Merge branch 'develop' into guard-page-tests

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

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

@@ -68,14 +68,6 @@ basic_json(basic_json&& other) noexcept;
      `std::unordered_map`, `std::multimap`, and `std::unordered_multimap` with a `key_type` compatible to `string_t`
      and a `value_type` from which a `basic_json` value can be constructed.
     - **strings**: `string_t`, string literals, and all compatible string containers can be used.
-
-    !!! note "Rvalue containers are moved from"
-
-        If `val` is an rvalue of a compatible array-like or object-like container other than `array_t`/`object_t`
-        (e.g., `json j = std::move(vec);` or `json j(std::vector<std::string>{...});`), the elements are moved into
-        the JSON value instead of copied. Afterwards, the elements of the source container are in a valid but
-        unspecified state (**moved-from**). Keys of associative containers are `const` and therefore still copied.
-        Lvalues and `const` rvalues are copied, and the source is left unchanged.
     - **numbers**: [`number_integer_t`](number_integer_t.md), [`number_unsigned_t`](number_unsigned_t.md),
      [`number_float_t`](number_float_t.md), and all convertible number types such as `int`, `size_t`, `int64_t`, `float`
      or `double` can be used.
@@ -244,9 +236,7 @@ basic_json(basic_json&& other) noexcept;
 2. No-throw guarantee: this constructor never throws exceptions.
 3. Depends on the called constructor. For types directly supported by the library (i.e., all types for which no
    `to_json()` function was provided), a strong guarantee holds: if an exception is thrown, there are no changes to any
-   JSON value. **Exception:** when `val` is an rvalue array-like or object-like container, its elements are moved one
-   by one; if an exception is thrown in the middle of the conversion (e.g., an allocation failure), the JSON value is
-   unchanged, but the source container may be left partially moved-from.
+   JSON value.
 4. Depends on the called constructor. For types directly supported by the library (i.e., all types for which no
    `to_json()` function was provided), a strong guarantee holds: if an exception is thrown, there are no changes to any
    JSON value.

docs/mkdocs/docs/home/releases.md

@@ -9,15 +9,6 @@ published on the [GitHub releases page](https://github.com/nlohmann/json/release
     This documentation is built from the `develop` branch and may describe changes that are not part of a release
     yet. Their version numbers are followed by an <span class="unreleased-version">unreleased</span> badge.
 
-## Unreleased
-
-- Converting an rvalue container to JSON (`json j = std::move(vec);`, `json j = std::map<std::string, std::string>{...};`)
-  now **moves** the elements instead of copying them (e.g., `std::vector<std::string>` with 100,000 strings: 4.7 ms to
-  2.3 ms). Two consequences: the source container is left in a valid but unspecified (moved-from) state, and if an
-  exception is thrown during the conversion, the source may be partially moved-from, so the strong exception guarantee
-  no longer holds for the source of an rvalue conversion (the JSON value itself is unaffected). Lvalues and `const`
-  objects are still copied. See [`basic_json`](../api/basic_json/basic_json.md).
-
 ## v3.12.0 (2025-04-11)
 
 Fixes bugs found in 3.11.3 and adds several features. All changes are backward-compatible.

include/nlohmann/detail/conversions/from_json.hpp

@@ -266,22 +266,6 @@ template<typename ConstructibleArrayType>
 void from_json_array_reserve(ConstructibleArrayType& /*arr*/, std::size_t /*size*/, priority_tag<0> /*unused*/)
 {}
 
-// append through push_back() where available; containers without it (such as
-// std::set) fall back to insert(end(), ...), which is what std::inserter did
-template<typename ConstructibleArrayType, typename ValueType>
-auto from_json_array_append(ConstructibleArrayType& arr, ValueType&& value, priority_tag<1> /*unused*/)
--> decltype(arr.push_back(std::forward<ValueType>(value)), void())
-{
-    arr.push_back(std::forward<ValueType>(value));
-}
-
-template<typename ConstructibleArrayType, typename ValueType>
-void from_json_array_append(ConstructibleArrayType& arr, ValueType&& value, priority_tag<0> /*unused*/)
-{
-    using std::end;
-    arr.insert(end(arr), std::forward<ValueType>(value));
-}
-
 template<typename BasicJsonType, typename ConstructibleArrayType,
          enable_if_t<
              std::is_assignable<ConstructibleArrayType&, ConstructibleArrayType>::value,
@@ -291,15 +275,17 @@ auto from_json_array_impl(const BasicJsonType& j, ConstructibleArrayType& arr, p
     j.template get<typename ConstructibleArrayType::value_type>(),
     void())
 {
+    using std::end;
+
     ConstructibleArrayType ret;
-    const auto* inner_array = j.template get_ptr<const typename BasicJsonType::array_t*>();
-    from_json_array_reserve(ret, inner_array->size(), priority_tag<1> {});
-    for (const auto& elem : *inner_array)
+    from_json_array_reserve(ret, j.size(), priority_tag<1> {});
+    std::transform(j.begin(), j.end(),
+                   std::inserter(ret, end(ret)), [](const BasicJsonType & i)
     {
         // get<BasicJsonType>() returns *this, this won't call a from_json
         // method when value_type is BasicJsonType
-        from_json_array_append(ret, elem.template get<typename ConstructibleArrayType::value_type>(), priority_tag<1> {});
-    }
+        return i.template get<typename ConstructibleArrayType::value_type>();
+    });
     arr = std::move(ret);
 }
 
@@ -397,13 +383,9 @@ inline void from_json(const BasicJsonType& j, ConstructibleObjectType& obj)
     ConstructibleObjectType ret;
     const auto* inner_object = j.template get_ptr<const typename BasicJsonType::object_t*>();
     from_json_object_reserve(ret, inner_object->size(), priority_tag<1> {});
-    using value_type = typename ConstructibleObjectType::value_type;
     for (const auto& p : *inner_object)
     {
-        // the keys of the source are sorted for the usual object types, so
-        // hinting the end makes every insertion constant-time (for containers
-        // that order their keys the same way)
-        ret.insert(ret.end(), value_type(p.first, p.second.template get<typename ConstructibleObjectType::mapped_type>()));
+        ret.emplace(p.first, p.second.template get<typename ConstructibleObjectType::mapped_type>());
     }
     obj = std::move(ret);
 }

include/nlohmann/detail/conversions/to_json.hpp

@@ -167,17 +167,6 @@ struct external_constructor<value_t::array>
         j.replace_value(value_t::array, value);
     }
 
-    /// an rvalue container: move its elements
-    template<typename BasicJsonType, typename CompatibleArrayType>
-    static void construct_moving(BasicJsonType& j, CompatibleArrayType& arr)
-    {
-        using std::begin;
-        using std::end;
-
-        const typename BasicJsonType::json_value value(j.template create<typename BasicJsonType::array_t>(std::make_move_iterator(begin(arr)), std::make_move_iterator(end(arr))));
-        j.replace_value(value_t::array, value);
-    }
-
     template<typename BasicJsonType>
     static void construct(BasicJsonType& j, const std::vector<bool>& arr)
     {
@@ -228,17 +217,6 @@ struct external_constructor<value_t::object>
         j.replace_value(value_t::object, value);
     }
 
-    /// an rvalue container: move its values
-    template<typename BasicJsonType, typename CompatibleObjectType>
-    static void construct_moving(BasicJsonType& j, CompatibleObjectType& obj)
-    {
-        using std::begin;
-        using std::end;
-
-        const typename BasicJsonType::json_value value(j.template create<typename BasicJsonType::object_t>(std::make_move_iterator(begin(obj)), std::make_move_iterator(end(obj))));
-        j.replace_value(value_t::object, value);
-    }
-
     template < typename BasicJsonType, typename CompatibleObjectType,
                enable_if_t < !std::is_same<CompatibleObjectType, typename BasicJsonType::object_t>::value, int > = 0 >
     static void construct(BasicJsonType& j, const CompatibleObjectType& obj)
@@ -376,66 +354,6 @@ inline void to_json(BasicJsonType& j, const CompatibleArrayType& arr)
     external_constructor<value_t::array>::construct(j, arr);
 }
 
-// types that have a dedicated to_json overload and must not be treated as generic containers
-template<typename T>
-struct has_dedicated_to_json : std::false_type {};
-
-#if JSON_HAS_FILESYSTEM || JSON_HAS_EXPERIMENTAL_FILESYSTEM
-template<>
-struct has_dedicated_to_json<std_fs::path> : std::true_type {};
-#endif
-
-#if defined(__cpp_lib_char8_t)
-template<typename Tr, typename Allocator>
-struct has_dedicated_to_json<std::basic_string<char8_t, Tr, Allocator>> : std::true_type {};
-#endif
-
-#if JSON_HAS_RANGE_VIEW_CONVERSION
-template<typename T>
-struct is_range_view_type : is_compatible_range_view<T> {};
-#else
-template<typename T>
-struct is_range_view_type : std::false_type {};
-#endif
-
-#if JSON_USE_OBJECTS_FOR_ENUM_KEYED_MAPS
-template<typename T>
-struct is_enum_keyed_map_type : is_enum_keyed_map<T> {};
-#else
-template<typename T>
-struct is_enum_keyed_map_type : std::false_type {};
-#endif
-
-// rvalue (non-const) container: the generic to_json takes its elements by move
-template<typename T>
-using is_movable_container_rvalue = conjunction <
-                                    negation<std::is_lvalue_reference<T>>,
-                                    negation<std::is_const<T>>,
-                                    negation<has_dedicated_to_json<T>>,
-                                    negation<is_basic_json<T>>,
-                                    negation<is_range_view_type<T>>,
-                                    negation<is_enum_keyed_map_type<T>>,
-                                    negation<std::is_same<T, std::vector<bool>>> >;
-
-// rvalue array-like containers
-template<typename BasicJsonType, typename T>
-using is_rvalue_array_to_json = conjunction <
-                                is_movable_container_rvalue<T>,
-                                negation<std::is_same<T, typename BasicJsonType::array_t>>,
-                                negation<std::is_same<T, typename BasicJsonType::binary_t>>,
-                                is_compatible_array_type<BasicJsonType, T>,
-                                negation<is_compatible_object_type<BasicJsonType, T>>,
-                                negation<is_compatible_string_type<BasicJsonType, T>>,
-                                negation<is_compatible_binary_type<BasicJsonType, T>> >;
-
-// rvalue containers: their elements are moved instead of copied
-template < typename BasicJsonType, typename CompatibleArrayType,
-           enable_if_t < is_rvalue_array_to_json<BasicJsonType, CompatibleArrayType>::value, int > = 0 >
-inline void to_json(BasicJsonType& j, CompatibleArrayType && arr)
-{
-    external_constructor<value_t::array>::construct_moving(j, arr);
-}
-
 #if JSON_HAS_RANGE_VIEW_CONVERSION
 template < typename BasicJsonType, typename T,
            enable_if_t < is_compatible_range_view<std::remove_cvref_t<T>>::value
@@ -509,20 +427,6 @@ inline void to_json(BasicJsonType& j, const EnumKeyedMap& map)
 }
 #endif
 
-// rvalue object-like containers
-template<typename BasicJsonType, typename T>
-using is_rvalue_object_to_json = conjunction <
-                                 is_movable_container_rvalue<T>,
-                                 negation<std::is_same<T, typename BasicJsonType::object_t>>,
-                                 is_compatible_object_type<BasicJsonType, T> >;
-
-template < typename BasicJsonType, typename CompatibleObjectType,
-           enable_if_t < is_rvalue_object_to_json<BasicJsonType, CompatibleObjectType>::value, int > = 0 >
-inline void to_json(BasicJsonType& j, CompatibleObjectType && obj)
-{
-    external_constructor<value_t::object>::construct_moving(j, obj);
-}
-
 template<typename BasicJsonType>
 inline void to_json(BasicJsonType& j, typename BasicJsonType::object_t&& obj)
 {

include/nlohmann/detail/input/json_sax.hpp

@@ -674,19 +674,16 @@ class json_sax_dom_callback_parser
         if (keep && ref_stack.back())
         {
             auto& obj = *ref_stack.back()->m_data.m_value.object;
-            // a single lookup: insert the placeholder, or find the existing member
-            const auto inserted = obj.emplace(val, discarded);
-            const auto it = inserted.first;
-            if (!inserted.second)
+            const auto it = obj.find(val);
+            if (it != obj.end())
             {
                 // this is a duplicate key (legal in JSON); remember its
                 // current value so it can be restored later if the new
                 // value is rejected by the callback, instead of being
                 // erased together with the discarded placeholder
                 duplicate_key_stash.emplace_back(&(it->second), it->second);
-                it->second = discarded;
             }
-            object_element = &(it->second);
+            object_element = &(obj[val] = discarded);
         }
 
         return true;

include/nlohmann/detail/json_pointer.hpp

@@ -16,6 +16,8 @@
     #include <iosfwd> // ostream
 #endif  // JSON_NO_IO
 #include <limits> // max
+#include <map> // map
+#include <numeric> // accumulate
 #include <string> // string
 #include <utility> // move
 #include <vector> // vector
@@ -67,21 +69,12 @@ class json_pointer
     /// @sa https://json.nlohmann.me/api/json_pointer/to_string/
     string_t to_string() const
     {
-        // one buffer: every token adds its escaped form (at least its length) and a slash
-        std::size_t length = 0;
-        for (const auto& reference_token : reference_tokens)
+        return std::accumulate(reference_tokens.begin(), reference_tokens.end(),
+                               string_t{},
+                               [](const string_t& a, const string_t& b)
         {
-            length += reference_token.size() + 1;
-        }
-
-        string_t result;
-        result.reserve(length);
-        for (const auto& reference_token : reference_tokens)
-        {
-            result.append("/", 1);
-            detail::escape_into(result, reference_token);
-        }
-        return result;
+            return detail::concat<string_t>(a, '/', detail::escape(b));
+        });
     }
 
     /// @brief return a string representation of the JSON pointer
@@ -136,29 +129,21 @@ class json_pointer
     friend json_pointer operator/(const json_pointer& lhs,
                                   const json_pointer& rhs)
     {
-        json_pointer result;
-        result.reference_tokens.reserve(lhs.reference_tokens.size() + rhs.reference_tokens.size());
-        result.reference_tokens.insert(result.reference_tokens.end(), lhs.reference_tokens.begin(), lhs.reference_tokens.end());
-        result.reference_tokens.insert(result.reference_tokens.end(), rhs.reference_tokens.begin(), rhs.reference_tokens.end());
-        return result;
+        return json_pointer(lhs) /= rhs;
     }
 
     /// @brief create a new JSON pointer by appending the unescaped token at the end of the JSON pointer
     /// @sa https://json.nlohmann.me/api/json_pointer/operator_slash/
     friend json_pointer operator/(const json_pointer& lhs, string_t token) // NOLINT(performance-unnecessary-value-param)
     {
-        json_pointer result;
-        result.reference_tokens.reserve(lhs.reference_tokens.size() + 1);
-        result.reference_tokens.insert(result.reference_tokens.end(), lhs.reference_tokens.begin(), lhs.reference_tokens.end());
-        result.reference_tokens.push_back(std::move(token));
-        return result;
+        return json_pointer(lhs) /= std::move(token);
     }
 
     /// @brief create a new JSON pointer by appending the array-index-token at the end of the JSON pointer
     /// @sa https://json.nlohmann.me/api/json_pointer/operator_slash/
     friend json_pointer operator/(const json_pointer& lhs, std::size_t array_idx)
     {
-        return lhs / detail::to_string<string_t>(array_idx);
+        return json_pointer(lhs) /= array_idx;
     }
 
     /// @brief returns the parent of this JSON pointer
@@ -170,8 +155,8 @@ class json_pointer
             return *this;
         }
 
-        json_pointer res;
-        res.reference_tokens = std::vector<string_t>(reference_tokens.begin(), reference_tokens.end() - 1);
+        json_pointer res = *this;
+        res.pop_back();
         return res;
     }
 
@@ -260,14 +245,14 @@ class json_pointer
 
   private:
     /// @throw out_of_range.405 always
-    JSON_HEDLEY_NEVER_INLINE JSON_HEDLEY_NO_RETURN static void throw_no_parent()
+    JSON_HEDLEY_NO_RETURN static void throw_no_parent()
     {
         JSON_THROW(detail::out_of_range::create(detail::exception_id::patch_on_root, "JSON pointer has no parent", nullptr));
     }
 
     /// @throw out_of_range.404 always
     template<typename BasicJsonContext>
-    JSON_HEDLEY_NEVER_INLINE JSON_HEDLEY_NO_RETURN static void throw_unresolved(const string_t& reference_token, BasicJsonContext context)
+    JSON_HEDLEY_NO_RETURN static void throw_unresolved(const string_t& reference_token, BasicJsonContext context)
     {
         static_cast<void>(reference_token); // unused when JSON_NOEXCEPTION is defined
         static_cast<void>(context);
@@ -320,28 +305,6 @@ class json_pointer
             return array_index_status::not_a_number;
         }
 
-        // fast path: up to 18 decimal digits cannot overflow unsigned long long or
-        // size_type (9 digits for a 32-bit size_type), so strtoull and errno are not needed
-        constexpr std::size_t max_fast_digits = sizeof(size_type) >= 8 ? 18 : 9;
-        if (!s.empty() && s.size() <= max_fast_digits)
-        {
-            size_type acc = 0;
-            for (std::size_t i = 0; i < s.size(); ++i)
-            {
-                const char c = s[i];
-                if (JSON_HEDLEY_UNLIKELY(c < '0' || c > '9'))
-                {
-                    break; // not a plain number: let strtoull decide
-                }
-                acc = static_cast<size_type>(acc * 10 + static_cast<size_type>(c - '0'));
-                if (JSON_HEDLEY_UNLIKELY(i == s.size() - 1))
-                {
-                    idx = acc;
-                    return array_index_status::ok;
-                }
-            }
-        }
-
         const char* p = s.data();
         char* p_end = nullptr; // NOLINT(misc-const-correctness)
         errno = 0; // strtoull doesn't reset errno
@@ -398,83 +361,6 @@ class json_pointer
         return idx;
     }
 
-    /*!
-    @brief compare with a JSON pointer string without splitting it into tokens
-
-    @throw parse_error.107  if the string is not empty or begins with '/'
-    @throw parse_error.108  if character '~' is not followed by '0' or '1'
-    */
-    bool equals_string(const string_t& reference_string) const
-    {
-        if (reference_string.empty())
-        {
-            return reference_tokens.empty();
-        }
-
-        if (JSON_HEDLEY_UNLIKELY(reference_string[0] != '/'))
-        {
-            JSON_THROW(detail::parse_error::create(detail::exception_id::pointer_missing_slash, 1, detail::concat("JSON pointer must be empty or begin with '/' - was: '", reference_string, "'"), nullptr));
-        }
-
-        // the whole string is validated, whether or not it matches
-        const std::size_t size = reference_string.size();
-        for (std::size_t pos = reference_string.find_first_of('~');
-                pos != string_t::npos;
-                pos = reference_string.find_first_of('~', pos + 1))
-        {
-            if (JSON_HEDLEY_UNLIKELY(pos == size - 1 || (reference_string[pos + 1] != '0' && reference_string[pos + 1] != '1')))
-            {
-                JSON_THROW(detail::parse_error::create(detail::exception_id::pointer_invalid_escape, 0, "escape character '~' must be followed with '0' or '1'", nullptr));
-            }
-        }
-
-        // compare token by token, unescaping the string on the fly
-        std::size_t pos = 0; // the slash in front of the next token
-        for (const auto& reference_token : reference_tokens)
-        {
-            if (pos >= size)
-            {
-                return false;
-            }
-
-            std::size_t i = pos + 1;
-            std::size_t j = 0;
-            const std::size_t token_size = reference_token.size();
-            while (i < size && reference_string[i] != '/')
-            {
-                char c = reference_string[i++];
-                if (c == '~')
-                {
-                    c = (reference_string[i++] == '0') ? '~' : '/';
-                }
-                if (j == token_size || reference_token[j] != c)
-                {
-                    return false;
-                }
-                ++j;
-            }
-            if (j != token_size)
-            {
-                return false;
-            }
-            pos = i;
-        }
-        return pos == size;
-    }
-
-    /// @brief object member access with a key that is only copied if it is inserted
-    template<typename BasicJsonType>
-    static BasicJsonType& object_member(BasicJsonType& object, const string_t& key)
-    {
-        auto& members = *object.m_data.m_value.object;
-        const auto it = members.find(key);
-        if (it != members.end())
-        {
-            return it->second;
-        }
-        return object.operator[](key);
-    }
-
   JSON_PRIVATE_UNLESS_TESTED:
     json_pointer top() const
     {
@@ -498,141 +384,84 @@ class json_pointer
     the result independent of the order in which the flattened object is
     iterated, which is unspecified for some object types.
 
-    The prefixes form a tree and are numbered (number 0 is the empty prefix),
-    so each of them is stored only once (as a node) rather than as a copy of
-    all of its reference tokens. The tree does not own the reference tokens:
-    it refers to the tokens of the parsed keys, which must outlive it.
+    The prefixes form a tree and are numbered, so each of them is stored only
+    once (as a node) rather than as a copy of all of its reference tokens.
     */
     struct prefix_tree
     {
-        // open-addressing hash table from (parent, last reference token) to
-        // the number of the node; empty slots have token == nullptr
-        struct slot
-        {
-            std::size_t hash;
-            std::size_t parent;
-            const string_t* token;
-            std::size_t id;
-
-            slot() noexcept
-                : hash(0), parent(0), token(nullptr), id(0)
-            {}
-
-            slot(std::size_t h, std::size_t p, const string_t* t, std::size_t i) noexcept
-                : hash(h), parent(p), token(t), id(i)
-            {}
-        };
-
-        std::vector<slot> slots;
-        std::size_t used = 0;
-
-        static std::size_t hash_of(std::size_t parent, const string_t& token) noexcept
-        {
-            std::size_t h = parent * static_cast<std::size_t>(0x9E3779B97F4A7C15ULL);
-            for (std::size_t i = 0; i < token.size(); ++i)
-            {
-                h = (h ^ static_cast<unsigned char>(token[i])) * static_cast<std::size_t>(0x100000001B3ULL);
-            }
-            return h ^ (h >> 29u);
-        }
-
-        void grow()
-        {
-            std::vector<slot> old(slots.size() * 2);
-            old.swap(slots);
-            const std::size_t mask = slots.size() - 1;
-            for (const auto& s : old)
-            {
-                if (s.token != nullptr)
-                {
-                    std::size_t i = s.hash & mask;
-                    while (slots[i].token != nullptr)
-                    {
-                        i = (i + 1) & mask;
-                    }
-                    slots[i] = s;
-                }
-            }
-        }
-
-        // parent[id] is the number of the prefix without its last token
-        std::vector<std::size_t> parent;
+        // children[id] maps a reference token to the number of the prefix
+        // extended by that token; number 0 is the empty prefix
+        std::vector<std::map<string_t, std::size_t>> children;
         // is_array[id] is true iff some flattened key has the reference token
         // 0 directly below the prefix with number id
         std::vector<bool> is_array;
 
         // start with the empty prefix only
         prefix_tree()
-            : slots(16)
-            , parent(1, 0)
+            : children(1)
             , is_array(1, false)
         {}
 
         // return the number of the prefix with number id extended by
         // reference_token, adding it if it is new
-        std::size_t add_child(std::size_t id, const string_t& reference_token)
+        std::size_t add_child(std::size_t id, string_t&& reference_token)
         {
-            const std::size_t hash = hash_of(id, reference_token);
-            const std::size_t mask = slots.size() - 1;
-            std::size_t i = hash & mask;
-            while (slots[i].token != nullptr)
-            {
-                if (slots[i].hash == hash && slots[i].parent == id && *slots[i].token == reference_token)
-                {
-                    return slots[i].id;
-                }
-                i = (i + 1) & mask;
-            }
-
-            // new prefix
-            const std::size_t child = parent.size();
-            slots[i] = slot(hash, id, &reference_token, child);
             if (reference_token == "0")
             {
                 is_array[id] = true;
             }
-            parent.push_back(id);
-            is_array.push_back(false);
 
-            // keep the load factor below 1/2
-            if (++used * 2 > slots.size())
+            // read the number before the emplace_back below, which may
+            // reallocate children and invalidate the iterator
+            const std::size_t next = children.size();
+            const auto inserted = children[id].emplace(std::move(reference_token), next);
+            const std::size_t child = inserted.first->second;
+            if (inserted.second)
             {
-                grow();
+                children.emplace_back();
+                is_array.push_back(false);
             }
             return child;
         }
+
+        // return the number of the prefix with number id extended by
+        // reference_token, which must have been added before
+        std::size_t find_child(std::size_t id, const string_t& reference_token) const
+        {
+            const auto it = children[id].find(reference_token);
+            JSON_ASSERT(it != children[id].end());
+            return it->second;
+        }
     };
 
     /*!
     @brief create and return a reference to the pointed to value
 
-    @param[in] j  the value to create the pointed to value in
-    @param[in] tokens  the reference tokens of the pointer
-    @param[in] prefixes  prefixes[i] is the number in @a tree of the prefix
-                         consisting of the first i reference tokens
-
-    Complexity: Linear in the number of reference tokens.
+    Complexity: Linear in the number of reference tokens (times the logarithm
+    of the number of siblings for the prefix lookup).
 
     @throw parse_error.106 if an array index begins with '0'
     @throw parse_error.109 if array index is not a number
     @throw type_error.313 if value cannot be unflattened
     */
     template<typename BasicJsonType>
-    static BasicJsonType& get_and_create(BasicJsonType& j, const std::vector<string_t>& tokens,
-                                         const std::vector<std::size_t>& prefixes, const prefix_tree& tree)
+    BasicJsonType& get_and_create(BasicJsonType& j, const prefix_tree& tree) const
     {
         auto* result = &j;
 
+        // the number of the prefix consumed so far; used to look up whether
+        // the value to be created below is an array or an object
+        std::size_t id = 0;
+
         // in case no reference tokens exist, return a reference to the JSON value
         // j which will be overwritten by a primitive value
-        for (std::size_t i = 0; i < tokens.size(); ++i)
+        for (const auto& reference_token : reference_tokens)
         {
-            const auto& reference_token = tokens[i];
             switch (result->type())
             {
                 case detail::value_t::null:
                 {
-                    if (tree.is_array[prefixes[i]])
+                    if (tree.is_array[id])
                     {
                         // some reference token below this position is 0, so the
                         // value is an array
@@ -649,7 +478,7 @@ class json_pointer
                 case detail::value_t::object:
                 {
                     // create an entry in the object
-                    result = &object_member(*result, reference_token);
+                    result = &result->operator[](reference_token);
                     break;
                 }
 
@@ -676,6 +505,8 @@ class json_pointer
                 default:
                     JSON_THROW(detail::type_error::create(detail::exception_id::unflatten_invalid_value, "invalid value to unflatten", &j));
             }
+
+            id = tree.find_child(id, reference_token);
         }
 
         return *result;
@@ -727,7 +558,7 @@ class json_pointer
                 case detail::value_t::object:
                 {
                     // use unchecked object access
-                    ptr = &object_member(*ptr, reference_token);
+                    ptr = &ptr->operator[](reference_token);
                     break;
                 }
 
@@ -777,13 +608,8 @@ class json_pointer
             {
                 case detail::value_t::object:
                 {
-                    const auto it = ptr->m_data.m_value.object->find(reference_token);
-                    if (JSON_HEDLEY_UNLIKELY(it == ptr->m_data.m_value.object->end()))
-                    {
-                        // at() throws out_of_range.403 with the usual message
-                        ptr->at(reference_token);
-                    }
-                    ptr = &it->second;
+                    // note: at performs range check
+                    ptr = &ptr->at(reference_token);
                     break;
                 }
 
@@ -804,7 +630,7 @@ class json_pointer
                         JSON_THROW(detail::out_of_range::create(detail::exception_id::array_index_out_of_range, detail::concat(
                                 "array index ", std::to_string(idx), " is out of range"), ptr));
                     }
-                    ptr = &(*ptr->m_data.m_value.array)[idx];
+                    ptr = &ptr->operator[](idx);
                     break;
                 }
 
@@ -852,9 +678,7 @@ class json_pointer
                 {
                     // use unchecked object access; the const operator[]
                     // asserts that the key exists
-                    const auto it = ptr->m_data.m_value.object->find(reference_token);
-                    JSON_ASSERT(it != ptr->m_data.m_value.object->end());
-                    ptr = &it->second;
+                    ptr = &ptr->operator[](reference_token);
                     break;
                 }
 
@@ -868,9 +692,7 @@ class json_pointer
 
                     // use unchecked array access; the const operator[]
                     // asserts that the index exists
-                    const auto idx = array_index<BasicJsonType>(reference_token);
-                    JSON_ASSERT(idx < ptr->m_data.m_value.array->size());
-                    ptr = &(*ptr->m_data.m_value.array)[idx];
+                    ptr = &ptr->operator[](array_index<BasicJsonType>(reference_token));
                     break;
                 }
 
@@ -911,12 +733,12 @@ class json_pointer
             {
                 case detail::value_t::object:
                 {
-                    const auto it = ptr->m_data.m_value.object->find(reference_token);
-                    if (JSON_HEDLEY_UNLIKELY(it == ptr->m_data.m_value.object->end()))
+                    const auto it = ptr->find(reference_token);
+                    if (JSON_HEDLEY_UNLIKELY(it == ptr->end()))
                     {
                         return nullptr;
                     }
-                    ptr = &it->second;
+                    ptr = &*it;
                     break;
                 }
 
@@ -953,7 +775,7 @@ class json_pointer
                     {
                         return nullptr;
                     }
-                    ptr = &(*ptr->m_data.m_value.array)[idx];
+                    ptr = &ptr->operator[](idx);
                     break;
                 }
 
@@ -986,14 +808,13 @@ class json_pointer
             {
                 case detail::value_t::object:
                 {
-                    const auto it = ptr->m_data.m_value.object->find(reference_token);
-                    if (it == ptr->m_data.m_value.object->end())
+                    if (!ptr->contains(reference_token))
                     {
                         // we did not find the key in the object
                         return false;
                     }
 
-                    ptr = &it->second;
+                    ptr = &ptr->operator[](reference_token);
                     break;
                 }
 
@@ -1015,13 +836,13 @@ class json_pointer
                         return false;
                     }
 
-                    if (idx >= ptr->m_data.m_value.array->size())
+                    if (idx >= ptr->size())
                     {
                         // index out of range
                         return false;
                     }
 
-                    ptr = &(*ptr->m_data.m_value.array)[idx];
+                    ptr = &ptr->operator[](idx);
                     break;
                 }
 
@@ -1071,15 +892,6 @@ class json_pointer
             JSON_THROW(detail::parse_error::create(detail::exception_id::pointer_missing_slash, 1, detail::concat("JSON pointer must be empty or begin with '/' - was: '", reference_string, "'"), nullptr));
         }
 
-        // every slash starts a reference token
-        const std::size_t size = reference_string.size();
-        std::size_t token_count = 0;
-        for (std::size_t i = 0; i < size; ++i)
-        {
-            token_count += (reference_string[i] == '/') ? 1 : 0;
-        }
-        result.reserve(token_count);
-
         // extract the reference tokens:
         // - slash: position of the last read slash (or end of string)
         // - start: position after the previous slash
@@ -1101,52 +913,31 @@ class json_pointer
             const auto count = (slash == string_t::npos ? reference_string.size() : slash) - start;
             auto reference_token = string_t(reference_string.data() + start, count);
 
-            // check reference tokens are properly escaped; a token without
-            // a '~' (the common case) needs neither check nor unescaping
-            std::size_t pos = reference_token.find_first_of('~');
-            if (pos != string_t::npos)
+            // check reference tokens are properly escaped
+            for (std::size_t pos = reference_token.find_first_of('~');
+                    pos != string_t::npos;
+                    pos = reference_token.find_first_of('~', pos + 1))
             {
-                for (; pos != string_t::npos; pos = reference_token.find_first_of('~', pos + 1))
+                JSON_ASSERT(reference_token[pos] == '~');
+
+                // ~ must be followed by 0 or 1
+                if (JSON_HEDLEY_UNLIKELY(pos == reference_token.size() - 1 ||
+                                         (reference_token[pos + 1] != '0' &&
+                                          reference_token[pos + 1] != '1')))
                 {
-                    JSON_ASSERT(reference_token[pos] == '~');
-
-                    // ~ must be followed by 0 or 1
-                    if (JSON_HEDLEY_UNLIKELY(pos == reference_token.size() - 1 ||
-                                             (reference_token[pos + 1] != '0' &&
-                                              reference_token[pos + 1] != '1')))
-                    {
-                        JSON_THROW(detail::parse_error::create(detail::exception_id::pointer_invalid_escape, 0, "escape character '~' must be followed with '0' or '1'", nullptr));
-                    }
+                    JSON_THROW(detail::parse_error::create(detail::exception_id::pointer_invalid_escape, 0, "escape character '~' must be followed with '0' or '1'", nullptr));
                 }
-
-                detail::unescape(reference_token);
             }
 
             // finally, store the reference token
-            result.push_back(std::move(reference_token));
+            detail::unescape(reference_token);
+            result.push_back(reference_token);
         }
 
         return result;
     }
 
   private:
-    // Add the entry (key, v) to the object `obj`. Flattened paths are pairwise
-    // distinct, so objects that can append a key known to be absent
-    // (ordered_map) skip the lookup, which is linear and would make flatten
-    // quadratic; all other object types use operator[].
-    template<typename ObjectType, typename ValueType>
-    static auto add_flattened(ObjectType& obj, const string_t& key, ValueType&& v, int /*unused*/)
-    -> decltype(obj.emplace_new_key(key, std::forward<ValueType>(v)), void())
-    {
-        obj.emplace_new_key(key, std::forward<ValueType>(v));
-    }
-
-    template<typename ObjectType, typename ValueType>
-    static void add_flattened(ObjectType& obj, const string_t& key, ValueType&& v, ...)
-    {
-        obj[key] = std::forward<ValueType>(v);
-    }
-
     /*!
     @param[in] reference_string  the reference string to the current value
     @param[in] value             the value to consider
@@ -1191,8 +982,7 @@ class json_pointer
 
         // flatten `v`, whose path is `path`: primitives and empty containers
         // are added to the result right away; other containers get a frame
-        auto& object = *result.m_data.m_value.object;
-        const auto enter = [&stack, &path, &object](const BasicJsonType & v)
+        const auto enter = [&stack, &path, &result](const BasicJsonType & v)
         {
             switch (v.type())
             {
@@ -1201,7 +991,7 @@ class json_pointer
                     if (v.m_data.m_value.array->empty())
                     {
                         // flatten empty array as null
-                        add_flattened(object, path, nullptr, 0);
+                        result[path] = nullptr;
                     }
                     else
                     {
@@ -1215,7 +1005,7 @@ class json_pointer
                     if (v.m_data.m_value.object->empty())
                     {
                         // flatten empty object as null
-                        add_flattened(object, path, nullptr, 0);
+                        result[path] = nullptr;
                     }
                     else
                     {
@@ -1235,7 +1025,7 @@ class json_pointer
                 default:
                 {
                     // add a primitive value with its reference string
-                    add_flattened(object, path, v, 0);
+                    result[path] = v;
                     return;
                 }
             }
@@ -1281,10 +1071,6 @@ class json_pointer
                 enter(it->second);
             }
         }
-
-        // the entries were added without going through basic_json, so the
-        // parent pointers (JSON_DIAGNOSTICS) have to be set now
-        result.set_parents();
     }
 
     /*!
@@ -1308,53 +1094,21 @@ class json_pointer
 
         BasicJsonType result;
 
-        // parse every key once; the reference tokens are kept for the second
-        // pass (the vectors are never resized, so the tree may refer to them)
-        std::vector<std::vector<string_t>> keys;
-        keys.reserve(value.m_data.m_value.object->size());
-        for (const auto& element : *value.m_data.m_value.object)
-        {
-            json_pointer ptr(element.first);
-            keys.push_back(std::move(ptr.reference_tokens));
-        }
-
         // collect the pointer prefixes that have a reference token 0 among
         // their children; the values below them are arrays, all others are
         // objects (see prefix_tree)
         prefix_tree tree;
-        // the number of the prefix with i + 1 tokens of the previous key; keys
-        // are often sorted, so most of the prefix is the same as for the
-        // previous key and need not be looked up again
-        std::vector<std::size_t> path;
-        const std::vector<string_t>* previous = nullptr;
-        // the number of the complete prefix (i.e., the key) of each key
-        std::vector<std::size_t> leaves;
-        leaves.reserve(keys.size());
-        for (const auto& tokens : keys)
+        for (const auto& element : *value.m_data.m_value.object)
         {
-            std::size_t common = 0;
-            if (previous != nullptr)
+            json_pointer ptr(element.first);
+            std::size_t id = 0;
+            for (auto& reference_token : ptr.reference_tokens)
             {
-                const std::size_t limit = (std::min)(tokens.size(), previous->size());
-                while (common < limit && tokens[common] == (*previous)[common])
-                {
-                    ++common;
-                }
+                id = tree.add_child(id, std::move(reference_token));
             }
-            path.resize(common);
-            std::size_t id = common == 0 ? 0 : path[common - 1];
-            for (std::size_t i = common; i < tokens.size(); ++i)
-            {
-                id = tree.add_child(id, tokens[i]);
-                path.push_back(id);
-            }
-            leaves.push_back(id);
-            previous = &tokens;
         }
 
         // iterate the JSON object values
-        std::vector<std::size_t> prefixes;
-        std::size_t key_index = 0;
         for (const auto& element : *value.m_data.m_value.object)
         {
             if (JSON_HEDLEY_UNLIKELY(!element.second.is_primitive()))
@@ -1362,21 +1116,11 @@ class json_pointer
                 JSON_THROW(detail::type_error::create(detail::exception_id::unflatten_value_not_primitive, "values in object must be primitive", &element.second));
             }
 
-            const auto& tokens = keys[key_index];
-            // number the prefixes of this key from its last one to the first
-            prefixes.resize(tokens.size());
-            for (std::size_t i = tokens.size(), id = leaves[key_index]; i > 0; --i)
-            {
-                id = tree.parent[id];
-                prefixes[i - 1] = id;
-            }
-            ++key_index;
-
             // Assign the value to the reference pointed to by JSON pointer. Note
             // that if the JSON pointer is "" (i.e., points to the whole value),
             // function get_and_create returns a reference to the result itself.
             // An assignment will then create a primitive value.
-            get_and_create(result, tokens, prefixes, tree) = element.second;
+            json_pointer(element.first).get_and_create(result, tree) = element.second;
         }
 
         return result;
@@ -1415,7 +1159,7 @@ class json_pointer
         = delete;
 #else
     {
-        return equals_string(rhs);
+        return *this == json_pointer(rhs);
     }
 #endif
 
@@ -1499,7 +1243,7 @@ inline bool operator==(const json_pointer<RefStringTypeLhs>& lhs,
     = delete;
 #else
 {
-    return lhs.equals_string(rhs);
+    return lhs == json_pointer<RefStringTypeLhs>(rhs);
 }
 #endif
 
@@ -1512,7 +1256,7 @@ inline bool operator==(const StringType& lhs,
     = delete;
 #else
 {
-    return rhs.equals_string(lhs);
+    return json_pointer<RefStringTypeRhs>(lhs) == rhs;
 }
 #endif
 

include/nlohmann/detail/string_escape.hpp

@@ -9,7 +9,6 @@
 #pragma once
 
 #include <cstddef> // size_t
-#include <utility> // move
 
 #include <nlohmann/detail/abi_macros.hpp>
 
@@ -25,46 +24,39 @@ namespace detail
  * Note the order of escaping "~" to "~0" and "/" to "~1" is important.
  *
  * The string is rebuilt in a single pass, appending whole runs between the
- * characters that need escaping, while repeated replace() calls would move
- * the tail of the string once per escaped character. @ref escape_into appends
- * the escaped string to an existing one.
+ * characters that need escaping. Scanning with find_first_of() keeps the
+ * common case -- nothing to escape -- as fast as a single search, while
+ * repeated replace() calls would move the tail of the string once per
+ * escaped character.
  */
-template<typename StringType>
-inline void escape_into(StringType& out, const StringType& s)
-{
-    const std::size_t size = s.size();
-    std::size_t run = 0;
-    for (std::size_t i = 0; i < size; ++i)
-    {
-        const char c = s[i];
-        if (c == '~' || c == '/')
-        {
-            out.append(s.data() + run, i - run);
-            out.append(c == '~' ? "~0" : "~1", 2);
-            run = i + 1;
-        }
-    }
-    out.append(s.data() + run, size - run);
-}
-
 template<typename StringType>
 inline StringType escape(const StringType& s)
 {
-    // a single scan for both special characters; nothing to escape is the common case
-    const std::size_t size = s.size();
-    std::size_t i = 0;
-    while (i < size && s[i] != '~' && s[i] != '/')
+    auto next_special = [&s](std::size_t from)
     {
-        ++i;
-    }
-    if (i == size)
+        const auto tilde = s.find_first_of('~', from);
+        const auto slash = s.find_first_of('/', from);
+        return tilde < slash ? tilde : slash; // npos is the largest value
+    };
+
+    auto pos = next_special(0);
+    if (pos == StringType::npos)
     {
         return s;
     }
 
     StringType result;
-    result.reserve(size + 2);
-    escape_into(result, s);
+    result.reserve(s.size() + 2);
+
+    std::size_t run = 0;
+    while (pos != StringType::npos)
+    {
+        result.append(s.data() + run, pos - run);
+        result.append(s[pos] == '~' ? "~0" : "~1", 2);
+        run = pos + 1;
+        pos = next_special(run);
+    }
+    result.append(s.data() + run, s.size() - run);
     return result;
 }
 
@@ -109,7 +101,7 @@ inline void unescape(StringType& s)
         pos = s.find_first_of('~', run);
     }
     result.append(s.data() + run, s.size() - run);
-    s = std::move(result);
+    s = result;
 }
 
 }  // namespace detail

include/nlohmann/json.hpp

@@ -6562,18 +6562,24 @@ public:
         };
 
         // wrapper for "add" operation; add value at ptr
-        const auto operation_add = [&result](json_pointer & ptr, basic_json val)
+        const auto operation_add = [&result](json_pointer & ptr, const basic_json & val)
         {
             // adding to the root of the target document means replacing it
             if (ptr.empty())
             {
-                result = std::move(val);
+                result = val;
                 return;
             }
 
-            // get reference to the parent of the JSON pointer ptr; a missing
-            // parent (or one of its ancestors) is reported by at()
-            auto last_path = std::move(ptr.reference_tokens.back());
+            // make sure the top element of the pointer exists
+            json_pointer const top_pointer = ptr.top();
+            if (top_pointer != ptr)
+            {
+                result.at(top_pointer);
+            }
+
+            // get reference to the parent of the JSON pointer ptr
+            const auto last_path = ptr.back();
             ptr.pop_back();
             // parent must exist when performing patch add per RFC6902 specs
             basic_json& parent = result.at(ptr);
@@ -6584,7 +6590,7 @@ public:
                 case value_t::object:
                 {
                     // use operator[] to add value
-                    parent[std::move(last_path)] = std::move(val);
+                    parent[last_path] = val;
                     break;
                 }
 
@@ -6593,7 +6599,7 @@ public:
                     if (last_path == "-")
                     {
                         // special case: append to back
-                        parent.push_back(std::move(val));
+                        parent.push_back(val);
                     }
                     else
                     {
@@ -6605,7 +6611,7 @@ public:
                         }
 
                         // default case: insert add offset
-                        parent.insert(parent.begin() + static_cast<difference_type>(idx), std::move(val));
+                        parent.insert(parent.begin() + static_cast<difference_type>(idx), val);
                     }
                     break;
                 }
@@ -6628,8 +6634,7 @@ public:
         const auto operation_remove = [this, & result](json_pointer & ptr)
         {
             // get reference to the parent of the JSON pointer ptr
-            static_cast<void>(ptr.back()); // throws out_of_range.405 if ptr is the root
-            const auto last_path = std::move(ptr.reference_tokens.back());
+            const auto last_path = ptr.back();
             ptr.pop_back();
             basic_json& parent = result.at(ptr);
 
@@ -6729,8 +6734,8 @@ public:
             }
 
             // collect mandatory members
-            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 auto op = get_value("op", "op", true).template get<string_t>();
+            const auto path = get_value(op, "path", true).template get<string_t>();
             json_pointer ptr(path);
 
             switch (get_op(op))
@@ -6756,7 +6761,7 @@ public:
 
                 case patch_operations::move:
                 {
-                    const string_t& from_path = *get_value("move", "from", true).m_data.m_value.string;
+                    const auto from_path = get_value("move", "from", true).template get<string_t>();
                     json_pointer from_ptr(from_path);
 
                     if (JSON_HEDLEY_UNLIKELY(is_proper_prefix(from_ptr, ptr)))
@@ -6765,28 +6770,29 @@ public:
                     }
 
                     // the "from" location must exist - use at()
-                    // a root "from" is rejected by operation_remove below, which must leave result intact
-                    basic_json v = from_ptr.empty() ? basic_json(result) : std::move(result.at(from_ptr));
+                    basic_json const v = result.at(from_ptr);
 
                     // The move operation is functionally identical to a
                     // "remove" operation on the "from" location, followed
                     // immediately by an "add" operation at the target
                     // location with the value that was just removed.
                     operation_remove(from_ptr);
-                    operation_add(ptr, std::move(v));
+                    operation_add(ptr, v);
                     break;
                 }
 
                 case patch_operations::copy:
                 {
-                    const string_t& from_path = *get_value("copy", "from", true).m_data.m_value.string;
+                    const auto from_path = get_value("copy", "from", true).template get<string_t>();
                     const json_pointer from_ptr(from_path);
 
+                    // the "from" location must exist - use at()
+                    basic_json const v = result.at(from_ptr);
+
                     // The copy is functionally identical to an "add"
                     // operation at the target location using the value
-                    // specified in the "from" member; the "from" location
-                    // must exist - use at()
-                    operation_add(ptr, result.at(from_ptr));
+                    // specified in the "from" member.
+                    operation_add(ptr, v);
                     break;
                 }
 

include/nlohmann/ordered_map.hpp

@@ -143,17 +143,6 @@ public:
         return {std::prev(this->end()), true};
     }
 
-    /// @brief add an element at the end without checking whether the key exists
-    /// @note The caller must guarantee that @a key is not yet contained, otherwise
-    ///       the container holds duplicate keys. This avoids the linear search of
-    ///       emplace() and operator[] when many keys known to be new are added.
-    template<class V, detail::enable_if_t<
-                 detail::is_constructible<T, V>::value, int> = 0>
-    void emplace_new_key(const key_type& key, V && t)
-    {
-        append(key, std::forward<V>(t));
-    }
-
     T& operator[](const key_type& key)
     {
         return emplace(key, T{}).first->second;

tests/benchmarks/src/benchmarks.cpp

@@ -9,10 +9,7 @@
 #include <benchmark/benchmark.h>
 #include <nlohmann/json.hpp>
 #include <fstream>
-#include <array>
-#include <deque>
 #include <numeric>
-#include <set>
 #include <vector>
 #include <test_data.hpp>
 
@@ -624,27 +621,4 @@ static void FromCborChunkedString(benchmark::State& state, const std::size_t chu
 
 BENCHMARK_CAPTURE(FromCborChunkedString, 10000 chunks, 10000);
 
-// conversion of a JSON array into standard containers
-template<typename Container>
-static void GetArray(benchmark::State& state)
-{
-    json j = json::array();
-    for (int i = 0; i < 1000; ++i)
-    {
-        j.push_back(i);
-    }
-
-    for (auto _ : state)
-    {
-        auto c = j.get<Container>();
-        benchmark::DoNotOptimize(c);
-    }
-    state.SetItemsProcessed(state.iterations() * 1000);
-}
-
-BENCHMARK_TEMPLATE(GetArray, std::vector<int>);
-BENCHMARK_TEMPLATE(GetArray, std::deque<int>);
-BENCHMARK_TEMPLATE(GetArray, std::set<int>);
-BENCHMARK_TEMPLATE(GetArray, std::array<int, 1000>);
-
 BENCHMARK_MAIN();

tests/src/unit-algorithms.cpp

@@ -9,7 +9,6 @@
 #include "doctest_compatibility.h"
 
 #include <algorithm>
-#include <numeric>
 #include <nlohmann/json.hpp>
 using nlohmann::json;
 

tests/src/unit-guard-page.cpp

@@ -0,0 +1,447 @@
+//     __ _____ _____ _____
+//  __|  |   __|     |   | |  JSON for Modern C++ (supporting code)
+// |  |  |__   |  |  | | | |  version 3.12.0
+// |_____|_____|_____|_|___|  https://github.com/nlohmann/json
+//
+// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
+// SPDX-License-Identifier: MIT
+
+// The fast paths for contiguous input (bulk string scanning, SWAR searches,
+// UTF-8 prefix validation, the 8-digit number loop, the 8-byte indentation
+// skip, the BSON/BON8 bulk string readers) load several bytes at a time. This
+// test places every input directly in front of (or directly behind) an
+// inaccessible page, so reading even one byte outside the input crashes, with
+// or without sanitizers. ASan alone misses over-reads into the slack of the
+// same heap allocation.
+
+#include "doctest_compatibility.h"
+
+#include <nlohmann/json.hpp>
+using nlohmann::json;
+
+#include <cstdint>
+#include <cstring>
+#include <string>
+#include <utility>
+#include <vector>
+
+#if defined(_WIN32)
+    #define JSON_TEST_GUARD_PAGE_WINDOWS
+    #ifndef NOMINMAX
+        #define NOMINMAX
+    #endif
+    #ifndef WIN32_LEAN_AND_MEAN
+        #define WIN32_LEAN_AND_MEAN
+    #endif
+    #include <windows.h>
+#elif defined(__unix__) || defined(__APPLE__)
+    #define JSON_TEST_GUARD_PAGE_POSIX
+    #include <sys/mman.h>
+    #include <unistd.h>
+#endif
+
+#if defined(JSON_TEST_GUARD_PAGE_WINDOWS) || defined(JSON_TEST_GUARD_PAGE_POSIX)
+
+namespace
+{
+// Three pages: an inaccessible one, a readable one, an inaccessible one. An
+// input is copied either to the end of the middle page (any read past its last
+// byte faults) or to its start (any read before its first byte faults).
+class guarded_buffer
+{
+  public:
+    guarded_buffer()
+        : page(page_size())
+    {
+#if defined(JSON_TEST_GUARD_PAGE_WINDOWS)
+        void* const p = VirtualAlloc(nullptr, 3 * page, MEM_RESERVE | MEM_COMMIT, PAGE_NOACCESS);
+        REQUIRE(p != nullptr);
+        base = static_cast<unsigned char*>(p);
+        DWORD old_protect = 0;
+        REQUIRE(VirtualProtect(base + page, page, PAGE_READWRITE, &old_protect) != 0);
+#else
+        void* const p = mmap(nullptr, 3 * page, PROT_NONE, MAP_PRIVATE | MAP_ANON, -1, 0);
+        REQUIRE(p != MAP_FAILED);
+        base = static_cast<unsigned char*>(p);
+        REQUIRE(mprotect(base + page, page, PROT_READ | PROT_WRITE) == 0);
+#endif
+    }
+
+    ~guarded_buffer()
+    {
+#if defined(JSON_TEST_GUARD_PAGE_WINDOWS)
+        VirtualFree(base, 0, MEM_RELEASE);
+#else
+        munmap(base, 3 * page);
+#endif
+    }
+
+    guarded_buffer(const guarded_buffer&) = delete;
+    guarded_buffer& operator=(const guarded_buffer&) = delete;
+    guarded_buffer(guarded_buffer&&) = delete;
+    guarded_buffer& operator=(guarded_buffer&&) = delete;
+
+    // copies @a input so its last byte is the last readable byte
+    const std::uint8_t* at_end(const std::string& input)
+    {
+        REQUIRE(input.size() <= page);
+        unsigned char* const first = base + (2 * page) - input.size();
+        std::memcpy(first, input.data(), input.size());
+        return first;
+    }
+
+    // copies @a input so its first byte is the first readable byte
+    const std::uint8_t* at_start(const std::string& input)
+    {
+        REQUIRE(input.size() <= page);
+        unsigned char* const first = base + page;
+        std::memcpy(first, input.data(), input.size());
+        return first;
+    }
+
+  private:
+    static std::size_t page_size()
+    {
+#if defined(JSON_TEST_GUARD_PAGE_WINDOWS)
+        SYSTEM_INFO info;
+        GetSystemInfo(&info);
+        return static_cast<std::size_t>(info.dwPageSize);
+#else
+        return static_cast<std::size_t>(sysconf(_SC_PAGESIZE));
+#endif
+    }
+
+    std::size_t page = 0;
+    unsigned char* base = nullptr;
+};
+
+// the serialization of the result of @a f, or the exception message; @a f
+// takes the allow_exceptions flag, which is false without exceptions, where
+// an error yields a discarded value instead
+template<typename F>
+std::string outcome(F f)
+{
+#if defined(JSON_NOEXCEPTION)
+    return "value: " + f(false).dump(-1, ' ', false, json::error_handler_t::keep);
+#else
+    try
+    {
+        return "value: " + f(true).dump(-1, ' ', false, json::error_handler_t::keep);
+    }
+    catch (const json::exception& e)
+    {
+        return std::string("error: ") + e.what();
+    }
+#endif
+}
+
+// a SAX handler that only counts events, so sax_parse runs without a DOM
+struct counting_sax : nlohmann::json_sax<json>
+{
+    std::size_t events = 0;
+    std::string error{}; // NOLINT(readability-redundant-member-init)
+
+    bool null() override
+    {
+        return count();
+    }
+    bool boolean(bool /*val*/) override
+    {
+        return count();
+    }
+    bool number_integer(number_integer_t /*val*/) override
+    {
+        return count();
+    }
+    bool number_unsigned(number_unsigned_t /*val*/) override
+    {
+        return count();
+    }
+    bool number_float(number_float_t /*val*/, const string_t& /*s*/) override
+    {
+        return count();
+    }
+    bool string(string_t& /*val*/) override
+    {
+        return count();
+    }
+    bool binary(binary_t& /*val*/) override
+    {
+        return count();
+    }
+    bool start_object(std::size_t /*elements*/) override
+    {
+        return count();
+    }
+    bool key(string_t& /*val*/) override
+    {
+        return count();
+    }
+    bool end_object() override
+    {
+        return count();
+    }
+    bool start_array(std::size_t /*elements*/) override
+    {
+        return count();
+    }
+    bool end_array() override
+    {
+        return count();
+    }
+    bool parse_error(std::size_t position, const std::string& /*last_token*/, const nlohmann::detail::exception& ex) override
+    {
+        error = std::to_string(position) + " " + ex.what();
+        return false;
+    }
+
+  private:
+    bool count()
+    {
+        ++events;
+        return true;
+    }
+};
+
+// all prefixes of each seed, so the input ends at every byte of it
+std::vector<std::string> all_prefixes(const std::vector<std::string>& seeds)
+{
+    std::vector<std::string> result;
+    for (const auto& seed : seeds)
+    {
+        for (std::size_t n = 0; n <= seed.size(); ++n)
+        {
+            result.push_back(seed.substr(0, n));
+        }
+    }
+    return result;
+}
+
+std::vector<std::string> json_seeds()
+{
+    std::vector<std::string> seeds =
+    {
+        // string runs: ASCII, escapes, \u escapes, surrogate pairs
+        "\"abcdefghijklmnopqrstuvwxyz0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ\"",
+        R"("ab\ncd\"ef\\gh\u00e4ij\uD83D\uDE00kl\u12")",
+        // 2-, 3- and 4-byte UTF-8 sequences, then invalid UTF-8
+        std::string("\"\xC3\xA4\xE2\x82\xAC\xF0\x9F\x98\x80\xC3\xA4\xE2\x82\xAC\xF0\x9F\x98\x80") + "abcdefgh\"",
+        "\"abcdefgh\xC3\x28 \xED\xA0\x80 \xF4\x90\x80\x80 \xF8 \xC0\xAF\"",
+        std::string("\"abcdefg\x01") + "abcdefgh\"",
+        // numbers, so the 8-digit loop runs up to the end
+        "12345678",
+        "1234567890123456",
+        "12345678901234567890123",
+        "-0.000000001234567890123456789",
+        "3.14159265358979323846264338327950288e+100",
+        "-1.2345678901234567e-12",
+        "1E-5",
+        "[1.5,2e10,-3E-5,0.000000001,123456789012345678]",
+        // literals
+        "[true,false,null]",
+        // comments (only parsed with ignore_comments)
+        "/* comment */ [1, // line comment\n 2] /**/",
+        // a pretty-printed document
+        json::parse(R"({"a": [1, 2.5, "three", {"b": null, "c": [true, false]}], "d": {"e": {"f": {"g": "h"}}}})").dump(4),
+        json::parse(R"({"a": [1, 2.5, "three", {"b": null, "c": [true, false]}], "d": {"e": {"f": {"g": "h"}}}})").dump(8, '\t'),
+    };
+
+    // indentation runs of every length, with and without a closing bracket
+    for (std::size_t n = 0; n <= 20; ++n)
+    {
+        seeds.push_back("[\n" + std::string(n, ' ') + "1,\n" + std::string(n, ' ') + "2\n]");
+    }
+
+    return all_prefixes(seeds);
+}
+
+// a value whose binary serializations contain long strings and keys, numbers
+// of every width, and nested containers
+json binary_document()
+{
+    json j;
+    j["a key that is longer than eight bytes"] = "a string value that is longer than eight bytes";
+    j["\xC3\xA4\xE2\x82\xAC\xF0\x9F\x98\x80"] = "\xF0\x9F\x98\x80\xE2\x82\xAC\xC3\xA4 utf-8 0123456789";
+    j["numbers"] = {0, 1, -1, 255, -256, 65536, -2147483649LL, 4294967296ULL, 1.5, -2.25e100};
+    j["nested"] = {{"x", {{"y", {true, false, nullptr}}}}};
+    j["s"] = "";
+    return j;
+}
+
+// readers for check_binary(), callable with a container or an iterator range
+// followed by the allow_exceptions flag
+#define JSON_TEST_GUARD_PAGE_READER(name, from)                                     \
+    struct name                                                                     \
+    {                                                                               \
+        template<typename... Args>                                                  \
+        json operator()(bool allow_exceptions, Args&& ... args) const               \
+        {                                                                           \
+            return json::from(std::forward<Args>(args)..., true, allow_exceptions); \
+        }                                                                           \
+    };
+JSON_TEST_GUARD_PAGE_READER(read_bson, from_bson)
+JSON_TEST_GUARD_PAGE_READER(read_bon8, from_bon8)
+JSON_TEST_GUARD_PAGE_READER(read_cbor, from_cbor)
+JSON_TEST_GUARD_PAGE_READER(read_msgpack, from_msgpack)
+JSON_TEST_GUARD_PAGE_READER(read_ubjson, from_ubjson)
+JSON_TEST_GUARD_PAGE_READER(read_bjdata, from_bjdata)
+#undef JSON_TEST_GUARD_PAGE_READER
+
+// reads every prefix of @a bytes at both ends of the guarded page and from a
+// std::string, which must give the same outcome
+template<typename Reader>
+void check_binary(guarded_buffer& guard, const std::vector<std::uint8_t>& bytes, Reader parse)
+{
+    for (const auto& input : all_prefixes({std::string(bytes.begin(), bytes.end())}))
+    {
+        CAPTURE(input)
+        const std::string expected = outcome([&](bool allow)
+        {
+            return parse(allow, input);
+        });
+        for (int placement = 0; placement < 2; ++placement)
+        {
+            const std::uint8_t* const first = placement == 0 ? guard.at_end(input) : guard.at_start(input);
+            CHECK(outcome([&](bool allow)
+            {
+                return parse(allow, first, first + input.size());
+            }) == expected);
+        }
+    }
+}
+} // namespace
+
+TEST_CASE("guard page")
+{
+    guarded_buffer guard;
+
+    SECTION("string scanning")
+    {
+        // fills that drive each function to a different stop
+        const std::vector<std::string> fills =
+        {
+            std::string(64, 'a'),
+            std::string(64, '"'),
+            std::string(64, '\\'),
+            std::string(64, '\x01'),
+            std::string(64, '\x7F'),
+            std::string(64, '\xFF'),
+        };
+        std::vector<std::string> patterns = fills;
+        {
+            std::string utf8;
+            while (utf8.size() < 64)
+            {
+                utf8 += "\xC3\xA4\xE2\x82\xAC\xF0\x9F\x98\x80" "ab";
+            }
+            patterns.push_back(utf8);
+        }
+        {
+            std::string bytes;
+            for (unsigned int i = 0; i < 64; ++i)
+            {
+                bytes.push_back(static_cast<char>((i * 37u) & 0xFFu));
+            }
+            patterns.push_back(bytes);
+        }
+
+        for (const auto& pattern : patterns)
+        {
+            for (std::size_t n = 0; n <= 64; ++n)
+            {
+                const std::string input = pattern.substr(0, n);
+                for (int placement = 0; placement < 2; ++placement)
+                {
+                    const unsigned char* const p = placement == 0 ? guard.at_end(input) : guard.at_start(input);
+
+                    CHECK(nlohmann::detail::find_string_special(p, n) <= n);
+                    CHECK(nlohmann::detail::find_ascii_copyable_run(p, n) <= n);
+                    CHECK(nlohmann::detail::valid_utf8_prefix(p, n) <= n);
+#if defined(JSON_USE_SIMDUTF) && defined(JSON_HAS_CPP_17)
+                    CHECK(nlohmann::detail::find_string_delimiter(p, n) <= n);
+#endif
+                    CHECK(nlohmann::detail::string_bulk_run(p, n) <= n);
+                    CHECK(nlohmann::detail::scalar_string_bulk_run(p, n) <= n);
+                    for (std::size_t i = 0; i < n; ++i)
+                    {
+                        CHECK(nlohmann::detail::validate_one_utf8(p + i, n - i) <= n - i);
+                    }
+                }
+            }
+        }
+    }
+
+    SECTION("Eisel-Lemire")
+    {
+        const std::vector<std::string> numbers = all_prefixes(
+        {
+            "1234567812345678123456781234567812345678",
+            "-1.2345678901234567890123456789e-123",
+            "0.00000000000000000000000000000000000001",
+            "98765432.10987654",
+        });
+        for (const auto& number : numbers)
+        {
+            double out = 0;
+            const char* const end = reinterpret_cast<const char*>(guard.at_end(number));
+            static_cast<void>(nlohmann::detail::parse_float_eisel_lemire(end, end + number.size(), out));
+            const char* const start = reinterpret_cast<const char*>(guard.at_start(number));
+            static_cast<void>(nlohmann::detail::parse_float_eisel_lemire(start, start + number.size(), out));
+        }
+    }
+
+    SECTION("JSON")
+    {
+        for (const auto& input : json_seeds())
+        {
+            CAPTURE(input)
+            const std::string expected = outcome([&](bool allow)
+            {
+                return json::parse(input, nullptr, allow);
+            });
+            const std::string expected_comments = outcome([&](bool allow)
+            {
+                return json::parse(input, nullptr, allow, true);
+            });
+            const bool expected_accept = json::accept(input);
+            counting_sax expected_sax;
+            const bool expected_sax_result = json::sax_parse(input, &expected_sax);
+
+            for (int placement = 0; placement < 2; ++placement)
+            {
+                const std::uint8_t* const first = placement == 0 ? guard.at_end(input) : guard.at_start(input);
+                const std::uint8_t* const last = first + input.size();
+
+                CHECK(outcome([&](bool allow)
+                {
+                    return json::parse(first, last, nullptr, allow);
+                }) == expected);
+                CHECK(outcome([&](bool allow)
+                {
+                    return json::parse(first, last, nullptr, allow, true);
+                }) == expected_comments);
+                CHECK(json::accept(first, last) == expected_accept);
+
+                counting_sax sax;
+                CHECK(json::sax_parse(first, last, &sax) == expected_sax_result);
+                CHECK(sax.events == expected_sax.events);
+                CHECK(sax.error == expected_sax.error);
+            }
+        }
+    }
+
+    SECTION("binary formats")
+    {
+        // every prefix ends inside a value, e.g., inside a BSON key or BON8
+        // string without its terminator
+        const json j = binary_document();
+        check_binary(guard, json::to_bson(j), read_bson());
+        check_binary(guard, json::to_bon8(j), read_bon8());
+        check_binary(guard, json::to_cbor(j), read_cbor());
+        check_binary(guard, json::to_msgpack(j), read_msgpack());
+        check_binary(guard, json::to_ubjson(j), read_ubjson());
+        check_binary(guard, json::to_bjdata(j), read_bjdata());
+    }
+}
+
+#endif

tests/src/unit-json_pointer.cpp

@@ -23,14 +23,8 @@ using nlohmann::json;
     using namespace nlohmann::literals; // NOLINT(google-build-using-namespace)
 #endif
 
-#include <cerrno>
-#include <cstdlib>
-#include <limits>
 #include <map>
-#include <random>
 #include <sstream>
-#include <string>
-#include <vector>
 
 TEST_CASE("JSON pointers")
 {
@@ -1077,242 +1071,3 @@ TEST_CASE("flatten of structured values")
               R"({"/z":"s","/a~1b/~0":1,"/a~1b/k":null,"/a/0":1,"/a/1/c":null,"/a/1/b":null,"/a/2/0/x~0~1/0":true,"/a/2/0/x~0~1/1":null,"/a/2/0/w":2})");
     }
 }
-
-TEST_CASE("flatten of ordered_json")
-{
-    using nlohmann::ordered_json;
-
-    SECTION("keeps the document order of the leaves")
-    {
-        const ordered_json j = ordered_json::parse(R"({
-            "z": 1, "a": {"y": [true, null, {}], "b": "x", "": []},
-            "m~n": 2.5, "o/p": {"k": {}}, "0": [[1], [2, 3]]
-        })");
-
-        const ordered_json flat = j.flatten();
-        std::vector<std::string> keys;
-        for (const auto& el : flat.items())
-        {
-            keys.push_back(el.key());
-        }
-        const std::vector<std::string> expected =
-        {
-            "/z", "/a/y/0", "/a/y/1", "/a/y/2", "/a/b", "/a/", "/m~0n", "/o~1p/k", "/0/0/0", "/0/1/0", "/0/1/1"
-        };
-        CHECK(keys == expected);
-        CHECK(flat.size() == expected.size());
-        CHECK(flat["/m~0n"] == 2.5);
-        CHECK(flat["/a/y/2"].is_null());
-    }
-
-    SECTION("round-trips and agrees with json")
-    {
-        ordered_json j;
-        for (int i = 0; i < 200; ++i)
-        {
-            j["k" + std::to_string(i)] = {{"v", i}, {"l", {i, i + 1, "s"}}};
-        }
-        const ordered_json flat = j.flatten();
-        CHECK(flat.size() == 800);
-        CHECK(flat.unflatten() == j);
-
-        // same entries as for a sorted object
-        const nlohmann::json plain = nlohmann::json::parse(j.dump());
-        CHECK(nlohmann::json::parse(flat.dump()) == plain.flatten());
-    }
-
-    SECTION("primitive and empty root")
-    {
-        CHECK(ordered_json(1).flatten() == ordered_json({{"", 1}}));
-        CHECK(ordered_json::array().flatten() == ordered_json({{"", nullptr}}));
-    }
-}
-namespace
-{
-// reference implementation of the array index rules (RFC 6901, Sect. 4) based on strtoull
-enum class index_class
-{
-    ok,
-    leading_zero,
-    not_a_number,
-    unresolved,
-    exceeds_size_type
-};
-
-index_class classify_index(const std::string& s, std::size_t& idx)
-{
-    if (s.size() > 1 && s[0] == '0')
-    {
-        return index_class::leading_zero;
-    }
-    if (!s.empty() && s != "-" && !(s[0] >= '0' && s[0] <= '9'))
-    {
-        return index_class::not_a_number;
-    }
-    char* end = nullptr;
-    errno = 0;
-    const unsigned long long res = std::strtoull(s.c_str(), &end, 10); // NOLINT(runtime/int)
-    if (end == s.c_str() || errno == ERANGE || static_cast<std::size_t>(end - s.c_str()) != s.size())
-    {
-        return index_class::unresolved;
-    }
-    if (res >= static_cast<unsigned long long>((std::numeric_limits<std::size_t>::max)())) // NOLINT(runtime/int)
-    {
-        return index_class::exceeds_size_type;
-    }
-    idx = static_cast<std::size_t>(res);
-    return index_class::ok;
-}
-
-// the observable behavior of json_pointer::at() and contains() for an array index token
-void check_index_token(const std::string& token)
-{
-    const json array = {10, 20, 30};
-    const json::json_pointer ptr("/" + token);
-
-    std::size_t idx = 0;
-    const auto cls = classify_index(token, idx);
-    const bool exists = cls == index_class::ok && idx < array.size();
-
-    CAPTURE(token)
-    CHECK(array.contains(ptr) == (exists && token != "-"));
-
-    if (token == "-")
-    {
-        CHECK_THROWS_AS(array.at(ptr), json::out_of_range&);
-        return;
-    }
-
-    switch (cls)
-    {
-        case index_class::leading_zero:
-            CHECK_THROWS_AS(array.at(ptr), json::parse_error&);
-            break;
-        case index_class::not_a_number:
-            CHECK_THROWS_AS(array.at(ptr), json::parse_error&);
-            break;
-        case index_class::unresolved:
-        case index_class::exceeds_size_type:
-            CHECK_THROWS_AS(array.at(ptr), json::out_of_range&);
-            break;
-        case index_class::ok:
-        default:
-            if (exists)
-            {
-                CHECK(array.at(ptr) == array[idx]);
-            }
-            else
-            {
-                CHECK_THROWS_AS(array.at(ptr), json::out_of_range&);
-            }
-            break;
-    }
-}
-} // namespace
-
-TEST_CASE("JSON pointer array index tokens match strtoull semantics")
-{
-    SECTION("boundary values")
-    {
-        const std::string max_digits = std::to_string((std::numeric_limits<std::size_t>::max)());
-        const std::vector<std::string> tokens =
-        {
-            "", "-", "0", "1", "2", "3", "00", "01", "007", "+1", "-1", " 1", "1 ", "1a", "a1", "0x1", "1e1", "1.0",
-            "999999999", "1000000000", "99999999999999999", "999999999999999999", "1000000000000000000",
-            "9999999999999999999", "18446744073709551614", max_digits, "18446744073709551616",
-            "99999999999999999999999", "000000000000000000000"
-        };
-        for (const auto& token : tokens)
-        {
-            check_index_token(token);
-        }
-    }
-
-    SECTION("random tokens")
-    {
-        std::mt19937 gen(42);
-        const std::string alphabet = "0123456789012345678901234567890123456789-+ ex";
-        for (int i = 0; i < 5000; ++i)
-        {
-            std::string token(static_cast<std::size_t>(gen() % 23), '0');
-            for (auto& c : token)
-            {
-                c = alphabet[gen() % alphabet.size()];
-            }
-            check_index_token(token);
-        }
-    }
-}
-
-TEST_CASE("JSON pointer operations on pointers with escaped tokens")
-{
-    const std::vector<std::string> strings =
-    {
-        "", "/", "//", "/a", "/a/b", "/a~1b", "/~0", "/~01", "/~10", "/a~0~1/b/", "/0/1/2", "/ ", "/a/", "/~1/~0"
-    };
-
-    for (const auto& str : strings)
-    {
-        CAPTURE(str)
-        const json::json_pointer ptr(str);
-        CHECK(ptr.to_string() == str);
-        CHECK(ptr / "x" / "y" / std::size_t{3} == json::json_pointer(str + "/x/y/3"));
-        CHECK(ptr.parent_pointer() == (str.empty() ? ptr : json::json_pointer(str.substr(0, str.rfind('/')))));
-
-        // comparison with a string, in place, and with every other pointer
-#if !defined(JSON_TEST_DEPRECATED_FUNCTIONS_DELETED)
-        for (const auto& other : strings)
-        {
-            CAPTURE(other)
-            CHECK((ptr == other) == (str == other));
-            CHECK((other == ptr) == (str == other));
-            CHECK((ptr != other) == (str != other));
-        }
-        CHECK_THROWS_AS(ptr == "x", json::parse_error&);
-        CHECK_THROWS_AS(ptr == "/~", json::parse_error&);
-        CHECK_THROWS_AS(ptr == "/b/~2", json::parse_error&);
-#endif
-    }
-}
-
-TEST_CASE("JSON pointer lookups")
-{
-    json j = {{"a", {{"b", {1, 2, 3}}}}, {"", 7}, {"~/", {{"x", nullptr}}}};
-    const json& cj = j;
-
-    CHECK(cj[json::json_pointer("/a/b/2")] == 3);
-    CHECK(cj.at(json::json_pointer("/a/b/1")) == 2);
-    CHECK(cj.at(json::json_pointer("/")) == 7);
-    CHECK(cj.contains(json::json_pointer("/~0~1/x")));
-    CHECK(!cj.contains(json::json_pointer("/a/c")));
-    CHECK(cj.value(json::json_pointer("/a/b/0"), 5) == 1);
-    CHECK(cj.value(json::json_pointer("/a/b/3"), 5) == 5);
-    CHECK(cj.value(json::json_pointer("/a/zz"), 5) == 5);
-
-    CHECK_THROWS_AS(cj.at(json::json_pointer("/a/c")), json::out_of_range&);
-    CHECK_THROWS_AS(cj.at(json::json_pointer("/a/b/3")), json::out_of_range&);
-
-    // non-const access reuses existing entries and creates missing ones
-    j[json::json_pointer("/a/b/1")] = 20;
-    j[json::json_pointer("/n/m")] = 1;
-    CHECK(j["a"]["b"] == json({1, 20, 3}));
-    CHECK(j["n"]["m"] == 1);
-}
-
-TEST_CASE("JSON patch with moves and copies")
-{
-    json doc = {{"a", {{"b", {1, 2, 3}}}}, {"c", {{"d", "x"}}}};
-
-    CHECK(doc.patch(json::parse(R"([{"op":"move","from":"/a/b","path":"/c/e"}])")) ==
-          json::parse(R"({"a":{},"c":{"d":"x","e":[1,2,3]}})"));
-    CHECK(doc.patch(json::parse(R"([{"op":"copy","from":"/a/b","path":"/c/e"}])")) ==
-          json::parse(R"({"a":{"b":[1,2,3]},"c":{"d":"x","e":[1,2,3]}})"));
-    CHECK(doc.patch(json::parse(R"([{"op":"move","from":"/a/b/0","path":"/a/b/2"}])")) ==
-          json::parse(R"({"a":{"b":[2,3,1]},"c":{"d":"x"}})"));
-
-    // a failing move leaves a copy-patched document untouched
-    CHECK_THROWS_AS(doc.patch(json::parse(R"([{"op":"move","from":"","path":""}])")), json::out_of_range&);
-    json inplace = doc;
-    CHECK_THROWS_AS(inplace.patch_inplace(json::parse(R"([{"op":"move","from":"","path":""}])")), json::out_of_range&);
-    CHECK(inplace == doc);
-}

tests/src/unit-to_json-rvalue.cpp

@@ -1,257 +0,0 @@
-//     __ _____ _____ _____
-//  __|  |   __|     |   | |  JSON for Modern C++ (supporting code)
-// |  |  |__   |  |  | | | |  version 3.12.0
-// |_____|_____|_____|_|___|  https://github.com/nlohmann/json
-//
-// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
-// SPDX-License-Identifier: MIT
-
-#include "doctest_compatibility.h"
-
-#include <nlohmann/json.hpp>
-using nlohmann::json;
-
-#include <array>
-#include <deque>
-#include <forward_list>
-#include <list>
-#include <map>
-#include <set>
-#include <string>
-#include <unordered_map>
-#include <utility>
-#include <valarray>
-#include <vector>
-
-#if (defined(__cplusplus) && __cplusplus >= 201703L) || (defined(_HAS_CXX17) && _HAS_CXX17 == 1)
-    #if __has_include(<filesystem>)
-        #include <filesystem>
-        #define TO_JSON_RVALUE_HAS_FS 1
-    #endif
-#endif
-
-namespace
-{
-// element type that counts how it is converted to JSON: a conversion from an
-// lvalue copies, a conversion from an rvalue moves
-struct tracked
-{
-    std::string payload;
-    bool moved_from = false;
-
-    explicit tracked(std::string p) : payload(std::move(p)) {}
-    tracked(const tracked&) = default;
-    tracked& operator=(const tracked&) = default;
-    tracked(tracked&& other) noexcept : payload(std::move(other.payload)), moved_from(other.moved_from)
-    {
-        other.moved_from = true;
-    }
-    tracked& operator=(tracked&& other) noexcept
-    {
-        payload = std::move(other.payload);
-        moved_from = other.moved_from;
-        other.moved_from = true;
-        return *this;
-    }
-    ~tracked() = default;
-};
-
-int tracked_copies = 0; // NOLINT(cppcoreguidelines-avoid-non-const-global-variables,misc-use-internal-linkage)
-int tracked_moves = 0;  // NOLINT(cppcoreguidelines-avoid-non-const-global-variables,misc-use-internal-linkage)
-
-void to_json(json& j, const tracked& t)
-{
-    ++tracked_copies;
-    j = t.payload;
-}
-
-void to_json(json& j, tracked&& t)
-{
-    ++tracked_moves;
-    j = std::move(t.payload);
-    t.moved_from = true;
-}
-
-// user type with its own rvalue-aware serializer
-struct udt_container
-{
-    std::vector<int> values;
-};
-} // namespace
-
-namespace nlohmann
-{
-template<>
-struct adl_serializer<udt_container>
-{
-    static void to_json(json& j, const udt_container& c)
-    {
-        j = c.values;
-        j.push_back("copied");
-    }
-    static void to_json(json& j, udt_container&& c)
-    {
-        j = std::move(c.values);
-        j.push_back("moved");
-    }
-};
-} // namespace nlohmann
-
-TEST_CASE("to_json from rvalue containers")
-{
-    const std::string long_a(64, 'a');
-    const std::string long_b(64, 'b');
-
-    SECTION("vector<std::string>: elements are moved")
-    {
-        std::vector<std::string> v{long_a, long_b};
-        const json j = std::move(v);
-        CHECK(j == json::array({long_a, long_b}));
-        for (const auto& s : v) // NOLINT(bugprone-use-after-move,hicpp-invalid-access-moved)
-        {
-            CHECK(s.empty()); // long strings leave the source element empty when moved
-        }
-    }
-
-    SECTION("vector<std::string>: lvalues are copied and left untouched")
-    {
-        const std::vector<std::string> v{long_a, long_b};
-        const json j = v;
-        CHECK(j == json::array({long_a, long_b}));
-        CHECK(v[0] == long_a);
-        CHECK(v[1] == long_b);
-
-        std::vector<std::string> v2{long_a, long_b};
-        const json j2 = v2;
-        CHECK(j2 == j);
-        CHECK(v2[0] == long_a);
-        CHECK(v2[1] == long_b);
-    }
-
-    SECTION("tracked elements: rvalue moves, lvalue copies")
-    {
-        tracked_copies = 0;
-        tracked_moves = 0;
-
-        std::vector<tracked> v;
-        v.emplace_back("x");
-        v.emplace_back("y");
-
-        const json copy = v;
-        CHECK(copy == json::array({"x", "y"}));
-        CHECK(tracked_copies == 2);
-        CHECK(tracked_moves == 0);
-        CHECK_FALSE(v[0].moved_from);
-
-        const json moved = std::move(v);
-        CHECK(moved == copy);
-        CHECK(tracked_copies == 2);
-        CHECK(tracked_moves == 2);
-    }
-
-    SECTION("const rvalue is copied")
-    {
-        tracked_copies = 0;
-        tracked_moves = 0;
-        const std::vector<tracked> v(2, tracked("z"));
-        const json j = std::move(v); // NOLINT(performance-move-const-arg,hicpp-move-const-arg)
-        CHECK(j == json::array({"z", "z"}));
-        CHECK(tracked_copies == 2);
-        CHECK(tracked_moves == 0);
-    }
-
-    SECTION("other sequence containers")
-    {
-        CHECK(json(std::deque<std::string> {long_a, long_b}) == json::array({long_a, long_b}));
-        CHECK(json(std::list<std::string> {long_a, long_b}) == json::array({long_a, long_b}));
-        CHECK(json(std::forward_list<std::string> {long_a, long_b}) == json::array({long_a, long_b}));
-        CHECK(json(std::array<std::string, 2> {{long_a, long_b}}) == json::array({long_a, long_b}));
-        CHECK(json(std::set<std::string> {long_a, long_b}) == json::array({long_a, long_b}));
-        CHECK(json(std::vector<bool> {true, false}) == json::array({true, false}));
-        CHECK(json(std::vector<int> {1, 2, 3}) == json::array({1, 2, 3}));
-        CHECK(json(std::vector<std::vector<std::string>> {{long_a}, {long_b}}) == json::array({json::array({long_a}), json::array({long_b})}));
-        CHECK(json(std::vector<json> {1, "a"}) == json::array({1, "a"}));
-    }
-
-    SECTION("valarray")
-    {
-        std::valarray<int> va(3);
-        va[0] = 1;
-        va[1] = 2;
-        va[2] = 3;
-        CHECK(json(std::move(va)) == json::array({1, 2, 3})); // NOLINT(performance-move-const-arg,hicpp-move-const-arg)
-        CHECK(json(std::valarray<int>(2)) == json::array({0, 0}));
-    }
-
-    SECTION("array_t and json arrays")
-    {
-        json::array_t arr{1, 2};
-        CHECK(json(std::move(arr)) == json::array({1, 2}));
-        json a = json::array({1, 2});
-        const json b = std::move(a);
-        CHECK(b == json::array({1, 2}));
-    }
-
-    SECTION("object-like containers")
-    {
-        std::map<std::string, std::string> m{{"a", long_a}, {"b", long_b}};
-        const json j = std::move(m);
-        CHECK(j == json({{"a", long_a}, {"b", long_b}}));
-        for (const auto& kv : m) // NOLINT(bugprone-use-after-move,hicpp-invalid-access-moved)
-        {
-            CHECK(kv.second.empty()); // values moved, keys (const) copied
-        }
-
-        const std::map<std::string, std::string> cm{{"a", long_a}};
-        const json jc = cm;
-        CHECK(jc["a"] == long_a);
-        CHECK(cm.at("a") == long_a);
-
-        std::unordered_map<std::string, std::string> um{{"a", long_a}};
-        CHECK(json(std::move(um)) == json({{"a", long_a}}));
-
-        std::multimap<std::string, int> mm{{"a", 1}};
-        CHECK(json(std::move(mm)) == json({{"a", 1}}));
-
-        tracked_copies = 0;
-        tracked_moves = 0;
-        std::map<std::string, tracked> mt;
-        mt.emplace("k", tracked("v"));
-        const json jt = std::move(mt);
-        CHECK(jt == json({{"k", "v"}}));
-        CHECK(tracked_moves == 1);
-        CHECK(tracked_copies == 0);
-
-        json::object_t obj{{"a", 1}};
-        CHECK(json(std::move(obj)) == json({{"a", 1}}));
-    }
-
-    SECTION("user type with its own to_json overloads")
-    {
-        udt_container c{{1, 2}};
-        const json lv = c;
-        CHECK(lv == json::array({1, 2, "copied"}));
-        const json rv = std::move(c);
-        CHECK(rv == json::array({1, 2, "moved"}));
-    }
-
-    SECTION("assignment and implicit conversion")
-    {
-        std::vector<std::string> v{long_a};
-        json j;
-        j = std::move(v);
-        CHECK(j == json::array({long_a}));
-        json k = {std::vector<std::string>{long_b}};
-        CHECK(k.size() == 1);
-    }
-
-#ifdef TO_JSON_RVALUE_HAS_FS
-    SECTION("std::filesystem::path rvalue is still a string")
-    {
-        CHECK(json(std::filesystem::path("a/b")) == json("a/b"));
-#ifdef __cpp_lib_char8_t
-        CHECK(json(std::u8string(u8"a/b")) == json("a/b"));
-#endif
-    }
-#endif
-}