b));
     }
 
-    template < bool E, typename std::enable_if < E != Editable, int >::type = 0 >
-    friend bool operator!=(const basic_json_view& a, const basic_json_view<BasicJsonType, E>& b)
+    template < view_mode M, typename std::enable_if < M != Mode, int >::type = 0 >
+    friend bool operator!=(const basic_json_view& a, const basic_json_view<BasicJsonType, M>& b)
     {
         return !(a == b);
     }
@@ -727,7 +731,7 @@ class basic_json_view
         {
             return BasicJsonType(value_t::discarded);
         }
-        return unedited() ? detail::view::materialize<BasicJsonType, false>(*m_doc, m_node) : detail::view::materialize<BasicJsonType, Editable>(*m_doc, m_node);
+        return unedited() ? detail::view::materialize<BasicJsonType, false>(*m_doc, m_node) : detail::view::materialize<BasicJsonType, is_editable>(*m_doc, m_node);
     }
 
     /// byte offset of this value in the source text (for strings: of the
@@ -740,8 +744,8 @@ class basic_json_view
     }
 
   private:
-    template<typename, bool> friend class basic_json_document;
-    template<typename, bool> friend class basic_json_view;
+    template<typename, view_mode> friend class basic_json_document;
+    template<typename, view_mode> friend class basic_json_view;
     template<typename, typename> friend class detail::view::editor;
     friend iterator;
 
@@ -757,11 +761,11 @@ class basic_json_view
     }
 
     /// the template argument as a runtime condition: testing it directly in
-    /// `Editable && ...` makes the condition constant, which MSVC reports as
+    /// `is_editable && ...` makes the condition constant, which MSVC reports as
     /// C4127
     static bool editable() noexcept
     {
-        return Editable;
+        return is_editable;
     }
 
     /// the number of source bytes of this value (estimated for values with
@@ -810,7 +814,7 @@ class basic_json_view
             const node* const k = detail::view::find_member<false>(*m_doc, m_node, key.data(), key.size());
             return k != nullptr ? basic_json_view(m_doc, k + 1) : basic_json_view();
         }
-        const node* const k = detail::view::find_member<Editable>(*m_doc, m_node, key.data(), key.size());
+        const node* const k = detail::view::find_member<is_editable>(*m_doc, m_node, key.data(), key.size());
         return k != nullptr ? basic_json_view(m_doc, navigation::value(k + 1)) : basic_json_view();
     }
 
@@ -824,7 +828,7 @@ class basic_json_view
     /// the member of this object with @a key (the last one if the key occurs more than once), or nullptr
     NLOHMANN_VIEW_ALWAYS_INLINE const node* find_key(string_view_t key) const
     {
-        return find_key(key, std::integral_constant<bool, Editable> {});
+        return find_key(key, std::integral_constant<bool, is_editable> {});
     }
 
     NLOHMANN_VIEW_ALWAYS_INLINE const node* find_key(string_view_t key, std::true_type /*editable*/) const
@@ -846,7 +850,7 @@ class basic_json_view
         {
             return basic_json_view(m_doc, detail::view::element_at<false>(*m_doc, m_node, idx));
         }
-        return basic_json_view(m_doc, navigation::value(detail::view::element_at<Editable>(*m_doc, m_node, idx)));
+        return basic_json_view(m_doc, navigation::value(detail::view::element_at<is_editable>(*m_doc, m_node, idx)));
     }
 
     // --- get() dispatch ---
@@ -952,16 +956,19 @@ Borrowed parses keep a pointer to the caller's text, which must outlive the
 document. Owned parses (parse_copy, rvalue std::string, streams, and inputs
 that are not contiguous byte ranges) keep their own copy.
 */
-template<typename BasicJsonType, bool Editable = false>
+template<typename BasicJsonType, view_mode Mode = view_mode::read_only>
 class basic_json_document
 {
+    /// whether the document can be edited
+    static constexpr bool is_editable = Mode == view_mode::editable;
+
     using document_data = detail::view::document_data;
 
     static_assert(sizeof(typename BasicJsonType::number_integer_t) == 8 && sizeof(typename BasicJsonType::number_unsigned_t) == 8,
                   "json_view supports 64-bit integer types only");
 
   public:
-    using view_type = basic_json_view<BasicJsonType, Editable>;
+    using view_type = basic_json_view<BasicJsonType, Mode>;
     using value_t = detail::value_t;
 
     /// an empty (discarded) document
@@ -1175,6 +1182,10 @@ class basic_json_document
     /// how load() checks an image (full, bounds, or none)
     using image_check = detail::view::image_check;
 
+#if NLOHMANN_VIEW_LITTLE_ENDIAN
+    // (the image format is little-endian: big-endian targets have no save()
+    // and load(), so that a call fails to compile instead of always throwing)
+
     /// The document as an image that load() reads without parsing: the node
     /// index, the text, and the decoded strings. An edited document is
     /// written in its current state (floats that are not finite become null,
@@ -1216,6 +1227,7 @@ class basic_json_document
         detail::view::load_image(*d.m_data, d.m_data->owned_image.data(), d.m_data->owned_image.size(), check);
         return d;
     }
+#endif
 
     ///////////
     // edits //
@@ -1357,7 +1369,7 @@ class basic_json_document
 
     detail::view::editor<BasicJsonType, view_type> editor()
     {
-        static_assert(Editable, "only an editable document can be edited: use basic_json_document<BasicJsonType, true> (json_editable_document)");
+        static_assert(is_editable, "only an editable document can be edited: use basic_json_document<BasicJsonType, view_mode::editable> (json_editable_document)");
         if (NLOHMANN_VIEW_UNLIKELY(!m_data || m_data->discarded))
         {
             detail::view::throw_invalid_iterator(detail::exception_id::iterator_from_other_value, "view does not belong to this document");
@@ -1642,13 +1654,13 @@ using ordered_json_document = basic_json_document<ordered_json>;
 /// a value of an ordered_json_document
 using ordered_json_view = basic_json_view<ordered_json>;
 /// an editable parsed JSON text for json
-using json_editable_document = basic_json_document<json, true>;
+using json_editable_document = basic_json_document<json, view_mode::editable>;
 /// a value of a json_editable_document
-using json_editable_view = basic_json_view<json, true>;
+using json_editable_view = basic_json_view<json, view_mode::editable>;
 /// an editable parsed JSON text for ordered_json
-using ordered_json_editable_document = basic_json_document<ordered_json, true>;
+using ordered_json_editable_document = basic_json_document<ordered_json, view_mode::editable>;
 /// a value of an ordered_json_editable_document
-using ordered_json_editable_view = basic_json_view<ordered_json, true>;
+using ordered_json_editable_view = basic_json_view<ordered_json, view_mode::editable>;
 
 NLOHMANN_JSON_NAMESPACE_END
 

single_include/nlohmann/json.hpp

@@ -5565,7 +5565,7 @@ enum class exception_id : int
     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
     document_binary_value = 319, ///< a binary value is stored in a json_document
-    document_image_unsupported = 320, ///< a json_document image cannot be saved or loaded (discarded document, big-endian target)
+    document_image_unsupported = 320, ///< a discarded json_document cannot be saved as an image
     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

tests/src/unit-json_view_builder.cpp

@@ -592,7 +592,7 @@ TEST_CASE("json_view node integer bits")
                 })
         {
             CAPTURE(v)
-            n.kind = 0x5A;
+            n.kind = static_cast<nlohmann::detail::view::node_kind>(0x5A);
             n.flags = 0xA5;
             n.extra = 0x1234;
             n.off = 0x89ABCDEFu;
@@ -601,7 +601,7 @@ TEST_CASE("json_view node integer bits")
             CHECK(n.len == static_cast<std::uint32_t>(v));
             CHECK(n.next == static_cast<std::uint32_t>(v >> 32));
             // the other fields are untouched
-            CHECK(n.kind == 0x5A);
+            CHECK(static_cast<std::uint8_t>(n.kind) == 0x5A);
             CHECK(n.flags == 0xA5);
             CHECK(n.extra == 0x1234);
             CHECK(n.off == 0x89ABCDEFu);

tests/src/unit-json_view_dump.cpp

@@ -35,9 +35,9 @@ using json_view_test::has_duplicate_keys;
 #include <string>
 #include <vector>
 
-// These tests were split off unit-json_view.cpp, whose object file got too large for the MinGW
-// linker (see json_view_test_helpers.hpp). Like that file, this one is also built
-// with C++17, as it mentions JSON_HAS_CPP_17.
+// These tests were split off unit-json_view.cpp, whose object file got too large
+// for the MinGW linker (see json_view_test_helpers.hpp). Like that file, this one
+// is also built with C++17, as it mentions JSON_HAS_CPP_17.
 
 TEST_CASE("json_view dump")
 {
@@ -150,71 +150,6 @@ TEST_CASE("json_view dump")
             CHECK(many_doc.root().dump() == json::parse(many_tokens).dump());
         }
 
-        // tokens of 16 and 17 digits without an exponent (like GeoJSON
-        // coordinates), which dump() converts in batches: doubles exactly
-        // halfway between two candidates for the shortest digits, random
-        // digits, and digits near a shorter decimal (...99999997,
-        // ...00000003), whose rounding carries; in pairs and among other
-        // values, so that the batches are interrupted; the last token near the
-        // end of the text
-        {
-            std::mt19937_64 tokens(5627); // NOLINT(cert-msc32-c,cert-msc51-cpp,bugprone-random-generator-seed)
-            const auto draw = [&tokens](std::size_t n)
-            {
-                const std::uint64_t r = tokens() % n;
-                return static_cast<std::size_t>(r);
-            };
-            std::string coordinates = "[754570942.33984373,257769445.56835938,858106901.94921875,97944964.876953125,"
-                                      "[0.5,1e-7],[1.5,-0.0,2.5],[1E2,12.5,0.1,3.25,4.5,5.75,6.125,7.0,8.5],[],[1.5],[1,2.5],[2.5,\"x\"],[[1.5],2.5],";
-            for (int i = 0; i < 20000; ++i)
-            {
-                const std::size_t length = 16 + draw(2);
-                std::string digits(1, static_cast<char>('1' + draw(9)));
-                const std::size_t kept = draw(3) == 0 ? length : 2 + draw(length - 3);
-                for (std::size_t k = 1; k < kept; ++k)
-                {
-                    digits += static_cast<char>('0' + draw(10));
-                }
-                digits += std::string(length - kept, draw(2) == 0 ? '9' : '0');
-                digits.back() = static_cast<char>('0' + draw(10));
-                const std::size_t point = 1 + draw(9);
-                const std::string token = (draw(2) == 0 ? "-" : "") + digits.substr(0, point) + "." + digits.substr(point);
-                coordinates += (i != 0 ? "," : "") + (draw(8) == 0 ? "{\"x\":" + token + ",\"s\":\"a\"}" : "[" + token + "," + token + "]");
-            }
-            coordinates += ",-65.613616999999977]";
-            const json_document parsed = json_document::parse(coordinates);
-            const ordered_json j = ordered_json::parse(coordinates);
-            CHECK(parsed.root().dump() == j.dump());
-            CHECK(parsed.root().dump(1) == j.dump(1));
-            CHECK(parsed.root().dump(-1, ' ', true) == j.dump(-1, ' ', true));
-            CHECK(parsed.root().back().get<double>() == j.back().get<double>());
-            CHECK(parsed.root().back().dump() == "-65.61361699999998");
-            std::size_t i = 0;
-            for (const json_view v : parsed.root())
-            {
-                const ordered_json& e = j[i++];
-                CHECK(v.dump() == e.dump());
-                if (v.is_array() && v.size() != 0 && v[0].is_number())
-                {
-                    CHECK(v[0].get<double>() == e[0].get<double>());
-                }
-            }
-
-            // an editable document: edits move some arrays, so that the walk
-            // leaves the order of the parsed nodes
-            ordered_json_editable_document editable = ordered_json_editable_document::parse(coordinates);
-            ordered_json expected = j;
-            for (std::size_t k = 0; k < 20000; k += 97)
-            {
-                if (expected[k].is_array())
-                {
-                    editable.push_back(editable.root()[k], ordered_json(1.5));
-                    expected[k].push_back(1.5);
-                }
-            }
-            CHECK(editable.root().dump() == expected.dump());
-        }
-
         // random doubles, written as parse() and dump() would
         std::mt19937_64 rng(1170); // NOLINT(cert-msc32-c,cert-msc51-cpp,bugprone-random-generator-seed)
         std::string many = "[";
@@ -236,4 +171,768 @@ TEST_CASE("json_view dump")
         const nlohmann::basic_json_document<json_float> float_document = nlohmann::basic_json_document<json_float>::parse("[0.1, 1.5e10, 3.4028235e38]");
         CHECK(float_document.root().dump() == json_float::parse("[0.1, 1.5e10, 3.4028235e38]").dump());
     }
+
+    SECTION("members in document order, all of them")
+    {
+        const json_document d = json_document::parse(R"({"b": 1, "a": 2, "b": 3})");
+        CHECK(d.root().dump() == R"({"b":1,"a":2,"b":3})");
+        CHECK(d.root().dump(1) == "{\n \"b\": 1,\n \"a\": 2,\n \"b\": 3\n}");
+        // dump() writes all members, though the lookup finds the first
+        CHECK(d.root()["b"].dump() == "1");
+    }
+
+    SECTION("deep nesting")
+    {
+        const std::string deep = std::string(100000, '[') + std::string(100000, ']');
+        const json_document deep_document = json_document::parse(deep);
+        CHECK(deep_document.root().dump() == deep);
+    }
+
+    SECTION("ensure_ascii: a character that needs an escape at each position of a string")
+    {
+        // string lengths around the width of the vector steps, in a string value, a key, and a value near the end of the text
+        for (const char* const special :
+                {
+                    "\xC3\xA9", "\xE4\xB8\xAD", "\xF0\x9F\x98\x80", "\x7F", "\\n", "\\u0001", "\\\"", "\\\\"
+                })
+        {
+            for (std::size_t length = 0; length <= 40; ++length)
+            {
+                for (std::size_t position = 0; position <= length; ++position)
+                {
+                    std::string content(length, 'a');
+                    content.insert(position, special);
+                    const std::array<std::string, 3> texts =
+                    {
+                        {
+                            "\"" + content + "\"",
+                            "[\"" + content + "\"]",
+                            "{\"" + content + "\":1}",
+                        }
+                    };
+                    for (const std::string& text : texts)
+                    {
+                        CAPTURE(text)
+                        const ordered_json_document d = ordered_json_document::parse(text);
+                        const ordered_json j = ordered_json::parse(text);
+                        CHECK(d.root().dump(-1, ' ', true) == j.dump(-1, ' ', true));
+                        CHECK(d.root().dump(2, ' ', true) == j.dump(2, ' ', true));
+                        CHECK(d.root().dump() == j.dump());
+                    }
+                }
+            }
+        }
+    }
+
+    SECTION("ensure_ascii: every character of the Basic Multilingual Plane and some beyond")
+    {
+        // (the two- and three-byte sequences, including the ranges that need a check: E0, ED, EF BF BF)
+        std::string text = "[";
+        std::size_t in_chunk = 0;
+        const auto append = [&](std::uint32_t cp)
+        {
+            if (cp < 0x80)
+            {
+                if (cp < 0x20 || cp == '"' || cp == '\\')
+                {
+                    return;
+                }
+                text += static_cast<char>(cp);
+            }
+            else if (cp < 0x800)
+            {
+                text += static_cast<char>(0xC0 | (cp >> 6));
+                text += static_cast<char>(0x80 | (cp & 0x3F));
+            }
+            else if (cp < 0x10000)
+            {
+                text += static_cast<char>(0xE0 | (cp >> 12));
+                text += static_cast<char>(0x80 | ((cp >> 6) & 0x3F));
+                text += static_cast<char>(0x80 | (cp & 0x3F));
+            }
+            else
+            {
+                text += static_cast<char>(0xF0 | (cp >> 18));
+                text += static_cast<char>(0x80 | ((cp >> 12) & 0x3F));
+                text += static_cast<char>(0x80 | ((cp >> 6) & 0x3F));
+                text += static_cast<char>(0x80 | (cp & 0x3F));
+            }
+        };
+        for (std::uint32_t cp = 0x20; cp < 0x10400; ++cp)
+        {
+            if (cp >= 0xD800 && cp < 0xE000)
+            {
+                continue;
+            }
+            if (in_chunk == 0)
+            {
+                text += text.size() > 1 ? ",\"" : "\"";
+            }
+            append(cp);
+            if (++in_chunk == 37)
+            {
+                text += "\"";
+                in_chunk = 0;
+            }
+        }
+        text += in_chunk != 0 ? "\"]" : "]";
+        const ordered_json_document d = ordered_json_document::parse(text);
+        const ordered_json j = ordered_json::parse(text);
+        CHECK(d.root().dump(-1, ' ', true) == j.dump(-1, ' ', true));
+        CHECK(d.root().dump(2, ' ', true) == j.dump(2, ' ', true));
+        CHECK(d.root().dump() == j.dump());
+        CHECK(d.root().dump(2) == j.dump(2));
+    }
+
+    SECTION("deep nesting, indented")
+    {
+        // indentations of up to and beyond the width of the writer's fixed-size copy
+        for (const int depth :
+                {
+                    1, 5, 20, 70, 300
+                })
+        {
+            std::string text;
+            for (int i = 0; i < depth; ++i)
+            {
+                text += i % 2 == 0 ? "[1," : R"({"k":2,"\u00e9":)";
+            }
+            text += "[]";
+            for (int i = depth - 1; i >= 0; --i)
+            {
+                text += i % 2 == 0 ? "]" : "}";
+            }
+            const ordered_json_document d = ordered_json_document::parse(text);
+            const ordered_json j = ordered_json::parse(text);
+            for (const int indent :
+                    {
+                        0, 1, 2, 3, 8
+                    })
+            {
+                CHECK(d.root().dump(indent) == j.dump(indent));
+                CHECK(d.root().dump(indent, '\t') == j.dump(indent, '\t'));
+            }
+        }
+    }
+
+    SECTION("the output buffer of a small value is small")
+    {
+        // an escaped key after the value: its node lies in the arena, so the
+        // source extent of the value cannot be read from the next node
+        const std::string big(100000, 'a');
+        const std::string text = R"({"small":1,"list":[1,2,3],"k\n":")" + big + R"("})";
+        const json_document d = json_document::parse(text);
+        const auto small = d.root()["small"].dump();
+        CHECK(small == "1");
+        CHECK(small.capacity() < 4096);
+        const auto list = d.root()["list"].dump();
+        CHECK(list == "[1,2,3]");
+        CHECK(list.capacity() < 4096);
+        CHECK(d.root()["list"].dump(2).capacity() < 4096);
+
+        // the whole document and the large value are unaffected
+        CHECK(d.root().dump() == ordered_json::parse(text).dump());
+        CHECK(d.root()["k\n"].dump() == "\"" + big + "\"");
+    }
+
+    SECTION("output that outgrows the estimate")
+    {
+        // ensure_ascii writes six bytes for each two-byte character
+        std::string chars;
+        for (int i = 0; i < 5000; ++i)
+        {
+            chars += "\xC3\xA9";
+        }
+        const json_document d = json_document::parse(R"({"a":")" + chars + R"(","k\n":1})");
+        const json expected = json::parse("\"" + chars + "\"");
+        CHECK(d.root()["a"].dump(-1, ' ', true) == expected.dump(-1, ' ', true));
+        CHECK(d.root()["a"].dump(-1, ' ', true).size() == 2 + (5000 * 6));
+    }
+
+    SECTION("ensure_ascii with strings of the source, decoded strings, and edited strings")
+    {
+        // plain ASCII, non-ASCII, escaped (decoded), and mixed strings, as values and as keys;
+        // the second text has a DEL, which ensure_ascii writes as an escape
+        for (const char* const del :
+                {"", "\x7F"
+                })
+        {
+            const std::string text = std::string("{\"plain\":\"abc\",\"caf\xC3\xA9\":\"\xC3\xA9\xE2\x82\xAC\xF0\x9F\x98\x80\",")
+                                     + "\"esc\\n\\\"\":\"a\\tb\\u00e4\\ud83d\\ude00\",\"del\":\"a" + del + "b\",\"\":\"\"," // NOLINT(modernize-raw-string-literal)
+                                     + "\"list\":[\"x\",\"\xC3\xBC\",\"\\\\\",\"long ASCII string with more than thirty-two bytes in it\","
+                                     + "\"long string with more than thirty-two bytes and one non-ASCII byte \xC3\xB6\"],"
+                                     + "\"n\":[1,2.5,-0,true,null]}";
+            const ordered_json j = ordered_json::parse(text);
+            const ordered_json_document d = ordered_json_document::parse(text);
+            CHECK(d.root().dump(-1, ' ', true) == j.dump(-1, ' ', true));
+            CHECK(d.root().dump(4, ' ', true) == j.dump(4, ' ', true));
+            CHECK(d.root().dump() == j.dump());
+            CHECK(d.root()["list"].dump(-1, ' ', true) == j["list"].dump(-1, ' ', true));
+            CHECK(d.root()["del"].dump(-1, ' ', true) == j["del"].dump(-1, ' ', true));
+
+            // strings that an edit wrote (the source strings that they replace were plain)
+            ordered_json_editable_document e = ordered_json_editable_document::parse(text);
+            ordered_json k = j;
+            e.set(e.root()["plain"], std::string("\xC3\xA4gypten"));
+            k["plain"] = "\xC3\xA4gypten";
+            e.set(e.root()["list"][0], std::string("ascii after edit"));
+            k["list"][0] = "ascii after edit";
+            e.set(e.root()["list"][1], std::string("\xC3\xA4"));
+            k["list"][1] = "\xC3\xA4";
+            e.set(e.root()["del"], std::string("tab\there"));
+            k["del"] = "tab\there";
+            CHECK(e.root().dump(-1, ' ', true) == k.dump(-1, ' ', true));
+            CHECK(e.root().dump(2, ' ', true) == k.dump(2, ' ', true));
+            CHECK(e.root().dump() == k.dump());
+
+            // strings that were edited from or to ASCII text
+            e.set(e.root()["list"][2], std::string("\xC3\xA4"));
+            k["list"][2] = "\xC3\xA4";
+            e.set(e.root()["list"][4], std::string("plain again"));
+            k["list"][4] = "plain again";
+            CHECK(e.root().dump(-1, ' ', true) == k.dump(-1, ' ', true));
+        }
+    }
+
+    SECTION("ensure_ascii with DEL or a non-ASCII character at every position")
+    {
+        // the check whether a string of the source has no byte >= 0x7F reads
+        // eight bytes at a time and then the rest one by one
+        for (std::size_t length = 1; length <= 20; ++length)
+        {
+            for (std::size_t pos = 0; pos < length; ++pos)
+            {
+                for (const char* const c :
+                        {
+                            "\x7F", "\x7E", "\xC3\xA4", "\xC3\xBF" // NOLINT(modernize-raw-string-literal)
+                        })
+                {
+                    const std::string s = std::string(pos, 'a') + c + std::string(length - pos - 1, 'b');
+                    std::string text = "[\"";
+                    text.append(s).append("\",{\"").append(s).append("\":1}]");
+                    const json_document d = json_document::parse(text);
+                    const json j = json::parse(text);
+                    CHECK(d.root().dump(-1, ' ', true) == j.dump(-1, ' ', true));
+                    CHECK(d.root().dump(1, ' ', true) == j.dump(1, ' ', true));
+                }
+            }
+        }
+    }
+
+    SECTION("streams and discarded views")
+    {
+        const json_document d = json_document::parse(R"({"a": [1, 2]})");
+        std::ostringstream compact;
+        compact << d.root();
+        CHECK(compact.str() == R"({"a":[1,2]})");
+        std::ostringstream pretty;
+        pretty << std::setw(2) << std::setfill('.') << d.root() << d.root()["a"];
+        CHECK(pretty.str() == "{\n..\"a\": [\n....1,\n....2\n..]\n}[1,2]");
+        CHECK(json_view().dump() == json(json::value_t::discarded).dump());
+    }
+}
+
+TEST_CASE("json_view comparison")
+{
+    SECTION("equality of the values parse() produces")
+    {
+        generator g;
+        std::vector<std::string> texts;
+        for (int i = 0; i < 600; ++i)
+        {
+            std::string text;
+            g.value(text, 0);
+            texts.push_back(text);
+            // the same value written differently: sorted keys, canonical numbers
+            texts.push_back(json::parse(text).dump(1));
+        }
+        for (std::size_t i = 0; i + 2 < texts.size(); ++i)
+        {
+            for (std::size_t k = i; k < i + 3; ++k)
+            {
+                CAPTURE(texts[i])
+                CAPTURE(texts[k])
+                const json_document a = json_document::parse(texts[i]);
+                const json_document b = json_document::parse(texts[k]);
+                const json ja = json::parse(texts[i]);
+                const json jb = json::parse(texts[k]);
+                CHECK((a.root() == b.root()) == (ja == jb));
+                CHECK((a.root() != b.root()) == (ja != jb));
+                CHECK((a.root() == jb) == (ja == jb));
+                CHECK((jb == a.root()) == (ja == jb));
+                CHECK((a.root() != jb) == (ja != jb));
+                CHECK((jb != a.root()) == (ja != jb));
+
+                // ordered_json compares members in order
+                const ordered_json_document oa = ordered_json_document::parse(texts[i]);
+                const ordered_json_document ob = ordered_json_document::parse(texts[k]);
+                const ordered_json oja = ordered_json::parse(texts[i]);
+                const ordered_json ojb = ordered_json::parse(texts[k]);
+                CHECK((oa.root() == ob.root()) == (oja == ojb));
+                CHECK((oa.root() == ojb) == (oja == ojb));
+            }
+        }
+    }
+
+    SECTION("numbers, duplicate keys, member order")
+    {
+        const auto same = [](const char* x, const char* y)
+        {
+            const json_document dx = json_document::parse(x);
+            const json_document dy = json_document::parse(y);
+            return dx.root() == dy.root();
+        };
+        CHECK(same("1", "1.0"));
+        CHECK(same("[1, -1, 2.5]", "[1.0, -1.0, 25e-1]"));
+        CHECK(!same("1", "1.5"));
+        CHECK(same("18446744073709551615", "18446744073709551615"));
+        CHECK(same(R"({"a": 1, "a": 2})", R"({"a": 2})"));
+        CHECK(!same(R"({"a": 1, "a": 2})", R"({"a": 1})"));
+        CHECK(same(R"({"a": 1, "b": 2})", R"({"b": 2, "a": 1})"));
+        CHECK(!same(R"({"a": 1})", R"({"a": 1, "b": 2})"));
+        CHECK(!same("[1, 2]", "[2, 1]"));
+        CHECK(!same("\"a\"", "\"b\""));
+        CHECK(same("\"\\u00e9\"", "\"\xc3\xa9\""));
+        CHECK(!same("null", "false"));
+        CHECK(!same("[]", "{}"));
+        const ordered_json_document dup = ordered_json_document::parse(R"({"a": 1, "b": 2, "a": 3})");
+        const ordered_json_document last = ordered_json_document::parse(R"({"a": 3, "b": 2})");
+        CHECK(dup.root() == last.root());
+        // (== compares as parse() resolves duplicates, a lookup finds the first)
+        CHECK(dup.root()["a"].materialize() == 1);
+        CHECK(dup.root()["a"] != last.root()["a"]);
+        const ordered_json_document ab = ordered_json_document::parse(R"({"a": 1, "b": 2})");
+        const ordered_json_document ba = ordered_json_document::parse(R"({"b": 2, "a": 1})");
+        CHECK(ab.root() != ba.root());
+
+        // discarded values compare as basic_json's do
+        const json discarded(json::value_t::discarded);
+        CHECK((json_view() == json_view()) == (discarded == discarded)); // NOLINT(readability-container-size-empty): operator== is tested
+        CHECK((json_view() == discarded) == (discarded == discarded)); // NOLINT(readability-container-size-empty)
+        const json_document null_document = json_document::parse("null");
+        CHECK(!(json_view() == null_document.root())); // NOLINT(readability-container-size-empty)
+        CHECK(!(null_document.root() == discarded));
+    }
+
+    SECTION("deep nesting")
+    {
+        const std::string deep = std::string(100000, '[') + std::string(100000, ']');
+        const json_document a = json_document::parse(deep);
+        const json_document b = json_document::parse(deep);
+        CHECK(a.root() == b.root());
+        CHECK(a.root() == json::parse(deep));
+        const std::string other = std::string(100000, '[') + "1" + std::string(100000, ']');
+        const json_document c = json_document::parse(other);
+        CHECK(a.root() != c.root());
+    }
+}
+
+TEST_CASE("json_view large objects")
+{
+    // objects with 128 members or more are looked up with a hash index
+    for (const std::size_t members :
+            {
+                127u, 128u, 129u, 10000u
+            })
+    {
+        CAPTURE(members)
+        std::string text = "{";
+        for (std::size_t i = 0; i < members; ++i)
+        {
+            text += (i != 0 ? ",\"" : "\"") + std::string(i % 23, 'k') + std::to_string(i) + (i % 7 == 0 ? "\\n" : "") + "\":" + std::to_string(i);
+        }
+        text += R"(,"":"empty key","k1":"a duplicate of an earlier key"})";
+        const json_document d = json_document::parse(text);
+        const json_view v = d.root();
+        const json j = json::parse(text);
+        for (std::size_t i = 0; i < members; ++i)
+        {
+            const std::string key = std::string(i % 23, 'k') + std::to_string(i) + (i % 7 == 0 ? "\n" : "");
+            CHECK(v[key].get<std::size_t>() == i);
+            CHECK(v.contains(key));
+            CHECK(v.find(key).key() == key);
+            CHECK(v.at(key).get<std::size_t>() == i);
+            CHECK(!v.contains(key + "x"));
+        }
+        CHECK(v[""].get_string() == "empty key");
+        CHECK(v["k1"].get<int>() == 1); // the first of duplicate keys, as for small objects
+        CHECK(!v.contains("missing"));
+        CHECK_THROWS_WITH_AS(v.at("missing"), "[json.exception.out_of_range.403] key 'missing' not found", json::out_of_range&);
+        CHECK(v == j);
+        CHECK(v.materialize() == j);
+    }
+
+    SECTION("duplicate keys: the first member wins, with and without a table")
+    {
+        // an object of `total` members: the keys "k0".."k<n-1>" in order, then
+        // three keys repeated twice more (one copy in the middle, one at the
+        // end), and two keys repeated once; the value of a member is its
+        // position, so that the first member of a key can be told apart
+        struct member
+        {
+            std::string key;
+            std::size_t position;
+        };
+        const auto make_members = [](std::size_t total)
+        {
+            std::vector<std::string> keys;
+            for (std::size_t i = 0; i + 8 < total; ++i)
+            {
+                keys.push_back("k" + std::to_string(i));
+            }
+            const std::size_t n = keys.size();
+            const std::array<std::size_t, 3> triple = {{3, 17, n - 1}};
+            const std::array<std::size_t, 2> twice = {{5, n / 2}};
+            std::vector<std::string> ordered = keys;
+            for (const std::size_t i : triple)
+            {
+                ordered.insert(ordered.begin() + static_cast<std::ptrdiff_t>(ordered.size() / 2), keys[i]);
+            }
+            for (const std::size_t i : twice)
+            {
+                ordered.insert(ordered.begin() + static_cast<std::ptrdiff_t>(ordered.size() / 3), keys[i]);
+            }
+            for (const std::size_t i : triple)
+            {
+                ordered.push_back(keys[i]);
+            }
+            std::vector<member> result;
+            result.reserve(ordered.size());
+            for (std::size_t i = 0; i < ordered.size(); ++i)
+            {
+                result.push_back({ordered[i], i});
+            }
+            return result;
+        };
+
+        // 100 and 127 members: no table; 128 members and more: a table
+        for (const std::size_t total :
+                {
+                    100u, 127u, 128u, 200u, 5000u
+                })
+        {
+            CAPTURE(total)
+            const std::vector<member> members = make_members(total);
+            REQUIRE(members.size() >= total);
+            REQUIRE(members.size() >= 100);
+            std::string text = "{";
+            std::map<std::string, std::size_t> first;
+            std::map<std::string, std::size_t> last;
+            std::map<std::string, std::size_t> occurrences;
+            for (const member& m : members)
+            {
+                text += (text.size() > 1 ? ",\"" : "\"") + m.key + "\":" + std::to_string(m.position);
+                first.insert({m.key, m.position});
+                last[m.key] = m.position;
+                ++occurrences[m.key];
+            }
+            text += '}';
+            REQUIRE(first.size() < members.size());
+
+            const json_document d = json_document::parse(text);
+            const json_view v = d.root();
+            const json j = json::parse(text);
+            CHECK(v.size() == members.size()); // every occurrence is visited
+            const json m = v.materialize();
+            for (const auto& entry : first)
+            {
+                CAPTURE(entry.first)
+                const std::size_t expected = entry.second;
+                CHECK(v[entry.first].get<std::size_t>() == expected);
+                CHECK(v.at(entry.first).get<std::size_t>() == expected);
+                CHECK(v.find(entry.first).value().get<std::size_t>() == expected);
+                CHECK(v.value(entry.first, std::size_t{0}) == expected);
+                CHECK(v.contains(entry.first));
+                CHECK(v.count(entry.first) == occurrences[entry.first]);
+                const std::string pointer = "/" + entry.first;
+                CHECK(v[json::json_pointer(pointer)].get<std::size_t>() == expected);
+                CHECK(v.at(json::json_pointer(pointer)).get<std::size_t>() == expected);
+                CHECK(v.value(json::json_pointer(pointer), std::size_t{0}) == expected);
+                CHECK(v.contains(json::json_pointer(pointer)));
+                // materialize() and parse() keep the last value instead
+                CHECK(j[entry.first].get<std::size_t>() == last.at(entry.first));
+                CHECK(m[entry.first].get<std::size_t>() == last.at(entry.first));
+            }
+            CHECK(!v.contains("k"));
+            CHECK(v["missing"].is_discarded());
+            CHECK(v.materialize() == j);
+            CHECK(v == j);
+        }
+    }
+
+    SECTION("colliding keys")
+    {
+        // the hash is not seeded, so keys that all land in one place must not
+        // make the table build quadratic: such an object gets no table and is
+        // searched linearly
+        constexpr std::size_t members = 300;
+        constexpr std::size_t table_size = 1024; // the table size for 300 members: the next power of two >= 600
+        std::vector<std::string> colliding;
+        std::vector<std::string> spread;
+        for (std::uint64_t counter = 0; colliding.size() < members || spread.size() < members; ++counter)
+        {
+            std::string key(8, 'a');
+            std::uint64_t x = counter;
+            for (std::size_t i = 0; i < 8; ++i, x /= 26)
+            {
+                key[i] = static_cast<char>('a' + (x % 26));
+            }
+            const bool lands_in_slot_zero = (nlohmann::detail::view::key_hash(key.data(), key.size()) & (table_size - 1)) == 0;
+            if (lands_in_slot_zero && colliding.size() < members)
+            {
+                colliding.push_back(key);
+            }
+            else if (!lands_in_slot_zero && spread.size() < members)
+            {
+                spread.push_back(key);
+            }
+        }
+
+        const auto make_text = [](const std::vector<std::string>& keys)
+        {
+            std::string text = "{";
+            for (std::size_t i = 0; i < keys.size(); ++i)
+            {
+                text += (i != 0 ? ",\"" : "\"") + keys[i] + "\":" + std::to_string(i % 10);
+            }
+            return text + "}";
+        };
+        const std::string colliding_text = make_text(colliding);
+        const std::string spread_text = make_text(spread);
+
+        json_document with_collisions = json_document::parse(colliding_text);
+        json_document without_collisions = json_document::parse(spread_text);
+        for (const auto* pair :
+                {
+                    &colliding, &spread
+                })
+        {
+            const json_view v = (pair == &colliding ? with_collisions : without_collisions).root();
+            for (std::size_t i = 0; i < members; ++i)
+            {
+                CAPTURE(i)
+                CHECK(v[(*pair)[i]].get<std::size_t>() == i % 10);
+                CHECK(v.at((*pair)[i]).get<std::size_t>() == i % 10);
+                CHECK(v.find((*pair)[i]).key() == (*pair)[i]);
+                CHECK(!v.contains((*pair)[i] + "x"));
+            }
+            CHECK(!v.contains("missing"));
+        }
+        CHECK(with_collisions.root() == json::parse(colliding_text));
+
+        // only the object with the spread keys got a table (both texts have the
+        // same length, so the tables are the only difference)
+        with_collisions.shrink_to_fit();
+        without_collisions.shrink_to_fit();
+        CHECK(without_collisions.memory_usage() >= with_collisions.memory_usage() + (table_size * sizeof(std::uint32_t)));
+    }
+
+    SECTION("keys that differ in their last bytes are spread over the table")
+    {
+        // The hash must spread the usual families of keys (numbered names, hex
+        // strings, dates, short names): a key farther than index_max_displacement
+        // from its home slot would leave the object without a table. The keys
+        // are placed with linear probing, as the table does.
+        const auto max_displacement = [](const std::vector<std::string>& keys)
+        {
+            std::size_t slots = 16;
+            while (slots < 2 * keys.size())
+            {
+                slots *= 2;
+            }
+            std::vector<bool> used(slots, false);
+            std::size_t farthest = 0;
+            for (const std::string& key : keys)
+            {
+                std::size_t i = nlohmann::detail::conditional_static_cast<std::size_t>(nlohmann::detail::view::key_hash(key.data(), key.size())) & (slots - 1);
+                std::size_t distance = 0;
+                while (used[i])
+                {
+                    i = (i + 1) & (slots - 1);
+                    ++distance;
+                }
+                used[i] = true;
+                farthest = (std::max)(farthest, distance);
+            }
+            return farthest;
+        };
+        // the keys of a printf-like pattern with one %d, %0Nd or %0Nx, formatted with a stream
+        // (a format string that is not a literal is a Flawfinder error)
+        const auto numbered = [](const char* format, int count, int step)
+        {
+            const std::string pattern(format);
+            const std::size_t percent = pattern.find('%');
+            std::size_t conversion = percent + 1;
+            std::size_t width = 0;
+            while (pattern[conversion] >= '0' && pattern[conversion] <= '9')
+            {
+                width = (width * 10) + static_cast<std::size_t>(pattern[conversion] - '0');
+                ++conversion;
+            }
+            const bool hex = pattern[conversion] == 'x';
+            std::vector<std::string> keys;
+            for (int i = 0; i < count; ++i)
+            {
+                std::ostringstream key;
+                key << pattern.substr(0, percent) << std::setfill('0') << std::setw(static_cast<int>(width))
+                    << (hex ? std::hex : std::dec) << (i * step) << pattern.substr(conversion + 1);
+                keys.push_back(key.str());
+            }
+            return keys;
+        };
+        for (const char* format :
+                {"key%d", "%d", "item_%04d", "a%05d", "%03dxyz", "id%d", "user_%d", "%d_suffix", "0x%04x", "A%07d", "12345678%d", "1234567%d", "123456789%d",
+                 "configuration_parameter_value_%04d_extra", "2026-01-%02dT00:00:00Z"
+                })
+        {
+            CAPTURE(format)
+            CHECK(max_displacement(numbered(format, std::string(format).find("%02d") != std::string::npos ? 60 : 1000, 1)) < nlohmann::detail::view::index_max_displacement); // NOLINT(abseil-string-find-str-contains)
+            CHECK(max_displacement(numbered(format, 600, 7)) < nlohmann::detail::view::index_max_displacement);
+        }
+        std::mt19937_64 rng(7); // NOLINT(cert-msc32-c,cert-msc51-cpp,bugprone-random-generator-seed)
+        for (const std::size_t length :
+                {
+                    std::size_t{1}, std::size_t{2}, std::size_t{3}, std::size_t{5}, std::size_t{7}, std::size_t{8}, std::size_t{9}, std::size_t{12}, std::size_t{16}, std::size_t{17}, std::size_t{33}
+                })
+        {
+            CAPTURE(length)
+            std::set<std::string> distinct;
+            // (there are 26 and 676 keys of one and two letters)
+            std::size_t wanted = 700;
+            if (length == 1)
+            {
+                wanted = 26;
+            }
+            else if (length == 2)
+            {
+                wanted = 500;
+            }
+            while (distinct.size() < wanted)
+            {
+                std::string key(length, 'a');
+                for (char& c : key)
+                {
+                    c = static_cast<char>('a' + (rng() % 26));
+                }
+                distinct.insert(key);
+            }
+            CHECK(max_displacement(std::vector<std::string>(distinct.begin(), distinct.end())) < nlohmann::detail::view::index_max_displacement);
+        }
+    }
+
+    SECTION("keys of every length that differ in one byte")
+    {
+        // In a large object, a key is found by comparing its bytes with those of the member the
+        // table points to: up to 16 bytes as two overlapping words, longer ones with memcmp.
+        // Keys of every length from 0 to 40, and keys that differ from them in one byte.
+        std::mt19937_64 rng(2026); // NOLINT(cert-msc32-c,cert-msc51-cpp,bugprone-random-generator-seed)
+        std::vector<std::string> keys;
+        std::set<std::string> distinct;
+        for (std::size_t length = 0; length <= 40; ++length)
+        {
+            for (int copy = 0; copy < 5; ++copy)
+            {
+                std::string key(length, 'a');
+                for (char& c : key)
+                {
+                    c = static_cast<char>('a' + (rng() % 26));
+                }
+                if (distinct.insert(key).second)
+                {
+                    keys.push_back(key);
+                }
+            }
+        }
+        std::string text = "{";
+        for (std::size_t i = 0; i < keys.size(); ++i)
+        {
+            text += (i != 0 ? ",\"" : "\"") + keys[i] + "\":" + std::to_string(i);
+        }
+        text += "}";
+        REQUIRE(keys.size() >= 128); // (a table is built for 128 members)
+        const json_document d = json_document::parse(text);
+        const json_view v = d.root();
+        for (std::size_t i = 0; i < keys.size(); ++i)
+        {
+            CAPTURE(keys[i])
+            CHECK(v[keys[i]].get<std::size_t>() == i);
+            CHECK(v.at(keys[i]).get<std::size_t>() == i);
+            CHECK(v.contains(keys[i]));
+            for (std::size_t at = 0; at < keys[i].size(); ++at)
+            {
+                std::string other = keys[i];
+                other[at] = other[at] == 'z' ? 'y' : 'z';
+                CAPTURE(other)
+                CHECK(v.contains(other) == (distinct.count(other) != 0));
+            }
+            CHECK(v.contains(keys[i] + "a") == (distinct.count(keys[i] + "a") != 0));
+            if (!keys[i].empty())
+            {
+                CHECK(v.contains(keys[i].substr(1)) == (distinct.count(keys[i].substr(1)) != 0));
+            }
+        }
+    }
+
+    SECTION("shrink_to_fit releases the tables' spare capacity")
+    {
+        const auto make_text = [](int objects, int members)
+        {
+            std::string text = "[";
+            for (int object = 0; object < objects; ++object)
+            {
+                text += object != 0 ? ",{" : "{";
+                for (int i = 0, n = members + object; i < n; ++i)
+                {
+                    text += (i != 0 ? ",\"" : "\"") + std::to_string(i) + "\":" + std::to_string(i);
+                }
+                text += '}';
+            }
+            return text + "]";
+        };
+        const std::string small_text = make_text(5, 150);
+        const std::string big_text = make_text(40, 400);
+
+        // reading a big text, and then a small one, leaves the spare capacity
+        // of the big one: shrink_to_fit() brings the document to the size of
+        // one parsed from the small text alone
+        json_document d = json_document::parse(big_text);
+        const std::size_t big = d.memory_usage();
+        d.read(small_text);
+        CHECK(d.memory_usage() >= big);
+        d.shrink_to_fit();
+        json_document fresh = json_document::parse(small_text);
+        fresh.shrink_to_fit();
+        CHECK(d.memory_usage() == fresh.memory_usage());
+        CHECK(d.memory_usage() < big / 2);
+        CHECK(d.root() == json::parse(small_text));
+        for (int object = 0; object < 5; ++object)
+        {
+            const json_view v = d.root()[static_cast<std::size_t>(object)];
+            for (int i = 0, n = 150 + object; i < n; ++i)
+            {
+                CHECK(v[std::to_string(i)].get<int>() == i);
+            }
+        }
+    }
+
+    SECTION("nested, reused, and in arrays")
+    {
+        std::string inner = "{";
+        for (int i = 0; i < 300; ++i)
+        {
+            inner += (i != 0 ? ",\"m" : "\"m") + std::to_string(i) + "\":" + std::to_string(i);
+        }
+        inner += '}';
+        const std::string text = "[" + inner + ",{\"x\":" + inner + "}," + inner + "]";
+        json_document d = json_document::parse(text);
+        CHECK(d.root()[0]["m299"].get<int>() == 299);
+        CHECK(d.root()[1]["x"]["m150"].get<int>() == 150);
+        CHECK(d.root()[2]["m0"].get<int>() == 0);
+        const std::size_t with_index = d.memory_usage();
+        d.read(std::string("{\"small\": 1}"));
+        CHECK(d.root()["small"].get<int>() == 1);
+        d.read(text);
+        CHECK(d.root()[2]["m7"].get<int>() == 7);
+        CHECK(d.memory_usage() >= with_index / 2);
+    }
 }

tests/src/unit-json_view_dump_escape.cpp

@@ -1,302 +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
-
-#include "doctest_compatibility.h"
-
-#include <nlohmann/json_view.hpp>
-using nlohmann::json;
-using nlohmann::ordered_json;
-using nlohmann::json_document;
-using nlohmann::ordered_json_editable_document;
-using nlohmann::json_view;
-using nlohmann::ordered_json_document;
-using nlohmann::ordered_json_view;
-
-#include "json_view_test_helpers.hpp"
-using json_view_test::generator;
-using json_view_test::has_duplicate_keys;
-
-#include <algorithm>
-#include <array>
-#include <cmath>
-#include <cstddef>
-#include <cstdint>
-#include <cstring>
-#include <iomanip>
-#include <map>
-#include <random>
-#include <set>
-#include <sstream>
-#include <string>
-#include <vector>
-
-// These tests were split off unit-json_view_dump.cpp, whose object file got too large for the MinGW
-// linker (see json_view_test_helpers.hpp). Like that file, this one is also built
-// with C++17, as it mentions JSON_HAS_CPP_17.
-
-TEST_CASE("json_view dump: escaping, nesting, and output buffers")
-{
-    SECTION("members in document order, all of them")
-    {
-        const json_document d = json_document::parse(R"({"b": 1, "a": 2, "b": 3})");
-        CHECK(d.root().dump() == R"({"b":1,"a":2,"b":3})");
-        CHECK(d.root().dump(1) == "{\n \"b\": 1,\n \"a\": 2,\n \"b\": 3\n}");
-        // dump() writes all members, though the lookup finds the first
-        CHECK(d.root()["b"].dump() == "1");
-    }
-
-    SECTION("deep nesting")
-    {
-        const std::string deep = std::string(100000, '[') + std::string(100000, ']');
-        const json_document deep_document = json_document::parse(deep);
-        CHECK(deep_document.root().dump() == deep);
-    }
-
-    SECTION("ensure_ascii: a character that needs an escape at each position of a string")
-    {
-        // string lengths around the width of the vector steps, in a string value, a key, and a value near the end of the text
-        for (const char* const special :
-                {
-                    "\xC3\xA9", "\xE4\xB8\xAD", "\xF0\x9F\x98\x80", "\x7F", "\\n", "\\u0001", "\\\"", "\\\\"
-                })
-        {
-            for (std::size_t length = 0; length <= 40; ++length)
-            {
-                for (std::size_t position = 0; position <= length; ++position)
-                {
-                    std::string content(length, 'a');
-                    content.insert(position, special);
-                    const std::array<std::string, 3> texts =
-                    {
-                        {
-                            "\"" + content + "\"",
-                            "[\"" + content + "\"]",
-                            "{\"" + content + "\":1}",
-                        }
-                    };
-                    for (const std::string& text : texts)
-                    {
-                        CAPTURE(text)
-                        const ordered_json_document d = ordered_json_document::parse(text);
-                        const ordered_json j = ordered_json::parse(text);
-                        CHECK(d.root().dump(-1, ' ', true) == j.dump(-1, ' ', true));
-                        CHECK(d.root().dump(2, ' ', true) == j.dump(2, ' ', true));
-                        CHECK(d.root().dump() == j.dump());
-                    }
-                }
-            }
-        }
-    }
-
-    SECTION("ensure_ascii: every character of the Basic Multilingual Plane and some beyond")
-    {
-        // (the two- and three-byte sequences, including the ranges that need a check: E0, ED, EF BF BF)
-        std::string text = "[";
-        std::size_t in_chunk = 0;
-        const auto append = [&](std::uint32_t cp)
-        {
-            if (cp < 0x80)
-            {
-                if (cp < 0x20 || cp == '"' || cp == '\\')
-                {
-                    return;
-                }
-                text += static_cast<char>(cp);
-            }
-            else if (cp < 0x800)
-            {
-                text += static_cast<char>(0xC0 | (cp >> 6));
-                text += static_cast<char>(0x80 | (cp & 0x3F));
-            }
-            else if (cp < 0x10000)
-            {
-                text += static_cast<char>(0xE0 | (cp >> 12));
-                text += static_cast<char>(0x80 | ((cp >> 6) & 0x3F));
-                text += static_cast<char>(0x80 | (cp & 0x3F));
-            }
-            else
-            {
-                text += static_cast<char>(0xF0 | (cp >> 18));
-                text += static_cast<char>(0x80 | ((cp >> 12) & 0x3F));
-                text += static_cast<char>(0x80 | ((cp >> 6) & 0x3F));
-                text += static_cast<char>(0x80 | (cp & 0x3F));
-            }
-        };
-        for (std::uint32_t cp = 0x20; cp < 0x10400; ++cp)
-        {
-            if (cp >= 0xD800 && cp < 0xE000)
-            {
-                continue;
-            }
-            if (in_chunk == 0)
-            {
-                text += text.size() > 1 ? ",\"" : "\"";
-            }
-            append(cp);
-            if (++in_chunk == 37)
-            {
-                text += "\"";
-                in_chunk = 0;
-            }
-        }
-        text += in_chunk != 0 ? "\"]" : "]";
-        const ordered_json_document d = ordered_json_document::parse(text);
-        const ordered_json j = ordered_json::parse(text);
-        CHECK(d.root().dump(-1, ' ', true) == j.dump(-1, ' ', true));
-        CHECK(d.root().dump(2, ' ', true) == j.dump(2, ' ', true));
-        CHECK(d.root().dump() == j.dump());
-        CHECK(d.root().dump(2) == j.dump(2));
-    }
-
-    SECTION("deep nesting, indented")
-    {
-        // indentations of up to and beyond the width of the writer's fixed-size copy
-        for (const int depth :
-                {
-                    1, 5, 20, 70, 300
-                })
-        {
-            std::string text;
-            for (int i = 0; i < depth; ++i)
-            {
-                text += i % 2 == 0 ? "[1," : R"({"k":2,"\u00e9":)";
-            }
-            text += "[]";
-            for (int i = depth - 1; i >= 0; --i)
-            {
-                text += i % 2 == 0 ? "]" : "}";
-            }
-            const ordered_json_document d = ordered_json_document::parse(text);
-            const ordered_json j = ordered_json::parse(text);
-            for (const int indent :
-                    {
-                        0, 1, 2, 3, 8
-                    })
-            {
-                CHECK(d.root().dump(indent) == j.dump(indent));
-                CHECK(d.root().dump(indent, '\t') == j.dump(indent, '\t'));
-            }
-        }
-    }
-
-    SECTION("the output buffer of a small value is small")
-    {
-        // an escaped key after the value: its node lies in the arena, so the
-        // source extent of the value cannot be read from the next node
-        const std::string big(100000, 'a');
-        const std::string text = R"({"small":1,"list":[1,2,3],"k\n":")" + big + R"("})";
-        const json_document d = json_document::parse(text);
-        const auto small = d.root()["small"].dump();
-        CHECK(small == "1");
-        CHECK(small.capacity() < 4096);
-        const auto list = d.root()["list"].dump();
-        CHECK(list == "[1,2,3]");
-        CHECK(list.capacity() < 4096);
-        CHECK(d.root()["list"].dump(2).capacity() < 4096);
-
-        // the whole document and the large value are unaffected
-        CHECK(d.root().dump() == ordered_json::parse(text).dump());
-        CHECK(d.root()["k\n"].dump() == "\"" + big + "\"");
-    }
-
-    SECTION("output that outgrows the estimate")
-    {
-        // ensure_ascii writes six bytes for each two-byte character
-        std::string chars;
-        for (int i = 0; i < 5000; ++i)
-        {
-            chars += "\xC3\xA9";
-        }
-        const json_document d = json_document::parse(R"({"a":")" + chars + R"(","k\n":1})");
-        const json expected = json::parse("\"" + chars + "\"");
-        CHECK(d.root()["a"].dump(-1, ' ', true) == expected.dump(-1, ' ', true));
-        CHECK(d.root()["a"].dump(-1, ' ', true).size() == 2 + (5000 * 6));
-    }
-
-    SECTION("ensure_ascii with strings of the source, decoded strings, and edited strings")
-    {
-        // plain ASCII, non-ASCII, escaped (decoded), and mixed strings, as values and as keys;
-        // the second text has a DEL, which ensure_ascii writes as an escape
-        for (const char* const del :
-                {"", "\x7F"
-                })
-        {
-            const std::string text = std::string("{\"plain\":\"abc\",\"caf\xC3\xA9\":\"\xC3\xA9\xE2\x82\xAC\xF0\x9F\x98\x80\",")
-                                     + "\"esc\\n\\\"\":\"a\\tb\\u00e4\\ud83d\\ude00\",\"del\":\"a" + del + "b\",\"\":\"\"," // NOLINT(modernize-raw-string-literal)
-                                     + "\"list\":[\"x\",\"\xC3\xBC\",\"\\\\\",\"long ASCII string with more than thirty-two bytes in it\","
-                                     + "\"long string with more than thirty-two bytes and one non-ASCII byte \xC3\xB6\"],"
-                                     + "\"n\":[1,2.5,-0,true,null]}";
-            const ordered_json j = ordered_json::parse(text);
-            const ordered_json_document d = ordered_json_document::parse(text);
-            CHECK(d.root().dump(-1, ' ', true) == j.dump(-1, ' ', true));
-            CHECK(d.root().dump(4, ' ', true) == j.dump(4, ' ', true));
-            CHECK(d.root().dump() == j.dump());
-            CHECK(d.root()["list"].dump(-1, ' ', true) == j["list"].dump(-1, ' ', true));
-            CHECK(d.root()["del"].dump(-1, ' ', true) == j["del"].dump(-1, ' ', true));
-
-            // strings that an edit wrote (the source strings that they replace were plain)
-            ordered_json_editable_document e = ordered_json_editable_document::parse(text);
-            ordered_json k = j;
-            e.set(e.root()["plain"], std::string("\xC3\xA4gypten"));
-            k["plain"] = "\xC3\xA4gypten";
-            e.set(e.root()["list"][0], std::string("ascii after edit"));
-            k["list"][0] = "ascii after edit";
-            e.set(e.root()["list"][1], std::string("\xC3\xA4"));
-            k["list"][1] = "\xC3\xA4";
-            e.set(e.root()["del"], std::string("tab\there"));
-            k["del"] = "tab\there";
-            CHECK(e.root().dump(-1, ' ', true) == k.dump(-1, ' ', true));
-            CHECK(e.root().dump(2, ' ', true) == k.dump(2, ' ', true));
-            CHECK(e.root().dump() == k.dump());
-
-            // strings that were edited from or to ASCII text
-            e.set(e.root()["list"][2], std::string("\xC3\xA4"));
-            k["list"][2] = "\xC3\xA4";
-            e.set(e.root()["list"][4], std::string("plain again"));
-            k["list"][4] = "plain again";
-            CHECK(e.root().dump(-1, ' ', true) == k.dump(-1, ' ', true));
-        }
-    }
-
-    SECTION("ensure_ascii with DEL or a non-ASCII character at every position")
-    {
-        // the check whether a string of the source has no byte >= 0x7F reads
-        // eight bytes at a time and then the rest one by one
-        for (std::size_t length = 1; length <= 20; ++length)
-        {
-            for (std::size_t pos = 0; pos < length; ++pos)
-            {
-                for (const char* const c :
-                        {
-                            "\x7F", "\x7E", "\xC3\xA4", "\xC3\xBF" // NOLINT(modernize-raw-string-literal)
-                        })
-                {
-                    const std::string s = std::string(pos, 'a') + c + std::string(length - pos - 1, 'b');
-                    std::string text = "[\"";
-                    text.append(s).append("\",{\"").append(s).append("\":1}]");
-                    const json_document d = json_document::parse(text);
-                    const json j = json::parse(text);
-                    CHECK(d.root().dump(-1, ' ', true) == j.dump(-1, ' ', true));
-                    CHECK(d.root().dump(1, ' ', true) == j.dump(1, ' ', true));
-                }
-            }
-        }
-    }
-
-    SECTION("streams and discarded views")
-    {
-        const json_document d = json_document::parse(R"({"a": [1, 2]})");
-        std::ostringstream compact;
-        compact << d.root();
-        CHECK(compact.str() == R"({"a":[1,2]})");
-        std::ostringstream pretty;
-        pretty << std::setw(2) << std::setfill('.') << d.root() << d.root()["a"];
-        CHECK(pretty.str() == "{\n..\"a\": [\n....1,\n....2\n..]\n}[1,2]");
-        CHECK(json_view().dump() == json(json::value_t::discarded).dump());
-    }
-}

tests/src/unit-json_view_edit_values.cpp

@@ -26,12 +26,79 @@ using nlohmann::json_editable_view;
 #include <limits>
 #include <map>
 #include <string>
+#include <type_traits>
 #include <utility>
 #include <vector>
 
 // These tests were split off unit-json_view_edit.cpp, whose object file got too
 // large for the MinGW linker (see json_view_test_helpers.hpp).
 
+namespace
+{
+// the three ways a function can accept views: editable ones, read-only ones, or both
+template<typename BasicJsonType>
+int accepts_editable(nlohmann::basic_json_view<BasicJsonType, nlohmann::view_mode::editable> /*unused*/)
+{
+    return 1;
+}
+
+template<typename BasicJsonType>
+int accepts_read_only(nlohmann::basic_json_view<BasicJsonType, nlohmann::view_mode::read_only> /*unused*/)
+{
+    return 2;
+}
+
+template<typename BasicJsonType, nlohmann::view_mode Mode>
+int accepts_any(nlohmann::basic_json_view<BasicJsonType, Mode> /*unused*/)
+{
+    return Mode == nlohmann::view_mode::editable ? 3 : 4;
+}
+
+template<typename View>
+auto overload(View v) -> decltype(accepts_editable(v))
+{
+    return accepts_editable(v);
+}
+
+template<typename View>
+auto overload(View v) -> decltype(accepts_read_only(v))
+{
+    return accepts_read_only(v);
+}
+} // namespace
+
+TEST_CASE("json_view modes")
+{
+    using nlohmann::basic_json_document;
+    using nlohmann::basic_json_view;
+    using nlohmann::ordered_json;
+    using nlohmann::view_mode;
+
+    SECTION("read-only is the default, and the shortcuts name the modes")
+    {
+        static_assert(std::is_same<basic_json_view<json>, basic_json_view<json, view_mode::read_only>>::value, "default mode");
+        static_assert(std::is_same<basic_json_document<json>, basic_json_document<json, view_mode::read_only>>::value, "default mode");
+        static_assert(std::is_same<nlohmann::json_view, basic_json_view<json, view_mode::read_only>>::value, "json_view");
+        static_assert(std::is_same<json_editable_view, basic_json_view<json, view_mode::editable>>::value, "json_editable_view");
+        static_assert(std::is_same<json_editable_document, basic_json_document<json, view_mode::editable>>::value, "json_editable_document");
+        static_assert(std::is_same<nlohmann::ordered_json_editable_view, basic_json_view<ordered_json, view_mode::editable>>::value, "ordered_json_editable_view");
+        static_assert(std::is_same<json_editable_document::view_type, json_editable_view>::value, "view_type");
+        static_assert(std::is_same<json_document::view_type, nlohmann::json_view>::value, "view_type");
+    }
+
+    SECTION("a function template selects views by their mode")
+    {
+        const json_document d = json_document::parse("[1]");
+        const json_editable_document e = json_editable_document::parse("[1]");
+        const nlohmann::ordered_json_editable_document o = nlohmann::ordered_json_editable_document::parse("[1]");
+        CHECK(overload(e.root()) == 1);
+        CHECK(overload(o.root()) == 1);
+        CHECK(overload(d.root()) == 2);
+        CHECK(accepts_any(e.root()) == 3);
+        CHECK(accepts_any(d.root()) == 4);
+    }
+}
+
 TEST_CASE("json_view edits: views and values")
 {
     SECTION("a value that is no longer part of the document")
@@ -100,7 +167,7 @@ TEST_CASE("json_view edits: views and values")
         // doubles have their own path to the output; other float types are
         // written as basic_json writes them, non-finite values as null
         using json_float = nlohmann::basic_json<std::map, std::vector, std::string, bool, std::int64_t, std::uint64_t, float>;
-        using document_float = nlohmann::basic_json_document<json_float, true>;
+        using document_float = nlohmann::basic_json_document<json_float, nlohmann::view_mode::editable>;
         document_float d = document_float::parse("[1.5]");
         d.push_back(d.root(), std::numeric_limits<float>::quiet_NaN());
         d.push_back(d.root(), -std::numeric_limits<float>::infinity());

tests/src/unit-json_view_image.cpp

@@ -28,11 +28,25 @@ using nlohmann::detail::view::node;
 #include <random>
 #include <sstream>
 #include <string>
+#include <type_traits>
 #include <utility>
 #include <vector>
 
 #include <test_data.hpp>
 
+namespace json_view_image_test
+{
+// whether a document type has save() and load() (only on little-endian targets)
+template<typename T, typename = void>
+struct has_save : std::false_type {};
+template<typename T>
+struct has_save<T, decltype(static_cast<void>(std::declval<const T&>().save()))> : std::true_type {};
+template<typename T, typename = void>
+struct has_load : std::false_type {};
+template<typename T>
+struct has_load<T, decltype(static_cast<void>(T::load(std::declval<const std::vector<std::uint8_t>&>())))> : std::true_type {};
+} // namespace json_view_image_test
+
 #if !(defined(__BYTE_ORDER__) && defined(__ORDER_BIG_ENDIAN__) && __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)
 
 namespace
@@ -171,6 +185,9 @@ std::uint32_t rng()
 
 TEST_CASE("json_view images: round trips")
 {
+    static_assert(json_view_image_test::has_save<json_document>::value && json_view_image_test::has_load<json_document>::value, "save() and load() on a little-endian target");
+    static_assert(json_view_image_test::has_save<ordered_json_editable_document>::value && json_view_image_test::has_load<ordered_json_editable_document>::value, "save() and load() on a little-endian target");
+
     SECTION("small documents")
     {
         for (const char* text :
@@ -480,7 +497,7 @@ TEST_CASE("json_view images: edited documents")
             {
                 CAPTURE(i)
                 CHECK((node_at(image, i).flags & nlohmann::detail::view::node_flags::linked) == 0);
-                CHECK(node_at(image, i).kind != nlohmann::detail::view::kind_link);
+                CHECK((node_at(image, i).kind != nlohmann::detail::view::node_kind::link));
             }
             for (const image_check check :
                     {
@@ -810,13 +827,13 @@ TEST_CASE("json_view images: check")
         {
             rejected(corrupted(image, 12, [&](node & n)
             {
-                n.kind = kind;
+                n.kind = static_cast<nlohmann::detail::view::node_kind>(kind);
             }), true);
         }
         // a key that is not a string
         rejected(corrupted(image, 1, [](node & n)
         {
-            n.kind = 0;
+            n.kind = nlohmann::detail::view::node_kind::null;
             n.len = 0;
             n.off = 0;
         }), true);
@@ -960,11 +977,11 @@ TEST_CASE("json_view images: check")
         }), true);
         rejected(corrupted(image, 0, [](node & n)
         {
-            n.kind = 2; // an array: the "keys" are values, and the counts do not match
+            n.kind = nlohmann::detail::view::node_kind::array; // an array: the "keys" are values, and the counts do not match
         }), true);
         const std::vector<std::uint8_t> as_array = corrupted(image, 16, [](node & n)
         {
-            n.kind = 2; // {} as []: fine
+            n.kind = nlohmann::detail::view::node_kind::array; // {} as []: fine
         });
         CHECK(load_result(as_array, image_check::full).empty());
         const std::string expected_dump = R"({"s":"x\"y","i":-12,"u":7,"f":1.5e+300,"b":true,"n":null,"a":["t",[]]})";
@@ -1013,13 +1030,13 @@ TEST_CASE("json_view images: check")
         rejected(at_token(u6, 0, '8'), false);      // 8 != 7
         rejected(corrupted(image, 4, [](node & n)
         {
-            n.kind = 6; // "-12" as unsigned: a sign
+            n.kind = nlohmann::detail::view::node_kind::number_unsigned; // "-12" as unsigned: a sign
             n.extra = 3;
         }), false);
         // a non-negative number_integer (as edits write it): fine
         const std::vector<std::uint8_t> positive = corrupted(image, 6, [](node & n)
         {
-            n.kind = 5;
+            n.kind = nlohmann::detail::view::node_kind::number_integer;
             n.extra = 0;
         });
         CHECK(load_result(positive, image_check::full).empty());
@@ -1027,7 +1044,7 @@ TEST_CASE("json_view images: check")
         CHECK(pos.root()["u"].is_number_integer());
         rejected(corrupted(image, 8, [](node & n)
         {
-            n.kind = 6; // a float token as integer
+            n.kind = nlohmann::detail::view::node_kind::number_unsigned; // a float token as integer
             n.extra = 7;
         }), false);
     }
@@ -1197,7 +1214,7 @@ TEST_CASE("json_view images: check")
         {
             std::vector<std::uint8_t> b = img;
             node n = node_at(b, i);
-            n.kind = kind;
+            n.kind = static_cast<nlohmann::detail::view::node_kind>(kind);
             n.extra = extra;
             set_node(b, i, n);
             return load_result(b, image_check::full);
@@ -1275,8 +1292,12 @@ TEST_CASE("json_view images: damaged images")
 
 TEST_CASE("json_view images: big-endian targets")
 {
+    // the image format is little-endian: save() and load() do not exist here
+    static_assert(!json_view_image_test::has_save<json_document>::value, "no save() on a big-endian target");
+    static_assert(!json_view_image_test::has_load<json_document>::value, "no load() on a big-endian target");
+    static_assert(!json_view_image_test::has_save<json_editable_document>::value, "no save() on a big-endian target");
     const json_document d = json_document::parse("[1]");
-    CHECK_THROWS_WITH_AS(d.save(), "[json.exception.type_error.320] json_document images need a little-endian target", json::type_error&);
+    CHECK(d.root().size() == 1);
 }
 
 #endif

tests/src/unit-json_view_large.cpp

@@ -1,545 +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
-
-#include "doctest_compatibility.h"
-
-#include <nlohmann/json_view.hpp>
-using nlohmann::json;
-using nlohmann::ordered_json;
-using nlohmann::json_document;
-using nlohmann::ordered_json_editable_document;
-using nlohmann::json_view;
-using nlohmann::ordered_json_document;
-using nlohmann::ordered_json_view;
-
-#include "json_view_test_helpers.hpp"
-using json_view_test::generator;
-using json_view_test::has_duplicate_keys;
-
-#include <algorithm>
-#include <array>
-#include <cmath>
-#include <cstddef>
-#include <cstdint>
-#include <cstring>
-#include <iomanip>
-#include <map>
-#include <random>
-#include <set>
-#include <sstream>
-#include <string>
-#include <vector>
-
-// These tests were split off unit-json_view_dump.cpp, whose object file got too large for the MinGW
-// linker (see json_view_test_helpers.hpp). Like that file, this one is also built
-// with C++17, as it mentions JSON_HAS_CPP_17.
-
-TEST_CASE("json_view comparison")
-{
-    SECTION("equality of the values parse() produces")
-    {
-        generator g;
-        std::vector<std::string> texts;
-        for (int i = 0; i < 600; ++i)
-        {
-            std::string text;
-            g.value(text, 0);
-            texts.push_back(text);
-            // the same value written differently: sorted keys, canonical numbers
-            texts.push_back(json::parse(text).dump(1));
-        }
-        for (std::size_t i = 0; i + 2 < texts.size(); ++i)
-        {
-            for (std::size_t k = i; k < i + 3; ++k)
-            {
-                CAPTURE(texts[i])
-                CAPTURE(texts[k])
-                const json_document a = json_document::parse(texts[i]);
-                const json_document b = json_document::parse(texts[k]);
-                const json ja = json::parse(texts[i]);
-                const json jb = json::parse(texts[k]);
-                CHECK((a.root() == b.root()) == (ja == jb));
-                CHECK((a.root() != b.root()) == (ja != jb));
-                CHECK((a.root() == jb) == (ja == jb));
-                CHECK((jb == a.root()) == (ja == jb));
-                CHECK((a.root() != jb) == (ja != jb));
-                CHECK((jb != a.root()) == (ja != jb));
-
-                // ordered_json compares members in order
-                const ordered_json_document oa = ordered_json_document::parse(texts[i]);
-                const ordered_json_document ob = ordered_json_document::parse(texts[k]);
-                const ordered_json oja = ordered_json::parse(texts[i]);
-                const ordered_json ojb = ordered_json::parse(texts[k]);
-                CHECK((oa.root() == ob.root()) == (oja == ojb));
-                CHECK((oa.root() == ojb) == (oja == ojb));
-            }
-        }
-    }
-
-    SECTION("numbers, duplicate keys, member order")
-    {
-        const auto same = [](const char* x, const char* y)
-        {
-            const json_document dx = json_document::parse(x);
-            const json_document dy = json_document::parse(y);
-            return dx.root() == dy.root();
-        };
-        CHECK(same("1", "1.0"));
-        CHECK(same("[1, -1, 2.5]", "[1.0, -1.0, 25e-1]"));
-        CHECK(!same("1", "1.5"));
-        CHECK(same("18446744073709551615", "18446744073709551615"));
-        CHECK(same(R"({"a": 1, "a": 2})", R"({"a": 2})"));
-        CHECK(!same(R"({"a": 1, "a": 2})", R"({"a": 1})"));
-        CHECK(same(R"({"a": 1, "b": 2})", R"({"b": 2, "a": 1})"));
-        CHECK(!same(R"({"a": 1})", R"({"a": 1, "b": 2})"));
-        CHECK(!same("[1, 2]", "[2, 1]"));
-        CHECK(!same("\"a\"", "\"b\""));
-        CHECK(same("\"\\u00e9\"", "\"\xc3\xa9\""));
-        CHECK(!same("null", "false"));
-        CHECK(!same("[]", "{}"));
-        const ordered_json_document dup = ordered_json_document::parse(R"({"a": 1, "b": 2, "a": 3})");
-        const ordered_json_document last = ordered_json_document::parse(R"({"a": 3, "b": 2})");
-        CHECK(dup.root() == last.root());
-        // (== compares as parse() resolves duplicates, a lookup finds the first)
-        CHECK(dup.root()["a"].materialize() == 1);
-        CHECK(dup.root()["a"] != last.root()["a"]);
-        const ordered_json_document ab = ordered_json_document::parse(R"({"a": 1, "b": 2})");
-        const ordered_json_document ba = ordered_json_document::parse(R"({"b": 2, "a": 1})");
-        CHECK(ab.root() != ba.root());
-
-        // discarded values compare as basic_json's do
-        const json discarded(json::value_t::discarded);
-        CHECK((json_view() == json_view()) == (discarded == discarded)); // NOLINT(readability-container-size-empty): operator== is tested
-        CHECK((json_view() == discarded) == (discarded == discarded)); // NOLINT(readability-container-size-empty)
-        const json_document null_document = json_document::parse("null");
-        CHECK(!(json_view() == null_document.root())); // NOLINT(readability-container-size-empty)
-        CHECK(!(null_document.root() == discarded));
-    }
-
-    SECTION("deep nesting")
-    {
-        const std::string deep = std::string(100000, '[') + std::string(100000, ']');
-        const json_document a = json_document::parse(deep);
-        const json_document b = json_document::parse(deep);
-        CHECK(a.root() == b.root());
-        CHECK(a.root() == json::parse(deep));
-        const std::string other = std::string(100000, '[') + "1" + std::string(100000, ']');
-        const json_document c = json_document::parse(other);
-        CHECK(a.root() != c.root());
-    }
-}
-
-TEST_CASE("json_view large objects")
-{
-    // objects with 128 members or more are looked up with a hash index
-    for (const std::size_t members :
-            {
-                127u, 128u, 129u, 10000u
-            })
-    {
-        CAPTURE(members)
-        std::string text = "{";
-        for (std::size_t i = 0; i < members; ++i)
-        {
-            text += (i != 0 ? ",\"" : "\"") + std::string(i % 23, 'k') + std::to_string(i) + (i % 7 == 0 ? "\\n" : "") + "\":" + std::to_string(i);
-        }
-        text += R"(,"":"empty key","k1":"a duplicate of an earlier key"})";
-        const json_document d = json_document::parse(text);
-        const json_view v = d.root();
-        const json j = json::parse(text);
-        for (std::size_t i = 0; i < members; ++i)
-        {
-            const std::string key = std::string(i % 23, 'k') + std::to_string(i) + (i % 7 == 0 ? "\n" : "");
-            CHECK(v[key].get<std::size_t>() == i);
-            CHECK(v.contains(key));
-            CHECK(v.find(key).key() == key);
-            CHECK(v.at(key).get<std::size_t>() == i);
-            CHECK(!v.contains(key + "x"));
-        }
-        CHECK(v[""].get_string() == "empty key");
-        CHECK(v["k1"].get<int>() == 1); // the first of duplicate keys, as for small objects
-        CHECK(!v.contains("missing"));
-        CHECK_THROWS_WITH_AS(v.at("missing"), "[json.exception.out_of_range.403] key 'missing' not found", json::out_of_range&);
-        CHECK(v == j);
-        CHECK(v.materialize() == j);
-    }
-
-    SECTION("duplicate keys: the first member wins, with and without a table")
-    {
-        // an object of `total` members: the keys "k0".."k<n-1>" in order, then
-        // three keys repeated twice more (one copy in the middle, one at the
-        // end), and two keys repeated once; the value of a member is its
-        // position, so that the first member of a key can be told apart
-        struct member
-        {
-            std::string key;
-            std::size_t position;
-        };
-        const auto make_members = [](std::size_t total)
-        {
-            std::vector<std::string> keys;
-            for (std::size_t i = 0; i + 8 < total; ++i)
-            {
-                keys.push_back("k" + std::to_string(i));
-            }
-            const std::size_t n = keys.size();
-            const std::array<std::size_t, 3> triple = {{3, 17, n - 1}};
-            const std::array<std::size_t, 2> twice = {{5, n / 2}};
-            std::vector<std::string> ordered = keys;
-            for (const std::size_t i : triple)
-            {
-                ordered.insert(ordered.begin() + static_cast<std::ptrdiff_t>(ordered.size() / 2), keys[i]);
-            }
-            for (const std::size_t i : twice)
-            {
-                ordered.insert(ordered.begin() + static_cast<std::ptrdiff_t>(ordered.size() / 3), keys[i]);
-            }
-            for (const std::size_t i : triple)
-            {
-                ordered.push_back(keys[i]);
-            }
-            std::vector<member> result;
-            result.reserve(ordered.size());
-            for (std::size_t i = 0; i < ordered.size(); ++i)
-            {
-                result.push_back({ordered[i], i});
-            }
-            return result;
-        };
-
-        // 100 and 127 members: no table; 128 members and more: a table
-        for (const std::size_t total :
-                {
-                    100u, 127u, 128u, 200u, 5000u
-                })
-        {
-            CAPTURE(total)
-            const std::vector<member> members = make_members(total);
-            REQUIRE(members.size() >= total);
-            REQUIRE(members.size() >= 100);
-            std::string text = "{";
-            std::map<std::string, std::size_t> first;
-            std::map<std::string, std::size_t> last;
-            std::map<std::string, std::size_t> occurrences;
-            for (const member& m : members)
-            {
-                text += (text.size() > 1 ? ",\"" : "\"") + m.key + "\":" + std::to_string(m.position);
-                first.insert({m.key, m.position});
-                last[m.key] = m.position;
-                ++occurrences[m.key];
-            }
-            text += '}';
-            REQUIRE(first.size() < members.size());
-
-            const json_document d = json_document::parse(text);
-            const json_view v = d.root();
-            const json j = json::parse(text);
-            CHECK(v.size() == members.size()); // every occurrence is visited
-            const json m = v.materialize();
-            for (const auto& entry : first)
-            {
-                CAPTURE(entry.first)
-                const std::size_t expected = entry.second;
-                CHECK(v[entry.first].get<std::size_t>() == expected);
-                CHECK(v.at(entry.first).get<std::size_t>() == expected);
-                CHECK(v.find(entry.first).value().get<std::size_t>() == expected);
-                CHECK(v.value(entry.first, std::size_t{0}) == expected);
-                CHECK(v.contains(entry.first));
-                CHECK(v.count(entry.first) == occurrences[entry.first]);
-                const std::string pointer = "/" + entry.first;
-                CHECK(v[json::json_pointer(pointer)].get<std::size_t>() == expected);
-                CHECK(v.at(json::json_pointer(pointer)).get<std::size_t>() == expected);
-                CHECK(v.value(json::json_pointer(pointer), std::size_t{0}) == expected);
-                CHECK(v.contains(json::json_pointer(pointer)));
-                // materialize() and parse() keep the last value instead
-                CHECK(j[entry.first].get<std::size_t>() == last.at(entry.first));
-                CHECK(m[entry.first].get<std::size_t>() == last.at(entry.first));
-            }
-            CHECK(!v.contains("k"));
-            CHECK(v["missing"].is_discarded());
-            CHECK(v.materialize() == j);
-            CHECK(v == j);
-        }
-    }
-
-    SECTION("colliding keys")
-    {
-        // the hash is not seeded, so keys that all land in one place must not
-        // make the table build quadratic: such an object gets no table and is
-        // searched linearly
-        constexpr std::size_t members = 300;
-        constexpr std::size_t table_size = 1024; // the table size for 300 members: the next power of two >= 600
-        std::vector<std::string> colliding;
-        std::vector<std::string> spread;
-        for (std::uint64_t counter = 0; colliding.size() < members || spread.size() < members; ++counter)
-        {
-            std::string key(8, 'a');
-            std::uint64_t x = counter;
-            for (std::size_t i = 0; i < 8; ++i, x /= 26)
-            {
-                key[i] = static_cast<char>('a' + (x % 26));
-            }
-            const bool lands_in_slot_zero = (nlohmann::detail::view::key_hash(key.data(), key.size()) & (table_size - 1)) == 0;
-            if (lands_in_slot_zero && colliding.size() < members)
-            {
-                colliding.push_back(key);
-            }
-            else if (!lands_in_slot_zero && spread.size() < members)
-            {
-                spread.push_back(key);
-            }
-        }
-
-        const auto make_text = [](const std::vector<std::string>& keys)
-        {
-            std::string text = "{";
-            for (std::size_t i = 0; i < keys.size(); ++i)
-            {
-                text += (i != 0 ? ",\"" : "\"") + keys[i] + "\":" + std::to_string(i % 10);
-            }
-            return text + "}";
-        };
-        const std::string colliding_text = make_text(colliding);
-        const std::string spread_text = make_text(spread);
-
-        json_document with_collisions = json_document::parse(colliding_text);
-        json_document without_collisions = json_document::parse(spread_text);
-        for (const auto* pair :
-                {
-                    &colliding, &spread
-                })
-        {
-            const json_view v = (pair == &colliding ? with_collisions : without_collisions).root();
-            for (std::size_t i = 0; i < members; ++i)
-            {
-                CAPTURE(i)
-                CHECK(v[(*pair)[i]].get<std::size_t>() == i % 10);
-                CHECK(v.at((*pair)[i]).get<std::size_t>() == i % 10);
-                CHECK(v.find((*pair)[i]).key() == (*pair)[i]);
-                CHECK(!v.contains((*pair)[i] + "x"));
-            }
-            CHECK(!v.contains("missing"));
-        }
-        CHECK(with_collisions.root() == json::parse(colliding_text));
-
-        // only the object with the spread keys got a table (both texts have the
-        // same length, so the tables are the only difference)
-        with_collisions.shrink_to_fit();
-        without_collisions.shrink_to_fit();
-        CHECK(without_collisions.memory_usage() >= with_collisions.memory_usage() + (table_size * sizeof(std::uint32_t)));
-    }
-
-    SECTION("keys that differ in their last bytes are spread over the table")
-    {
-        // The hash must spread the usual families of keys (numbered names, hex
-        // strings, dates, short names): a key farther than index_max_displacement
-        // from its home slot would leave the object without a table. The keys
-        // are placed with linear probing, as the table does.
-        const auto max_displacement = [](const std::vector<std::string>& keys)
-        {
-            std::size_t slots = 16;
-            while (slots < 2 * keys.size())
-            {
-                slots *= 2;
-            }
-            std::vector<bool> used(slots, false);
-            std::size_t farthest = 0;
-            for (const std::string& key : keys)
-            {
-                std::size_t i = nlohmann::detail::conditional_static_cast<std::size_t>(nlohmann::detail::view::key_hash(key.data(), key.size())) & (slots - 1);
-                std::size_t distance = 0;
-                while (used[i])
-                {
-                    i = (i + 1) & (slots - 1);
-                    ++distance;
-                }
-                used[i] = true;
-                farthest = (std::max)(farthest, distance);
-            }
-            return farthest;
-        };
-        // the keys of a printf-like pattern with one %d, %0Nd or %0Nx, formatted with a stream
-        // (a format string that is not a literal is a Flawfinder error)
-        const auto numbered = [](const char* format, int count, int step)
-        {
-            const std::string pattern(format);
-            const std::size_t percent = pattern.find('%');
-            std::size_t conversion = percent + 1;
-            std::size_t width = 0;
-            while (pattern[conversion] >= '0' && pattern[conversion] <= '9')
-            {
-                width = (width * 10) + static_cast<std::size_t>(pattern[conversion] - '0');
-                ++conversion;
-            }
-            const bool hex = pattern[conversion] == 'x';
-            std::vector<std::string> keys;
-            for (int i = 0; i < count; ++i)
-            {
-                std::ostringstream key;
-                key << pattern.substr(0, percent) << std::setfill('0') << std::setw(static_cast<int>(width))
-                    << (hex ? std::hex : std::dec) << (i * step) << pattern.substr(conversion + 1);
-                keys.push_back(key.str());
-            }
-            return keys;
-        };
-        for (const char* format :
-                {"key%d", "%d", "item_%04d", "a%05d", "%03dxyz", "id%d", "user_%d", "%d_suffix", "0x%04x", "A%07d", "12345678%d", "1234567%d", "123456789%d",
-                 "configuration_parameter_value_%04d_extra", "2026-01-%02dT00:00:00Z"
-                })
-        {
-            CAPTURE(format)
-            CHECK(max_displacement(numbered(format, std::string(format).find("%02d") != std::string::npos ? 60 : 1000, 1)) < nlohmann::detail::view::index_max_displacement); // NOLINT(abseil-string-find-str-contains)
-            CHECK(max_displacement(numbered(format, 600, 7)) < nlohmann::detail::view::index_max_displacement);
-        }
-        std::mt19937_64 rng(7); // NOLINT(cert-msc32-c,cert-msc51-cpp,bugprone-random-generator-seed)
-        for (const std::size_t length :
-                {
-                    std::size_t{1}, std::size_t{2}, std::size_t{3}, std::size_t{5}, std::size_t{7}, std::size_t{8}, std::size_t{9}, std::size_t{12}, std::size_t{16}, std::size_t{17}, std::size_t{33}
-                })
-        {
-            CAPTURE(length)
-            std::set<std::string> distinct;
-            // (there are 26 and 676 keys of one and two letters)
-            std::size_t wanted = 700;
-            if (length == 1)
-            {
-                wanted = 26;
-            }
-            else if (length == 2)
-            {
-                wanted = 500;
-            }
-            while (distinct.size() < wanted)
-            {
-                std::string key(length, 'a');
-                for (char& c : key)
-                {
-                    c = static_cast<char>('a' + (rng() % 26));
-                }
-                distinct.insert(key);
-            }
-            CHECK(max_displacement(std::vector<std::string>(distinct.begin(), distinct.end())) < nlohmann::detail::view::index_max_displacement);
-        }
-    }
-
-    SECTION("keys of every length that differ in one byte")
-    {
-        // In a large object, a key is found by comparing its bytes with those of the member the
-        // table points to: up to 16 bytes as two overlapping words, longer ones with memcmp.
-        // Keys of every length from 0 to 40, and keys that differ from them in one byte.
-        std::mt19937_64 rng(2026); // NOLINT(cert-msc32-c,cert-msc51-cpp,bugprone-random-generator-seed)
-        std::vector<std::string> keys;
-        std::set<std::string> distinct;
-        for (std::size_t length = 0; length <= 40; ++length)
-        {
-            for (int copy = 0; copy < 5; ++copy)
-            {
-                std::string key(length, 'a');
-                for (char& c : key)
-                {
-                    c = static_cast<char>('a' + (rng() % 26));
-                }
-                if (distinct.insert(key).second)
-                {
-                    keys.push_back(key);
-                }
-            }
-        }
-        std::string text = "{";
-        for (std::size_t i = 0; i < keys.size(); ++i)
-        {
-            text += (i != 0 ? ",\"" : "\"") + keys[i] + "\":" + std::to_string(i);
-        }
-        text += "}";
-        REQUIRE(keys.size() >= 128); // (a table is built for 128 members)
-        const json_document d = json_document::parse(text);
-        const json_view v = d.root();
-        for (std::size_t i = 0; i < keys.size(); ++i)
-        {
-            CAPTURE(keys[i])
-            CHECK(v[keys[i]].get<std::size_t>() == i);
-            CHECK(v.at(keys[i]).get<std::size_t>() == i);
-            CHECK(v.contains(keys[i]));
-            for (std::size_t at = 0; at < keys[i].size(); ++at)
-            {
-                std::string other = keys[i];
-                other[at] = other[at] == 'z' ? 'y' : 'z';
-                CAPTURE(other)
-                CHECK(v.contains(other) == (distinct.count(other) != 0));
-            }
-            CHECK(v.contains(keys[i] + "a") == (distinct.count(keys[i] + "a") != 0));
-            if (!keys[i].empty())
-            {
-                CHECK(v.contains(keys[i].substr(1)) == (distinct.count(keys[i].substr(1)) != 0));
-            }
-        }
-    }
-
-    SECTION("shrink_to_fit releases the tables' spare capacity")
-    {
-        const auto make_text = [](int objects, int members)
-        {
-            std::string text = "[";
-            for (int object = 0; object < objects; ++object)
-            {
-                text += object != 0 ? ",{" : "{";
-                for (int i = 0, n = members + object; i < n; ++i)
-                {
-                    text += (i != 0 ? ",\"" : "\"") + std::to_string(i) + "\":" + std::to_string(i);
-                }
-                text += '}';
-            }
-            return text + "]";
-        };
-        const std::string small_text = make_text(5, 150);
-        const std::string big_text = make_text(40, 400);
-
-        // reading a big text, and then a small one, leaves the spare capacity
-        // of the big one: shrink_to_fit() brings the document to the size of
-        // one parsed from the small text alone
-        json_document d = json_document::parse(big_text);
-        const std::size_t big = d.memory_usage();
-        d.read(small_text);
-        CHECK(d.memory_usage() >= big);
-        d.shrink_to_fit();
-        json_document fresh = json_document::parse(small_text);
-        fresh.shrink_to_fit();
-        CHECK(d.memory_usage() == fresh.memory_usage());
-        CHECK(d.memory_usage() < big / 2);
-        CHECK(d.root() == json::parse(small_text));
-        for (int object = 0; object < 5; ++object)
-        {
-            const json_view v = d.root()[static_cast<std::size_t>(object)];
-            for (int i = 0, n = 150 + object; i < n; ++i)
-            {
-                CHECK(v[std::to_string(i)].get<int>() == i);
-            }
-        }
-    }
-
-    SECTION("nested, reused, and in arrays")
-    {
-        std::string inner = "{";
-        for (int i = 0; i < 300; ++i)
-        {
-            inner += (i != 0 ? ",\"m" : "\"m") + std::to_string(i) + "\":" + std::to_string(i);
-        }
-        inner += '}';
-        const std::string text = "[" + inner + ",{\"x\":" + inner + "}," + inner + "]";
-        json_document d = json_document::parse(text);
-        CHECK(d.root()[0]["m299"].get<int>() == 299);
-        CHECK(d.root()[1]["x"]["m150"].get<int>() == 150);
-        CHECK(d.root()[2]["m0"].get<int>() == 0);
-        const std::size_t with_index = d.memory_usage();
-        d.read(std::string("{\"small\": 1}"));
-        CHECK(d.root()["small"].get<int>() == 1);
-        d.read(text);
-        CHECK(d.root()[2]["m7"].get<int>() == 7);
-        CHECK(d.memory_usage() >= with_index / 2);
-    }
-}