Rename names that Flawfinder takes for the file function open()

The comparison cursors' open() is now enter(), and a test's open and
close strings are head and tail.

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

include/nlohmann/detail/json_pointer.hpp

@@ -15,7 +15,7 @@
 #include <cstddef> // size_t
 #include <cstdint> // uint64_t
 #include <cstdlib> // strtoull
-#include <cstring> // memchr, memcmp, memcpy
+#include <cstring> // memcmp, memcpy
 #ifndef JSON_NO_IO
     #include <iosfwd> // ostream
 #endif  // JSON_NO_IO
@@ -303,12 +303,6 @@ class json_pointer
         exceeds_size_type  ///< @a s converts to an integer that exceeds size_type
     };
 
-    /// whether a reference token is "-" (a plain comparison with a string literal is not always inlined)
-    static bool is_dash(const string_t& s) noexcept
-    {
-        return s.size() == 1 && s[0] == '-';
-    }
-
     /*!
     @param[in] s    reference token to be converted into an array index
     @param[out] idx the integer representation of @a s if @ref array_index_status::ok
@@ -334,7 +328,7 @@ class json_pointer
         // error condition (cf. RFC 6901, Sect. 4); this also covers single-
         // character tokens, so "/x" and "/xy" fail alike; "-" and the empty
         // token are left to the conversion below and are reported as unresolved
-        if (JSON_HEDLEY_UNLIKELY(!s.empty() && !is_dash(s) && !(s[0] >= '0' && s[0] <= '9')))
+        if (JSON_HEDLEY_UNLIKELY(!s.empty() && s != "-" && !(s[0] >= '0' && s[0] <= '9')))
         {
             return array_index_status::not_a_number;
         }
@@ -481,40 +475,9 @@ class json_pointer
         return pos == size;
     }
 
-    /// reserve room for @a n elements of an array type that has reserve()
-    template<typename ArrayType>
-    static auto reserve_elements(ArrayType& array, const std::size_t n, detail::priority_tag<1> /*unused*/)
-    -> decltype(array.reserve(n), void())
-    {
-        array.reserve(n);
-    }
-
-    template<typename ArrayType>
-    static void reserve_elements(ArrayType& /*array*/, const std::size_t /*n*/, detail::priority_tag<0> /*unused*/)
-    {}
-
     /// @brief object member access with a key that is only copied if it is inserted
-    ///
-    /// Objects that can find the position of a key and insert there
-    /// (std::map) search once, others look the key up and add it if it is missing.
     template<typename BasicJsonType>
-    static auto object_member_impl(BasicJsonType& object, const string_t& key, detail::priority_tag<1> /*unused*/)
-    -> decltype(object.m_data.m_value.object->emplace_hint(object.m_data.m_value.object->lower_bound(key), key, nullptr), std::declval<BasicJsonType&>())
-    {
-        auto& members = *object.m_data.m_value.object;
-        auto it = members.lower_bound(key);
-        if (it != members.end() && !members.key_comp()(key, it->first))
-        {
-            return it->second;
-        }
-
-        const auto old_capacity = object.container_capacity();
-        it = members.emplace_hint(it, key, nullptr);
-        return object.set_parent_after_insert(it->second, old_capacity);
-    }
-
-    template<typename BasicJsonType>
-    static BasicJsonType& object_member_impl(BasicJsonType& object, const string_t& key, detail::priority_tag<0> /*unused*/)
+    static BasicJsonType& object_member(BasicJsonType& object, const string_t& key)
     {
         auto& members = *object.m_data.m_value.object;
         const auto it = members.find(key);
@@ -525,12 +488,6 @@ class json_pointer
         return object.operator[](key);
     }
 
-    template<typename BasicJsonType>
-    static BasicJsonType& object_member(BasicJsonType& object, const string_t& key)
-    {
-        return object_member_impl(object, key, detail::priority_tag<1> {});
-    }
-
   JSON_PRIVATE_UNLESS_TESTED:
     json_pointer top() const
     {
@@ -763,103 +720,48 @@ class json_pointer
         }
     }
 
-    /*!
-    @brief the values along the pointer last resolved by @ref resolve_plain
-
-    A patch from @ref basic_json::diff lists its operations in document order,
-    so consecutive pointers share most of their reference tokens; the values
-    along the previous pointer are kept to resume from the common prefix.
-    `steps[k]` is the value after the first `k` reference tokens together with
-    the length of the prefix of `*path` that holds them. A value stays valid as
-    long as no operation changes its container: callers keep only values up to
-    the parent of the pointer they modify, or call `reset()`.
-    */
-    template<typename BasicJsonType>
-    struct plain_steps
-    {
-        const string_t* path = nullptr;
-        std::vector<std::pair<std::size_t, BasicJsonType*>> steps{};
-
-        void reset() noexcept
-        {
-            path = nullptr;
-            steps.clear();
-        }
-    };
-
     /*!
     @brief resolve a plain JSON pointer without building its reference tokens
 
-    @param[in] root    the value the pointer starts at
+    @param[in] ptr     the value the pointer starts at
     @param[in] path    a JSON pointer string
     @param[in] length  the number of leading bytes of @a path to resolve; 0 or
                        the position of a slash
     @param[in,out] token  a string to hold the reference tokens, to reuse its storage
-    @param[in,out] cache  the values along the previously resolved pointer;
-                          @a path must outlive the next call
 
     @return the pointed to value, or `nullptr` if the pointer does not denote
-            an existing value, or does so in a way that is not plain: an array
-            index that is malformed or out of range, or a "-", or a reference
-            token with an escape. No exception is
-            thrown for these; callers use @ref json_pointer instead, which
-            handles them.
+            an existing value, or does so in a way that is not plain: a
+            reference token with an escape, an array index that is malformed or
+            out of range, or a "-". No exception is thrown for these; callers
+            use @ref json_pointer instead, which handles them.
     */
     template<typename BasicJsonType>
-    static BasicJsonType* resolve_plain(BasicJsonType* root, const string_t& path, const std::size_t length, string_t& token, plain_steps<BasicJsonType>& cache)
+    static BasicJsonType* resolve_plain(BasicJsonType* ptr, const string_t& path, const std::size_t length, string_t& token)
     {
-        auto& steps = cache.steps;
-
-        // resume from the deepest step that is also a prefix of this path
-        std::size_t depth = 1;
-        if (cache.path != nullptr && !steps.empty() && steps[0].second == root)
-        {
-            const string_t& previous = *cache.path;
-            for (depth = steps.size(); depth > 1; --depth)
-            {
-                // a step ends at a token boundary of the previous path
-                const std::size_t prefix = steps[depth - 1].first;
-                if (prefix <= length && (prefix == length || path[prefix] == '/') && std::memcmp(path.data(), previous.data(), prefix) == 0)
-                {
-                    break;
-                }
-            }
-            steps.resize(depth);
-        }
-        else
-        {
-            steps.assign(1, std::make_pair(std::size_t{0}, root));
-        }
-        cache.path = &path;
-
-        BasicJsonType* ptr = steps[depth - 1].second;
-        for (std::size_t pos = steps[depth - 1].first; pos < length;)
+        for (std::size_t pos = 0; pos < length;)
         {
             if (JSON_HEDLEY_UNLIKELY(path[pos] != '/'))
             {
                 return nullptr;
             }
 
-            // the reference token between the slash at pos and the next one,
-            // which must not have an escape
-            const char* const begin = path.data() + pos + 1;
-            const char* const limit = path.data() + length;
-            const char* end = begin;
-            while (end < limit && *end != '/')
+            // the reference token between the slash at pos and the next one
+            std::size_t end = path.find_first_of('/', pos + 1);
+            if (end == string_t::npos || end > length)
             {
-                if (JSON_HEDLEY_UNLIKELY(*end == '~'))
-                {
-                    return nullptr;
-                }
-                ++end;
+                end = length;
+            }
+            token.clear();
+            token.append(path.data() + pos + 1, end - pos - 1);
+            if (JSON_HEDLEY_UNLIKELY(token.find_first_of('~') != string_t::npos))
+            {
+                return nullptr;
             }
 
             switch (ptr->type())
             {
                 case detail::value_t::object:
                 {
-                    token.clear();
-                    token.append(begin, static_cast<std::size_t>(end - begin));
                     const auto it = ptr->m_data.m_value.object->find(token);
                     if (JSON_HEDLEY_UNLIKELY(it == ptr->m_data.m_value.object->end()))
                     {
@@ -871,24 +773,8 @@ class json_pointer
 
                 case detail::value_t::array:
                 {
-                    // an index of up to 18 digits without a leading zero fits into size_type
-                    // (9 digits for a 32-bit size_type); everything else is left to json_pointer
-                    constexpr std::size_t max_digits = sizeof(typename BasicJsonType::size_type) >= 8 ? 18 : 9;
-                    const std::size_t digits = static_cast<std::size_t>(end - begin);
-                    if (JSON_HEDLEY_UNLIKELY(digits == 0 || digits > max_digits || (digits > 1 && *begin == '0')))
-                    {
-                        return nullptr;
-                    }
-                    typename BasicJsonType::size_type idx = 0;
-                    for (const char* c = begin; c != end; ++c)
-                    {
-                        if (JSON_HEDLEY_UNLIKELY(*c < '0' || *c > '9'))
-                        {
-                            return nullptr;
-                        }
-                        idx = static_cast<typename BasicJsonType::size_type>((idx * 10) + static_cast<typename BasicJsonType::size_type>(*c - '0'));
-                    }
-                    if (JSON_HEDLEY_UNLIKELY(idx >= ptr->m_data.m_value.array->size()))
+                    typename BasicJsonType::size_type idx{};
+                    if (JSON_HEDLEY_UNLIKELY(parse_array_index<BasicJsonType>(token, idx) != array_index_status::ok || idx >= ptr->m_data.m_value.array->size()))
                     {
                         return nullptr;
                     }
@@ -907,8 +793,7 @@ class json_pointer
                 default:
                     return nullptr;
             }
-            pos = static_cast<std::size_t>(end - path.data());
-            steps.emplace_back(pos, ptr);
+            pos = end;
         }
 
         return ptr;
@@ -1022,7 +907,7 @@ class json_pointer
 
                 case detail::value_t::array:
                 {
-                    if (JSON_HEDLEY_UNLIKELY(is_dash(reference_token)))
+                    if (JSON_HEDLEY_UNLIKELY(reference_token == "-"))
                     {
                         // "-" always fails the range check
                         JSON_THROW(detail::out_of_range::create(detail::exception_id::pointer_past_the_end_index, detail::concat(
@@ -1093,7 +978,7 @@ class json_pointer
 
                 case detail::value_t::array:
                 {
-                    if (JSON_HEDLEY_UNLIKELY(is_dash(reference_token)))
+                    if (JSON_HEDLEY_UNLIKELY(reference_token == "-"))
                     {
                         // "-" cannot be used for const access
                         JSON_THROW(detail::out_of_range::create(detail::exception_id::pointer_past_the_end_index, detail::concat("array index '-' (", std::to_string(ptr->m_data.m_value.array->size()), ") is out of range"), ptr));
@@ -1155,7 +1040,7 @@ class json_pointer
 
                 case detail::value_t::array:
                 {
-                    if (JSON_HEDLEY_UNLIKELY(is_dash(reference_token)))
+                    if (JSON_HEDLEY_UNLIKELY(reference_token == "-"))
                     {
                         // "-" always fails the range check
                         return nullptr;
@@ -1232,7 +1117,7 @@ class json_pointer
 
                 case detail::value_t::array:
                 {
-                    if (JSON_HEDLEY_UNLIKELY(is_dash(reference_token)))
+                    if (JSON_HEDLEY_UNLIKELY(reference_token == "-"))
                     {
                         // "-" always fails the range check
                         return false;
@@ -1391,52 +1276,6 @@ class json_pointer
         obj[key] = std::forward<ValueType>(v);
     }
 
-    /// the number of entries that flattening @a value adds: its primitive
-    /// values and empty containers
-    template<typename BasicJsonType>
-    static std::size_t count_flattened(const BasicJsonType& value)
-    {
-        std::size_t count = 0;
-        std::vector<const BasicJsonType*> pending(1, &value);
-        while (!pending.empty())
-        {
-            const BasicJsonType* const v = pending.back();
-            pending.pop_back();
-            if (v->is_array() && !v->m_data.m_value.array->empty())
-            {
-                for (const auto& element : *v->m_data.m_value.array)
-                {
-                    pending.push_back(&element);
-                }
-            }
-            else if (v->is_object() && !v->m_data.m_value.object->empty())
-            {
-                for (const auto& member : *v->m_data.m_value.object)
-                {
-                    pending.push_back(&member.second);
-                }
-            }
-            else
-            {
-                ++count;
-            }
-        }
-        return count;
-    }
-
-    // Reserve the storage for @a value of objects that have a reserve(), so
-    // that it does not have to be moved while it grows
-    template<typename ObjectType, typename BasicJsonType>
-    static auto reserve_flattened(ObjectType& obj, const BasicJsonType& value, detail::priority_tag<1> /*unused*/)
-    -> decltype(obj.reserve(std::size_t {}), void())
-    {
-        obj.reserve(count_flattened(value));
-    }
-
-    template<typename ObjectType, typename BasicJsonType>
-    static void reserve_flattened(ObjectType& /*obj*/, const BasicJsonType& /*value*/, detail::priority_tag<0> /*unused*/)
-    {}
-
     /// append the decimal representation of @a i to @a out
     static void append_index(string_t& out, std::size_t i)
     {
@@ -1546,7 +1385,6 @@ class json_pointer
             }
         };
 
-        reserve_flattened(object, value, detail::priority_tag<1> {});
         enter(value);
         while (!stack.empty())
         {
@@ -1554,9 +1392,8 @@ class json_pointer
             // frame, which would invalidate a reference to it
             const BasicJsonType* const container = stack.back().container;
 
-            // the path of the previous child is replaced by the path of the
-            // next one; for an array element in one resize
-            const std::size_t path_length = stack.back().path_length;
+            // drop the path of the previous child
+            path.resize(stack.back().path_length);
 
             if (container->is_array())
             {
@@ -1570,20 +1407,8 @@ class json_pointer
 
                 // iterate array and use index as a reference string
                 ++stack.back().index;
-                std::array<char, 24> digits{};
-                std::size_t pos = digits.size();
-                std::size_t rest = i;
-                do
-                {
-                    digits[--pos] = static_cast<char>('0' + rest % 10);
-                    rest /= 10;
-                }
-                while (rest != 0);
-                const std::size_t count = digits.size() - pos;
-                path.resize(path_length + 1 + count);
-                char* const out = &path[path_length];
-                out[0] = '/';
-                std::memcpy(out + 1, digits.data() + pos, count);
+                path.push_back('/');
+                append_index(path, i);
                 enter(array[i]);
             }
             else
@@ -1597,7 +1422,6 @@ class json_pointer
 
                 // iterate object and use keys as reference string
                 ++stack.back().member;
-                path.resize(path_length);
                 path.push_back('/');
                 detail::escape_into(path, it->first);
                 enter(it->second);
@@ -1693,28 +1517,8 @@ class json_pointer
                 {
                     end = key.size();
                 }
-                const std::size_t token_size = end - pos - 1;
-
-                // a token that is a plain index of up to 9 digits, which is
-                // the case for almost all array elements, is not copied
-                std::size_t index = 0;
-                bool plain_index = current->type() == detail::value_t::array && token_size != 0 && token_size <= 9 && (token_size == 1 || data[pos + 1] != '0');
-                for (std::size_t k = pos + 1; plain_index && k < end; ++k)
-                {
-                    plain_index = data[k] >= '0' && data[k] <= '9';
-                    index = (index * 10) + static_cast<std::size_t>(data[k] - '0');
-                }
-                if (plain_index)
-                {
-                    current = &current->operator[](static_cast<typename BasicJsonType::size_type>(index));
-                    values.push_back(current);
-                    ends.push_back(end);
-                    pos = end;
-                    continue;
-                }
-
                 token.clear();
-                token.append(data + pos + 1, token_size);
+                token.append(data + pos + 1, end - pos - 1);
                 if (token.find_first_of('~') != string_t::npos)
                 {
                     detail::unescape(token);
@@ -1724,13 +1528,10 @@ class json_pointer
                 {
                     case detail::value_t::null:
                     {
-                        // a first child 0 makes the value an array without a look-up
-                        if ((token_size == 1 && data[pos + 1] == '0') || arrays.contains(data, pos))
+                        if (arrays.contains(data, pos))
                         {
                             // some reference token below this position is 0, so the
                             // value is an array
-                            *current = BasicJsonType(detail::value_t::array);
-                            reserve_elements(*current->m_data.m_value.array, 2, detail::priority_tag<1> {});
                             current = &current->operator[](array_index<BasicJsonType>(token));
                         }
                         else

include/nlohmann/detail/view/image.hpp

@@ -255,6 +255,82 @@ struct number_token
     bool is_float; ///< a fraction or an exponent
 };
 
+/// advance over ASCII digits, eight bytes at a time
+inline const unsigned char* digit_run(const unsigned char* p, const unsigned char* e) noexcept
+{
+    constexpr std::uint64_t ones = 0x0101010101010101ull;
+    while (e - p >= 8)
+    {
+        // (the digits become 0..9; a byte above 9, or with bit 7 set, is no digit. A carry
+        // out of a byte with bit 7 set only affects the bytes above, after the first one
+        // that count_trailing_zeros finds.)
+        const std::uint64_t x = read_eight_bytes(p) ^ (ones * 0x30u);
+        const std::uint64_t not_digit = ((x + (ones * 0x76u)) | x) & (ones * 0x80u);
+        if (not_digit != 0)
+        {
+            return p + (static_cast<std::size_t>(count_trailing_zeros(not_digit)) / 8);
+        }
+        p += 8;
+    }
+    while (p != e && is_digit(*p))
+    {
+        ++p;
+    }
+    return p;
+}
+
+/// whether the n bytes at p are ASCII digits (n > 0)
+inline bool all_digits(const unsigned char* p, std::size_t n) noexcept
+{
+    constexpr std::uint64_t ones = 0x0101010101010101ull;
+    const auto digits = [](const unsigned char* q)
+    {
+        const std::uint64_t x = read_eight_bytes(q) ^ (ones * 0x30u);
+        return (((x + (ones * 0x76u)) | x) & (ones * 0x80u)) == 0;
+    };
+    if (n >= 8)
+    {
+        std::size_t i = 0;
+        for (; i + 8 < n; i += 8)
+        {
+            if (!digits(p + i))
+            {
+                return false;
+            }
+        }
+        return digits(p + n - 8); // (overlapping the bytes before: they are digits)
+    }
+    for (std::size_t i = 0; i < n; ++i)
+    {
+        if (!is_digit(p[i]))
+        {
+            return false;
+        }
+    }
+    return true;
+}
+
+/// Whether a float token has the shape that the parser records for most of
+/// them: [-]digits.digits, with the numbers of digits of the node's layout
+/// (extra). Then the token is a number of that layout, and the general scan
+/// that follows is not needed.
+inline bool plain_float_token(const unsigned char* s, std::size_t len, std::uint16_t extra) noexcept
+{
+    const std::size_t int_digits = extra & 0xFFu;
+    const std::size_t frac_digits = extra >> 8u;
+    if (int_digits == 0 || int_digits >= 255 || frac_digits == 0 || frac_digits >= 255 || len == 0)
+    {
+        return false;
+    }
+    const std::size_t negative = *s == '-' ? 1 : 0;
+    if (len != negative + int_digits + 1 + frac_digits)
+    {
+        return false;
+    }
+    const unsigned char* const p = s + negative;
+    return !(int_digits > 1 && *p == '0') && p[int_digits] == '.' && all_digits(p, int_digits) && all_digits(p + int_digits + 1, frac_digits);
+}
+
 /// whether [s, s + len) is a JSON number (the grammar the parser accepts)
 inline bool scan_number_token(const unsigned char* s, std::size_t len, number_token& t)
 {
@@ -273,11 +349,7 @@ inline bool scan_number_token(const unsigned char* s, std::size_t len, number_to
     }
     else if (*p >= '1' && *p <= '9')
     {
-        do
-        {
-            ++p;
-        }
-        while (p != e && is_digit(*p));
+        p = digit_run(p + 1, e);
     }
     else
     {
@@ -289,10 +361,7 @@ inline bool scan_number_token(const unsigned char* s, std::size_t len, number_to
     if (p != e && *p == '.')
     {
         const unsigned char* const f0 = ++p;
-        while (p != e && is_digit(*p))
-        {
-            ++p;
-        }
+        p = digit_run(p, e);
         if (p == f0)
         {
             return false;
@@ -403,10 +472,15 @@ struct float_range
 template<typename Check>
 bool check_distinct_ranges(std::vector<byte_range>& ranges, Check check)
 {
-    std::sort(ranges.begin(), ranges.end(), [](const byte_range & a, const byte_range & b)
+    // (save() writes the ranges in the order of the nodes, which is sorted already)
+    const auto before = [](const byte_range & a, const byte_range & b)
     {
         return a.off != b.off ? a.off < b.off : a.len < b.len;
-    });
+    };
+    if (!std::is_sorted(ranges.begin(), ranges.end(), before))
+    {
+        std::sort(ranges.begin(), ranges.end(), before);
+    }
     std::size_t end = 0;
     for (std::size_t i = 0; i < ranges.size(); ++i)
     {
@@ -428,7 +502,8 @@ bool check_distinct_ranges(std::vector<byte_range>& ranges, Check check)
 /// record layouts that match it), tokens must not overlap.
 inline bool check_float_ranges(std::vector<float_range>& ranges, const unsigned char* text)
 {
-    std::sort(ranges.begin(), ranges.end(), [](const float_range & a, const float_range & b)
+    // (save() writes the tokens in the order of the nodes, which is sorted already)
+    const auto before = [](const float_range & a, const float_range & b)
     {
         if (a.off != b.off)
         {
@@ -439,7 +514,11 @@ inline bool check_float_ranges(std::vector<float_range>& ranges, const unsigned
             return a.len < b.len;
         }
         return a.extra < b.extra;
-    });
+    };
+    if (!std::is_sorted(ranges.begin(), ranges.end(), before))
+    {
+        std::sort(ranges.begin(), ranges.end(), before);
+    }
     std::size_t end = 0;
     std::size_t i = 0;
     while (i < ranges.size())
@@ -449,14 +528,18 @@ inline bool check_float_ranges(std::vector<float_range>& ranges, const unsigned
         {
             return false;
         }
-        number_token t{};
         const unsigned char* const s = text + r.off;
-        if (!scan_number_token(s, r.len, t) || !float_token_finite(s, r.len, t))
+        std::uint16_t layout = r.extra;
+        if (!plain_float_token(s, r.len, r.extra))
         {
-            return false;
+            number_token t{};
+            if (!scan_number_token(s, r.len, t) || !float_token_finite(s, r.len, t))
+            {
+                return false;
+            }
+            // the digit layout the parser records (or "many", as compaction writes it)
+            layout = float_layout(t);
         }
-        // the digit layout the parser records (or "many", as compaction writes it)
-        const std::uint16_t layout = float_layout(t);
         for (; i < ranges.size() && ranges[i].off == r.off && ranges[i].len == r.len; ++i)
         {
             if (ranges[i].extra != layout && ranges[i].extra != 0xFFFFu)

include/nlohmann/detail/view/node.hpp

@@ -120,6 +120,74 @@ NLOHMANN_VIEW_ALWAYS_INLINE std::uint32_t number_length(const node& n) noexcept
            : (n.extra & 0xFFu) + (n.kind == static_cast<std::uint8_t>(value_t::number_integer) ? 1u : 0u);
 }
 
+/// whether n bytes are equal; the short texts of JSON (keys, numbers, most
+/// strings) are compared by two overlapping loads instead of a library call
+NLOHMANN_VIEW_ALWAYS_INLINE bool bytes_equal(const char* x, const char* y, std::size_t n) noexcept
+{
+    const auto load8 = [](const char* p)
+    {
+        std::uint64_t v = 0;
+        std::memcpy(&v, p, sizeof(v));
+        return v;
+    };
+    const auto load4 = [](const char* p)
+    {
+        std::uint32_t v = 0;
+        std::memcpy(&v, p, sizeof(v));
+        return v;
+    };
+    if (n >= 8)
+    {
+        std::size_t i = 0;
+        for (; i + 8 < n; i += 8)
+        {
+            if (load8(x + i) != load8(y + i))
+            {
+                return false;
+            }
+        }
+        return load8(x + n - 8) == load8(y + n - 8);
+    }
+    if (n >= 4)
+    {
+        return load4(x) == load4(y) && load4(x + n - 4) == load4(y + n - 4);
+    }
+    for (std::size_t i = 0; i < n; ++i)
+    {
+        if (x[i] != y[i])
+        {
+            return false;
+        }
+    }
+    return true;
+}
+
+/// whether the n1 bytes at x are before the n2 bytes at y (memcmp() order, then the shorter first);
+/// the first difference is found eight bytes at a time
+NLOHMANN_VIEW_ALWAYS_INLINE bool bytes_less(const char* x, std::size_t n1, const char* y, std::size_t n2) noexcept
+{
+    const std::size_t n = n1 < n2 ? n1 : n2;
+    std::size_t i = 0;
+    for (; i + 8 <= n; i += 8)
+    {
+        const std::uint64_t u = read_eight_bytes(x + i);
+        const std::uint64_t v = read_eight_bytes(y + i);
+        if (u != v)
+        {
+            const auto shift = static_cast<unsigned>(count_trailing_zeros(u ^ v)) & ~7u; // (the first byte that differs)
+            return ((u >> shift) & 0xFFu) < ((v >> shift) & 0xFFu);
+        }
+    }
+    for (; i < n; ++i)
+    {
+        if (x[i] != y[i])
+        {
+            return static_cast<unsigned char>(x[i]) < static_cast<unsigned char>(y[i]);
+        }
+    }
+    return n1 < n2;
+}
+
 /// estimated number of nodes for an input of `size` bytes (one node per ~12
 /// bytes covers typical documents without regrowth)
 inline std::size_t estimate_nodes(std::size_t size) noexcept

include/nlohmann/json.hpp

@@ -6878,72 +6878,6 @@ public:
     /// @name JSON Patch functions
     /// @{
 
-  private:
-    /// the members of an operation of a JSON patch that are of interest
-    struct patch_members
-    {
-        basic_json* op = nullptr;
-        basic_json* path = nullptr;
-        basic_json* value = nullptr;
-        basic_json* from = nullptr;
-    };
-
-    /// @brief find the members "op", "path", "value", and "from" of the object @a val in one pass
-    static patch_members find_patch_members(const basic_json& val, std::true_type /*key_type is string_t*/)
-    {
-        patch_members members;
-        for (auto& member : *val.m_data.m_value.object)
-        {
-            const string_t& key = member.first;
-            switch (key.size())
-            {
-                case 2:
-                    if (key == "op")
-                    {
-                        members.op = &member.second;
-                    }
-                    break;
-                case 4:
-                    if (key == "path")
-                    {
-                        members.path = &member.second;
-                    }
-                    else if (key == "from")
-                    {
-                        members.from = &member.second;
-                    }
-                    break;
-                case 5:
-                    if (key == "value")
-                    {
-                        members.value = &member.second;
-                    }
-                    break;
-                default:
-                    break;
-            }
-        }
-        return members;
-    }
-
-    /// @brief find the members by lookup for key types other than string_t
-    static patch_members find_patch_members(const basic_json& val, std::false_type /*key_type is not string_t*/)
-    {
-        const auto find_member = [&val](const char* name) -> basic_json *
-        {
-            const auto it = val.m_data.m_value.object->find(string_t(name));
-            return it != val.m_data.m_value.object->end() ? &it->second : nullptr;
-        };
-
-        patch_members members;
-        members.op = find_member("op");
-        members.path = find_member("path");
-        members.value = find_member("value");
-        members.from = find_member("from");
-        return members;
-    }
-
-  public:
     /// @brief applies a JSON patch in-place without copying the object
     /// @sa https://json.nlohmann.me/api/basic_json/patch/
     void patch_inplace(const basic_json& json_patch)
@@ -7117,18 +7051,18 @@ public:
         // a diff creates them: apply the operation and return true; return
         // false, with nothing changed, for all others
         string_t token;
-        typename json_pointer::template plain_steps<basic_json> steps;
-        const auto try_plain = [&result, &token, &steps](patch_operations operation, const string_t& path, const patch_members & members, const basic_json & val)
+        const string_t value_key = "value";
+        const auto try_plain = [&result, &token, &value_key](patch_operations operation, const string_t& path, const basic_json & val)
         {
-            if (path.empty())
+            if (path.empty() || path.find_first_of('~') != string_t::npos)
             {
                 return false;
             }
 
             // a missing "value" is reported below
-            const basic_json* const value_ptr = members.value;
-            const basic_json& value = value_ptr != nullptr ? *value_ptr : val;
-            if (operation != patch_operations::remove && value_ptr == nullptr)
+            const auto value_it = val.m_data.m_value.object->find(value_key);
+            const basic_json& value = value_it != val.m_data.m_value.object->end() ? value_it->second : val;
+            if (operation != patch_operations::remove && value_it == val.m_data.m_value.object->end())
             {
                 return false;
             }
@@ -7137,7 +7071,7 @@ public:
             {
                 case patch_operations::replace:
                 {
-                    basic_json* const target = json_pointer::resolve_plain(&result, path, path.size(), token, steps);
+                    basic_json* const target = json_pointer::resolve_plain(&result, path, path.size(), token);
                     if (target == nullptr)
                     {
                         return false;
@@ -7148,7 +7082,7 @@ public:
 
                 case patch_operations::test:
                 {
-                    const basic_json* const target = json_pointer::resolve_plain(&result, path, path.size(), token, steps);
+                    const basic_json* const target = json_pointer::resolve_plain(&result, path, path.size(), token);
                     // a failing test is reported below
                     return target != nullptr && *target == value;
                 }
@@ -7168,17 +7102,13 @@ public:
                     }
                     --slash;
 
-                    basic_json* const parent = json_pointer::resolve_plain(&result, path, slash, token, steps);
+                    basic_json* const parent = json_pointer::resolve_plain(&result, path, slash, token);
                     if (parent == nullptr)
                     {
                         return false;
                     }
                     token.clear();
                     token.append(path.data() + slash + 1, path.size() - slash - 1);
-                    if (token.find_first_of('~') != string_t::npos)
-                    {
-                        return false;
-                    }
 
                     if (operation == patch_operations::add)
                     {
@@ -7234,32 +7164,31 @@ public:
             }
         };
 
-        // the name of the first member to check
-        const string_t op_member = "op";
-
         // iterate and apply the operations
         for (const auto& val : json_patch)
         {
             // wrapper to get a value for an operation
-            const auto get_value = [&val](basic_json * found,
-                                          const string_t& op,
-                                          const char* member,
+            const auto get_value = [&val](const string_t& op,
+                                          const string_t& member,
                                           bool string_type) -> basic_json &
             {
+                // find value
+                auto it = val.m_data.m_value.object->find(member);
+
                 // check if the desired value is present
-                if (JSON_HEDLEY_UNLIKELY(found == nullptr))
+                if (JSON_HEDLEY_UNLIKELY(it == val.m_data.m_value.object->end()))
                 {
-                    detail::throw_patch_missing_member(op, string_t(member), false, val);
+                    detail::throw_patch_missing_member(op, member, false, val);
                 }
 
                 // check if the result is of type string
-                if (JSON_HEDLEY_UNLIKELY(string_type && !found->is_string()))
+                if (JSON_HEDLEY_UNLIKELY(string_type && !it->second.is_string()))
                 {
-                    detail::throw_patch_missing_member(op, string_t(member), true, val);
+                    detail::throw_patch_missing_member(op, member, true, val);
                 }
 
                 // no error: return value
-                return *found;
+                return it->second;
             };
 
             // type check: every element of the array must be an object
@@ -7268,30 +7197,26 @@ public:
                 detail::throw_patch_not_an_array(val);
             }
 
-            const patch_members members = find_patch_members(val, std::is_same<typename object_t::key_type, string_t> {});
-
             // collect mandatory members
-            const string_t& op = *get_value(members.op, op_member, "op", true).m_data.m_value.string;
-            const string_t& path = *get_value(members.path, op, "path", true).m_data.m_value.string;
+            const string_t& op = *get_value("op", "op", true).m_data.m_value.string;
+            const string_t& path = *get_value(op, "path", true).m_data.m_value.string;
             const patch_operations operation = get_op(op);
 
             // the usual operations on a plain pointer are applied without
             // building the pointer's reference tokens; anything else (and
             // every error) is handled below
-            if (try_plain(operation, path, members, val))
+            if (try_plain(operation, path, val))
             {
                 continue;
             }
 
-            // the general operations may change any container
-            steps.reset();
             json_pointer ptr(path);
 
             switch (operation)
             {
                 case patch_operations::add:
                 {
-                    operation_add(ptr, get_value(members.value, "add", "value", false));
+                    operation_add(ptr, get_value("add", "value", false));
                     break;
                 }
 
@@ -7304,13 +7229,13 @@ public:
                 case patch_operations::replace:
                 {
                     // the "path" location must exist - use at()
-                    result.at(ptr) = get_value(members.value, "replace", "value", false);
+                    result.at(ptr) = get_value("replace", "value", false);
                     break;
                 }
 
                 case patch_operations::move:
                 {
-                    const string_t& from_path = *get_value(members.from, "move", "from", true).m_data.m_value.string;
+                    const string_t& from_path = *get_value("move", "from", true).m_data.m_value.string;
                     json_pointer from_ptr(from_path);
 
                     if (JSON_HEDLEY_UNLIKELY(is_proper_prefix(from_ptr, ptr)))
@@ -7333,7 +7258,7 @@ public:
 
                 case patch_operations::copy:
                 {
-                    const string_t& from_path = *get_value(members.from, "copy", "from", true).m_data.m_value.string;
+                    const string_t& from_path = *get_value("copy", "from", true).m_data.m_value.string;
                     const json_pointer from_ptr(from_path);
 
                     // The copy is functionally identical to an "add"
@@ -7351,7 +7276,7 @@ public:
                     {
                         // check if "value" matches the one at "path"
                         // the "path" location must exist - use at()
-                        success = (result.at(ptr) == get_value(members.value, "test", "value", false));
+                        success = (result.at(ptr) == get_value("test", "value", false));
                     }
                     JSON_INTERNAL_CATCH (out_of_range&)
                     {
@@ -7443,18 +7368,13 @@ public:
     /// @brief append an operation @a op for @a path to @a result, with @a value if it is not null
     static void diff_operation(basic_json& result, const char* op, const string_t& path, const basic_json* value)
     {
-        // the keys are distinct and in the order of std::map; the members are
-        // added without looking them up
         basic_json entry(value_t::object);
-        auto& members = *entry.m_data.m_value.object;
-        typename object_t::iterator hint = members.end();
-        json_pointer::add_flattened(members, hint, string_t("op"), string_t(op), detail::priority_tag<2> {});
-        json_pointer::add_flattened(members, hint, string_t("path"), path, detail::priority_tag<2> {});
+        entry["op"] = op;
+        entry["path"] = path;
         if (value != nullptr)
         {
-            json_pointer::add_flattened(members, hint, string_t("value"), *value, detail::priority_tag<2> {});
+            entry["value"] = *value;
         }
-        entry.set_parents();
         result.push_back(std::move(entry));
     }
 
@@ -7476,50 +7396,6 @@ public:
         diff_operation(result, "add", path, &value);
     }
 
-    /// @brief the values in the target of the members of a source object, for the
-    ///        objects of up to 16 members without allocating
-    ///
-    /// reserve() must be called with the number of values that are added.
-    class diff_target_values
-    {
-      public:
-        diff_target_values() = default;
-        diff_target_values(const diff_target_values&) = delete;
-        diff_target_values& operator=(const diff_target_values&) = delete;
-        ~diff_target_values() = default;
-
-        void reserve(const std::size_t n)
-        {
-            if (n > inline_size)
-            {
-                large.resize(n);
-                items = large.data();
-            }
-        }
-
-        void push_back(const basic_json* value)
-        {
-            items[count++] = value;
-        }
-
-        std::size_t size() const noexcept
-        {
-            return count;
-        }
-
-        const basic_json* operator[](const std::size_t i) const noexcept
-        {
-            return items[i];
-        }
-
-      private:
-        static constexpr std::size_t inline_size = 16;
-        std::size_t count = 0;
-        const basic_json** items = inline_items;
-        std::vector<const basic_json*> large{}; // NOLINT(readability-redundant-member-init)
-        const basic_json* inline_items[inline_size]; // NOLINT(cppcoreguidelines-pro-type-member-init,hicpp-member-init)
-    };
-
     /// @brief append "/" and the decimal representation of @a index to @a path
     static void diff_append_index(string_t& path, std::size_t index)
     {
@@ -7600,9 +7476,8 @@ public:
     operations that remove every member of @a source and add every member of
     @a target to @a result, and returns false.
     */
-    template<typename TargetValues>
     static bool diff_object_keys(basic_json& result, const basic_json& source, const basic_json& target,
-                                 const string_t& path, TargetValues& target_values,
+                                 const string_t& path, std::vector<const basic_json*>& target_values,
                                  std::vector<const_iterator>& added)
     {
         // first pass: one lookup per source key
@@ -7816,7 +7691,7 @@ public:
 
             case value_t::object:
             {
-                diff_target_values target_values;
+                std::vector<const basic_json*> target_values;
                 std::vector<const_iterator> added;
                 if (diff_object_keys(result, source, target, path, target_values, added))
                 {

include/nlohmann/json_view.hpp

@@ -723,8 +723,12 @@ class basic_json_view
     template<typename, bool> friend class basic_json_document;
     template<typename, bool> friend class basic_json_view;
     template<typename, typename> friend class detail::view::editor;
+    template<typename, typename> friend class detail::view::view_side;
     friend iterator;
 
+    /// whether the view is one of an editable document
+    static constexpr bool is_editable = Editable;
+
     basic_json_view(const document_data* d, const node* n) noexcept
         : m_doc(d), m_node(n)
     {}

single_include/nlohmann/json.hpp

@@ -22357,7 +22357,7 @@ NLOHMANN_JSON_NAMESPACE_END
 #include <cstddef> // size_t
 #include <cstdint> // uint64_t
 #include <cstdlib> // strtoull
-#include <cstring> // memchr, memcmp, memcpy
+#include <cstring> // memcmp, memcpy
 #ifndef JSON_NO_IO
     #include <iosfwd> // ostream
 #endif  // JSON_NO_IO
@@ -22653,12 +22653,6 @@ class json_pointer
         exceeds_size_type  ///< @a s converts to an integer that exceeds size_type
     };
 
-    /// whether a reference token is "-" (a plain comparison with a string literal is not always inlined)
-    static bool is_dash(const string_t& s) noexcept
-    {
-        return s.size() == 1 && s[0] == '-';
-    }
-
     /*!
     @param[in] s    reference token to be converted into an array index
     @param[out] idx the integer representation of @a s if @ref array_index_status::ok
@@ -22684,7 +22678,7 @@ class json_pointer
         // error condition (cf. RFC 6901, Sect. 4); this also covers single-
         // character tokens, so "/x" and "/xy" fail alike; "-" and the empty
         // token are left to the conversion below and are reported as unresolved
-        if (JSON_HEDLEY_UNLIKELY(!s.empty() && !is_dash(s) && !(s[0] >= '0' && s[0] <= '9')))
+        if (JSON_HEDLEY_UNLIKELY(!s.empty() && s != "-" && !(s[0] >= '0' && s[0] <= '9')))
         {
             return array_index_status::not_a_number;
         }
@@ -22831,40 +22825,9 @@ class json_pointer
         return pos == size;
     }
 
-    /// reserve room for @a n elements of an array type that has reserve()
-    template<typename ArrayType>
-    static auto reserve_elements(ArrayType& array, const std::size_t n, detail::priority_tag<1> /*unused*/)
-    -> decltype(array.reserve(n), void())
-    {
-        array.reserve(n);
-    }
-
-    template<typename ArrayType>
-    static void reserve_elements(ArrayType& /*array*/, const std::size_t /*n*/, detail::priority_tag<0> /*unused*/)
-    {}
-
     /// @brief object member access with a key that is only copied if it is inserted
-    ///
-    /// Objects that can find the position of a key and insert there
-    /// (std::map) search once, others look the key up and add it if it is missing.
     template<typename BasicJsonType>
-    static auto object_member_impl(BasicJsonType& object, const string_t& key, detail::priority_tag<1> /*unused*/)
-    -> decltype(object.m_data.m_value.object->emplace_hint(object.m_data.m_value.object->lower_bound(key), key, nullptr), std::declval<BasicJsonType&>())
-    {
-        auto& members = *object.m_data.m_value.object;
-        auto it = members.lower_bound(key);
-        if (it != members.end() && !members.key_comp()(key, it->first))
-        {
-            return it->second;
-        }
-
-        const auto old_capacity = object.container_capacity();
-        it = members.emplace_hint(it, key, nullptr);
-        return object.set_parent_after_insert(it->second, old_capacity);
-    }
-
-    template<typename BasicJsonType>
-    static BasicJsonType& object_member_impl(BasicJsonType& object, const string_t& key, detail::priority_tag<0> /*unused*/)
+    static BasicJsonType& object_member(BasicJsonType& object, const string_t& key)
     {
         auto& members = *object.m_data.m_value.object;
         const auto it = members.find(key);
@@ -22875,12 +22838,6 @@ class json_pointer
         return object.operator[](key);
     }
 
-    template<typename BasicJsonType>
-    static BasicJsonType& object_member(BasicJsonType& object, const string_t& key)
-    {
-        return object_member_impl(object, key, detail::priority_tag<1> {});
-    }
-
   JSON_PRIVATE_UNLESS_TESTED:
     json_pointer top() const
     {
@@ -23113,103 +23070,48 @@ class json_pointer
         }
     }
 
-    /*!
-    @brief the values along the pointer last resolved by @ref resolve_plain
-
-    A patch from @ref basic_json::diff lists its operations in document order,
-    so consecutive pointers share most of their reference tokens; the values
-    along the previous pointer are kept to resume from the common prefix.
-    `steps[k]` is the value after the first `k` reference tokens together with
-    the length of the prefix of `*path` that holds them. A value stays valid as
-    long as no operation changes its container: callers keep only values up to
-    the parent of the pointer they modify, or call `reset()`.
-    */
-    template<typename BasicJsonType>
-    struct plain_steps
-    {
-        const string_t* path = nullptr;
-        std::vector<std::pair<std::size_t, BasicJsonType*>> steps{};
-
-        void reset() noexcept
-        {
-            path = nullptr;
-            steps.clear();
-        }
-    };
-
     /*!
     @brief resolve a plain JSON pointer without building its reference tokens
 
-    @param[in] root    the value the pointer starts at
+    @param[in] ptr     the value the pointer starts at
     @param[in] path    a JSON pointer string
     @param[in] length  the number of leading bytes of @a path to resolve; 0 or
                        the position of a slash
     @param[in,out] token  a string to hold the reference tokens, to reuse its storage
-    @param[in,out] cache  the values along the previously resolved pointer;
-                          @a path must outlive the next call
 
     @return the pointed to value, or `nullptr` if the pointer does not denote
-            an existing value, or does so in a way that is not plain: an array
-            index that is malformed or out of range, or a "-", or a reference
-            token with an escape. No exception is
-            thrown for these; callers use @ref json_pointer instead, which
-            handles them.
+            an existing value, or does so in a way that is not plain: a
+            reference token with an escape, an array index that is malformed or
+            out of range, or a "-". No exception is thrown for these; callers
+            use @ref json_pointer instead, which handles them.
     */
     template<typename BasicJsonType>
-    static BasicJsonType* resolve_plain(BasicJsonType* root, const string_t& path, const std::size_t length, string_t& token, plain_steps<BasicJsonType>& cache)
+    static BasicJsonType* resolve_plain(BasicJsonType* ptr, const string_t& path, const std::size_t length, string_t& token)
     {
-        auto& steps = cache.steps;
-
-        // resume from the deepest step that is also a prefix of this path
-        std::size_t depth = 1;
-        if (cache.path != nullptr && !steps.empty() && steps[0].second == root)
-        {
-            const string_t& previous = *cache.path;
-            for (depth = steps.size(); depth > 1; --depth)
-            {
-                // a step ends at a token boundary of the previous path
-                const std::size_t prefix = steps[depth - 1].first;
-                if (prefix <= length && (prefix == length || path[prefix] == '/') && std::memcmp(path.data(), previous.data(), prefix) == 0)
-                {
-                    break;
-                }
-            }
-            steps.resize(depth);
-        }
-        else
-        {
-            steps.assign(1, std::make_pair(std::size_t{0}, root));
-        }
-        cache.path = &path;
-
-        BasicJsonType* ptr = steps[depth - 1].second;
-        for (std::size_t pos = steps[depth - 1].first; pos < length;)
+        for (std::size_t pos = 0; pos < length;)
         {
             if (JSON_HEDLEY_UNLIKELY(path[pos] != '/'))
             {
                 return nullptr;
             }
 
-            // the reference token between the slash at pos and the next one,
-            // which must not have an escape
-            const char* const begin = path.data() + pos + 1;
-            const char* const limit = path.data() + length;
-            const char* end = begin;
-            while (end < limit && *end != '/')
+            // the reference token between the slash at pos and the next one
+            std::size_t end = path.find_first_of('/', pos + 1);
+            if (end == string_t::npos || end > length)
             {
-                if (JSON_HEDLEY_UNLIKELY(*end == '~'))
-                {
-                    return nullptr;
-                }
-                ++end;
+                end = length;
+            }
+            token.clear();
+            token.append(path.data() + pos + 1, end - pos - 1);
+            if (JSON_HEDLEY_UNLIKELY(token.find_first_of('~') != string_t::npos))
+            {
+                return nullptr;
             }
 
             switch (ptr->type())
             {
                 case detail::value_t::object:
                 {
-                    token.clear();
-                    token.append(begin, static_cast<std::size_t>(end - begin));
                     const auto it = ptr->m_data.m_value.object->find(token);
                     if (JSON_HEDLEY_UNLIKELY(it == ptr->m_data.m_value.object->end()))
                     {
@@ -23221,24 +23123,8 @@ class json_pointer
 
                 case detail::value_t::array:
                 {
-                    // an index of up to 18 digits without a leading zero fits into size_type
-                    // (9 digits for a 32-bit size_type); everything else is left to json_pointer
-                    constexpr std::size_t max_digits = sizeof(typename BasicJsonType::size_type) >= 8 ? 18 : 9;
-                    const std::size_t digits = static_cast<std::size_t>(end - begin);
-                    if (JSON_HEDLEY_UNLIKELY(digits == 0 || digits > max_digits || (digits > 1 && *begin == '0')))
-                    {
-                        return nullptr;
-                    }
-                    typename BasicJsonType::size_type idx = 0;
-                    for (const char* c = begin; c != end; ++c)
-                    {
-                        if (JSON_HEDLEY_UNLIKELY(*c < '0' || *c > '9'))
-                        {
-                            return nullptr;
-                        }
-                        idx = static_cast<typename BasicJsonType::size_type>((idx * 10) + static_cast<typename BasicJsonType::size_type>(*c - '0'));
-                    }
-                    if (JSON_HEDLEY_UNLIKELY(idx >= ptr->m_data.m_value.array->size()))
+                    typename BasicJsonType::size_type idx{};
+                    if (JSON_HEDLEY_UNLIKELY(parse_array_index<BasicJsonType>(token, idx) != array_index_status::ok || idx >= ptr->m_data.m_value.array->size()))
                     {
                         return nullptr;
                     }
@@ -23257,8 +23143,7 @@ class json_pointer
                 default:
                     return nullptr;
             }
-            pos = static_cast<std::size_t>(end - path.data());
-            steps.emplace_back(pos, ptr);
+            pos = end;
         }
 
         return ptr;
@@ -23372,7 +23257,7 @@ class json_pointer
 
                 case detail::value_t::array:
                 {
-                    if (JSON_HEDLEY_UNLIKELY(is_dash(reference_token)))
+                    if (JSON_HEDLEY_UNLIKELY(reference_token == "-"))
                     {
                         // "-" always fails the range check
                         JSON_THROW(detail::out_of_range::create(detail::exception_id::pointer_past_the_end_index, detail::concat(
@@ -23443,7 +23328,7 @@ class json_pointer
 
                 case detail::value_t::array:
                 {
-                    if (JSON_HEDLEY_UNLIKELY(is_dash(reference_token)))
+                    if (JSON_HEDLEY_UNLIKELY(reference_token == "-"))
                     {
                         // "-" cannot be used for const access
                         JSON_THROW(detail::out_of_range::create(detail::exception_id::pointer_past_the_end_index, detail::concat("array index '-' (", std::to_string(ptr->m_data.m_value.array->size()), ") is out of range"), ptr));
@@ -23505,7 +23390,7 @@ class json_pointer
 
                 case detail::value_t::array:
                 {
-                    if (JSON_HEDLEY_UNLIKELY(is_dash(reference_token)))
+                    if (JSON_HEDLEY_UNLIKELY(reference_token == "-"))
                     {
                         // "-" always fails the range check
                         return nullptr;
@@ -23582,7 +23467,7 @@ class json_pointer
 
                 case detail::value_t::array:
                 {
-                    if (JSON_HEDLEY_UNLIKELY(is_dash(reference_token)))
+                    if (JSON_HEDLEY_UNLIKELY(reference_token == "-"))
                     {
                         // "-" always fails the range check
                         return false;
@@ -23741,52 +23626,6 @@ class json_pointer
         obj[key] = std::forward<ValueType>(v);
     }
 
-    /// the number of entries that flattening @a value adds: its primitive
-    /// values and empty containers
-    template<typename BasicJsonType>
-    static std::size_t count_flattened(const BasicJsonType& value)
-    {
-        std::size_t count = 0;
-        std::vector<const BasicJsonType*> pending(1, &value);
-        while (!pending.empty())
-        {
-            const BasicJsonType* const v = pending.back();
-            pending.pop_back();
-            if (v->is_array() && !v->m_data.m_value.array->empty())
-            {
-                for (const auto& element : *v->m_data.m_value.array)
-                {
-                    pending.push_back(&element);
-                }
-            }
-            else if (v->is_object() && !v->m_data.m_value.object->empty())
-            {
-                for (const auto& member : *v->m_data.m_value.object)
-                {
-                    pending.push_back(&member.second);
-                }
-            }
-            else
-            {
-                ++count;
-            }
-        }
-        return count;
-    }
-
-    // Reserve the storage for @a value of objects that have a reserve(), so
-    // that it does not have to be moved while it grows
-    template<typename ObjectType, typename BasicJsonType>
-    static auto reserve_flattened(ObjectType& obj, const BasicJsonType& value, detail::priority_tag<1> /*unused*/)
-    -> decltype(obj.reserve(std::size_t {}), void())
-    {
-        obj.reserve(count_flattened(value));
-    }
-
-    template<typename ObjectType, typename BasicJsonType>
-    static void reserve_flattened(ObjectType& /*obj*/, const BasicJsonType& /*value*/, detail::priority_tag<0> /*unused*/)
-    {}
-
     /// append the decimal representation of @a i to @a out
     static void append_index(string_t& out, std::size_t i)
     {
@@ -23896,7 +23735,6 @@ class json_pointer
             }
         };
 
-        reserve_flattened(object, value, detail::priority_tag<1> {});
         enter(value);
         while (!stack.empty())
         {
@@ -23904,9 +23742,8 @@ class json_pointer
             // frame, which would invalidate a reference to it
             const BasicJsonType* const container = stack.back().container;
 
-            // the path of the previous child is replaced by the path of the
-            // next one; for an array element in one resize
-            const std::size_t path_length = stack.back().path_length;
+            // drop the path of the previous child
+            path.resize(stack.back().path_length);
 
             if (container->is_array())
             {
@@ -23920,20 +23757,8 @@ class json_pointer
 
                 // iterate array and use index as a reference string
                 ++stack.back().index;
-                std::array<char, 24> digits{};
-                std::size_t pos = digits.size();
-                std::size_t rest = i;
-                do
-                {
-                    digits[--pos] = static_cast<char>('0' + rest % 10);
-                    rest /= 10;
-                }
-                while (rest != 0);
-                const std::size_t count = digits.size() - pos;
-                path.resize(path_length + 1 + count);
-                char* const out = &path[path_length];
-                out[0] = '/';
-                std::memcpy(out + 1, digits.data() + pos, count);
+                path.push_back('/');
+                append_index(path, i);
                 enter(array[i]);
             }
             else
@@ -23947,7 +23772,6 @@ class json_pointer
 
                 // iterate object and use keys as reference string
                 ++stack.back().member;
-                path.resize(path_length);
                 path.push_back('/');
                 detail::escape_into(path, it->first);
                 enter(it->second);
@@ -24043,28 +23867,8 @@ class json_pointer
                 {
                     end = key.size();
                 }
-                const std::size_t token_size = end - pos - 1;
-
-                // a token that is a plain index of up to 9 digits, which is
-                // the case for almost all array elements, is not copied
-                std::size_t index = 0;
-                bool plain_index = current->type() == detail::value_t::array && token_size != 0 && token_size <= 9 && (token_size == 1 || data[pos + 1] != '0');
-                for (std::size_t k = pos + 1; plain_index && k < end; ++k)
-                {
-                    plain_index = data[k] >= '0' && data[k] <= '9';
-                    index = (index * 10) + static_cast<std::size_t>(data[k] - '0');
-                }
-                if (plain_index)
-                {
-                    current = &current->operator[](static_cast<typename BasicJsonType::size_type>(index));
-                    values.push_back(current);
-                    ends.push_back(end);
-                    pos = end;
-                    continue;
-                }
-
                 token.clear();
-                token.append(data + pos + 1, token_size);
+                token.append(data + pos + 1, end - pos - 1);
                 if (token.find_first_of('~') != string_t::npos)
                 {
                     detail::unescape(token);
@@ -24074,13 +23878,10 @@ class json_pointer
                 {
                     case detail::value_t::null:
                     {
-                        // a first child 0 makes the value an array without a look-up
-                        if ((token_size == 1 && data[pos + 1] == '0') || arrays.contains(data, pos))
+                        if (arrays.contains(data, pos))
                         {
                             // some reference token below this position is 0, so the
                             // value is an array
-                            *current = BasicJsonType(detail::value_t::array);
-                            reserve_elements(*current->m_data.m_value.array, 2, detail::priority_tag<1> {});
                             current = &current->operator[](array_index<BasicJsonType>(token));
                         }
                         else
@@ -39387,72 +39188,6 @@ public:
     /// @name JSON Patch functions
     /// @{
 
-  private:
-    /// the members of an operation of a JSON patch that are of interest
-    struct patch_members
-    {
-        basic_json* op = nullptr;
-        basic_json* path = nullptr;
-        basic_json* value = nullptr;
-        basic_json* from = nullptr;
-    };
-
-    /// @brief find the members "op", "path", "value", and "from" of the object @a val in one pass
-    static patch_members find_patch_members(const basic_json& val, std::true_type /*key_type is string_t*/)
-    {
-        patch_members members;
-        for (auto& member : *val.m_data.m_value.object)
-        {
-            const string_t& key = member.first;
-            switch (key.size())
-            {
-                case 2:
-                    if (key == "op")
-                    {
-                        members.op = &member.second;
-                    }
-                    break;
-                case 4:
-                    if (key == "path")
-                    {
-                        members.path = &member.second;
-                    }
-                    else if (key == "from")
-                    {
-                        members.from = &member.second;
-                    }
-                    break;
-                case 5:
-                    if (key == "value")
-                    {
-                        members.value = &member.second;
-                    }
-                    break;
-                default:
-                    break;
-            }
-        }
-        return members;
-    }
-
-    /// @brief find the members by lookup for key types other than string_t
-    static patch_members find_patch_members(const basic_json& val, std::false_type /*key_type is not string_t*/)
-    {
-        const auto find_member = [&val](const char* name) -> basic_json *
-        {
-            const auto it = val.m_data.m_value.object->find(string_t(name));
-            return it != val.m_data.m_value.object->end() ? &it->second : nullptr;
-        };
-
-        patch_members members;
-        members.op = find_member("op");
-        members.path = find_member("path");
-        members.value = find_member("value");
-        members.from = find_member("from");
-        return members;
-    }
-
-  public:
     /// @brief applies a JSON patch in-place without copying the object
     /// @sa https://json.nlohmann.me/api/basic_json/patch/
     void patch_inplace(const basic_json& json_patch)
@@ -39626,18 +39361,18 @@ public:
         // a diff creates them: apply the operation and return true; return
         // false, with nothing changed, for all others
         string_t token;
-        typename json_pointer::template plain_steps<basic_json> steps;
-        const auto try_plain = [&result, &token, &steps](patch_operations operation, const string_t& path, const patch_members & members, const basic_json & val)
+        const string_t value_key = "value";
+        const auto try_plain = [&result, &token, &value_key](patch_operations operation, const string_t& path, const basic_json & val)
         {
-            if (path.empty())
+            if (path.empty() || path.find_first_of('~') != string_t::npos)
             {
                 return false;
             }
 
             // a missing "value" is reported below
-            const basic_json* const value_ptr = members.value;
-            const basic_json& value = value_ptr != nullptr ? *value_ptr : val;
-            if (operation != patch_operations::remove && value_ptr == nullptr)
+            const auto value_it = val.m_data.m_value.object->find(value_key);
+            const basic_json& value = value_it != val.m_data.m_value.object->end() ? value_it->second : val;
+            if (operation != patch_operations::remove && value_it == val.m_data.m_value.object->end())
             {
                 return false;
             }
@@ -39646,7 +39381,7 @@ public:
             {
                 case patch_operations::replace:
                 {
-                    basic_json* const target = json_pointer::resolve_plain(&result, path, path.size(), token, steps);
+                    basic_json* const target = json_pointer::resolve_plain(&result, path, path.size(), token);
                     if (target == nullptr)
                     {
                         return false;
@@ -39657,7 +39392,7 @@ public:
 
                 case patch_operations::test:
                 {
-                    const basic_json* const target = json_pointer::resolve_plain(&result, path, path.size(), token, steps);
+                    const basic_json* const target = json_pointer::resolve_plain(&result, path, path.size(), token);
                     // a failing test is reported below
                     return target != nullptr && *target == value;
                 }
@@ -39677,17 +39412,13 @@ public:
                     }
                     --slash;
 
-                    basic_json* const parent = json_pointer::resolve_plain(&result, path, slash, token, steps);
+                    basic_json* const parent = json_pointer::resolve_plain(&result, path, slash, token);
                     if (parent == nullptr)
                     {
                         return false;
                     }
                     token.clear();
                     token.append(path.data() + slash + 1, path.size() - slash - 1);
-                    if (token.find_first_of('~') != string_t::npos)
-                    {
-                        return false;
-                    }
 
                     if (operation == patch_operations::add)
                     {
@@ -39743,32 +39474,31 @@ public:
             }
         };
 
-        // the name of the first member to check
-        const string_t op_member = "op";
-
         // iterate and apply the operations
         for (const auto& val : json_patch)
         {
             // wrapper to get a value for an operation
-            const auto get_value = [&val](basic_json * found,
-                                          const string_t& op,
-                                          const char* member,
+            const auto get_value = [&val](const string_t& op,
+                                          const string_t& member,
                                           bool string_type) -> basic_json &
             {
+                // find value
+                auto it = val.m_data.m_value.object->find(member);
+
                 // check if the desired value is present
-                if (JSON_HEDLEY_UNLIKELY(found == nullptr))
+                if (JSON_HEDLEY_UNLIKELY(it == val.m_data.m_value.object->end()))
                 {
-                    detail::throw_patch_missing_member(op, string_t(member), false, val);
+                    detail::throw_patch_missing_member(op, member, false, val);
                 }
 
                 // check if the result is of type string
-                if (JSON_HEDLEY_UNLIKELY(string_type && !found->is_string()))
+                if (JSON_HEDLEY_UNLIKELY(string_type && !it->second.is_string()))
                 {
-                    detail::throw_patch_missing_member(op, string_t(member), true, val);
+                    detail::throw_patch_missing_member(op, member, true, val);
                 }
 
                 // no error: return value
-                return *found;
+                return it->second;
             };
 
             // type check: every element of the array must be an object
@@ -39777,30 +39507,26 @@ public:
                 detail::throw_patch_not_an_array(val);
             }
 
-            const patch_members members = find_patch_members(val, std::is_same<typename object_t::key_type, string_t> {});
-
             // collect mandatory members
-            const string_t& op = *get_value(members.op, op_member, "op", true).m_data.m_value.string;
-            const string_t& path = *get_value(members.path, op, "path", true).m_data.m_value.string;
+            const string_t& op = *get_value("op", "op", true).m_data.m_value.string;
+            const string_t& path = *get_value(op, "path", true).m_data.m_value.string;
             const patch_operations operation = get_op(op);
 
             // the usual operations on a plain pointer are applied without
             // building the pointer's reference tokens; anything else (and
             // every error) is handled below
-            if (try_plain(operation, path, members, val))
+            if (try_plain(operation, path, val))
             {
                 continue;
             }
 
-            // the general operations may change any container
-            steps.reset();
             json_pointer ptr(path);
 
             switch (operation)
             {
                 case patch_operations::add:
                 {
-                    operation_add(ptr, get_value(members.value, "add", "value", false));
+                    operation_add(ptr, get_value("add", "value", false));
                     break;
                 }
 
@@ -39813,13 +39539,13 @@ public:
                 case patch_operations::replace:
                 {
                     // the "path" location must exist - use at()
-                    result.at(ptr) = get_value(members.value, "replace", "value", false);
+                    result.at(ptr) = get_value("replace", "value", false);
                     break;
                 }
 
                 case patch_operations::move:
                 {
-                    const string_t& from_path = *get_value(members.from, "move", "from", true).m_data.m_value.string;
+                    const string_t& from_path = *get_value("move", "from", true).m_data.m_value.string;
                     json_pointer from_ptr(from_path);
 
                     if (JSON_HEDLEY_UNLIKELY(is_proper_prefix(from_ptr, ptr)))
@@ -39842,7 +39568,7 @@ public:
 
                 case patch_operations::copy:
                 {
-                    const string_t& from_path = *get_value(members.from, "copy", "from", true).m_data.m_value.string;
+                    const string_t& from_path = *get_value("copy", "from", true).m_data.m_value.string;
                     const json_pointer from_ptr(from_path);
 
                     // The copy is functionally identical to an "add"
@@ -39860,7 +39586,7 @@ public:
                     {
                         // check if "value" matches the one at "path"
                         // the "path" location must exist - use at()
-                        success = (result.at(ptr) == get_value(members.value, "test", "value", false));
+                        success = (result.at(ptr) == get_value("test", "value", false));
                     }
                     JSON_INTERNAL_CATCH (out_of_range&)
                     {
@@ -39952,18 +39678,13 @@ public:
     /// @brief append an operation @a op for @a path to @a result, with @a value if it is not null
     static void diff_operation(basic_json& result, const char* op, const string_t& path, const basic_json* value)
     {
-        // the keys are distinct and in the order of std::map; the members are
-        // added without looking them up
         basic_json entry(value_t::object);
-        auto& members = *entry.m_data.m_value.object;
-        typename object_t::iterator hint = members.end();
-        json_pointer::add_flattened(members, hint, string_t("op"), string_t(op), detail::priority_tag<2> {});
-        json_pointer::add_flattened(members, hint, string_t("path"), path, detail::priority_tag<2> {});
+        entry["op"] = op;
+        entry["path"] = path;
         if (value != nullptr)
         {
-            json_pointer::add_flattened(members, hint, string_t("value"), *value, detail::priority_tag<2> {});
+            entry["value"] = *value;
         }
-        entry.set_parents();
         result.push_back(std::move(entry));
     }
 
@@ -39985,50 +39706,6 @@ public:
         diff_operation(result, "add", path, &value);
     }
 
-    /// @brief the values in the target of the members of a source object, for the
-    ///        objects of up to 16 members without allocating
-    ///
-    /// reserve() must be called with the number of values that are added.
-    class diff_target_values
-    {
-      public:
-        diff_target_values() = default;
-        diff_target_values(const diff_target_values&) = delete;
-        diff_target_values& operator=(const diff_target_values&) = delete;
-        ~diff_target_values() = default;
-
-        void reserve(const std::size_t n)
-        {
-            if (n > inline_size)
-            {
-                large.resize(n);
-                items = large.data();
-            }
-        }
-
-        void push_back(const basic_json* value)
-        {
-            items[count++] = value;
-        }
-
-        std::size_t size() const noexcept
-        {
-            return count;
-        }
-
-        const basic_json* operator[](const std::size_t i) const noexcept
-        {
-            return items[i];
-        }
-
-      private:
-        static constexpr std::size_t inline_size = 16;
-        std::size_t count = 0;
-        const basic_json** items = inline_items;
-        std::vector<const basic_json*> large{}; // NOLINT(readability-redundant-member-init)
-        const basic_json* inline_items[inline_size]; // NOLINT(cppcoreguidelines-pro-type-member-init,hicpp-member-init)
-    };
-
     /// @brief append "/" and the decimal representation of @a index to @a path
     static void diff_append_index(string_t& path, std::size_t index)
     {
@@ -40109,9 +39786,8 @@ public:
     operations that remove every member of @a source and add every member of
     @a target to @a result, and returns false.
     */
-    template<typename TargetValues>
     static bool diff_object_keys(basic_json& result, const basic_json& source, const basic_json& target,
-                                 const string_t& path, TargetValues& target_values,
+                                 const string_t& path, std::vector<const basic_json*>& target_values,
                                  std::vector<const_iterator>& added)
     {
         // first pass: one lookup per source key
@@ -40325,7 +40001,7 @@ public:
 
             case value_t::object:
             {
-                diff_target_values target_values;
+                std::vector<const basic_json*> target_values;
                 std::vector<const_iterator> added;
                 if (diff_object_keys(result, source, target, path, target_values, added))
                 {

tests/src/unit-json_view_dump.cpp

@@ -345,6 +345,33 @@ TEST_CASE("json_view comparison")
         }
     }
 
+    SECTION("objects whose first keys differ or repeat")
+    {
+        const char* const texts[] =
+        {
+            R"({"a":1,"b":2})", R"({"a":1,"c":2})", R"({"b":1,"a":2})", R"({"a":1,"a":2,"b":3})", R"({"a":2,"b":3})",
+            R"({"a":1,"b":1,"a":2})", R"({"a":2,"b":1})", R"({"a":1,"a":2})", R"({"b":1})", R"({"a":1,"b":2,"c":3,"d":4,"e":5})",
+            R"({"a":1,"b":2,"c":3,"d":4,"f":5})", R"({"a":1,"b":2,"c":3,"a":4,"e":5})", R"({"a":4,"b":2,"c":3,"e":5})",
+            R"({"\u0061":1,"b":2})", R"({})", R"([{"a":1,"b":2}])", R"([{"a":1,"c":2}])"
+        };
+        for (const char* const x : texts)
+        {
+            for (const char* const y : texts)
+            {
+                CAPTURE(x)
+                CAPTURE(y)
+                const ordered_json_document dx = ordered_json_document::parse(x);
+                const ordered_json_document dy = ordered_json_document::parse(y);
+                const ordered_json_editable_document ex = ordered_json_editable_document::parse(x);
+                const ordered_json jx = ordered_json::parse(x);
+                const ordered_json jy = ordered_json::parse(y);
+                CHECK((dx.root() == dy.root()) == (jx == jy));
+                CHECK((dx.root() == jy) == (jx == jy));
+                CHECK((ex.root() == dy.root()) == (jx == jy));
+            }
+        }
+    }
+
     SECTION("numbers, duplicate keys, member order")
     {
         const auto same = [](const char* x, const char* y)
@@ -385,6 +412,129 @@ TEST_CASE("json_view comparison")
         CHECK(!(null_document.root() == discarded));
     }
 
+    SECTION("values that are the same text, or the same value written differently, at any depth")
+    {
+        // nested arrays and objects around depths where the walk over equal text gives up
+        for (const int depth :
+                {
+                    1, 5, 47, 48, 49, 50, 60, 300
+                })
+        {
+            CAPTURE(depth)
+            std::string head;
+            std::string tail;
+            for (int i = 0; i < depth; ++i)
+            {
+                head += i % 2 == 0 ? R"({"k":[1,"s",{"x":true},)" : R"([null,2.5,{"y":)";
+                tail = (i % 2 == 0 ? "]}" : "}]") + tail;
+            }
+            // the same text, one number changed, and one number written differently
+            const std::string text = head + "7" + tail;
+            const std::string changed = head + "8" + tail;
+            const std::string spelled = head + "7.0" + tail;
+            const json_document a = json_document::parse(text);
+            const json_document b = json_document::parse(text);
+            const json_document c = json_document::parse(changed);
+            const json_document d = json_document::parse(spelled);
+            CHECK(a.root() == b.root());
+            CHECK(a.root() != c.root());
+            CHECK(c.root() != a.root());
+            CHECK(a.root() == d.root());
+            CHECK(d.root() == a.root());
+            CHECK(a.root() == json::parse(text));
+            CHECK(a.root() != json::parse(changed));
+            CHECK(json::parse(spelled) == a.root());
+            const nlohmann::json_editable_document e = nlohmann::json_editable_document::parse(text);
+            CHECK(a.root() == e.root());
+            CHECK(e.root() == a.root());
+            CHECK(c.root() != e.root());
+            CHECK(e.root() == e.root());
+            const ordered_json_document oa = ordered_json_document::parse(text);
+            const ordered_json_document oc = ordered_json_document::parse(changed);
+            CHECK(oa.root() != oc.root());
+            CHECK(oa.root() == ordered_json::parse(text));
+            CHECK(oc.root() != ordered_json::parse(text));
+        }
+
+        // not the same text, but the same value
+        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);
+            const bool equal = dx.root() == dy.root();
+            CHECK(equal == (json::parse(x) == json::parse(y)));
+            CHECK(equal == (dx.root() == json::parse(y)));
+            return equal;
+        };
+        CHECK(same(R"({"a":1,"a":2})", R"({"a":3,"a":2})"));
+        CHECK(same(R"({"a":1,"b":[1,{"c":2,"c":3}]})", R"({"b":[1,{"c":9,"c":3}],"a":1})"));
+        CHECK(!same(R"({"a":1,"a":2})", R"({"a":2,"a":3})"));
+        CHECK(same("[1.0,-0,0,1e2]", "[1.00,0,-0,100.0]"));
+        CHECK(same(R"(["\u00e9","\n"])", "[\"\xc3\xa9\",\"\\n\"]"));
+        CHECK(!same(R"({"a":[1,2,{"b":null}]})", R"({"a":[1,2,{"b":false}]})"));
+        CHECK(!same(R"({"a":[1,2,{"b":null}]})", R"({"a":[1,2,{"c":null}]})"));
+        CHECK(!same(R"({"a":[1,2,{"b":null}]})", R"({"a":[1,2,{"b":null,"c":1}]})"));
+
+        // edited documents: moved sequences, links, and values of new nodes
+        nlohmann::json_editable_document edited = nlohmann::json_editable_document::parse(R"({"a":[1,2,3],"b":{"c":"d"},"e":0.5})");
+        const json_document plain = json_document::parse(R"({"a":[1,2,3,4],"b":{"c":"x","y":null},"e":0.5,"z":[]})");
+        edited.push_back(edited.root()["a"], 4);
+        edited.set(edited.root()["b"], "c", "x");
+        edited.set(edited.root()["b"], "y", nullptr);
+        edited.set(edited.root(), "z", json::array());
+        CHECK(edited.root() == plain.root());
+        CHECK(plain.root() == edited.root());
+        edited.erase(edited.root()["a"], 0);
+        CHECK(edited.root() != plain.root());
+        CHECK(edited.root()["a"] == json::parse("[2,3,4]"));
+        const json_document tail = json_document::parse("[2,3,4]");
+        CHECK(edited.root()["a"] == tail.root());
+    }
+
+    SECTION("large documents, with a difference at any place")
+    {
+        const auto make = [](std::size_t count, std::size_t changed, bool swap_members)
+        {
+            std::string text = R"({"b":1,"list":[)";
+            for (std::size_t i = 0; i < count; ++i)
+            {
+                text += (i != 0 ? "," : "");
+                const std::string id = std::to_string(i == changed ? i + 1 : i);
+                text += swap_members && i % 3 == 0 ? R"({"v":[1.5,"s",{"k":)" + id + R"(}],"id":)" + id + "}" : R"({"id":)" + id + R"(,"v":[1.5,"s",{"k":)" + id + "}]}";
+            }
+            return text + R"(],"a":{"y":2,"x":3}})";
+        };
+        const std::size_t count = 3000;
+        for (const std::size_t changed :
+                {
+                    count, std::size_t{0}, std::size_t{1}, count / 2, count - 1
+                })
+        {
+            for (const bool swap :
+                    {
+                        false, true
+                    })
+            {
+                CAPTURE(changed)
+                CAPTURE(swap)
+                const std::string text_a = make(count, count, false);
+                const std::string text_b = make(count, changed, swap);
+                const json_document a = json_document::parse(text_a);
+                const json_document b = json_document::parse(text_b);
+                const bool equal = changed == count;
+                CHECK((a.root() == b.root()) == equal);
+                CHECK((b.root() == a.root()) == equal);
+                CHECK((a.root() == json::parse(text_b)) == equal);
+                CHECK((json::parse(text_b) == a.root()) == equal);
+                CHECK((a.root()["list"] == b.root()["list"]) == equal);
+                const ordered_json_document oa = ordered_json_document::parse(text_a);
+                const ordered_json_document ob = ordered_json_document::parse(text_b);
+                CHECK((oa.root() == ob.root()) == (equal && !swap));
+                CHECK((oa.root() == ordered_json::parse(text_b)) == (equal && !swap));
+            }
+        }
+    }
+
     SECTION("deep nesting")
     {
         const std::string deep = std::string(100000, '[') + std::string(100000, ']');

tests/src/unit-json_view_image.cpp

@@ -682,6 +682,66 @@ TEST_CASE("json_view images: ownership")
 #if !defined(JSON_NOEXCEPTION)
 TEST_CASE("json_view images: errors")
 {
+#if !defined(JSON_NOEXCEPTION)
+    SECTION("float tokens: a changed byte is accepted if the text is still a number with the digits the node records")
+    {
+        for (const char* const token :
+                {
+                    "-12.375", "0.5", "123456.0", "-0.0", "9999999999999999999.5", "0.000000000000000000000001", "1.25e10", "5E-3"
+                })
+        {
+            CAPTURE(token)
+            const std::string text = std::string("[") + token + "]";
+            const json_document d = json_document::parse(text);
+            const std::vector<std::uint8_t> image = d.save();
+            const std::size_t at = text_at(image) + 1; // the first byte of the token
+            const std::uint16_t recorded = node_at(image, 1).extra;
+            CHECK(loaded_dump(image) == json::parse(text).dump());
+            for (std::size_t pos = 0; token[pos] != '\0'; ++pos)
+            {
+                for (unsigned int byte = 0; byte < 256; ++byte)
+                {
+                    std::vector<std::uint8_t> changed = image;
+                    changed[at + pos] = static_cast<std::uint8_t>(byte);
+                    std::string t = token;
+                    t[pos] = static_cast<char>(byte);
+                    // the digits of the integer part and of the fraction of the changed token
+                    std::size_t integer = 0;
+                    std::size_t fraction = 0;
+                    std::size_t k = (t[0] == '-') ? 1 : 0;
+                    for (; k < t.size() && t[k] >= '0' && t[k] <= '9'; ++k)
+                    {
+                        ++integer;
+                    }
+                    if (k < t.size() && t[k] == '.')
+                    {
+                        for (++k; k < t.size() && t[k] >= '0' && t[k] <= '9'; ++k)
+                        {
+                            ++fraction;
+                        }
+                    }
+                    // (as a JSON text, the token may have white space around it)
+                    const bool float_token = json::accept(t) && t.find_first_of(std::string(" \t\r\n\0", 5)) == std::string::npos && (t.find('.') != std::string::npos || t.find_first_of("eE") != std::string::npos)
+                                             && ((integer | (fraction << 8U)) == recorded);
+                    CAPTURE(pos)
+                    CAPTURE(byte)
+                    std::string result;
+                    try
+                    {
+                        result = loaded_dump(changed);
+                    }
+                    catch (const json::parse_error& e)
+                    {
+                        CHECK(std::string(e.what()) == check_failed);
+                        result = "rejected";
+                    }
+                    CHECK((result != "rejected") == float_token);
+                }
+            }
+        }
+    }
+#endif
+
     SECTION("a literal as the root: dump() after loading")
     {
         for (const char* text :