Merge branch 'develop' into benchmarks/value-operations

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

.github/workflows/windows.yml

@@ -166,21 +166,19 @@ jobs:
       # link, but the binaries clang 11.0.1 and clang 18.1.8 then produce crash
       # before doctest prints its first line - 39 of 102 tests on clang 18.
       # Keep the objects small by splitting the test files instead.
-      # The tests link with LLD: GNU ld fails on objects with more than 32767
-      # sections with "relocation truncated to fit: IMAGE_REL_AMD64_REL32
-      # against `.rdata'", as it stores the section an associative COMDAT
-      # section belongs to in 16 bits (x_associated in binutils'
-      # include/coff/internal.h) and so discards the jump tables of inline
-      # functions together with the wrong function. Each basic_json
-      # specialization and input type a test file instantiates adds many
-      # sections, so unit-msgpack.cpp and unit-regression2.cpp kept crossing
-      # that limit as the library grew.
+      # Objects with more than 65535 sections fail to link with "relocation
+      # truncated to fit: IMAGE_REL_AMD64_REL32 against `.rdata'": the MinGW
+      # linker stores the section an associative COMDAT section belongs to in
+      # 16 bits (x_associated in binutils' include/coff/internal.h), so it
+      # discards the jump tables of inline functions together with the wrong
+      # function. Each basic_json specialization a test file instantiates adds
+      # many sections, so test a second one in a file of its own.
       - name: Run CMake
         run: cmake -S . -B build ^
              -DCMAKE_CXX_COMPILER="C:/Program Files/LLVM/bin/clang++.exe" ^
              -DCMAKE_CXX_FLAGS="--target=x86_64-w64-mingw32 -stdlib=libstdc++ -pthread" ^
              -DCMAKE_CXX_FLAGS_DEBUG="-g0" ^
-             -DCMAKE_EXE_LINKER_FLAGS="-fuse-ld=lld -lwinpthread" ^
+             -DCMAKE_EXE_LINKER_FLAGS="-lwinpthread" ^
              -G"MinGW Makefiles" ^
              -DCMAKE_BUILD_TYPE=Debug ^
              -DJSON_BuildTests=On

include/nlohmann/detail/conversions/to_json.hpp

@@ -13,7 +13,7 @@
     #include <optional> // optional
 #endif
 
-#include <iterator> // begin, end, make_move_iterator, move_iterator
+#include <iterator> // begin, end
 #include <memory> // allocator_traits
 #include <string> //  basic_string, char_traits
 #include <tuple> // tuple, get
@@ -48,32 +48,6 @@ namespace detail
  * leave j with the type of the new value, but the pointer to the destroyed old one.
  */
 
-// a move iterator over the elements of an rvalue container, unless they are
-// const (e.g., std::set): libstdc++ before GCC 5 defines the reference of a
-// std::move_iterator as value_type&&, which cannot bind to a const element
-template<typename Iterator>
-std::move_iterator<Iterator> make_move_iterator_if_mutable_impl(const Iterator& it, std::true_type /*mutable*/)
-{
-    return std::make_move_iterator(it);
-}
-
-template<typename Iterator>
-Iterator make_move_iterator_if_mutable_impl(const Iterator& it, std::false_type /*mutable*/)
-{
-    return it;
-}
-
-template<typename Iterator>
-using is_mutable_iterator = std::integral_constant < bool,
-      !std::is_const<typename std::remove_reference<decltype(*std::declval<Iterator&>())>::type>::value >;
-
-template<typename Iterator>
-auto make_move_iterator_if_mutable(const Iterator& it)
--> decltype(make_move_iterator_if_mutable_impl(it, is_mutable_iterator<Iterator> {}))
-{
-    return make_move_iterator_if_mutable_impl(it, is_mutable_iterator<Iterator> {});
-}
-
 template<value_t> struct external_constructor;
 
 template<>
@@ -200,7 +174,7 @@ struct external_constructor<value_t::array>
         using std::begin;
         using std::end;
 
-        const typename BasicJsonType::json_value value(j.template create<typename BasicJsonType::array_t>(make_move_iterator_if_mutable(begin(arr)), make_move_iterator_if_mutable(end(arr))));
+        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);
     }
 
@@ -261,7 +235,7 @@ struct external_constructor<value_t::object>
         using std::begin;
         using std::end;
 
-        const typename BasicJsonType::json_value value(j.template create<typename BasicJsonType::object_t>(make_move_iterator_if_mutable(begin(obj)), make_move_iterator_if_mutable(end(obj))));
+        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);
     }
 
@@ -439,27 +413,25 @@ using is_movable_container_rvalue = negation<disjunction<
                                     std::is_const<T>,
                                     has_dedicated_to_json<T>,
                                     is_basic_json<T>,
+                                    is_range_view_type<T>,
                                     is_enum_keyed_map_type<T>,
                                     std::is_same<T, std::vector<bool>>>>;
 
-// rvalue array-like containers; object types are ruled out before views are
-// checked, as std::ranges::view<T> for the object_t of an ordered_json would
-// need that ordered_json to be complete (GCC 11, see #3312)
+// rvalue array-like containers
 template<typename BasicJsonType, typename T>
 using is_rvalue_array_to_json = conjunction<is_movable_container_rvalue<T>,
-      negation<is_compatible_object_type<BasicJsonType, T>>,
-      negation<is_range_view_type<T>>,
       is_compatible_array_type<BasicJsonType, T>,
       negation<disjunction<
       std::is_same<T, typename BasicJsonType::array_t>,
       std::is_same<T, typename BasicJsonType::binary_t>,
+      is_compatible_object_type<BasicJsonType, T>,
       is_compatible_string_type<BasicJsonType, T>,
       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) // NOLINT(cppcoreguidelines-missing-std-forward)
+inline void to_json(BasicJsonType& j, CompatibleArrayType && arr)
 {
     external_constructor<value_t::array>::construct_moving(j, arr);
 }
@@ -537,8 +509,7 @@ inline void to_json(BasicJsonType& j, const EnumKeyedMap& map)
 }
 #endif
 
-// rvalue object-like containers (views have no key_type and mapped_type, so
-// they are no compatible object type)
+// 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>>,
@@ -546,7 +517,7 @@ using is_rvalue_object_to_json = conjunction<is_movable_container_rvalue<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) // NOLINT(cppcoreguidelines-missing-std-forward)
+inline void to_json(BasicJsonType& j, CompatibleObjectType && obj)
 {
     external_constructor<value_t::object>::construct_moving(j, obj);
 }

include/nlohmann/detail/conversions/zmij.hpp

@@ -185,7 +185,7 @@ JSON_HEDLEY_ALWAYS_INLINE shortest_decimal to_shortest(std::uint64_t bits) noexc
     const uint128_parts p = umul192_hi128(p10.high, p10.low, bin_sig << static_cast<unsigned>(shift));
     std::uint64_t integral = p.high >> static_cast<unsigned>(extra_shift);
     // (no casts in the shifts: MSVC 2015 warns C4554 on them despite the parentheses)
-    constexpr auto fractional_low_shift = static_cast<unsigned>(extra_shift);
+    constexpr unsigned fractional_low_shift = static_cast<unsigned>(extra_shift);
     constexpr unsigned fractional_high_shift = 64u - fractional_low_shift;
     const std::uint64_t fractional = (p.high << fractional_high_shift) | (p.low >> fractional_low_shift);
     std::uint64_t digit = 0;

include/nlohmann/detail/exceptions.hpp

@@ -494,7 +494,8 @@ JSON_HEDLEY_NO_RETURN JSON_HEDLEY_NEVER_INLINE void throw_patch_missing_member(c
     static_cast<void>(string_type);
     static_cast<void>(val);
     // context-sensitive error message
-    JSON_THROW(parse_error::create(exception_id::patch_invalid_operation, 0, concat((op == "op") ? std::string("operation") : concat("operation '", op, '\''), string_type ? " must have string member '" : " must have member '", member, "'"), &val));
+    const std::string error_msg = (op == "op") ? std::string("operation") : concat("operation '", op, '\'');
+    JSON_THROW(parse_error::create(exception_id::patch_invalid_operation, 0, concat(error_msg, string_type ? " must have string member '" : " must have member '", member, "'"), &val));
 }
 
 template<typename StringType, typename BasicJsonType>

include/nlohmann/detail/iterators/iter_impl.hpp

@@ -680,12 +680,12 @@ class iter_impl // NOLINT(cppcoreguidelines-special-member-functions,hicpp-speci
     {
         JSON_ASSERT(m_object != nullptr);
 
-        if (JSON_HEDLEY_UNLIKELY(!m_object->is_object()))
+        if (JSON_HEDLEY_LIKELY(m_object->is_object()))
         {
-            throw_literal<invalid_iterator>(exception_id::iterator_key_not_object, "cannot use key() for non-object iterators", m_object);
+            return m_it.object_iterator->first;
         }
 
-        return m_it.object_iterator->first;
+        throw_literal<invalid_iterator>(exception_id::iterator_key_not_object, "cannot use key() for non-object iterators", m_object);
     }
 
     /*!

include/nlohmann/detail/json_pointer.hpp

@@ -11,7 +11,6 @@
 #include <algorithm> // all_of
 #include <cctype> // isdigit
 #include <cerrno> // errno, ERANGE
-#include <cstddef> // size_t
 #include <cstdlib> // strtoull
 #ifndef JSON_NO_IO
     #include <iosfwd> // ostream
@@ -335,7 +334,7 @@ class json_pointer
                 {
                     break; // not a plain number: let strtoull decide
                 }
-                acc = static_cast<size_type>((acc * 10) + static_cast<size_type>(c - '0'));
+                acc = static_cast<size_type>(acc * 10 + static_cast<size_type>(c - '0'));
                 if (JSON_HEDLEY_UNLIKELY(i == s.size() - 1))
                 {
                     idx = acc;
@@ -530,10 +529,10 @@ class json_pointer
 
         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 & (std::numeric_limits<std::size_t>::max)());
+            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 & (std::numeric_limits<std::size_t>::max)());
+                h = (h ^ static_cast<unsigned char>(token[i])) * static_cast<std::size_t>(0x100000001B3ULL);
             }
             return h ^ (h >> 29u);
         }

include/nlohmann/json.hpp

@@ -29,7 +29,6 @@
 #endif  // JSON_NO_IO
 #include <iterator> // make_move_iterator, random_access_iterator_tag
 #include <limits> // numeric_limits
-#include <map> // map
 #include <memory> // unique_ptr
 #include <set> // swap, operator!=
 #include <stdexcept> // length_error
@@ -755,20 +754,26 @@ private:
         // one level deep); stops at the first structured child it meets
         static bool all_children_leaves(const basic_json& v) noexcept
         {
-            // array_t only needs forward iterators (see custom_array_type)
             if (v.m_data.m_type == value_t::array)
             {
                 const auto& a = *v.m_data.m_value.array;
-                return std::all_of(a.begin(), a.end(), [](const basic_json & el)
+                for (auto it = a.rbegin(); it != a.rend(); ++it)
                 {
-                    return has_no_children(el);
-                });
+                    if (!has_no_children(*it))
+                    {
+                        return false;
+                    }
+                }
+                return true;
             }
-            const auto& o = *v.m_data.m_value.object;
-            return std::all_of(o.begin(), o.end(), [](const typename object_t::value_type & el)
+            for (const auto& el : *v.m_data.m_value.object)
             {
-                return has_no_children(el.second);
-            });
+                if (!has_no_children(el.second))
+                {
+                    return false;
+                }
+            }
+            return true;
         }
 
         // The walk in destroy_container() may take the children of a
@@ -1225,7 +1230,7 @@ public:
     }
 
     template < typename O = object_t, detail::enable_if_t < detail::has_stable_elements<O>::value, int > = 0 >
-    std::size_t object_capacity() const noexcept
+    static constexpr std::size_t object_capacity() noexcept
     {
         return 0;
     }
@@ -1237,7 +1242,7 @@ public:
     }
 
     template < typename O = object_t, detail::enable_if_t < !detail::has_stable_elements<O>::value && !detail::is_nlohmann_ordered_map<O>::value, int > = 0 >
-    std::size_t object_capacity() const noexcept
+    static constexpr std::size_t object_capacity() noexcept
     {
         return detail::unknown_size();
     }
@@ -3038,21 +3043,18 @@ public:
     JSON_HEDLEY_NO_RETURN JSON_HEDLEY_NEVER_INLINE
     static void throw_iterator_range_of_null(const basic_json* obj)
     {
-        static_cast<void>(obj); // unused when JSON_NOEXCEPTION is defined
         JSON_THROW(invalid_iterator::create(detail::exception_id::iterator_range_of_null, detail::concat("cannot construct with iterators from ", obj->type_name()), obj));
     }
 
     JSON_HEDLEY_NO_RETURN JSON_HEDLEY_NEVER_INLINE
     static void throw_incompatible_reference_type(const basic_json& obj)
     {
-        static_cast<void>(obj); // unused when JSON_NOEXCEPTION is defined
         JSON_THROW(type_error::create(detail::exception_id::incompatible_reference_type, detail::concat("incompatible ReferenceType for get_ref, actual type is ", obj.type_name()), &obj));
     }
 
     JSON_HEDLEY_NO_RETURN JSON_HEDLEY_NEVER_INLINE
     static void throw_array_index_exceeds_size_type(size_type idx)
     {
-        static_cast<void>(idx); // unused when JSON_NOEXCEPTION is defined
         JSON_THROW(std::length_error(detail::concat("array index ", std::to_string(idx), " exceeds size_type")));
     }
 
@@ -3060,8 +3062,6 @@ public:
     JSON_HEDLEY_NO_RETURN JSON_HEDLEY_NEVER_INLINE
     static void throw_array_index_out_of_range(size_type idx, const basic_json& j)
     {
-        static_cast<void>(idx); // unused when JSON_NOEXCEPTION is defined
-        static_cast<void>(j);
         JSON_THROW(out_of_range::create(detail::exception_id::array_index_out_of_range, detail::concat("array index ", std::to_string(idx), " is out of range"), &j));
     }
 
@@ -3070,8 +3070,6 @@ public:
     JSON_HEDLEY_NO_RETURN JSON_HEDLEY_NEVER_INLINE
     static void throw_key_not_found(const KeyType& key, const basic_json& j)
     {
-        static_cast<void>(key); // unused when JSON_NOEXCEPTION is defined
-        static_cast<void>(j);
         JSON_THROW(out_of_range::create(detail::exception_id::key_not_found, detail::concat("key '", key, "' not found"), &j));
     }
 
@@ -4895,19 +4893,19 @@ public:
     iterator insert(const_iterator pos, const basic_json& val) // NOLINT(performance-unnecessary-value-param)
     {
         // insert only works for arrays
-        if (JSON_HEDLEY_UNLIKELY(!is_array()))
+        if (JSON_HEDLEY_LIKELY(is_array()))
         {
-            detail::throw_cannot_use_with(detail::exception_id::insert_wrong_type, "insert()", *this);
+            // check if iterator pos fits to this JSON value
+            if (JSON_HEDLEY_UNLIKELY(pos.m_object != this))
+            {
+                detail::throw_literal<invalid_iterator>(detail::exception_id::iterator_from_other_value, "iterator does not fit current value", this);
+            }
+
+            // insert to array and return iterator
+            return insert_iterator(pos, val);
         }
 
-        // check if iterator pos fits to this JSON value
-        if (JSON_HEDLEY_UNLIKELY(pos.m_object != this))
-        {
-            detail::throw_literal<invalid_iterator>(detail::exception_id::iterator_from_other_value, "iterator does not fit current value", this);
-        }
-
-        // insert to array and return iterator
-        return insert_iterator(pos, val);
+        detail::throw_cannot_use_with(detail::exception_id::insert_wrong_type, "insert()", *this);
     }
 
     /// @brief inserts element into array
@@ -4915,21 +4913,21 @@ public:
     iterator insert(const_iterator pos, basic_json&& val) // NOLINT(performance-unnecessary-value-param)
     {
         // insert only works for arrays
-        if (JSON_HEDLEY_UNLIKELY(!is_array()))
+        if (JSON_HEDLEY_LIKELY(is_array()))
         {
-            detail::throw_cannot_use_with(detail::exception_id::insert_wrong_type, "insert()", *this);
+            // check if iterator pos fits to this JSON value
+            if (JSON_HEDLEY_UNLIKELY(pos.m_object != this))
+            {
+                detail::throw_literal<invalid_iterator>(detail::exception_id::iterator_from_other_value, "iterator does not fit current value", this);
+            }
+
+            // moving into a local first keeps this safe even if val aliases
+            // an element of this array
+            basic_json tmp(std::move(val));
+            return insert_iterator(pos, std::move(tmp));
         }
 
-        // check if iterator pos fits to this JSON value
-        if (JSON_HEDLEY_UNLIKELY(pos.m_object != this))
-        {
-            detail::throw_literal<invalid_iterator>(detail::exception_id::iterator_from_other_value, "iterator does not fit current value", this);
-        }
-
-        // moving into a local first keeps this safe even if val aliases
-        // an element of this array
-        basic_json tmp(std::move(val));
-        return insert_iterator(pos, std::move(tmp));
+        detail::throw_cannot_use_with(detail::exception_id::insert_wrong_type, "insert()", *this);
     }
 
     /// @brief inserts copies of element into array
@@ -4937,19 +4935,19 @@ public:
     iterator insert(const_iterator pos, size_type cnt, const basic_json& val) // NOLINT(performance-unnecessary-value-param)
     {
         // insert only works for arrays
-        if (JSON_HEDLEY_UNLIKELY(!is_array()))
+        if (JSON_HEDLEY_LIKELY(is_array()))
         {
-            detail::throw_cannot_use_with(detail::exception_id::insert_wrong_type, "insert()", *this);
+            // check if iterator pos fits to this JSON value
+            if (JSON_HEDLEY_UNLIKELY(pos.m_object != this))
+            {
+                detail::throw_literal<invalid_iterator>(detail::exception_id::iterator_from_other_value, "iterator does not fit current value", this);
+            }
+
+            // insert to array and return iterator
+            return insert_iterator(pos, cnt, val);
         }
 
-        // check if iterator pos fits to this JSON value
-        if (JSON_HEDLEY_UNLIKELY(pos.m_object != this))
-        {
-            detail::throw_literal<invalid_iterator>(detail::exception_id::iterator_from_other_value, "iterator does not fit current value", this);
-        }
-
-        // insert to array and return iterator
-        return insert_iterator(pos, cnt, val);
+        detail::throw_cannot_use_with(detail::exception_id::insert_wrong_type, "insert()", *this);
     }
 
     /// @brief inserts range of elements into array
@@ -5455,7 +5453,7 @@ public:
     // inline fast path for two values of the same non-owning scalar type; anything
     // else falls through to the out-of-line general comparison
 #define JSON_IMPLEMENT_SCALAR_FAST(op, null_result)                                                      \
-    if (lhs.m_data.m_type == rhs.m_data.m_type) /* NOLINT(readability/braces) */                         \
+    if (lhs.m_data.m_type == rhs.m_data.m_type)                                                          \
     {                                                                                                    \
         switch (lhs.m_data.m_type)                                                                       \
         {                                                                                                \

include/nlohmann/ordered_map.hpp

@@ -23,7 +23,6 @@
 #include <nlohmann/detail/abi_macros.hpp>
 #include <nlohmann/detail/macro_scope.hpp>
 #include <nlohmann/detail/meta/type_traits.hpp>
-#include <nlohmann/thirdparty/hedley/hedley.hpp>
 
 NLOHMANN_JSON_NAMESPACE_BEGIN
 

single_include/nlohmann/json.hpp

@@ -29,7 +29,6 @@
 #endif  // JSON_NO_IO
 #include <iterator> // make_move_iterator, random_access_iterator_tag
 #include <limits> // numeric_limits
-#include <map> // map
 #include <memory> // unique_ptr
 #include <set> // swap, operator!=
 #include <stdexcept> // length_error
@@ -5795,7 +5794,8 @@ JSON_HEDLEY_NO_RETURN JSON_HEDLEY_NEVER_INLINE void throw_patch_missing_member(c
     static_cast<void>(string_type);
     static_cast<void>(val);
     // context-sensitive error message
-    JSON_THROW(parse_error::create(exception_id::patch_invalid_operation, 0, concat((op == "op") ? std::string("operation") : concat("operation '", op, '\''), string_type ? " must have string member '" : " must have member '", member, "'"), &val));
+    const std::string error_msg = (op == "op") ? std::string("operation") : concat("operation '", op, '\'');
+    JSON_THROW(parse_error::create(exception_id::patch_invalid_operation, 0, concat(error_msg, string_type ? " must have string member '" : " must have member '", member, "'"), &val));
 }
 
 template<typename StringType, typename BasicJsonType>
@@ -6555,7 +6555,7 @@ NLOHMANN_JSON_NAMESPACE_END
     #include <optional> // optional
 #endif
 
-#include <iterator> // begin, end, make_move_iterator, move_iterator
+#include <iterator> // begin, end
 #include <memory> // allocator_traits
 #include <string> //  basic_string, char_traits
 #include <tuple> // tuple, get
@@ -7204,32 +7204,6 @@ namespace detail
  * leave j with the type of the new value, but the pointer to the destroyed old one.
  */
 
-// a move iterator over the elements of an rvalue container, unless they are
-// const (e.g., std::set): libstdc++ before GCC 5 defines the reference of a
-// std::move_iterator as value_type&&, which cannot bind to a const element
-template<typename Iterator>
-std::move_iterator<Iterator> make_move_iterator_if_mutable_impl(const Iterator& it, std::true_type /*mutable*/)
-{
-    return std::make_move_iterator(it);
-}
-
-template<typename Iterator>
-Iterator make_move_iterator_if_mutable_impl(const Iterator& it, std::false_type /*mutable*/)
-{
-    return it;
-}
-
-template<typename Iterator>
-using is_mutable_iterator = std::integral_constant < bool,
-      !std::is_const<typename std::remove_reference<decltype(*std::declval<Iterator&>())>::type>::value >;
-
-template<typename Iterator>
-auto make_move_iterator_if_mutable(const Iterator& it)
--> decltype(make_move_iterator_if_mutable_impl(it, is_mutable_iterator<Iterator> {}))
-{
-    return make_move_iterator_if_mutable_impl(it, is_mutable_iterator<Iterator> {});
-}
-
 template<value_t> struct external_constructor;
 
 template<>
@@ -7356,7 +7330,7 @@ struct external_constructor<value_t::array>
         using std::begin;
         using std::end;
 
-        const typename BasicJsonType::json_value value(j.template create<typename BasicJsonType::array_t>(make_move_iterator_if_mutable(begin(arr)), make_move_iterator_if_mutable(end(arr))));
+        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);
     }
 
@@ -7417,7 +7391,7 @@ struct external_constructor<value_t::object>
         using std::begin;
         using std::end;
 
-        const typename BasicJsonType::json_value value(j.template create<typename BasicJsonType::object_t>(make_move_iterator_if_mutable(begin(obj)), make_move_iterator_if_mutable(end(obj))));
+        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);
     }
 
@@ -7595,27 +7569,25 @@ using is_movable_container_rvalue = negation<disjunction<
                                     std::is_const<T>,
                                     has_dedicated_to_json<T>,
                                     is_basic_json<T>,
+                                    is_range_view_type<T>,
                                     is_enum_keyed_map_type<T>,
                                     std::is_same<T, std::vector<bool>>>>;
 
-// rvalue array-like containers; object types are ruled out before views are
-// checked, as std::ranges::view<T> for the object_t of an ordered_json would
-// need that ordered_json to be complete (GCC 11, see #3312)
+// rvalue array-like containers
 template<typename BasicJsonType, typename T>
 using is_rvalue_array_to_json = conjunction<is_movable_container_rvalue<T>,
-      negation<is_compatible_object_type<BasicJsonType, T>>,
-      negation<is_range_view_type<T>>,
       is_compatible_array_type<BasicJsonType, T>,
       negation<disjunction<
       std::is_same<T, typename BasicJsonType::array_t>,
       std::is_same<T, typename BasicJsonType::binary_t>,
+      is_compatible_object_type<BasicJsonType, T>,
       is_compatible_string_type<BasicJsonType, T>,
       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) // NOLINT(cppcoreguidelines-missing-std-forward)
+inline void to_json(BasicJsonType& j, CompatibleArrayType && arr)
 {
     external_constructor<value_t::array>::construct_moving(j, arr);
 }
@@ -7693,8 +7665,7 @@ inline void to_json(BasicJsonType& j, const EnumKeyedMap& map)
 }
 #endif
 
-// rvalue object-like containers (views have no key_type and mapped_type, so
-// they are no compatible object type)
+// 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>>,
@@ -7702,7 +7673,7 @@ using is_rvalue_object_to_json = conjunction<is_movable_container_rvalue<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) // NOLINT(cppcoreguidelines-missing-std-forward)
+inline void to_json(BasicJsonType& j, CompatibleObjectType && obj)
 {
     external_constructor<value_t::object>::construct_moving(j, obj);
 }
@@ -20744,12 +20715,12 @@ class iter_impl // NOLINT(cppcoreguidelines-special-member-functions,hicpp-speci
     {
         JSON_ASSERT(m_object != nullptr);
 
-        if (JSON_HEDLEY_UNLIKELY(!m_object->is_object()))
+        if (JSON_HEDLEY_LIKELY(m_object->is_object()))
         {
-            throw_literal<invalid_iterator>(exception_id::iterator_key_not_object, "cannot use key() for non-object iterators", m_object);
+            return m_it.object_iterator->first;
         }
 
-        return m_it.object_iterator->first;
+        throw_literal<invalid_iterator>(exception_id::iterator_key_not_object, "cannot use key() for non-object iterators", m_object);
     }
 
     /*!
@@ -20976,7 +20947,6 @@ NLOHMANN_JSON_NAMESPACE_END
 #include <algorithm> // all_of
 #include <cctype> // isdigit
 #include <cerrno> // errno, ERANGE
-#include <cstddef> // size_t
 #include <cstdlib> // strtoull
 #ifndef JSON_NO_IO
     #include <iosfwd> // ostream
@@ -21307,7 +21277,7 @@ class json_pointer
                 {
                     break; // not a plain number: let strtoull decide
                 }
-                acc = static_cast<size_type>((acc * 10) + static_cast<size_type>(c - '0'));
+                acc = static_cast<size_type>(acc * 10 + static_cast<size_type>(c - '0'));
                 if (JSON_HEDLEY_UNLIKELY(i == s.size() - 1))
                 {
                     idx = acc;
@@ -21502,10 +21472,10 @@ class json_pointer
 
         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 & (std::numeric_limits<std::size_t>::max)());
+            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 & (std::numeric_limits<std::size_t>::max)());
+                h = (h ^ static_cast<unsigned char>(token[i])) * static_cast<std::size_t>(0x100000001B3ULL);
             }
             return h ^ (h >> 29u);
         }
@@ -26484,7 +26454,7 @@ JSON_HEDLEY_ALWAYS_INLINE shortest_decimal to_shortest(std::uint64_t bits) noexc
     const uint128_parts p = umul192_hi128(p10.high, p10.low, bin_sig << static_cast<unsigned>(shift));
     std::uint64_t integral = p.high >> static_cast<unsigned>(extra_shift);
     // (no casts in the shifts: MSVC 2015 warns C4554 on them despite the parentheses)
-    constexpr auto fractional_low_shift = static_cast<unsigned>(extra_shift);
+    constexpr unsigned fractional_low_shift = static_cast<unsigned>(extra_shift);
     constexpr unsigned fractional_high_shift = 64u - fractional_low_shift;
     const std::uint64_t fractional = (p.high << fractional_high_shift) | (p.low >> fractional_low_shift);
     std::uint64_t digit = 0;
@@ -29734,8 +29704,6 @@ NLOHMANN_JSON_NAMESPACE_END
 
 // #include <nlohmann/detail/meta/type_traits.hpp>
 
-// #include <nlohmann/thirdparty/hedley/hedley.hpp>
-
 
 NLOHMANN_JSON_NAMESPACE_BEGIN
 
@@ -30820,20 +30788,26 @@ private:
         // one level deep); stops at the first structured child it meets
         static bool all_children_leaves(const basic_json& v) noexcept
         {
-            // array_t only needs forward iterators (see custom_array_type)
             if (v.m_data.m_type == value_t::array)
             {
                 const auto& a = *v.m_data.m_value.array;
-                return std::all_of(a.begin(), a.end(), [](const basic_json & el)
+                for (auto it = a.rbegin(); it != a.rend(); ++it)
                 {
-                    return has_no_children(el);
-                });
+                    if (!has_no_children(*it))
+                    {
+                        return false;
+                    }
+                }
+                return true;
             }
-            const auto& o = *v.m_data.m_value.object;
-            return std::all_of(o.begin(), o.end(), [](const typename object_t::value_type & el)
+            for (const auto& el : *v.m_data.m_value.object)
             {
-                return has_no_children(el.second);
-            });
+                if (!has_no_children(el.second))
+                {
+                    return false;
+                }
+            }
+            return true;
         }
 
         // The walk in destroy_container() may take the children of a
@@ -31290,7 +31264,7 @@ public:
     }
 
     template < typename O = object_t, detail::enable_if_t < detail::has_stable_elements<O>::value, int > = 0 >
-    std::size_t object_capacity() const noexcept
+    static constexpr std::size_t object_capacity() noexcept
     {
         return 0;
     }
@@ -31302,7 +31276,7 @@ public:
     }
 
     template < typename O = object_t, detail::enable_if_t < !detail::has_stable_elements<O>::value && !detail::is_nlohmann_ordered_map<O>::value, int > = 0 >
-    std::size_t object_capacity() const noexcept
+    static constexpr std::size_t object_capacity() noexcept
     {
         return detail::unknown_size();
     }
@@ -33103,21 +33077,18 @@ public:
     JSON_HEDLEY_NO_RETURN JSON_HEDLEY_NEVER_INLINE
     static void throw_iterator_range_of_null(const basic_json* obj)
     {
-        static_cast<void>(obj); // unused when JSON_NOEXCEPTION is defined
         JSON_THROW(invalid_iterator::create(detail::exception_id::iterator_range_of_null, detail::concat("cannot construct with iterators from ", obj->type_name()), obj));
     }
 
     JSON_HEDLEY_NO_RETURN JSON_HEDLEY_NEVER_INLINE
     static void throw_incompatible_reference_type(const basic_json& obj)
     {
-        static_cast<void>(obj); // unused when JSON_NOEXCEPTION is defined
         JSON_THROW(type_error::create(detail::exception_id::incompatible_reference_type, detail::concat("incompatible ReferenceType for get_ref, actual type is ", obj.type_name()), &obj));
     }
 
     JSON_HEDLEY_NO_RETURN JSON_HEDLEY_NEVER_INLINE
     static void throw_array_index_exceeds_size_type(size_type idx)
     {
-        static_cast<void>(idx); // unused when JSON_NOEXCEPTION is defined
         JSON_THROW(std::length_error(detail::concat("array index ", std::to_string(idx), " exceeds size_type")));
     }
 
@@ -33125,8 +33096,6 @@ public:
     JSON_HEDLEY_NO_RETURN JSON_HEDLEY_NEVER_INLINE
     static void throw_array_index_out_of_range(size_type idx, const basic_json& j)
     {
-        static_cast<void>(idx); // unused when JSON_NOEXCEPTION is defined
-        static_cast<void>(j);
         JSON_THROW(out_of_range::create(detail::exception_id::array_index_out_of_range, detail::concat("array index ", std::to_string(idx), " is out of range"), &j));
     }
 
@@ -33135,8 +33104,6 @@ public:
     JSON_HEDLEY_NO_RETURN JSON_HEDLEY_NEVER_INLINE
     static void throw_key_not_found(const KeyType& key, const basic_json& j)
     {
-        static_cast<void>(key); // unused when JSON_NOEXCEPTION is defined
-        static_cast<void>(j);
         JSON_THROW(out_of_range::create(detail::exception_id::key_not_found, detail::concat("key '", key, "' not found"), &j));
     }
 
@@ -34960,19 +34927,19 @@ public:
     iterator insert(const_iterator pos, const basic_json& val) // NOLINT(performance-unnecessary-value-param)
     {
         // insert only works for arrays
-        if (JSON_HEDLEY_UNLIKELY(!is_array()))
+        if (JSON_HEDLEY_LIKELY(is_array()))
         {
-            detail::throw_cannot_use_with(detail::exception_id::insert_wrong_type, "insert()", *this);
+            // check if iterator pos fits to this JSON value
+            if (JSON_HEDLEY_UNLIKELY(pos.m_object != this))
+            {
+                detail::throw_literal<invalid_iterator>(detail::exception_id::iterator_from_other_value, "iterator does not fit current value", this);
+            }
+
+            // insert to array and return iterator
+            return insert_iterator(pos, val);
         }
 
-        // check if iterator pos fits to this JSON value
-        if (JSON_HEDLEY_UNLIKELY(pos.m_object != this))
-        {
-            detail::throw_literal<invalid_iterator>(detail::exception_id::iterator_from_other_value, "iterator does not fit current value", this);
-        }
-
-        // insert to array and return iterator
-        return insert_iterator(pos, val);
+        detail::throw_cannot_use_with(detail::exception_id::insert_wrong_type, "insert()", *this);
     }
 
     /// @brief inserts element into array
@@ -34980,21 +34947,21 @@ public:
     iterator insert(const_iterator pos, basic_json&& val) // NOLINT(performance-unnecessary-value-param)
     {
         // insert only works for arrays
-        if (JSON_HEDLEY_UNLIKELY(!is_array()))
+        if (JSON_HEDLEY_LIKELY(is_array()))
         {
-            detail::throw_cannot_use_with(detail::exception_id::insert_wrong_type, "insert()", *this);
+            // check if iterator pos fits to this JSON value
+            if (JSON_HEDLEY_UNLIKELY(pos.m_object != this))
+            {
+                detail::throw_literal<invalid_iterator>(detail::exception_id::iterator_from_other_value, "iterator does not fit current value", this);
+            }
+
+            // moving into a local first keeps this safe even if val aliases
+            // an element of this array
+            basic_json tmp(std::move(val));
+            return insert_iterator(pos, std::move(tmp));
         }
 
-        // check if iterator pos fits to this JSON value
-        if (JSON_HEDLEY_UNLIKELY(pos.m_object != this))
-        {
-            detail::throw_literal<invalid_iterator>(detail::exception_id::iterator_from_other_value, "iterator does not fit current value", this);
-        }
-
-        // moving into a local first keeps this safe even if val aliases
-        // an element of this array
-        basic_json tmp(std::move(val));
-        return insert_iterator(pos, std::move(tmp));
+        detail::throw_cannot_use_with(detail::exception_id::insert_wrong_type, "insert()", *this);
     }
 
     /// @brief inserts copies of element into array
@@ -35002,19 +34969,19 @@ public:
     iterator insert(const_iterator pos, size_type cnt, const basic_json& val) // NOLINT(performance-unnecessary-value-param)
     {
         // insert only works for arrays
-        if (JSON_HEDLEY_UNLIKELY(!is_array()))
+        if (JSON_HEDLEY_LIKELY(is_array()))
         {
-            detail::throw_cannot_use_with(detail::exception_id::insert_wrong_type, "insert()", *this);
+            // check if iterator pos fits to this JSON value
+            if (JSON_HEDLEY_UNLIKELY(pos.m_object != this))
+            {
+                detail::throw_literal<invalid_iterator>(detail::exception_id::iterator_from_other_value, "iterator does not fit current value", this);
+            }
+
+            // insert to array and return iterator
+            return insert_iterator(pos, cnt, val);
         }
 
-        // check if iterator pos fits to this JSON value
-        if (JSON_HEDLEY_UNLIKELY(pos.m_object != this))
-        {
-            detail::throw_literal<invalid_iterator>(detail::exception_id::iterator_from_other_value, "iterator does not fit current value", this);
-        }
-
-        // insert to array and return iterator
-        return insert_iterator(pos, cnt, val);
+        detail::throw_cannot_use_with(detail::exception_id::insert_wrong_type, "insert()", *this);
     }
 
     /// @brief inserts range of elements into array
@@ -35520,7 +35487,7 @@ public:
     // inline fast path for two values of the same non-owning scalar type; anything
     // else falls through to the out-of-line general comparison
 #define JSON_IMPLEMENT_SCALAR_FAST(op, null_result)                                                      \
-    if (lhs.m_data.m_type == rhs.m_data.m_type) /* NOLINT(readability/braces) */                         \
+    if (lhs.m_data.m_type == rhs.m_data.m_type)                                                          \
     {                                                                                                    \
         switch (lhs.m_data.m_type)                                                                       \
         {                                                                                                \

tests/benchmarks/README.md

@@ -16,6 +16,13 @@ Micro-benchmarks for parsing, serialization and the binary formats, written with
 | `FromBinaryBuffer`, `FromBinaryFile` | read CBOR, MessagePack, UBJSON, BJData and BSON from a buffer or a `FILE*` |
 | `FromBinaryShape` | read deeply nested, container-heavy and scalar-heavy documents in every binary format |
 | `FromCborChunkedString` | read CBOR strings split into indefinite-length chunks |
+| `SaxParse` | parse with a SAX handler that only counts events, so no values are built |
+| `Copy`, `Destroy`, `Equal`, `Iterate` | copy, destroy, or compare a parsed document, or visit every value with range-based `for` loops |
+| `Flatten`, `FlattenOrdered`, `Unflatten` | `flatten()` for `json` and `ordered_json`, and `unflatten()` |
+| `Diff`, `Patch` | `diff()` against the document with every eighth scalar changed, and applying that patch |
+| `JsonPointerParse`, `JsonPointerToString`, `JsonPointerAt`, `JsonPointerContains` | the JSON pointers of every scalar in a document: parse them from strings, turn them back into strings, look them up with `at()` and `contains()` |
+| `GetVectorInt`, `GetVectorDouble`, `GetMap` | `get<std::vector<std::int64_t>>()`, `get<std::vector<double>>()` and `get<std::map<std::string, json>>()` on large arrays and a large flat object |
+| `ToJsonStrings` | create a `json` array from a `std::vector` of 100,000 strings, copied or moved |
 
 The input files are those of [nativejson-benchmark](https://github.com/miloyip/nativejson-benchmark) (`canada`,
 `citm_catalog`, `twitter`), a large `jeopardy` file, and number-heavy files (`floats`, `signed_ints`, ...).

tests/benchmarks/src/benchmarks.cpp

@@ -8,11 +8,14 @@
 
 #include <benchmark/benchmark.h>
 #include <nlohmann/json.hpp>
-#include <fstream>
 #include <array>
+#include <cstdint>
 #include <deque>
+#include <fstream>
+#include <map>
 #include <numeric>
 #include <set>
+#include <string>
 #include <vector>
 #include <test_data.hpp>
 
@@ -624,6 +627,526 @@ static void FromCborChunkedString(benchmark::State& state, const std::size_t chu
 
 BENCHMARK_CAPTURE(FromCborChunkedString, 10000 chunks, 10000);
 
+//////////////////////////////////////////////////////////////////////////////
+// SAX-parse JSON from string
+//
+// sax_parse() with a handler that does next to nothing runs the lexer and
+// parser without building values, so the gap to ParseString above is the cost
+// of building the DOM.
+//////////////////////////////////////////////////////////////////////////////
+
+static std::string read_file(const char* filename)
+{
+    std::ifstream f(filename);
+    return std::string((std::istreambuf_iterator<char>(f)), std::istreambuf_iterator<char>());
+}
+
+static json load_json(const char* filename)
+{
+    return json::parse(read_file(filename));
+}
+
+/// SAX handler that only counts the events, so that the handler costs next to nothing
+class counting_sax : public nlohmann::json_sax<json>
+{
+  public:
+    std::size_t events = 0;
+
+    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 json::exception& /*ex*/) override
+    {
+        return false;
+    }
+
+  private:
+    bool count()
+    {
+        ++events;
+        return true;
+    }
+};
+
+static void SaxParse(benchmark::State& state, const char* filename)
+{
+    const std::string str = read_file(filename);
+
+    for (auto _ : state)
+    {
+        counting_sax sax;
+        bool result = json::sax_parse(str, &sax);
+        benchmark::DoNotOptimize(result);
+        benchmark::DoNotOptimize(sax.events);
+    }
+
+    state.SetBytesProcessed(state.iterations() * str.size());
+}
+BENCHMARK_CAPTURE(SaxParse, canada,       TEST_DATA_DIRECTORY "/nativejson-benchmark/canada.json");
+BENCHMARK_CAPTURE(SaxParse, citm_catalog, TEST_DATA_DIRECTORY "/nativejson-benchmark/citm_catalog.json");
+BENCHMARK_CAPTURE(SaxParse, twitter,      TEST_DATA_DIRECTORY "/nativejson-benchmark/twitter.json");
+
+//////////////////////////////////////////////////////////////////////////////
+// work with values: copy, destroy, compare, iterate
+//
+// The parsed test files stand in for a document an application keeps around.
+// Each benchmark times one whole-document operation; setup and cleanup run
+// outside the timed section.
+//////////////////////////////////////////////////////////////////////////////
+
+static void Copy(benchmark::State& state, const char* filename)
+{
+    const json j = load_json(filename);
+
+    for (auto _ : state)
+    {
+        auto* copy = new json(j);
+
+        state.PauseTiming();
+        delete copy;
+        state.ResumeTiming();
+    }
+}
+BENCHMARK_CAPTURE(Copy, canada,       TEST_DATA_DIRECTORY "/nativejson-benchmark/canada.json");
+BENCHMARK_CAPTURE(Copy, citm_catalog, TEST_DATA_DIRECTORY "/nativejson-benchmark/citm_catalog.json");
+BENCHMARK_CAPTURE(Copy, twitter,      TEST_DATA_DIRECTORY "/nativejson-benchmark/twitter.json");
+
+static void Destroy(benchmark::State& state, const char* filename)
+{
+    const json j = load_json(filename);
+
+    for (auto _ : state)
+    {
+        state.PauseTiming();
+        auto* copy = new json(j);
+        state.ResumeTiming();
+
+        delete copy;
+    }
+}
+BENCHMARK_CAPTURE(Destroy, canada,       TEST_DATA_DIRECTORY "/nativejson-benchmark/canada.json");
+BENCHMARK_CAPTURE(Destroy, citm_catalog, TEST_DATA_DIRECTORY "/nativejson-benchmark/citm_catalog.json");
+BENCHMARK_CAPTURE(Destroy, twitter,      TEST_DATA_DIRECTORY "/nativejson-benchmark/twitter.json");
+
+static void Equal(benchmark::State& state, const char* filename)
+{
+    // two separate values, so that the comparison cannot stop at identical addresses
+    const json j = load_json(filename);
+    const json copy = j;
+
+    for (auto _ : state)
+    {
+        bool result = (j == copy);
+        benchmark::DoNotOptimize(result);
+    }
+}
+BENCHMARK_CAPTURE(Equal, canada,       TEST_DATA_DIRECTORY "/nativejson-benchmark/canada.json");
+BENCHMARK_CAPTURE(Equal, citm_catalog, TEST_DATA_DIRECTORY "/nativejson-benchmark/citm_catalog.json");
+BENCHMARK_CAPTURE(Equal, twitter,      TEST_DATA_DIRECTORY "/nativejson-benchmark/twitter.json");
+
+/// visit every value with range-based for loops, as client code walks a document
+static std::size_t count_values(const json& j)
+{
+    std::size_t result = 1;
+    if (j.is_structured())
+    {
+        for (const auto& element : j)
+        {
+            result += count_values(element);
+        }
+    }
+    return result;
+}
+
+static void Iterate(benchmark::State& state, const char* filename)
+{
+    const json j = load_json(filename);
+
+    for (auto _ : state)
+    {
+        std::size_t result = count_values(j);
+        benchmark::DoNotOptimize(result);
+    }
+
+    state.SetItemsProcessed(state.iterations() * static_cast<std::int64_t>(count_values(j)));
+}
+BENCHMARK_CAPTURE(Iterate, canada,       TEST_DATA_DIRECTORY "/nativejson-benchmark/canada.json");
+BENCHMARK_CAPTURE(Iterate, citm_catalog, TEST_DATA_DIRECTORY "/nativejson-benchmark/citm_catalog.json");
+BENCHMARK_CAPTURE(Iterate, twitter,      TEST_DATA_DIRECTORY "/nativejson-benchmark/twitter.json");
+
+//////////////////////////////////////////////////////////////////////////////
+// flatten and unflatten
+//////////////////////////////////////////////////////////////////////////////
+
+static void Flatten(benchmark::State& state, const char* filename)
+{
+    const json j = load_json(filename);
+
+    for (auto _ : state)
+    {
+        json flat = j.flatten();
+        benchmark::DoNotOptimize(flat);
+    }
+}
+BENCHMARK_CAPTURE(Flatten, canada,       TEST_DATA_DIRECTORY "/nativejson-benchmark/canada.json");
+BENCHMARK_CAPTURE(Flatten, citm_catalog, TEST_DATA_DIRECTORY "/nativejson-benchmark/citm_catalog.json");
+BENCHMARK_CAPTURE(Flatten, twitter,      TEST_DATA_DIRECTORY "/nativejson-benchmark/twitter.json");
+
+// ordered_json objects look keys up linearly, which flatten() used to do for
+// every value; canada (330,000 values in one flat object) is left out, as it
+// would take minutes with such versions
+static void FlattenOrdered(benchmark::State& state, const char* filename)
+{
+    const nlohmann::ordered_json j = nlohmann::ordered_json::parse(read_file(filename));
+
+    for (auto _ : state)
+    {
+        nlohmann::ordered_json flat = j.flatten();
+        benchmark::DoNotOptimize(flat);
+    }
+}
+BENCHMARK_CAPTURE(FlattenOrdered, citm_catalog, TEST_DATA_DIRECTORY "/nativejson-benchmark/citm_catalog.json");
+BENCHMARK_CAPTURE(FlattenOrdered, twitter,      TEST_DATA_DIRECTORY "/nativejson-benchmark/twitter.json");
+
+static void Unflatten(benchmark::State& state, const char* filename)
+{
+    const json flat = load_json(filename).flatten();
+
+    for (auto _ : state)
+    {
+        json j = flat.unflatten();
+        benchmark::DoNotOptimize(j);
+    }
+}
+BENCHMARK_CAPTURE(Unflatten, canada,       TEST_DATA_DIRECTORY "/nativejson-benchmark/canada.json");
+BENCHMARK_CAPTURE(Unflatten, citm_catalog, TEST_DATA_DIRECTORY "/nativejson-benchmark/citm_catalog.json");
+BENCHMARK_CAPTURE(Unflatten, twitter,      TEST_DATA_DIRECTORY "/nativejson-benchmark/twitter.json");
+
+//////////////////////////////////////////////////////////////////////////////
+// diff and patch
+//
+// The target is the document with every eighth scalar changed, so the patch
+// has one "replace" operation per changed value and the structure stays the
+// same.
+//////////////////////////////////////////////////////////////////////////////
+
+static void change_every_eighth_scalar(json& j, std::size_t& counter)
+{
+    if (j.is_structured())
+    {
+        for (auto& element : j)
+        {
+            change_every_eighth_scalar(element, counter);
+        }
+        return;
+    }
+
+    if (++counter % 8 != 0)
+    {
+        return;
+    }
+
+    switch (j.type())
+    {
+        case json::value_t::number_integer:
+            j = j.get<json::number_integer_t>() + 1;
+            break;
+        case json::value_t::number_unsigned:
+            j = j.get<json::number_unsigned_t>() + 1;
+            break;
+        case json::value_t::number_float:
+            j = j.get<json::number_float_t>() + 0.5;
+            break;
+        case json::value_t::string:
+            j = j.get<std::string>() + "!";
+            break;
+        case json::value_t::boolean:
+            j = !j.get<bool>();
+            break;
+        case json::value_t::null:
+        case json::value_t::object:
+        case json::value_t::array:
+        case json::value_t::binary:
+        case json::value_t::discarded:
+        default:
+            j = 0;
+            break;
+    }
+}
+
+static json changed_copy(const json& j)
+{
+    json result = j;
+    std::size_t counter = 0;
+    change_every_eighth_scalar(result, counter);
+    return result;
+}
+
+static void Diff(benchmark::State& state, const char* filename)
+{
+    const json source = load_json(filename);
+    const json target = changed_copy(source);
+
+    for (auto _ : state)
+    {
+        json patch = json::diff(source, target);
+        benchmark::DoNotOptimize(patch);
+    }
+
+    state.SetItemsProcessed(state.iterations() * static_cast<std::int64_t>(json::diff(source, target).size()));
+}
+BENCHMARK_CAPTURE(Diff, canada,       TEST_DATA_DIRECTORY "/nativejson-benchmark/canada.json");
+BENCHMARK_CAPTURE(Diff, citm_catalog, TEST_DATA_DIRECTORY "/nativejson-benchmark/citm_catalog.json");
+BENCHMARK_CAPTURE(Diff, twitter,      TEST_DATA_DIRECTORY "/nativejson-benchmark/twitter.json");
+
+static void Patch(benchmark::State& state, const char* filename)
+{
+    const json source = load_json(filename);
+    const json patch = json::diff(source, changed_copy(source));
+
+    for (auto _ : state)
+    {
+        json result = source.patch(patch);
+        benchmark::DoNotOptimize(result);
+    }
+
+    state.SetItemsProcessed(state.iterations() * static_cast<std::int64_t>(patch.size()));
+}
+BENCHMARK_CAPTURE(Patch, canada,       TEST_DATA_DIRECTORY "/nativejson-benchmark/canada.json");
+BENCHMARK_CAPTURE(Patch, citm_catalog, TEST_DATA_DIRECTORY "/nativejson-benchmark/citm_catalog.json");
+BENCHMARK_CAPTURE(Patch, twitter,      TEST_DATA_DIRECTORY "/nativejson-benchmark/twitter.json");
+
+//////////////////////////////////////////////////////////////////////////////
+// JSON Pointer
+//
+// The pointers are those of every scalar in the document, i.e., the keys of
+// its flattened form.
+//////////////////////////////////////////////////////////////////////////////
+
+static std::vector<std::string> pointer_strings(const json& j)
+{
+    std::vector<std::string> result;
+    const json flat = j.flatten();
+    result.reserve(flat.size());
+    for (auto it = flat.begin(); it != flat.end(); ++it)
+    {
+        result.push_back(it.key());
+    }
+    return result;
+}
+
+static std::vector<json::json_pointer> pointers(const json& j)
+{
+    const std::vector<std::string> strings = pointer_strings(j);
+    std::vector<json::json_pointer> result;
+    result.reserve(strings.size());
+    for (const auto& s : strings)
+    {
+        result.emplace_back(s);
+    }
+    return result;
+}
+
+static void JsonPointerParse(benchmark::State& state, const char* filename)
+{
+    const std::vector<std::string> strings = pointer_strings(load_json(filename));
+
+    for (auto _ : state)
+    {
+        for (const auto& s : strings)
+        {
+            json::json_pointer ptr(s);
+            benchmark::DoNotOptimize(ptr);
+        }
+    }
+
+    state.SetItemsProcessed(state.iterations() * static_cast<std::int64_t>(strings.size()));
+}
+BENCHMARK_CAPTURE(JsonPointerParse, citm_catalog, TEST_DATA_DIRECTORY "/nativejson-benchmark/citm_catalog.json");
+BENCHMARK_CAPTURE(JsonPointerParse, twitter,      TEST_DATA_DIRECTORY "/nativejson-benchmark/twitter.json");
+
+static void JsonPointerToString(benchmark::State& state, const char* filename)
+{
+    const std::vector<json::json_pointer> ptrs = pointers(load_json(filename));
+
+    for (auto _ : state)
+    {
+        for (const auto& ptr : ptrs)
+        {
+            std::string s = ptr.to_string();
+            benchmark::DoNotOptimize(s);
+        }
+    }
+
+    state.SetItemsProcessed(state.iterations() * static_cast<std::int64_t>(ptrs.size()));
+}
+BENCHMARK_CAPTURE(JsonPointerToString, citm_catalog, TEST_DATA_DIRECTORY "/nativejson-benchmark/citm_catalog.json");
+BENCHMARK_CAPTURE(JsonPointerToString, twitter,      TEST_DATA_DIRECTORY "/nativejson-benchmark/twitter.json");
+
+static void JsonPointerAt(benchmark::State& state, const char* filename)
+{
+    const json j = load_json(filename);
+    const std::vector<json::json_pointer> ptrs = pointers(j);
+
+    for (auto _ : state)
+    {
+        for (const auto& ptr : ptrs)
+        {
+            const json& value = j.at(ptr);
+            benchmark::DoNotOptimize(&value);
+        }
+    }
+
+    state.SetItemsProcessed(state.iterations() * static_cast<std::int64_t>(ptrs.size()));
+}
+BENCHMARK_CAPTURE(JsonPointerAt, citm_catalog, TEST_DATA_DIRECTORY "/nativejson-benchmark/citm_catalog.json");
+BENCHMARK_CAPTURE(JsonPointerAt, twitter,      TEST_DATA_DIRECTORY "/nativejson-benchmark/twitter.json");
+
+static void JsonPointerContains(benchmark::State& state, const char* filename)
+{
+    const json j = load_json(filename);
+    const std::vector<json::json_pointer> ptrs = pointers(j);
+
+    for (auto _ : state)
+    {
+        for (const auto& ptr : ptrs)
+        {
+            bool result = j.contains(ptr);
+            benchmark::DoNotOptimize(result);
+        }
+    }
+
+    state.SetItemsProcessed(state.iterations() * static_cast<std::int64_t>(ptrs.size()));
+}
+BENCHMARK_CAPTURE(JsonPointerContains, citm_catalog, TEST_DATA_DIRECTORY "/nativejson-benchmark/citm_catalog.json");
+BENCHMARK_CAPTURE(JsonPointerContains, twitter,      TEST_DATA_DIRECTORY "/nativejson-benchmark/twitter.json");
+
+//////////////////////////////////////////////////////////////////////////////
+// conversions from and to C++ containers
+//////////////////////////////////////////////////////////////////////////////
+
+static void GetVectorInt(benchmark::State& state, const char* filename)
+{
+    const json j = load_json(filename);
+
+    for (auto _ : state)
+    {
+        auto v = j.get<std::vector<std::int64_t>>();
+        benchmark::DoNotOptimize(v);
+    }
+
+    state.SetItemsProcessed(state.iterations() * static_cast<std::int64_t>(j.size()));
+}
+BENCHMARK_CAPTURE(GetVectorInt, signed_ints, TEST_DATA_DIRECTORY "/regression/signed_ints.json");
+
+static void GetVectorDouble(benchmark::State& state, const char* filename)
+{
+    const json j = load_json(filename);
+
+    for (auto _ : state)
+    {
+        auto v = j.get<std::vector<double>>();
+        benchmark::DoNotOptimize(v);
+    }
+
+    state.SetItemsProcessed(state.iterations() * static_cast<std::int64_t>(j.size()));
+}
+BENCHMARK_CAPTURE(GetVectorDouble, floats, TEST_DATA_DIRECTORY "/regression/floats.json");
+
+// a large flat object: the flattened document, one member per scalar
+static void GetMap(benchmark::State& state, const char* filename)
+{
+    const json j = load_json(filename).flatten();
+
+    for (auto _ : state)
+    {
+        auto m = j.get<std::map<std::string, json>>();
+        benchmark::DoNotOptimize(m);
+    }
+
+    state.SetItemsProcessed(state.iterations() * static_cast<std::int64_t>(j.size()));
+}
+BENCHMARK_CAPTURE(GetMap, citm_catalog, TEST_DATA_DIRECTORY "/nativejson-benchmark/citm_catalog.json");
+
+/// 100,000 strings, each too long for the small string optimization
+static std::vector<std::string> make_strings()
+{
+    std::vector<std::string> result;
+    result.reserve(100000);
+    for (std::size_t i = 0; i < 100000; ++i)
+    {
+        result.push_back("a string that does not fit in place: " + std::to_string(i));
+    }
+    return result;
+}
+
+static void ToJsonStrings(benchmark::State& state, const bool move)
+{
+    const std::vector<std::string> strings = make_strings();
+
+    for (auto _ : state)
+    {
+        state.PauseTiming();
+        std::vector<std::string> input = strings;
+        state.ResumeTiming();
+
+        auto* j = move ? new json(std::move(input)) : new json(input);
+
+        state.PauseTiming();
+        delete j;
+        state.ResumeTiming();
+    }
+
+    state.SetItemsProcessed(state.iterations() * static_cast<std::int64_t>(strings.size()));
+}
+BENCHMARK_CAPTURE(ToJsonStrings, copy, false);
+BENCHMARK_CAPTURE(ToJsonStrings, move, true);
+
 // conversion of a JSON array into standard containers
 template<typename Container>
 static void GetArray(benchmark::State& state)

tests/src/unit-constructor2.cpp

@@ -198,11 +198,11 @@ TEST_CASE("copy constructor and destructor across value types")
         const json src_uint = 7u;
         const json src_float = 2.5;
 
-        json c_null(src_null); // NOLINT(performance-unnecessary-copy-initialization): tests the copy constructor
-        json c_bool(src_bool); // NOLINT(performance-unnecessary-copy-initialization): tests the copy constructor
-        json c_int(src_int); // NOLINT(performance-unnecessary-copy-initialization): tests the copy constructor
-        json c_uint(src_uint); // NOLINT(performance-unnecessary-copy-initialization): tests the copy constructor
-        json c_float(src_float); // NOLINT(performance-unnecessary-copy-initialization): tests the copy constructor
+        json c_null(src_null);
+        json c_bool(src_bool);
+        json c_int(src_int);
+        json c_uint(src_uint);
+        json c_float(src_float);
 
         CHECK(c_null.is_null());
         CHECK(c_bool == true);
@@ -300,12 +300,12 @@ TEST_CASE("copy constructor and destructor across value types")
             REQUIRE(v.size() == 70);
 
             std::vector<json> copy(v);
-            CHECK((copy == v));
+            CHECK(copy == v);
 
             // mutating the copy leaves the original alone
             copy[5] = "changed";
             copy[6].push_back(1);
-            CHECK((copy != v));
+            CHECK(copy != v);
             CHECK(v[5] == std::string(5, 'x'));
             CHECK(v[6].size() == 3);
 

tests/src/unit-diagnostics.cpp

@@ -817,8 +817,8 @@ template<class Key, class T, class IgnoredLess = std::less<Key>,
              struct relocating_map : nlohmann::ordered_map<Key, T, IgnoredLess, Allocator>
 {
     using base_type = nlohmann::ordered_map<Key, T, IgnoredLess, Allocator>;
-    using iterator = typename base_type::iterator;
-    using Container = typename base_type::Container;
+    using typename base_type::iterator;
+    using typename base_type::Container;
     using base_type::base_type;
 
     template<typename... Args>

tests/src/unit-iterators1.cpp

@@ -1661,7 +1661,7 @@ TEST_CASE_TEMPLATE("reverse iteration and member access", Json, nlohmann::json,
         seen.clear();
         for (auto r = j.crbegin(); r != j.crend(); ++r)
         {
-            seen.push_back(r->template get<int>());
+            seen.push_back(*r);
         }
         CHECK(seen == std::vector<int> {4, 3, 2, 1});
     }

tests/src/unit-json_pointer.cpp

@@ -1230,11 +1230,11 @@ TEST_CASE("JSON pointer array index tokens match strtoull semantics")
 
     SECTION("random tokens")
     {
-        std::mt19937 gen(42); // NOLINT(cert-msc32-c,cert-msc51-cpp,bugprone-random-generator-seed): reproducible
+        std::mt19937 gen(42);
         const std::string alphabet = "0123456789012345678901234567890123456789-+ ex";
         for (int i = 0; i < 5000; ++i)
         {
-            std::string token(gen() % 23, '0');
+            std::string token(static_cast<std::size_t>(gen() % 23), '0');
             for (auto& c : token)
             {
                 c = alphabet[gen() % alphabet.size()];

tests/src/unit-serialization.cpp

@@ -1374,13 +1374,7 @@ void check_dump_against_reference(const std::string& s, const bool with_strict =
     };
     for (const auto error_handler : error_handlers)
     {
-#if defined(JSON_NOEXCEPTION)
-        // a strict dump of invalid UTF-8 calls std::abort() instead of throwing
-        static_cast<void>(with_strict);
-        if (error_handler == json::error_handler_t::strict)
-#else
         if (!with_strict && error_handler == json::error_handler_t::strict)
-#endif
         {
             continue;
         }
@@ -1435,7 +1429,7 @@ TEST_CASE("invalid UTF-8 at every position is handled like the reference")
         "\xF4\x90\x80\x80",
         // sequences cut short by ASCII, a control character, a quote, a
         // backslash, DEL, or the lead byte of a well-formed character
-        "\xC3" "a", "\xE2\x82" "\n", "\xE2\x82\"", "\xF0\x9F\x98\\", "\xC3\x7F", "\xC3\xC3\xA4", "\xE2\xF0\x9F\x98\x80", // NOLINT(bugprone-suspicious-missing-comma): "\xC3" "a" ends the hex escape
+        "\xC3" "a", "\xE2\x82" "\n", "\xE2\x82\"", "\xF0\x9F\x98\\", "\xC3\x7F", "\xC3\xC3\xA4", "\xE2\xF0\x9F\x98\x80",
         // truncated sequences
         "\xC3", "\xE2\x82", "\xF0\x9F\x98"
     };
@@ -1495,7 +1489,7 @@ TEST_CASE("invalid UTF-8 at every position is handled like the reference")
                 {
                     for (const auto& pattern : patterns)
                     {
-                        check_dump_against_reference(make_string(filler, pos, pattern, length - pos), bytes <= (filler.size() == 1 ? 17u : 8u));
+                        check_dump_against_reference(make_string(filler, pos, pattern, length - pos), bytes <= (filler.size() == 1 ? 17 : 8));
                     }
                 }
             }

tests/src/unit-testsuites.cpp

@@ -218,11 +218,7 @@ TEST_CASE("compliance tests from nativejson-benchmark")
             n1e308[0] = '[';
             n1e308[1] = '1';
             n1e308[310] = ']';
-#if JSON_STRICT_NUL_HANDLING
-            n1e308.resize(311); // a NUL byte after the value is a syntax error in strict mode
-#else
             n1e308[311] = '\0';
-#endif
             TEST_DOUBLE(n1e308, 1E308);
         }
 

tests/src/unit-throw_messages.cpp

@@ -54,8 +54,8 @@ TEST_CASE("exception messages of out-of-line throw sites")
 
     SECTION("at")
     {
-        const json& carr = arr;
-        const json& cobj = obj;
+        const json carr = arr;
+        const json cobj = obj;
         CHECK_MSG((void)arr.at(static_cast<json::size_type>(10)), "[json.exception.out_of_range.401] array index 10 is out of range");
         CHECK_MSG((void)carr.at(static_cast<json::size_type>(3)), "[json.exception.out_of_range.401] array index 3 is out of range");
         CHECK_MSG((void)num.at(static_cast<json::size_type>(0)), "[json.exception.type_error.304] cannot use at() with number");
@@ -65,7 +65,7 @@ TEST_CASE("exception messages of out-of-line throw sites")
         CHECK_MSG((void)num.at("a"), "[json.exception.type_error.304] cannot use at() with number");
 
         nlohmann::ordered_json oobj = {{"a", 1}};
-        const nlohmann::ordered_json& coobj = oobj;
+        const nlohmann::ordered_json coobj = oobj;
         CHECK_MSG((void)oobj.at("z"), "[json.exception.out_of_range.403] key 'z' not found");
         CHECK_MSG((void)coobj.at("z"), "[json.exception.out_of_range.403] key 'z' not found");
         CHECK_MSG((void)coobj.at(std::string("zz")), "[json.exception.out_of_range.403] key 'zz' not found");
@@ -94,10 +94,9 @@ TEST_CASE("exception messages of out-of-line throw sites")
         CHECK_MSG(obj.update(arr.begin(), arr2.end()), "[json.exception.invalid_iterator.210] iterators do not fit");
     }
 
-#if !defined(JSON_NOEXCEPTION) // patch_msg() catches the exceptions, which JSON_NOEXCEPTION turns into std::abort()
     SECTION("patch")
     {
-        const auto patch_msg = [](const char* doc, const char* patch) -> std::string
+        const auto patch_msg = [](const char* doc, const char* patch)
         {
             try
             {
@@ -106,23 +105,16 @@ TEST_CASE("exception messages of out-of-line throw sites")
             }
             catch (const json::exception& e)
             {
-                // with JSON_DIAGNOSTICS, what() names the offending value like "(/0) ",
-                // and with JSON_DIAGNOSTIC_POSITIONS its position like "(bytes 0-2) "; drop both
+                // with JSON_DIAGNOSTICS, what() names the offending value like "(/0) "; drop it
                 std::string msg = e.what();
-                for (const char* marker :
-            {
-                " (/", " (bytes "
-            })
+                const auto pos = msg.find(" (/");
+                if (pos != std::string::npos)
                 {
-                    const auto pos = msg.find(marker);
-                    if (pos != std::string::npos)
-                    {
-                        msg.erase(pos + 1, msg.find(") ", pos) - pos + 1);
-                    }
+                    msg.erase(pos + 1, msg.find(") ", pos) - pos + 1);
                 }
                 return msg;
             }
-            return {};
+            return std::string();
         };
 
         CHECK(patch_msg("{}", "{}") == "[json.exception.parse_error.104] parse error: JSON patch must be an array of objects");
@@ -140,5 +132,4 @@ TEST_CASE("exception messages of out-of-line throw sites")
         CHECK(patch_msg("{\"a\":1}", "[{\"op\":\"test\",\"path\":\"/a\",\"value\":2}]") == "[json.exception.other_error.501] unsuccessful: {\"op\":\"test\",\"path\":\"/a\",\"value\":2}");
         CHECK(patch_msg("{\"a\":1}", "[{\"op\":\"move\",\"path\":\"/a\"}]") == "[json.exception.parse_error.105] parse error: operation 'move' must have member 'from'");
     }
-#endif
 }