Merge branch 'develop' into claude/binary-reader-narrow-numbers

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

docs/mkdocs/docs/api/basic_json/number_float_t.md

@@ -55,6 +55,10 @@ This implementation does exactly follow this approach, as it uses double precisi
 smaller than `-1.79769313486232e+308` and values greater than `1.79769313486232e+308` will be stored as NaN internally
 and be serialized to `null`.
 
+During deserialization (from JSON text or any of the binary formats), a finite number that does not fit into
+`number_float_t` is rejected with [`out_of_range.406`](../../home/exceptions.md#jsonexceptionout_of_range406), for
+example a double-precision number in a binary format when `number_float_t` is `#!cpp float`.
+
 #### Storage
 
 Floating-point number values are stored directly inside a `basic_json` type.

docs/mkdocs/docs/api/basic_json/number_integer_t.md

@@ -47,8 +47,9 @@ With the default values for `NumberIntegerType` (`std::int64_t`), the default va
 
 When the default type is used, the maximal integer number that can be stored is `9223372036854775807` (INT64_MAX) and
 the minimal integer number that can be stored is `-9223372036854775808` (INT64_MIN). Integer numbers that are out of
-range will yield over/underflow when used in a constructor. During deserialization, too large or small integer numbers
-will automatically be stored as [`number_unsigned_t`](number_unsigned_t.md) or [`number_float_t`](number_float_t.md).
+range will yield over/underflow when used in a constructor. During deserialization (from JSON text or any of the binary
+formats), too large or small integer numbers will automatically be stored as [`number_unsigned_t`](number_unsigned_t.md)
+or [`number_float_t`](number_float_t.md).
 
 [RFC 8259](https://tools.ietf.org/html/rfc8259) further states:
 > Note that when such software is used, numbers that are integers and are in the range $[-2^{53}+1, 2^{53}-1]$ are

docs/mkdocs/docs/api/basic_json/number_unsigned_t.md

@@ -48,8 +48,9 @@ With the default values for `NumberUnsignedType` (`std::uint64_t`), the default
 
 When the default type is used, the maximal integer number that can be stored is `18446744073709551615` (UINT64_MAX) and
 the minimal integer number that can be stored is `0`. Integer numbers that are out of range will yield over/underflow
-when used in a constructor. During deserialization, too large or small integer numbers will automatically be stored
-as [`number_integer_t`](number_integer_t.md) or [`number_float_t`](number_float_t.md).
+when used in a constructor. During deserialization (from JSON text or any of the binary formats), too large or small
+integer numbers will automatically be stored as [`number_integer_t`](number_integer_t.md) or
+[`number_float_t`](number_float_t.md).
 
 [RFC 8259](https://tools.ietf.org/html/rfc8259) further states:
 > Note that when such software is used, numbers that are integers and are in the range $[-2^{53}+1, 2^{53}-1]$ are

docs/mkdocs/docs/features/binary_formats/cbor.md

@@ -168,9 +168,9 @@ The library maps CBOR types to JSON value types as follows:
 !!! warning "Negative integer overflow"
 
     CBOR negative integers (major type 1) are decoded as `-1 - n`. If the encoded magnitude `n` is too large for the
-    result to fit into `number_integer_t` (`std::int64_t` by default), parsing fails with a
-    [`parse_error.112`](../../home/exceptions.md#jsonexceptionparse_error112) exception rather than overflowing
-    silently.
+    result to fit into `number_integer_t` (`std::int64_t` by default), the result is stored as `number_float_t`, like
+    a too small integer in JSON text. For example, `-18446744073709551616` (`0x3B` followed by eight `0xFF` bytes) is
+    stored as `-1.8446744073709552e+19`.
 
 !!! warning "Object keys"
 

docs/mkdocs/docs/home/exceptions.md

@@ -331,9 +331,6 @@ An unexpected byte was read in a [binary format](../features/binary_formats/inde
     [json.exception.parse_error.112] parse error at byte 15: syntax error while parsing BSON binary: byte array length cannot be negative, is -1
     ```
     ```
-    [json.exception.parse_error.112] parse error at byte 9: syntax error while parsing CBOR value: negative integer overflow
-    ```
-    ```
     [json.exception.parse_error.112] parse error at byte 5: syntax error while parsing BSON document: document size 6 does not match the number of bytes read (5)
     ```
 
@@ -854,13 +851,18 @@ The JSON Patch operations 'remove' and 'add' cannot be applied to the root eleme
 
 ### json.exception.out_of_range.406
 
-A parsed number could not be stored as without changing it to NaN or INF.
+A parsed number could not be stored without changing it to NaN or INF. For the binary formats, this happens when a
+finite floating-point number does not fit into [`number_float_t`](../api/basic_json/number_float_t.md), for example a
+double-precision number when `number_float_t` is `#!cpp float`.
 
-!!! failure "Example message"
+!!! failure "Example messages"
 
     ```
     number overflow parsing '10E1000'
     ```
+    ```
+    [json.exception.out_of_range.406] syntax error while parsing CBOR value: number overflow
+    ```
 
 ### json.exception.out_of_range.407
 

include/nlohmann/detail/input/binary_reader.hpp

@@ -559,7 +559,7 @@ class binary_reader
             case 0x01: // double
             {
                 double number{};
-                return get_number<double, true>(input_format_t::bson, number) && sax->number_float(static_cast<number_float_t>(number), "");
+                return get_number<double, true>(input_format_t::bson, number) && emit_float(input_format_t::bson, number);
             }
 
             case 0x02: // string
@@ -600,19 +600,19 @@ class binary_reader
             case 0x10: // int32
             {
                 std::int32_t value{};
-                return get_number<std::int32_t, true>(input_format_t::bson, value) && sax->number_integer(value);
+                return get_number<std::int32_t, true>(input_format_t::bson, value) && emit_signed(input_format_t::bson, value);
             }
 
             case 0x12: // int64
             {
                 std::int64_t value{};
-                return get_number<std::int64_t, true>(input_format_t::bson, value) && sax->number_integer(value);
+                return get_number<std::int64_t, true>(input_format_t::bson, value) && emit_signed(input_format_t::bson, value);
             }
 
             case 0x11: // uint64
             {
                 std::uint64_t value{};
-                return get_number<std::uint64_t, true>(input_format_t::bson, value) && sax->number_unsigned(value);
+                return get_number<std::uint64_t, true>(input_format_t::bson, value) && emit_unsigned(input_format_t::bson, value);
             }
 
             default: // anything else is not supported (yet)
@@ -638,14 +638,19 @@ class binary_reader
         {
             return false;
         }
-        const auto max_val = static_cast<NumberType>((std::numeric_limits<number_integer_t>::max)());
-        if (number > max_val)
+
+        // the value is -1 - number, which fits into number_integer_t
+        // whenever number does
+        if (JSON_HEDLEY_LIKELY(value_in_range_of<number_integer_t>(number)))
         {
-            return sax->parse_error(chars_read, get_token_string(),
-                                    parse_error::create(112, chars_read,
-                                            exception_message(input_format_t::cbor, "negative integer overflow", "value"), nullptr));
+            return sax->number_integer(static_cast<number_integer_t>(-1) - static_cast<number_integer_t>(number));
         }
-        return sax->number_integer(static_cast<number_integer_t>(-1) - static_cast<number_integer_t>(number));
+
+        // like the lexer does for JSON text, store a value too small for
+        // number_integer_t as number_float_t; compute it as long double so
+        // that emit_float sees a finite value and can detect an overflow of
+        // number_float_t
+        return emit_float(input_format_t::cbor, static_cast<long double>(-1) - static_cast<long double>(number));
     }
 
     /*!
@@ -702,25 +707,25 @@ class binary_reader
             case 0x18: // Unsigned integer (one-byte uint8_t follows)
             {
                 std::uint8_t number{};
-                return get_number(input_format_t::cbor, number) && sax->number_unsigned(number);
+                return get_number(input_format_t::cbor, number) && emit_unsigned(input_format_t::cbor, number);
             }
 
             case 0x19: // Unsigned integer (two-byte uint16_t follows)
             {
                 std::uint16_t number{};
-                return get_number(input_format_t::cbor, number) && sax->number_unsigned(number);
+                return get_number(input_format_t::cbor, number) && emit_unsigned(input_format_t::cbor, number);
             }
 
             case 0x1A: // Unsigned integer (four-byte uint32_t follows)
             {
                 std::uint32_t number{};
-                return get_number(input_format_t::cbor, number) && sax->number_unsigned(number);
+                return get_number(input_format_t::cbor, number) && emit_unsigned(input_format_t::cbor, number);
             }
 
             case 0x1B: // Unsigned integer (eight-byte uint64_t follows)
             {
                 std::uint64_t number{};
-                return get_number(input_format_t::cbor, number) && sax->number_unsigned(number);
+                return get_number(input_format_t::cbor, number) && emit_unsigned(input_format_t::cbor, number);
             }
 
             // Negative integer -1-0x00..-1-0x17 (-1..-24)
@@ -1165,13 +1170,13 @@ class binary_reader
             case 0xFA: // Single-Precision Float (four-byte IEEE 754)
             {
                 float number{};
-                return get_number(input_format_t::cbor, number) && sax->number_float(static_cast<number_float_t>(number), "");
+                return get_number(input_format_t::cbor, number) && emit_float(input_format_t::cbor, number);
             }
 
             case 0xFB: // Double-Precision Float (eight-byte IEEE 754)
             {
                 double number{};
-                return get_number(input_format_t::cbor, number) && sax->number_float(static_cast<number_float_t>(number), "");
+                return get_number(input_format_t::cbor, number) && emit_float(input_format_t::cbor, number);
             }
 
             default: // anything else (0xFF is handled inside the other types)
@@ -1935,61 +1940,61 @@ class binary_reader
             case 0xCA: // float 32
             {
                 float number{};
-                return get_number(input_format_t::msgpack, number) && sax->number_float(static_cast<number_float_t>(number), "");
+                return get_number(input_format_t::msgpack, number) && emit_float(input_format_t::msgpack, number);
             }
 
             case 0xCB: // float 64
             {
                 double number{};
-                return get_number(input_format_t::msgpack, number) && sax->number_float(static_cast<number_float_t>(number), "");
+                return get_number(input_format_t::msgpack, number) && emit_float(input_format_t::msgpack, number);
             }
 
             case 0xCC: // uint 8
             {
                 std::uint8_t number{};
-                return get_number(input_format_t::msgpack, number) && sax->number_unsigned(number);
+                return get_number(input_format_t::msgpack, number) && emit_unsigned(input_format_t::msgpack, number);
             }
 
             case 0xCD: // uint 16
             {
                 std::uint16_t number{};
-                return get_number(input_format_t::msgpack, number) && sax->number_unsigned(number);
+                return get_number(input_format_t::msgpack, number) && emit_unsigned(input_format_t::msgpack, number);
             }
 
             case 0xCE: // uint 32
             {
                 std::uint32_t number{};
-                return get_number(input_format_t::msgpack, number) && sax->number_unsigned(number);
+                return get_number(input_format_t::msgpack, number) && emit_unsigned(input_format_t::msgpack, number);
             }
 
             case 0xCF: // uint 64
             {
                 std::uint64_t number{};
-                return get_number(input_format_t::msgpack, number) && sax->number_unsigned(number);
+                return get_number(input_format_t::msgpack, number) && emit_unsigned(input_format_t::msgpack, number);
             }
 
             case 0xD0: // int 8
             {
                 std::int8_t number{};
-                return get_number(input_format_t::msgpack, number) && sax->number_integer(number);
+                return get_number(input_format_t::msgpack, number) && emit_signed(input_format_t::msgpack, number);
             }
 
             case 0xD1: // int 16
             {
                 std::int16_t number{};
-                return get_number(input_format_t::msgpack, number) && sax->number_integer(number);
+                return get_number(input_format_t::msgpack, number) && emit_signed(input_format_t::msgpack, number);
             }
 
             case 0xD2: // int 32
             {
                 std::int32_t number{};
-                return get_number(input_format_t::msgpack, number) && sax->number_integer(number);
+                return get_number(input_format_t::msgpack, number) && emit_signed(input_format_t::msgpack, number);
             }
 
             case 0xD3: // int 64
             {
                 std::int64_t number{};
-                return get_number(input_format_t::msgpack, number) && sax->number_integer(number);
+                return get_number(input_format_t::msgpack, number) && emit_signed(input_format_t::msgpack, number);
             }
 
             case 0xDC: // array 16
@@ -2922,7 +2927,7 @@ class binary_reader
                         {
                             return sax->parse_error(chars_read, get_token_string(), out_of_range::create(408, exception_message(input_format, "excessive ndarray size caused overflow", "size"), nullptr));
                         }
-                        if (JSON_HEDLEY_UNLIKELY(!sax->number_unsigned(static_cast<number_unsigned_t>(i))))
+                        if (JSON_HEDLEY_UNLIKELY(!emit_unsigned(input_format, i)))
                         {
                             return false;
                         }
@@ -3054,37 +3059,37 @@ class binary_reader
                     break;
                 }
                 std::uint8_t number{};
-                return get_number(input_format, number) && sax->number_unsigned(number);
+                return get_number(input_format, number) && emit_unsigned(input_format, number);
             }
 
             case 'U':
             {
                 std::uint8_t number{};
-                return get_number(input_format, number) && sax->number_unsigned(number);
+                return get_number(input_format, number) && emit_unsigned(input_format, number);
             }
 
             case 'i':
             {
                 std::int8_t number{};
-                return get_number(input_format, number) && sax->number_integer(number);
+                return get_number(input_format, number) && emit_signed(input_format, number);
             }
 
             case 'I':
             {
                 std::int16_t number{};
-                return get_number(input_format, number) && sax->number_integer(number);
+                return get_number(input_format, number) && emit_signed(input_format, number);
             }
 
             case 'l':
             {
                 std::int32_t number{};
-                return get_number(input_format, number) && sax->number_integer(number);
+                return get_number(input_format, number) && emit_signed(input_format, number);
             }
 
             case 'L':
             {
                 std::int64_t number{};
-                return get_number(input_format, number) && sax->number_integer(number);
+                return get_number(input_format, number) && emit_signed(input_format, number);
             }
 
             case 'u':
@@ -3094,7 +3099,7 @@ class binary_reader
                     break;
                 }
                 std::uint16_t number{};
-                return get_number(input_format, number) && sax->number_unsigned(number);
+                return get_number(input_format, number) && emit_unsigned(input_format, number);
             }
 
             case 'm':
@@ -3104,7 +3109,7 @@ class binary_reader
                     break;
                 }
                 std::uint32_t number{};
-                return get_number(input_format, number) && sax->number_unsigned(number);
+                return get_number(input_format, number) && emit_unsigned(input_format, number);
             }
 
             case 'M':
@@ -3114,7 +3119,7 @@ class binary_reader
                     break;
                 }
                 std::uint64_t number{};
-                return get_number(input_format, number) && sax->number_unsigned(number);
+                return get_number(input_format, number) && emit_unsigned(input_format, number);
             }
 
             case 'h':
@@ -3172,13 +3177,13 @@ class binary_reader
             case 'd':
             {
                 float number{};
-                return get_number(input_format, number) && sax->number_float(static_cast<number_float_t>(number), "");
+                return get_number(input_format, number) && emit_float(input_format, number);
             }
 
             case 'D':
             {
                 double number{};
-                return get_number(input_format, number) && sax->number_float(static_cast<number_float_t>(number), "");
+                return get_number(input_format, number) && emit_float(input_format, number);
             }
 
             case 'H':
@@ -3344,8 +3349,8 @@ class binary_reader
         return enter_object(detail::unknown_size());
     }
 
-    // Note, UBJSON has no binary type of its own; BJData, which shares this
-    // reader, decodes optimized 'B' arrays as binary in get_ubjson_array().
+    // Note, no reader for UBJSON binary types is implemented because they do
+    // not exist
 
     bool get_ubjson_high_precision_number()
     {
@@ -3645,13 +3650,13 @@ class binary_reader
             case 0x8E: // binary32
             {
                 float number{};
-                return get_number(input_format_t::bon8, number) && sax->number_float(static_cast<number_float_t>(number), "");
+                return get_number(input_format_t::bon8, number) && emit_float(input_format_t::bon8, number);
             }
 
             case 0x8F: // binary64
             {
                 double number{};
-                return get_number(input_format_t::bon8, number) && sax->number_float(static_cast<number_float_t>(number), "");
+                return get_number(input_format_t::bon8, number) && emit_float(input_format_t::bon8, number);
             }
 
             case 0xF8:
@@ -3717,7 +3722,9 @@ class binary_reader
     @brief pass an integer to the SAX parser
 
     Non-negative integers are passed as unsigned, negative integers as signed
-    numbers, like the other binary formats do.
+    numbers, like the other binary formats do. A value that does not fit the
+    number type is passed as described for @ref emit_unsigned and
+    @ref emit_signed.
 
     @param[in] number  the integer
     @return whether the SAX parser accepted the value
@@ -3726,9 +3733,9 @@ class binary_reader
     {
         if (number >= 0)
         {
-            return sax->number_unsigned(static_cast<number_unsigned_t>(number));
+            return emit_unsigned(input_format_t::bon8, static_cast<std::uint64_t>(number));
         }
-        return sax->number_integer(static_cast<number_integer_t>(number));
+        return emit_signed(input_format_t::bon8, number);
     }
 
     /*!
@@ -3785,8 +3792,7 @@ class binary_reader
             value = (value << 8) | static_cast<std::int64_t>(current);
         }
 
-        return negative ? sax->number_integer(static_cast<number_integer_t>(-(value + offset)))
-               : sax->number_unsigned(static_cast<number_unsigned_t>(value + offset));
+        return emit_bon8_integer(negative ? -(value + offset) : value + offset);
     }
 
     /*!
@@ -4052,7 +4058,7 @@ class binary_reader
 #endif
     }
 
-    /*!
+    /*
     @brief read a number from the input
 
     @tparam NumberType the type of the number
@@ -4062,10 +4068,10 @@ class binary_reader
     @return whether conversion completed
 
     @note This function needs to respect the system's endianness, because
-          bytes in CBOR, MessagePack, UBJSON, and BON8 are stored in network
-          order (big endian) and therefore need reordering on little endian
-          systems. On the other hand, BSON and BJData use little endian and
-          should reorder on big endian systems.
+          bytes in CBOR, MessagePack, and UBJSON are stored in network order
+          (big endian) and therefore need reordering on little endian systems.
+          On the other hand, BSON and BJData use little endian and should reorder
+          on big endian systems.
     */
     template<typename NumberType, bool InputIsLittleEndian = false>
     bool get_number(const input_format_t format, NumberType& result)
@@ -4083,6 +4089,88 @@ class binary_reader
         return true;
     }
 
+    /*!
+    @brief pass a signed integer read from the input to the SAX parser
+
+    Like the lexer does for JSON text, a value that does not fit into
+    number_integer_t is passed as number_unsigned_t if it is non-negative and
+    fits there, and as number_float_t otherwise. With the default number
+    types, every integer the binary formats can encode fits, so this only
+    matters for narrower custom number types.
+
+    @tparam NumberType a signed integer type
+    @param[in] format  the current format (for diagnostics)
+    @param[in] number  the integer
+    @return whether the SAX parser accepted the value
+
+    @throw out_of_range.406 if @a number overflows number_float_t (see
+           @ref emit_float)
+    */
+    template<typename NumberType>
+    bool emit_signed(const input_format_t format, const NumberType number)
+    {
+        if (JSON_HEDLEY_LIKELY(value_in_range_of<number_integer_t>(number)))
+        {
+            return sax->number_integer(static_cast<number_integer_t>(number));
+        }
+        if (value_in_range_of<number_unsigned_t>(number))
+        {
+            return sax->number_unsigned(static_cast<number_unsigned_t>(number));
+        }
+        return emit_float(format, number);
+    }
+
+    /*!
+    @brief pass an unsigned integer read from the input to the SAX parser
+
+    Like the lexer does for JSON text, a value that does not fit into
+    number_unsigned_t is passed as number_float_t.
+
+    @tparam NumberType an unsigned integer type
+    @param[in] format  the current format (for diagnostics)
+    @param[in] number  the integer
+    @return whether the SAX parser accepted the value
+
+    @throw out_of_range.406 if @a number overflows number_float_t (see
+           @ref emit_float)
+    */
+    template<typename NumberType>
+    bool emit_unsigned(const input_format_t format, const NumberType number)
+    {
+        if (JSON_HEDLEY_LIKELY(value_in_range_of<number_unsigned_t>(number)))
+        {
+            return sax->number_unsigned(static_cast<number_unsigned_t>(number));
+        }
+        return emit_float(format, number);
+    }
+
+    /*!
+    @brief pass a floating-point number read from the input to the SAX parser
+
+    Like the lexer does for JSON text, a finite value that overflows
+    number_float_t is rejected instead of silently becoming infinity. Infinity
+    and NaN in the input are passed on unchanged. Integers only overflow if
+    number_float_t cannot represent 2^64, e.g., a half-precision type.
+
+    @tparam NumberType a floating-point or integer type
+    @param[in] format  the current format (for diagnostics)
+    @param[in] number  the number
+    @return whether the SAX parser accepted the value
+
+    @throw out_of_range.406 if a finite @a number overflows number_float_t
+    */
+    template<typename NumberType>
+    bool emit_float(const input_format_t format, const NumberType number)
+    {
+        const auto result = static_cast<number_float_t>(number);
+        if (JSON_HEDLEY_UNLIKELY(std::isfinite(number) && !std::isfinite(result)))
+        {
+            return sax->parse_error(chars_read, get_token_string(),
+                                    out_of_range::create(406, exception_message(format, "number overflow", "value"), nullptr));
+        }
+        return sax->number_float(result, "");
+    }
+
     /*!
     @brief create a string by reading characters from the input
 

include/nlohmann/detail/input/input_adapters.hpp

@@ -8,12 +8,12 @@
 
 #pragma once
 
-#include <algorithm> // min
 #include <array> // array
 #include <cstddef> // size_t
-#include <cstdint> // uint32_t
 #include <cstring> // strlen
 #include <iterator> // begin, end, iterator_traits, random_access_iterator_tag, distance, next
+#include <memory> // shared_ptr, make_shared, addressof
+#include <numeric> // accumulate
 #include <streambuf> // streambuf
 #include <string> // string, char_traits
 #include <type_traits> // enable_if, is_base_of, is_pointer, is_integral, remove_pointer
@@ -28,7 +28,6 @@
 #include <nlohmann/detail/iterators/iterator_traits.hpp>
 #include <nlohmann/detail/macro_scope.hpp>
 #include <nlohmann/detail/meta/type_traits.hpp>
-#include <nlohmann/detail/string_utils.hpp>
 
 NLOHMANN_JSON_NAMESPACE_BEGIN
 namespace detail
@@ -83,9 +82,8 @@ class file_input_adapter
 };
 
 /*!
-Input adapter for a (caching) istream. Does not skip a UTF Byte Order Mark
-itself; that is done by the lexer's skip_bom(). Does not support changing
-the underlying std::streambuf
+Input adapter for a (caching) istream. Ignores a UFT Byte Order Mark at
+beginning of input. Does not support changing the underlying std::streambuf
 in mid-input. Maintains underlying std::istream and std::streambuf to support
 subsequent use of standard std::istream operations to process any input
 characters following those used in parsing the JSON input.  Clears the
@@ -450,14 +448,32 @@ struct wide_string_input_helper<BaseInputAdapter, 4>
             // get the current character
             const auto wc = input.get_character();
 
-            if (wc <= 0x10FFFF)
+            // UTF-32 to UTF-8 encoding
+            if (wc < 0x80)
             {
-                // UTF-32 to UTF-8 encoding
-                utf8_bytes_filled = 0;
-                encode_utf8(static_cast<std::uint32_t>(wc), [&utf8_bytes, &utf8_bytes_filled](std::uint32_t byte)
-                {
-                    utf8_bytes[utf8_bytes_filled++] = static_cast<std::char_traits<char>::int_type>(byte);
-                });
+                utf8_bytes[0] = static_cast<std::char_traits<char>::int_type>(wc);
+                utf8_bytes_filled = 1;
+            }
+            else if (wc <= 0x7FF)
+            {
+                utf8_bytes[0] = static_cast<std::char_traits<char>::int_type>(0xC0u | ((static_cast<unsigned int>(wc) >> 6u) & 0x1Fu));
+                utf8_bytes[1] = static_cast<std::char_traits<char>::int_type>(0x80u | (static_cast<unsigned int>(wc) & 0x3Fu));
+                utf8_bytes_filled = 2;
+            }
+            else if (wc <= 0xFFFF)
+            {
+                utf8_bytes[0] = static_cast<std::char_traits<char>::int_type>(0xE0u | ((static_cast<unsigned int>(wc) >> 12u) & 0x0Fu));
+                utf8_bytes[1] = static_cast<std::char_traits<char>::int_type>(0x80u | ((static_cast<unsigned int>(wc) >> 6u) & 0x3Fu));
+                utf8_bytes[2] = static_cast<std::char_traits<char>::int_type>(0x80u | (static_cast<unsigned int>(wc) & 0x3Fu));
+                utf8_bytes_filled = 3;
+            }
+            else if (wc <= 0x10FFFF)
+            {
+                utf8_bytes[0] = static_cast<std::char_traits<char>::int_type>(0xF0u | ((static_cast<unsigned int>(wc) >> 18u) & 0x07u));
+                utf8_bytes[1] = static_cast<std::char_traits<char>::int_type>(0x80u | ((static_cast<unsigned int>(wc) >> 12u) & 0x3Fu));
+                utf8_bytes[2] = static_cast<std::char_traits<char>::int_type>(0x80u | ((static_cast<unsigned int>(wc) >> 6u) & 0x3Fu));
+                utf8_bytes[3] = static_cast<std::char_traits<char>::int_type>(0x80u | (static_cast<unsigned int>(wc) & 0x3Fu));
+                utf8_bytes_filled = 4;
             }
             else
             {
@@ -494,15 +510,24 @@ struct wide_string_input_helper<BaseInputAdapter, 2>
             // get the current character
             const auto wc = input.get_character();
 
-            if (0xD800 > wc || wc >= 0xE000)
+            // UTF-16 to UTF-8 encoding
+            if (wc < 0x80)
             {
-                // a UTF-16 code unit outside the surrogate range is a valid
-                // code point (at most U+FFFF) on its own
-                utf8_bytes_filled = 0;
-                encode_utf8(static_cast<std::uint32_t>(wc), [&utf8_bytes, &utf8_bytes_filled](std::uint32_t byte)
-                {
-                    utf8_bytes[utf8_bytes_filled++] = static_cast<std::char_traits<char>::int_type>(byte);
-                });
+                utf8_bytes[0] = static_cast<std::char_traits<char>::int_type>(wc);
+                utf8_bytes_filled = 1;
+            }
+            else if (wc <= 0x7FF)
+            {
+                utf8_bytes[0] = static_cast<std::char_traits<char>::int_type>(0xC0u | ((static_cast<unsigned int>(wc) >> 6u)));
+                utf8_bytes[1] = static_cast<std::char_traits<char>::int_type>(0x80u | (static_cast<unsigned int>(wc) & 0x3Fu));
+                utf8_bytes_filled = 2;
+            }
+            else if (0xD800 > wc || wc >= 0xE000)
+            {
+                utf8_bytes[0] = static_cast<std::char_traits<char>::int_type>(0xE0u | ((static_cast<unsigned int>(wc) >> 12u)));
+                utf8_bytes[1] = static_cast<std::char_traits<char>::int_type>(0x80u | ((static_cast<unsigned int>(wc) >> 6u) & 0x3Fu));
+                utf8_bytes[2] = static_cast<std::char_traits<char>::int_type>(0x80u | (static_cast<unsigned int>(wc) & 0x3Fu));
+                utf8_bytes_filled = 3;
             }
             else
             {
@@ -520,11 +545,11 @@ struct wide_string_input_helper<BaseInputAdapter, 2>
                     if (0xDC00 <= wc2 && wc2 <= 0xDFFF)
                     {
                         const auto charcode = 0x10000u + (((static_cast<unsigned int>(wc) & 0x3FFu) << 10u) | (wc2 & 0x3FFu));
-                        utf8_bytes_filled = 0;
-                        encode_utf8(charcode, [&utf8_bytes, &utf8_bytes_filled](std::uint32_t byte)
-                        {
-                            utf8_bytes[utf8_bytes_filled++] = static_cast<std::char_traits<char>::int_type>(byte);
-                        });
+                        utf8_bytes[0] = static_cast<std::char_traits<char>::int_type>(0xF0u | (charcode >> 18u));
+                        utf8_bytes[1] = static_cast<std::char_traits<char>::int_type>(0x80u | ((charcode >> 12u) & 0x3Fu));
+                        utf8_bytes[2] = static_cast<std::char_traits<char>::int_type>(0x80u | ((charcode >> 6u) & 0x3Fu));
+                        utf8_bytes[3] = static_cast<std::char_traits<char>::int_type>(0x80u | (charcode & 0x3Fu));
+                        utf8_bytes_filled = 4;
                         valid_pair = true;
                     }
                 }
@@ -837,9 +862,9 @@ auto input_adapter(T (&array)[N]) -> decltype(input_adapter(array, array + N)) /
     return input_adapter(array, array + N);
 }
 
-// This class only handles inputs that construct a contiguous_bytes_input_adapter
-// (e.g. span_input_adapter). It's required so that expressions like {ptr, len}
-// can be implicitly cast to the correct adapter.
+// This class only handles inputs of input_buffer_adapter type.
+// It's required so that expressions like {ptr, len} can be implicitly cast
+// to the correct adapter.
 class span_input_adapter
 {
   public:

include/nlohmann/detail/input/json_sax.hpp

@@ -10,7 +10,6 @@
 
 #include <algorithm> // find_if, min
 #include <cstddef>
-#include <limits> // numeric_limits
 #include <string> // string
 #include <type_traits> // enable_if_t
 #include <utility> // move, pair
@@ -176,88 +175,6 @@ template<typename ArrayType>
 inline void reserve_array(ArrayType& /*arr*/, std::size_t /*len*/, priority_tag<0> /*unused*/)
 {}
 
-#if JSON_DIAGNOSTIC_POSITIONS
-/*!
-@brief set the diagnostic positions of a value the DOM SAX parsers just stored
-
-Shared by json_sax_dom_parser and json_sax_dom_callback_parser. basic_json
-befriends this struct, as the position members are private.
-*/
-struct diagnostic_positions
-{
-    /*!
-    @param[in,out] v  the value that was just parsed
-    @param[in] lexer  the lexer that read it, or nullptr to leave @a v alone
-    */
-    template<typename BasicJsonType, typename LexerType>
-    static void set_from_lexer(BasicJsonType& v, LexerType* lexer)
-    {
-        if (lexer)
-        {
-            // Lexer has read past the current field value, so set the end position to the current position.
-            // The start position will be set below based on the length of the string representation
-            // of the value.
-            v.end_position = lexer->get_position();
-
-            switch (v.type())
-            {
-                case value_t::boolean:
-                {
-                    // 4 and 5 are the string length of "true" and "false"
-                    v.start_position = v.end_position - (v.m_data.m_value.boolean ? 4 : 5);
-                    break;
-                }
-
-                case value_t::null:
-                {
-                    // 4 is the string length of "null"
-                    v.start_position = v.end_position - 4;
-                    break;
-                }
-
-                case value_t::string:
-                {
-                    // escape sequences make the token longer than the value it
-                    // parses to, so the start position cannot be derived from
-                    // the value; use the offset the lexer recorded instead
-                    v.start_position = lexer->get_token_start_position();
-                    break;
-                }
-
-                case value_t::discarded:
-                {
-                    // an object or array the callback of
-                    // json_sax_dom_callback_parser rejected has no position
-                    v.end_position = std::string::npos;
-                    v.start_position = v.end_position;
-                    break;
-                }
-
-                case value_t::binary:
-                case value_t::number_integer:
-                case value_t::number_unsigned:
-                case value_t::number_float:
-                {
-                    v.start_position = v.end_position - lexer->get_string().size();
-                    break;
-                }
-
-                case value_t::object:
-                case value_t::array:
-                {
-                    // object and array are handled in start_object() and start_array() handlers
-                    // skip setting the values here.
-                    break;
-                }
-                default: // LCOV_EXCL_LINE
-                    // Handle all possible types discretely, default handler should never be reached.
-                    JSON_ASSERT(false); // NOLINT(cert-dcl03-c,hicpp-static-assert,misc-static-assert) LCOV_EXCL_LINE
-            }
-        }
-    }
-};
-#endif
-
 /*!
 @brief SAX implementation to create a JSON value from SAX events
 
@@ -459,6 +376,76 @@ class json_sax_dom_parser
 
   private:
 
+#if JSON_DIAGNOSTIC_POSITIONS
+    void handle_diagnostic_positions_for_json_value(BasicJsonType& v)
+    {
+        if (m_lexer_ref)
+        {
+            // Lexer has read past the current field value, so set the end position to the current position.
+            // The start position will be set below based on the length of the string representation
+            // of the value.
+            v.end_position = m_lexer_ref->get_position();
+
+            switch (v.type())
+            {
+                case value_t::boolean:
+                {
+                    // 4 and 5 are the string length of "true" and "false"
+                    v.start_position = v.end_position - (v.m_data.m_value.boolean ? 4 : 5);
+                    break;
+                }
+
+                case value_t::null:
+                {
+                    // 4 is the string length of "null"
+                    v.start_position = v.end_position - 4;
+                    break;
+                }
+
+                case value_t::string:
+                {
+                    // escape sequences make the token longer than the value it
+                    // parses to, so the start position cannot be derived from
+                    // the value; use the offset the lexer recorded instead
+                    v.start_position = m_lexer_ref->get_token_start_position();
+                    break;
+                }
+
+                // As we handle the start and end positions for values created during parsing,
+                // we do not expect the following value type to be called. Regardless, set the positions
+                // in case this is created manually or through a different constructor. Exclude from lcov
+                // since the exact condition of this switch is esoteric.
+                // LCOV_EXCL_START
+                case value_t::discarded:
+                {
+                    v.end_position = std::string::npos;
+                    v.start_position = v.end_position;
+                    break;
+                }
+                // LCOV_EXCL_STOP
+                case value_t::binary:
+                case value_t::number_integer:
+                case value_t::number_unsigned:
+                case value_t::number_float:
+                {
+                    v.start_position = v.end_position - m_lexer_ref->get_string().size();
+                    break;
+                }
+                case value_t::object:
+                case value_t::array:
+                {
+                    // object and array are handled in start_object() and start_array() handlers
+                    // skip setting the values here.
+                    break;
+                }
+                default: // LCOV_EXCL_LINE
+                    // Handle all possible types discretely, default handler should never be reached.
+                    JSON_ASSERT(false); // NOLINT(cert-dcl03-c,hicpp-static-assert,misc-static-assert,-warnings-as-errors) LCOV_EXCL_LINE
+            }
+        }
+    }
+#endif
+
     /*!
     @invariant If the ref stack is empty, then the passed value will be the new
                root.
@@ -474,7 +461,7 @@ class json_sax_dom_parser
             root = BasicJsonType(std::forward<Value>(v));
 
 #if JSON_DIAGNOSTIC_POSITIONS
-            diagnostic_positions::set_from_lexer(root, m_lexer_ref);
+            handle_diagnostic_positions_for_json_value(root);
 #endif
 
             return &root;
@@ -487,7 +474,7 @@ class json_sax_dom_parser
             ref_stack.back()->m_data.m_value.array->emplace_back(std::forward<Value>(v));
 
 #if JSON_DIAGNOSTIC_POSITIONS
-            diagnostic_positions::set_from_lexer(ref_stack.back()->m_data.m_value.array->back(), m_lexer_ref);
+            handle_diagnostic_positions_for_json_value(ref_stack.back()->m_data.m_value.array->back());
 #endif
 
             return &(ref_stack.back()->m_data.m_value.array->back());
@@ -498,7 +485,7 @@ class json_sax_dom_parser
         *object_element = BasicJsonType(std::forward<Value>(v));
 
 #if JSON_DIAGNOSTIC_POSITIONS
-        diagnostic_positions::set_from_lexer(*object_element, m_lexer_ref);
+        handle_diagnostic_positions_for_json_value(*object_element);
 #endif
 
         return object_element;
@@ -675,7 +662,7 @@ class json_sax_dom_callback_parser
 
 #if JSON_DIAGNOSTIC_POSITIONS
                     // Set start/end positions for discarded object.
-                    diagnostic_positions::set_from_lexer(*ref_stack.back(), m_lexer_ref);
+                    handle_diagnostic_positions_for_json_value(*ref_stack.back());
 #endif
                 }
             }
@@ -791,7 +778,7 @@ class json_sax_dom_callback_parser
 
 #if JSON_DIAGNOSTIC_POSITIONS
                     // Set start/end positions for discarded array.
-                    diagnostic_positions::set_from_lexer(*ref_stack.back(), m_lexer_ref);
+                    handle_diagnostic_positions_for_json_value(*ref_stack.back());
 #endif
                 }
             }
@@ -844,6 +831,72 @@ class json_sax_dom_callback_parser
 
   private:
 
+#if JSON_DIAGNOSTIC_POSITIONS
+    void handle_diagnostic_positions_for_json_value(BasicJsonType& v)
+    {
+        if (m_lexer_ref)
+        {
+            // Lexer has read past the current field value, so set the end position to the current position.
+            // The start position will be set below based on the length of the string representation
+            // of the value.
+            v.end_position = m_lexer_ref->get_position();
+
+            switch (v.type())
+            {
+                case value_t::boolean:
+                {
+                    // 4 and 5 are the string length of "true" and "false"
+                    v.start_position = v.end_position - (v.m_data.m_value.boolean ? 4 : 5);
+                    break;
+                }
+
+                case value_t::null:
+                {
+                    // 4 is the string length of "null"
+                    v.start_position = v.end_position - 4;
+                    break;
+                }
+
+                case value_t::string:
+                {
+                    // escape sequences make the token longer than the value it
+                    // parses to, so the start position cannot be derived from
+                    // the value; use the offset the lexer recorded instead
+                    v.start_position = m_lexer_ref->get_token_start_position();
+                    break;
+                }
+
+                case value_t::discarded:
+                {
+                    v.end_position = std::string::npos;
+                    v.start_position = v.end_position;
+                    break;
+                }
+
+                case value_t::binary:
+                case value_t::number_integer:
+                case value_t::number_unsigned:
+                case value_t::number_float:
+                {
+                    v.start_position = v.end_position - m_lexer_ref->get_string().size();
+                    break;
+                }
+
+                case value_t::object:
+                case value_t::array:
+                {
+                    // object and array are handled in start_object() and start_array() handlers
+                    // skip setting the values here.
+                    break;
+                }
+                default: // LCOV_EXCL_LINE
+                    // Handle all possible types discretely, default handler should never be reached.
+                    JSON_ASSERT(false); // NOLINT(cert-dcl03-c,hicpp-static-assert,misc-static-assert,-warnings-as-errors) LCOV_EXCL_LINE
+            }
+        }
+    }
+#endif
+
     /// if there is a pending duplicate-key stash entry for this exact slot,
     /// remove it from the stash; if restore_value is true, the stashed
     /// previous value is moved back into the slot first (use this when the
@@ -965,7 +1018,7 @@ class json_sax_dom_callback_parser
         auto value = BasicJsonType(std::forward<Value>(v));
 
 #if JSON_DIAGNOSTIC_POSITIONS
-        diagnostic_positions::set_from_lexer(value, m_lexer_ref);
+        handle_diagnostic_positions_for_json_value(value);
 #endif
 
         // check callback

include/nlohmann/detail/input/lexer.hpp

@@ -11,7 +11,6 @@
 #include <array> // array
 #include <clocale> // localeconv
 #include <cstddef> // size_t
-#include <cstdint> // uint32_t
 #include <cstdio> // snprintf
 #include <cstdlib> // strtof, strtod, strtold, strtoll, strtoull
 #include <initializer_list> // initializer_list
@@ -25,7 +24,6 @@
 #include <nlohmann/detail/input/string_scan.hpp>
 #include <nlohmann/detail/macro_scope.hpp>
 #include <nlohmann/detail/meta/type_traits.hpp>
-#include <nlohmann/detail/string_utils.hpp>
 
 NLOHMANN_JSON_NAMESPACE_BEGIN
 namespace detail
@@ -502,10 +500,32 @@ class lexer : public lexer_base<BasicJsonType>
                             JSON_ASSERT(0x00 <= codepoint && codepoint <= 0x10FFFF);
 
                             // translate codepoint into bytes
-                            encode_utf8(static_cast<std::uint32_t>(codepoint), [this](std::uint32_t byte)
+                            if (codepoint < 0x80)
                             {
-                                add(static_cast<char_int_type>(byte));
-                            });
+                                // 1-byte characters: 0xxxxxxx (ASCII)
+                                add(static_cast<char_int_type>(codepoint));
+                            }
+                            else if (codepoint <= 0x7FF)
+                            {
+                                // 2-byte characters: 110xxxxx 10xxxxxx
+                                add(static_cast<char_int_type>(0xC0u | (static_cast<unsigned int>(codepoint) >> 6u)));
+                                add(static_cast<char_int_type>(0x80u | (static_cast<unsigned int>(codepoint) & 0x3Fu)));
+                            }
+                            else if (codepoint <= 0xFFFF)
+                            {
+                                // 3-byte characters: 1110xxxx 10xxxxxx 10xxxxxx
+                                add(static_cast<char_int_type>(0xE0u | (static_cast<unsigned int>(codepoint) >> 12u)));
+                                add(static_cast<char_int_type>(0x80u | ((static_cast<unsigned int>(codepoint) >> 6u) & 0x3Fu)));
+                                add(static_cast<char_int_type>(0x80u | (static_cast<unsigned int>(codepoint) & 0x3Fu)));
+                            }
+                            else
+                            {
+                                // 4-byte characters: 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
+                                add(static_cast<char_int_type>(0xF0u | (static_cast<unsigned int>(codepoint) >> 18u)));
+                                add(static_cast<char_int_type>(0x80u | ((static_cast<unsigned int>(codepoint) >> 12u) & 0x3Fu)));
+                                add(static_cast<char_int_type>(0x80u | ((static_cast<unsigned int>(codepoint) >> 6u) & 0x3Fu)));
+                                add(static_cast<char_int_type>(0x80u | (static_cast<unsigned int>(codepoint) & 0x3Fu)));
+                            }
 
                             break;
                         }
@@ -1474,30 +1494,45 @@ scan_number_done:
     */
     token_type convert_number(token_type number_type, std::size_t mantissa_end)
     {
-        // accept() only needs to know whether the input is valid, so it sets
-        // discard_number_values (see json.hpp), and an integer token whose
-        // digit count shows that it fits is reported without calling
-        // convert_integer(). A number with up to 18 digits always fits into
-        // both std::uint64_t and std::int64_t (18 nines is about 1e18, below
-        // INT64_MAX, which is about 9.2e18). Longer tokens take the exact path
-        // below, including the fallback to floating point when the value does
-        // not fit.
+        // If the caller does not need the converted value (only whether the
+        // input is syntactically valid; see json_sax_acceptor/accept()), an
+        // unsigned/integer token can be reported without calling
+        // strtoull()/strtoll() at all, *provided* we can already tell from
+        // the digit count alone that the conversion cannot overflow 64 bits.
+        // Such tokens are always finite and are accepted unconditionally by
+        // the parser regardless of their actual value (parser::sax_parse_internal()
+        // never checks finiteness for value_unsigned/value_integer), so the
+        // classification below is all that is needed.
         //
-        // With a narrower number_unsigned_t/number_integer_t (e.g.
-        // std::uint32_t), the exact path would reclassify some of these tokens
-        // as (finite) floats, while this check reports integers. That does not
-        // change the result of accept(): it always parses through
-        // json_sax_acceptor, whose number callbacks discard their argument and
-        // return true, and the parser rejects neither integers nor finite
-        // floats. value_unsigned/value_integer are left unset here, so a caller
-        // that reads the converted value must not set discard_number_values.
+        // A decimal number with up to 18 digits is always representable in
+        // both std::uint64_t and std::int64_t (18 nines is ~1e18, well below
+        // both UINT64_MAX ~1.8e19 and INT64_MAX ~9.2e18), so strtoull()/strtoll()
+        // could not have set errno to ERANGE for it. Numbers with more digits
+        // (rare in practice) fall through to the exact code below, unchanged,
+        // so their handling -- including reclassification to value_float when
+        // the value overflows 64 bits, and rejection when it is not even
+        // finite as a double -- is bit-for-bit identical to before this
+        // optimization.
         //
-        // On contiguous input, scan_number_bulk_contiguous() converts integer
-        // tokens itself and does not pass them to this function, unless
-        // JSON_DIAGNOSTIC_POSITIONS is enabled. This check is therefore only
-        // reached for input without bulk access (e.g. streams), with
-        // JSON_DIAGNOSTIC_POSITIONS, or when scan_number_bulk_contiguous()
-        // falls back to scan_number().
+        // Note this reasons about std::uint64_t/std::int64_t, not about
+        // number_unsigned_t/number_integer_t (BasicJsonType's own, possibly
+        // narrower, template parameters -- e.g. std::uint32_t). That is fine
+        // *only* because discard_number_values is exclusively set by
+        // accept() (see json.hpp), and accept() always parses through the
+        // library's own json_sax_acceptor -- never a user-supplied SAX
+        // consumer -- whose number_unsigned()/number_integer()/number_float()
+        // callbacks unconditionally discard their argument and return true.
+        // So for every caller that can reach this branch, neither the token
+        // classification below nor the eventual (possibly narrowed, and on
+        // this fast path left stale/unset) value_unsigned/value_integer is
+        // ever consulted -- an unsigned/integer token is accepted outright,
+        // and even a >18-digit token that this fast path deliberately falls
+        // through for is, once reclassified to value_float, still finite
+        // (and thus accepted) for any digit count that fits in number_unsigned_t
+        // or number_integer_t regardless of that type's width. If this
+        // function is ever taught to run with discard_number_values true for
+        // a caller that *does* read the converted value, this reasoning (and
+        // the fast path below) would need to be revisited.
         if (discard_number_values)
         {
             constexpr std::size_t safe_digit_count = 18;
@@ -1988,7 +2023,7 @@ scan_number_done:
         return value_float;
     }
 
-    /// return current string value
+    /// return current string value (implicitly resets the token; useful only once)
     string_t& get_string()
     {
         // a number token holds '.' regardless of the locale (#4084)
@@ -2290,11 +2325,11 @@ scan_number_done:
     /// the position of the decimal point in token_buffer
     std::size_t decimal_point_position = std::string::npos;
 
-    /// whether the caller only needs the token types and never looks at the
-    /// converted numeric values; set only by accept(), which parses through
-    /// json_sax_acceptor. When set, convert_number() skips converting integer
-    /// tokens whose digit count guarantees that they fit into 64 bits (see
-    /// there)
+    /// whether the caller (e.g. accept()/json_sax_acceptor) only needs the
+    /// token classification and never looks at the converted numeric value;
+    /// when set, scan_number() may skip strtoull()/strtoll() for
+    /// value_unsigned/value_integer tokens whose digit count guarantees they
+    /// fit into 64 bits (see scan_number())
     const bool discard_number_values = false;
 };
 

include/nlohmann/detail/input/parser.hpp

@@ -54,8 +54,7 @@ using parser_callback_t =
 /*!
 @brief syntax analysis
 
-This class implements an iterative parser that keeps the open containers on
-an explicit stack and reports what it reads as SAX events.
+This class implements a recursive descent parser.
 */
 template<typename BasicJsonType, typename InputAdapterType>
 class parser
@@ -99,9 +98,28 @@ class parser
         if (callback)
         {
             json_sax_dom_callback_parser<BasicJsonType, InputAdapterType> sdp(result, callback, allow_exceptions, &m_lexer);
+            sax_parse_internal(&sdp);
+
+            if (strict)
+            {
+                // in strict mode, input must be completely read
+                if (get_token() != token_type::end_of_input)
+                {
+                    sdp.parse_error(m_lexer.get_position(),
+                                    m_lexer.get_token_string(),
+                                    parse_error::create(101, m_lexer.get_position(),
+                                                        exception_message(token_type::end_of_input, "value"), nullptr));
+                }
+            }
+            else
+            {
+                // the caller keeps using the input: position it right after
+                // the value by leaving the character that terminated it
+                m_lexer.release_lookahead();
+            }
 
             // in case of an error, return a discarded value
-            if (!parse_dom(sdp, strict))
+            if (sdp.is_errored())
             {
                 result = value_t::discarded;
                 return;
@@ -117,9 +135,26 @@ class parser
         else
         {
             json_sax_dom_parser<BasicJsonType, InputAdapterType> sdp(result, allow_exceptions, &m_lexer);
+            sax_parse_internal(&sdp);
+
+            if (strict)
+            {
+                // in strict mode, input must be completely read
+                if (get_token() != token_type::end_of_input)
+                {
+                    sdp.parse_error(m_lexer.get_position(),
+                                    m_lexer.get_token_string(),
+                                    parse_error::create(101, m_lexer.get_position(), exception_message(token_type::end_of_input, "value"), nullptr));
+                }
+            }
+            else
+            {
+                // see above
+                m_lexer.release_lookahead();
+            }
 
             // in case of an error, return a discarded value
-            if (!parse_dom(sdp, strict))
+            if (sdp.is_errored())
             {
                 result = value_t::discarded;
                 return;
@@ -172,46 +207,6 @@ class parser
     }
 
   private:
-    /*!
-    @brief run a DOM SAX parser to completion and position the lexer
-
-    Shared by both branches of @ref parse(): builds no SAX parser itself,
-    but drives an already-constructed @a json_sax_dom_parser or
-    @ref json_sax_dom_callback_parser through @ref sax_parse_internal(),
-    then applies the strict-EOF check (reporting parse_error.101 through
-    @a sdp on failure) or, in non-strict mode, releases the lookahead so
-    the caller can keep reading the input right after the parsed value.
-
-    @param[in,out] sdp     the DOM SAX parser to run
-    @param[in] strict      whether to expect the last token to be EOF
-    @return whether @a sdp did not report an error
-    */
-    template<typename DomSax>
-    bool parse_dom(DomSax& sdp, const bool strict)
-    {
-        sax_parse_internal(&sdp);
-
-        if (strict)
-        {
-            // in strict mode, input must be completely read
-            if (get_token() != token_type::end_of_input)
-            {
-                sdp.parse_error(m_lexer.get_position(),
-                                m_lexer.get_token_string(),
-                                parse_error::create(101, m_lexer.get_position(),
-                                                    exception_message(token_type::end_of_input, "value"), nullptr));
-            }
-        }
-        else
-        {
-            // the caller keeps using the input: position it right after
-            // the value by leaving the character that terminated it
-            m_lexer.release_lookahead();
-        }
-
-        return !sdp.is_errored();
-    }
-
     template<typename SAX>
     JSON_HEDLEY_NON_NULL(2)
     bool sax_parse_internal(SAX* sax)
@@ -444,9 +439,8 @@ class parser
 
                     // We are done with this array. Before we can parse a
                     // new value, we need to evaluate the new state first.
-                    // By setting skip_to_state_evaluation to true, the next
-                    // iteration skips parsing a value and evaluates the
-                    // enclosing state directly.
+                    // By setting skip_to_state_evaluation to false, we
+                    // are effectively jumping to the beginning of this if.
                     JSON_ASSERT(!states.empty());
                     states.pop_back();
                     skip_to_state_evaluation = true;
@@ -506,9 +500,8 @@ class parser
 
                 // We are done with this object. Before we can parse a
                 // new value, we need to evaluate the new state first.
-                // By setting skip_to_state_evaluation to true, the next
-                // iteration skips parsing a value and evaluates the
-                // enclosing state directly.
+                // By setting skip_to_state_evaluation to false, we
+                // are effectively jumping to the beginning of this if.
                 JSON_ASSERT(!states.empty());
                 states.pop_back();
                 skip_to_state_evaluation = true;

include/nlohmann/detail/string_utils.hpp

@@ -36,61 +36,6 @@ StringType to_string(std::size_t value)
     return result;
 }
 
-///////////////////
-// UTF-8 encoding //
-///////////////////
-
-/*!
-@brief encode a Unicode code point as UTF-8
-
-Used to turn a decoded code point back into bytes: by the wide-string input
-adapters in input_adapters.hpp (one code point per UTF-32 unit, per UTF-16
-unit outside the surrogate range, and per valid UTF-16 surrogate pair), and
-by the lexer's `\uXXXX`/`\uXXXX\uYYYY` handling in lexer.hpp. Passing a
-code point above U+10FFFF, or one in the surrogate range U+D800..U+DFFF, is
-undefined behavior; callers are expected to have rejected those already
-(the wide-string adapters pass malformed units through unencoded instead of
-calling this function, and the lexer rejects unpaired surrogates before
-reaching it).
-
-@tparam Out    a callable invoked with one byte (as std::uint32_t, 0x00..0xFF)
-               at a time, most significant byte first
-@param[in] cp   the code point to encode (at most U+10FFFF)
-@param[in] out  called once for each byte of the UTF-8 encoding of @a cp
-*/
-template<typename Out>
-void encode_utf8(std::uint32_t cp, Out&& out)
-{
-    JSON_ASSERT(cp <= 0x10FFFF);
-
-    if (cp < 0x80)
-    {
-        // 1-byte characters: 0xxxxxxx (ASCII)
-        out(cp);
-    }
-    else if (cp <= 0x7FF)
-    {
-        // 2-byte characters: 110xxxxx 10xxxxxx
-        out(0xC0u | (cp >> 6u));
-        out(0x80u | (cp & 0x3Fu));
-    }
-    else if (cp <= 0xFFFF)
-    {
-        // 3-byte characters: 1110xxxx 10xxxxxx 10xxxxxx
-        out(0xE0u | (cp >> 12u));
-        out(0x80u | ((cp >> 6u) & 0x3Fu));
-        out(0x80u | (cp & 0x3Fu));
-    }
-    else
-    {
-        // 4-byte characters: 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
-        out(0xF0u | (cp >> 18u));
-        out(0x80u | ((cp >> 12u) & 0x3Fu));
-        out(0x80u | ((cp >> 6u) & 0x3Fu));
-        out(0x80u | (cp & 0x3Fu));
-    }
-}
-
 ///////////////////
 // UTF-8 decoding //
 ///////////////////
@@ -106,23 +51,11 @@ This is a single-byte step of a "shift-based" UTF-8 decoder originally
 written by Björn Hoehrmann. See
 http://bjoern.hoehrmann.de/utf-8/decoder/dfa/ for details.
 
-The library checks UTF-8 well-formedness (RFC 3629, section 4) in four
-places, which differ in speed, diagnostics, and how they read the input:
-
-- decode() and @ref is_valid_utf8 below: the serializer (to escape and, in
-  strict mode, reject ill-formed UTF-8 when dumping a string) and the CBOR,
-  MessagePack, BSON, UBJSON and BJData readers (to reject ill-formed UTF-8 in
-  text strings at decode time).
-- the per-lead-byte switch in lexer::scan_string(): JSON text, with a
-  diagnostic for each kind of error.
-- validate_one_utf8() and valid_utf8_prefix() in string_scan.hpp: the lexer's
-  bulk string scan, the bulk path of the BON8 reader, and the BON8 writer.
-  They must accept exactly what the lexer's switch accepts.
-- the byte path of binary_reader::get_bon8_string(): BON8 input without bulk
-  access, and the bytes the bulk path leaves to it.
-
-All four must accept the same set of sequences, so a change to one needs a
-matching change to the others.
+This decoder is the single source of truth for UTF-8 validation in this
+library: it is used both by the serializer (to escape and, in strict mode,
+reject ill-formed UTF-8 when dumping a string) and by the binary readers
+(to reject ill-formed UTF-8 in CBOR/MessagePack/BSON/UBJSON text strings at
+decode time; see @ref is_valid_utf8 below).
 
 @param[in,out] state  the current decoder state
 @param[in,out] codep  codepoint (valid only if resulting state is UTF8_ACCEPT)

include/nlohmann/json.hpp

@@ -149,9 +149,6 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     friend class ::nlohmann::detail::json_sax_dom_parser;
     template<typename BasicJsonType, typename InputAdapterType>
     friend class ::nlohmann::detail::json_sax_dom_callback_parser;
-#if JSON_DIAGNOSTIC_POSITIONS
-    friend struct ::nlohmann::detail::diagnostic_positions;
-#endif
     friend class ::nlohmann::detail::exception;
 
     /// workaround type for MSVC

tests/src/unit-binary_formats.cpp

@@ -11,7 +11,12 @@
 #include <nlohmann/json.hpp>
 using nlohmann::json;
 
+#include <cmath>
 #include <fstream>
+#include <limits>
+#include <map>
+#include <string>
+#include <vector>
 #include "make_test_data_available.hpp"
 
 TEST_CASE("Binary Formats" * doctest::skip())
@@ -224,3 +229,139 @@ TEST_CASE("Binary Formats" * doctest::skip())
         CHECK((100.0 * double(ubjson_3_size) / double(json_size)) == Approx(89.450));
     }
 }
+
+namespace
+{
+// the binary formats as function pointers for "Binary formats with narrow number types";
+// named functions rather than lambdas, because clang 3.5 cannot convert a lambda
+// to a function pointer in the braced initializer of the format table
+using narrow_json = nlohmann::basic_json<std::map, std::vector, std::string, bool, std::int32_t, std::uint32_t, float>;
+using bytes = std::vector<std::uint8_t>;
+
+bytes encode_cbor(const json& j)
+{
+    return json::to_cbor(j);
+}
+narrow_json decode_cbor(const bytes& v, bool allow_exceptions)
+{
+    return narrow_json::from_cbor(v, true, allow_exceptions);
+}
+
+bytes encode_msgpack(const json& j)
+{
+    return json::to_msgpack(j);
+}
+narrow_json decode_msgpack(const bytes& v, bool allow_exceptions)
+{
+    return narrow_json::from_msgpack(v, true, allow_exceptions);
+}
+
+bytes encode_ubjson(const json& j)
+{
+    return json::to_ubjson(j);
+}
+narrow_json decode_ubjson(const bytes& v, bool allow_exceptions)
+{
+    return narrow_json::from_ubjson(v, true, allow_exceptions);
+}
+
+bytes encode_bjdata(const json& j)
+{
+    return json::to_bjdata(j);
+}
+narrow_json decode_bjdata(const bytes& v, bool allow_exceptions)
+{
+    return narrow_json::from_bjdata(v, true, allow_exceptions);
+}
+
+// BSON can only store numbers as object members
+bytes encode_bson(const json& j)
+{
+    return json::to_bson(json{{"a", j}});
+}
+narrow_json decode_bson(const bytes& v, bool allow_exceptions)
+{
+    const auto result = narrow_json::from_bson(v, true, allow_exceptions);
+    return result.is_discarded() ? result : result.at("a");
+}
+
+bytes encode_bon8(const json& j)
+{
+    return json::to_bon8(j);
+}
+narrow_json decode_bon8(const bytes& v, bool allow_exceptions)
+{
+    return narrow_json::from_bon8(v, true, allow_exceptions);
+}
+
+} // namespace
+
+TEST_CASE("Binary formats with narrow number types")
+{
+    // Numbers that do not fit the number types are handled like the lexer
+    // handles them in JSON text: an integer that fits neither integer type is
+    // stored as a floating-point number, and a finite floating-point number
+    // that overflows number_float_t is rejected with out_of_range.406.
+    struct binary_format
+    {
+        const char* name;
+        bytes (*encode)(const json&);
+        narrow_json (*decode)(const bytes&, bool);
+    };
+
+    const std::vector<binary_format> formats =
+    {
+        {"CBOR", encode_cbor, decode_cbor},
+        {"MessagePack", encode_msgpack, decode_msgpack},
+        {"UBJSON", encode_ubjson, decode_ubjson},
+        {"BJData", encode_bjdata, decode_bjdata},
+        {"BSON", encode_bson, decode_bson},
+        {"BON8", encode_bon8, decode_bon8},
+    };
+
+    for (const auto& format : formats)
+    {
+        const std::string name = format.name;
+        INFO("format := ", name);
+        const auto roundtrip = [&format](const json & j)
+        {
+            return format.decode(format.encode(j), true);
+        };
+
+        // integers that fit keep their type
+        CHECK(roundtrip(json(-5)).is_number_integer());
+        CHECK(roundtrip(json(-5)).get<std::int32_t>() == -5);
+        CHECK(roundtrip(json(3000000000u)).is_number_unsigned());
+        CHECK(roundtrip(json(3000000000u)).get<std::uint32_t>() == 3000000000u);
+
+        // integers that fit neither integer type are stored as float
+        CHECK(roundtrip(json(5000000000u)).is_number_float());
+        CHECK(roundtrip(json(5000000000u)).get<float>() == 5000000000.0f);
+        if (name != "BON8") // BON8 cannot encode integers above INT64_MAX
+        {
+            CHECK(roundtrip(json(10000000000000000000u)).is_number_float());
+            CHECK(roundtrip(json(10000000000000000000u)).get<float>() == 10000000000000000000.0f);
+        }
+        CHECK(roundtrip(json(-3000000000LL)).is_number_float());
+        CHECK(roundtrip(json(-3000000000LL)).get<float>() == -3000000000.0f);
+        CHECK(roundtrip(json(-5000000000LL)).is_number_float());
+        CHECK(roundtrip(json(-5000000000LL)).get<float>() == -5000000000.0f);
+
+        // floating-point numbers that fit
+        CHECK(roundtrip(json(1.5)).get<float>() == 1.5f);
+        const auto just_above_max = std::nextafter(static_cast<double>((std::numeric_limits<float>::max)()),
+                                    std::numeric_limits<double>::infinity());
+        CHECK(roundtrip(json(just_above_max)).get<float>() == (std::numeric_limits<float>::max)());
+
+        // infinity and NaN are passed on
+        CHECK(std::isinf(roundtrip(json(std::numeric_limits<double>::infinity())).get<float>()));
+        CHECK(std::isnan(roundtrip(json(std::numeric_limits<double>::quiet_NaN())).get<float>()));
+
+        // finite floating-point numbers that overflow number_float_t are rejected
+        const std::string message = "[json.exception.out_of_range.406] syntax error while parsing " + name
+                                    + " value: number overflow";
+        CHECK_THROWS_WITH_AS(roundtrip(json(1e300)), message.c_str(), narrow_json::out_of_range&);
+        CHECK_THROWS_WITH_AS(roundtrip(json(-1e300)), message.c_str(), narrow_json::out_of_range&);
+        CHECK(format.decode(format.encode(json(1e300)), false).is_discarded());
+    }
+}

tests/src/unit-cbor.cpp

@@ -3187,7 +3187,8 @@ TEST_CASE("Tagged values")
         // CBOR encodes negative integers as: result = -1 - n
         // For type 0x3B, n is an 8-byte uint64_t. Valid range for n with
         // the default int64_t is [0, INT64_MAX], producing results in [INT64_MIN, -1].
-        // When n > INT64_MAX, the result exceeds int64_t range and is rejected.
+        // When n > INT64_MAX, the result exceeds int64_t range and is stored
+        // as a floating-point number, as the lexer does for JSON text.
 
         SECTION("n = 0 is valid (result = -1)")
         {
@@ -3208,33 +3209,34 @@ TEST_CASE("Tagged values")
             CHECK(result.get<int64_t>() == (std::numeric_limits<int64_t>::min)());
         }
 
-        SECTION("n = INT64_MAX + 1 is rejected (overflow)")
+        SECTION("n = INT64_MAX + 1 is stored as float")
         {
             // n = INT64_MAX + 1 (0x8000000000000000)
-            // result = -1 - n = -9223372036854775809, which exceeds int64_t range
+            // result = -1 - n = -9223372036854775809, which exceeds int64_t range;
+            // the nearest double is -9223372036854775808.0
             const std::vector<uint8_t> input = {0x3B, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
-            json _;
-            CHECK_THROWS_WITH_AS(_ = json::from_cbor(input),
-                                 "[json.exception.parse_error.112] parse error at byte 9: syntax error while parsing CBOR value: negative integer overflow",
-                                 json::parse_error);
+            const auto result = json::from_cbor(input);
+            CHECK(result.is_number_float());
+            CHECK(result.get<double>() == -9223372036854775808.0);
+            CHECK(result == json::parse("-9223372036854775809"));
         }
 
-        SECTION("n = UINT64_MAX is rejected (overflow)")
+        SECTION("n = UINT64_MAX is stored as float")
         {
             // n = UINT64_MAX (0xFFFFFFFFFFFFFFFF)
             // result = -1 - n = -18446744073709551616, which exceeds int64_t range
             const std::vector<uint8_t> input = {0x3B, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};
-            json _;
-            CHECK_THROWS_WITH_AS(_ = json::from_cbor(input),
-                                 "[json.exception.parse_error.112] parse error at byte 9: syntax error while parsing CBOR value: negative integer overflow",
-                                 json::parse_error);
+            const auto result = json::from_cbor(input);
+            CHECK(result.is_number_float());
+            CHECK(result.get<double>() == -18446744073709551616.0);
+            CHECK(result == json::parse("-18446744073709551616"));
         }
 
-        SECTION("overflow with allow_exceptions=false returns discarded")
+        SECTION("overflow with allow_exceptions=false is not an error")
         {
             const std::vector<uint8_t> input = {0x3B, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
             const auto result = json::from_cbor(input, true, false);
-            CHECK(result.is_discarded());
+            CHECK(result.is_number_float());
         }
     }