Use the with_*_t aliases in the remaining tests and docs

#5787 missed the instantiations spelled as `basic_json <` (astyle's
formatting) or ending in the CustomBaseClass argument. Convert them,
including the binary_t.md example pointed out in review.

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

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

@@ -64,18 +64,7 @@ values of that type directly to a `basic_json` instance, and they will automatic
 rather than arrays:
 
 ```cpp
-using custom_json = nlohmann::basic_json<
-    nlohmann::ordered_map,  // ObjectType
-    std::vector,            // ArrayType
-    std::string,            // StringType
-    bool,                   // BooleanType
-    std::int64_t,           // NumberIntegerType
-    std::uint64_t,          // NumberUnsignedType
-    double,                 // NumberFloatType
-    std::allocator,         // AllocatorType
-    nlohmann::adl_serializer,
-    std::vector<std::byte>  // Custom BinaryType
->;
+using custom_json = nlohmann::ordered_json::with_binary_t<std::vector<std::byte>>;
 
 std::vector<std::byte> data{std::byte{1}, std::byte{2}, std::byte{3}};
 custom_json j = data;  // Creates a binary value, not an array

docs/mkdocs/docs/examples/as_base_class.cpp

@@ -15,19 +15,7 @@ class base_class_with_hidden_members
     }
 };
 
-using json = nlohmann::basic_json <
-             std::map,
-             std::vector,
-             std::string,
-             bool,
-             std::int64_t,
-             std::uint64_t,
-             double,
-             std::allocator,
-             nlohmann::adl_serializer,
-             std::vector<std::uint8_t>,
-             base_class_with_hidden_members
-             >;
+using json = nlohmann::json::with_base_class_t<base_class_with_hidden_members>;
 
 int main()
 {

include/nlohmann/detail/json_pointer.hpp

@@ -16,8 +16,8 @@
     #include <iosfwd> // ostream
 #endif  // JSON_NO_IO
 #include <limits> // max
-#include <map> // map
 #include <numeric> // accumulate
+#include <set> // set
 #include <string> // string
 #include <utility> // move
 #include <vector> // vector
@@ -359,45 +359,33 @@ class json_pointer
 
   private:
     /*!
-    @brief the pointer prefixes of a flattened object, and which of them denote arrays
+    @brief the reference token sequences that denote arrays
 
     @ref unflatten collects the pointer prefixes that have a reference token 0
     among their children; @ref get_and_create creates arrays exactly below
     those prefixes and objects everywhere else. Deciding this up front keeps
     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, 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
-    {
-        // 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;
-    };
+    using array_parents_t = std::set<std::vector<string_t>>;
 
     /*!
     @brief create and return a reference to the pointed to value
 
-    Complexity: Linear in the number of reference tokens (times the logarithm
-    of the number of siblings for the prefix lookup).
+    Complexity: Linear in the number of reference tokens.
 
     @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>
-    BasicJsonType& get_and_create(BasicJsonType& j, const prefix_tree& tree) const
+    BasicJsonType& get_and_create(BasicJsonType& j, const array_parents_t& array_parents) 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;
+        // the reference tokens that have been consumed so far; used to look up
+        // whether the value to be created below is an array or an object
+        std::vector<string_t> prefix;
 
         // in case no reference tokens exist, return a reference to the JSON value
         // j which will be overwritten by a primitive value
@@ -407,7 +395,7 @@ class json_pointer
             {
                 case detail::value_t::null:
                 {
-                    if (tree.is_array[id])
+                    if (array_parents.find(prefix) != array_parents.end())
                     {
                         // some reference token below this position is 0, so the
                         // value is an array
@@ -452,9 +440,7 @@ class json_pointer
                     JSON_THROW(detail::type_error::create(313, "invalid value to unflatten", &j));
             }
 
-            const auto it = tree.children[id].find(reference_token);
-            JSON_ASSERT(it != tree.children[id].end());
-            id = it->second;
+            prefix.push_back(reference_token);
         }
 
         return *result;
@@ -892,127 +878,64 @@ class json_pointer
     @param[in,out] result        the result object to insert values to
 
     @note Empty objects or arrays are flattened to `null`.
-
-    The value is walked with an explicit stack rather than the call stack, so
-    arbitrarily deeply nested values can be flattened.
-
-    @sa https://github.com/nlohmann/json/issues/5393
     */
     template<typename BasicJsonType>
     static void flatten(const string_t& reference_string,
                         const BasicJsonType& value,
                         BasicJsonType& result)
     {
-        using object_const_iterator = typename BasicJsonType::object_t::const_iterator;
-
-        // an array or object being walked: the container, the array index or
-        // object iterator of the next child, and the length of the path of the
-        // container itself
-        struct frame
+        switch (value.type())
         {
-            const BasicJsonType* container;
-            std::size_t index;
-            object_const_iterator member;
-            std::size_t path_length;
-        };
-
-        // The containers being flattened are kept on an explicit stack, and
-        // every child is flattened completely before the next one, so the
-        // entries come out in the same order as with a recursive walk. The
-        // path of the value being flattened is kept in one buffer that grows
-        // and shrinks with the stack, rather than in a new string per level.
-        std::vector<frame> stack;
-        string_t path = reference_string;
-
-        // flatten `v`, whose path is `path`: primitives and empty containers
-        // are added to the result right away; other containers get a frame
-        const auto enter = [&stack, &path, &result](const BasicJsonType & v)
-        {
-            switch (v.type())
+            case detail::value_t::array:
             {
-                case detail::value_t::array:
+                if (value.m_data.m_value.array->empty())
                 {
-                    if (v.m_data.m_value.array->empty())
-                    {
-                        // flatten empty array as null
-                        result[path] = nullptr;
-                    }
-                    else
-                    {
-                        stack.push_back({&v, 0, object_const_iterator(), path.size()});
-                    }
-                    return;
+                    // flatten empty array as null
+                    result[reference_string] = nullptr;
                 }
-
-                case detail::value_t::object:
+                else
                 {
-                    if (v.m_data.m_value.object->empty())
+                    // iterate array and use index as a reference string
+                    for (std::size_t i = 0; i < value.m_data.m_value.array->size(); ++i)
                     {
-                        // flatten empty object as null
-                        result[path] = nullptr;
+                        flatten(detail::concat<string_t>(reference_string, '/', std::to_string(i)),
+                                value.m_data.m_value.array->operator[](i), result);
                     }
-                    else
-                    {
-                        stack.push_back({&v, 0, v.m_data.m_value.object->begin(), path.size()});
-                    }
-                    return;
-                }
-
-                case detail::value_t::null:
-                case detail::value_t::string:
-                case detail::value_t::boolean:
-                case detail::value_t::number_integer:
-                case detail::value_t::number_unsigned:
-                case detail::value_t::number_float:
-                case detail::value_t::binary:
-                case detail::value_t::discarded:
-                default:
-                {
-                    // add a primitive value with its reference string
-                    result[path] = v;
-                    return;
                 }
+                break;
             }
-        };
 
-        enter(value);
-        while (!stack.empty())
-        {
-            // the frame is changed through stack.back(): enter() may push a
-            // frame, which would invalidate a reference to it
-            const BasicJsonType* const container = stack.back().container;
-
-            // drop the path of the previous child
-            path.resize(stack.back().path_length);
-
-            if (container->is_array())
+            case detail::value_t::object:
             {
-                const auto& array = *container->m_data.m_value.array;
-                const std::size_t i = stack.back().index;
-                if (i == array.size())
+                if (value.m_data.m_value.object->empty())
                 {
-                    stack.pop_back();
-                    continue;
+                    // flatten empty object as null
+                    result[reference_string] = nullptr;
                 }
-
-                // iterate array and use index as a reference string
-                ++stack.back().index;
-                detail::concat_into(path, '/', detail::to_string<string_t>(i));
-                enter(array[i]);
+                else
+                {
+                    // iterate object and use keys as reference string
+                    for (const auto& element : *value.m_data.m_value.object)
+                    {
+                        flatten(detail::concat<string_t>(reference_string, '/', detail::escape(element.first)), element.second, result);
+                    }
+                }
+                break;
             }
-            else
-            {
-                const object_const_iterator it = stack.back().member;
-                if (it == container->m_data.m_value.object->end())
-                {
-                    stack.pop_back();
-                    continue;
-                }
 
-                // iterate object and use keys as reference string
-                ++stack.back().member;
-                detail::concat_into(path, '/', detail::escape(it->first));
-                enter(it->second);
+            case detail::value_t::null:
+            case detail::value_t::string:
+            case detail::value_t::boolean:
+            case detail::value_t::number_integer:
+            case detail::value_t::number_unsigned:
+            case detail::value_t::number_float:
+            case detail::value_t::binary:
+            case detail::value_t::discarded:
+            default:
+            {
+                // add a primitive value with its reference string
+                result[reference_string] = value;
+                break;
             }
         }
     }
@@ -1040,31 +963,19 @@ class json_pointer
 
         // 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;
-        tree.children.emplace_back();
-        tree.is_array.push_back(false);
+        // objects (see array_parents_t)
+        array_parents_t array_parents;
         for (const auto& element : *value.m_data.m_value.object)
         {
             json_pointer ptr(element.first);
-            std::size_t id = 0;
+            std::vector<string_t> prefix;
             for (auto& reference_token : ptr.reference_tokens)
             {
                 if (reference_token == "0")
                 {
-                    tree.is_array[id] = true;
-                }
-
-                // do not keep a reference into tree.children across the
-                // push_back below, as it may reallocate
-                const std::size_t next = tree.children.size();
-                const auto inserted = tree.children[id].emplace(std::move(reference_token), next);
-                id = inserted.first->second;
-                if (inserted.second)
-                {
-                    tree.children.emplace_back();
-                    tree.is_array.push_back(false);
+                    array_parents.insert(prefix);
                 }
+                prefix.push_back(std::move(reference_token));
             }
         }
 
@@ -1080,7 +991,7 @@ class json_pointer
             // 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.
-            json_pointer(element.first).get_and_create(result, tree) = element.second;
+            json_pointer(element.first).get_and_create(result, array_parents) = element.second;
         }
 
         return result;

single_include/nlohmann/json.hpp

@@ -19928,8 +19928,8 @@ NLOHMANN_JSON_NAMESPACE_END
     #include <iosfwd> // ostream
 #endif  // JSON_NO_IO
 #include <limits> // max
-#include <map> // map
 #include <numeric> // accumulate
+#include <set> // set
 #include <string> // string
 #include <utility> // move
 #include <vector> // vector
@@ -20277,45 +20277,33 @@ class json_pointer
 
   private:
     /*!
-    @brief the pointer prefixes of a flattened object, and which of them denote arrays
+    @brief the reference token sequences that denote arrays
 
     @ref unflatten collects the pointer prefixes that have a reference token 0
     among their children; @ref get_and_create creates arrays exactly below
     those prefixes and objects everywhere else. Deciding this up front keeps
     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, 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
-    {
-        // 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;
-    };
+    using array_parents_t = std::set<std::vector<string_t>>;
 
     /*!
     @brief create and return a reference to the pointed to value
 
-    Complexity: Linear in the number of reference tokens (times the logarithm
-    of the number of siblings for the prefix lookup).
+    Complexity: Linear in the number of reference tokens.
 
     @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>
-    BasicJsonType& get_and_create(BasicJsonType& j, const prefix_tree& tree) const
+    BasicJsonType& get_and_create(BasicJsonType& j, const array_parents_t& array_parents) 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;
+        // the reference tokens that have been consumed so far; used to look up
+        // whether the value to be created below is an array or an object
+        std::vector<string_t> prefix;
 
         // in case no reference tokens exist, return a reference to the JSON value
         // j which will be overwritten by a primitive value
@@ -20325,7 +20313,7 @@ class json_pointer
             {
                 case detail::value_t::null:
                 {
-                    if (tree.is_array[id])
+                    if (array_parents.find(prefix) != array_parents.end())
                     {
                         // some reference token below this position is 0, so the
                         // value is an array
@@ -20370,9 +20358,7 @@ class json_pointer
                     JSON_THROW(detail::type_error::create(313, "invalid value to unflatten", &j));
             }
 
-            const auto it = tree.children[id].find(reference_token);
-            JSON_ASSERT(it != tree.children[id].end());
-            id = it->second;
+            prefix.push_back(reference_token);
         }
 
         return *result;
@@ -20810,127 +20796,64 @@ class json_pointer
     @param[in,out] result        the result object to insert values to
 
     @note Empty objects or arrays are flattened to `null`.
-
-    The value is walked with an explicit stack rather than the call stack, so
-    arbitrarily deeply nested values can be flattened.
-
-    @sa https://github.com/nlohmann/json/issues/5393
     */
     template<typename BasicJsonType>
     static void flatten(const string_t& reference_string,
                         const BasicJsonType& value,
                         BasicJsonType& result)
     {
-        using object_const_iterator = typename BasicJsonType::object_t::const_iterator;
-
-        // an array or object being walked: the container, the array index or
-        // object iterator of the next child, and the length of the path of the
-        // container itself
-        struct frame
+        switch (value.type())
         {
-            const BasicJsonType* container;
-            std::size_t index;
-            object_const_iterator member;
-            std::size_t path_length;
-        };
-
-        // The containers being flattened are kept on an explicit stack, and
-        // every child is flattened completely before the next one, so the
-        // entries come out in the same order as with a recursive walk. The
-        // path of the value being flattened is kept in one buffer that grows
-        // and shrinks with the stack, rather than in a new string per level.
-        std::vector<frame> stack;
-        string_t path = reference_string;
-
-        // flatten `v`, whose path is `path`: primitives and empty containers
-        // are added to the result right away; other containers get a frame
-        const auto enter = [&stack, &path, &result](const BasicJsonType & v)
-        {
-            switch (v.type())
+            case detail::value_t::array:
             {
-                case detail::value_t::array:
+                if (value.m_data.m_value.array->empty())
                 {
-                    if (v.m_data.m_value.array->empty())
-                    {
-                        // flatten empty array as null
-                        result[path] = nullptr;
-                    }
-                    else
-                    {
-                        stack.push_back({&v, 0, object_const_iterator(), path.size()});
-                    }
-                    return;
+                    // flatten empty array as null
+                    result[reference_string] = nullptr;
                 }
-
-                case detail::value_t::object:
+                else
                 {
-                    if (v.m_data.m_value.object->empty())
+                    // iterate array and use index as a reference string
+                    for (std::size_t i = 0; i < value.m_data.m_value.array->size(); ++i)
                     {
-                        // flatten empty object as null
-                        result[path] = nullptr;
+                        flatten(detail::concat<string_t>(reference_string, '/', std::to_string(i)),
+                                value.m_data.m_value.array->operator[](i), result);
                     }
-                    else
-                    {
-                        stack.push_back({&v, 0, v.m_data.m_value.object->begin(), path.size()});
-                    }
-                    return;
-                }
-
-                case detail::value_t::null:
-                case detail::value_t::string:
-                case detail::value_t::boolean:
-                case detail::value_t::number_integer:
-                case detail::value_t::number_unsigned:
-                case detail::value_t::number_float:
-                case detail::value_t::binary:
-                case detail::value_t::discarded:
-                default:
-                {
-                    // add a primitive value with its reference string
-                    result[path] = v;
-                    return;
                 }
+                break;
             }
-        };
 
-        enter(value);
-        while (!stack.empty())
-        {
-            // the frame is changed through stack.back(): enter() may push a
-            // frame, which would invalidate a reference to it
-            const BasicJsonType* const container = stack.back().container;
-
-            // drop the path of the previous child
-            path.resize(stack.back().path_length);
-
-            if (container->is_array())
+            case detail::value_t::object:
             {
-                const auto& array = *container->m_data.m_value.array;
-                const std::size_t i = stack.back().index;
-                if (i == array.size())
+                if (value.m_data.m_value.object->empty())
                 {
-                    stack.pop_back();
-                    continue;
+                    // flatten empty object as null
+                    result[reference_string] = nullptr;
                 }
-
-                // iterate array and use index as a reference string
-                ++stack.back().index;
-                detail::concat_into(path, '/', detail::to_string<string_t>(i));
-                enter(array[i]);
+                else
+                {
+                    // iterate object and use keys as reference string
+                    for (const auto& element : *value.m_data.m_value.object)
+                    {
+                        flatten(detail::concat<string_t>(reference_string, '/', detail::escape(element.first)), element.second, result);
+                    }
+                }
+                break;
             }
-            else
-            {
-                const object_const_iterator it = stack.back().member;
-                if (it == container->m_data.m_value.object->end())
-                {
-                    stack.pop_back();
-                    continue;
-                }
 
-                // iterate object and use keys as reference string
-                ++stack.back().member;
-                detail::concat_into(path, '/', detail::escape(it->first));
-                enter(it->second);
+            case detail::value_t::null:
+            case detail::value_t::string:
+            case detail::value_t::boolean:
+            case detail::value_t::number_integer:
+            case detail::value_t::number_unsigned:
+            case detail::value_t::number_float:
+            case detail::value_t::binary:
+            case detail::value_t::discarded:
+            default:
+            {
+                // add a primitive value with its reference string
+                result[reference_string] = value;
+                break;
             }
         }
     }
@@ -20958,31 +20881,19 @@ class json_pointer
 
         // 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;
-        tree.children.emplace_back();
-        tree.is_array.push_back(false);
+        // objects (see array_parents_t)
+        array_parents_t array_parents;
         for (const auto& element : *value.m_data.m_value.object)
         {
             json_pointer ptr(element.first);
-            std::size_t id = 0;
+            std::vector<string_t> prefix;
             for (auto& reference_token : ptr.reference_tokens)
             {
                 if (reference_token == "0")
                 {
-                    tree.is_array[id] = true;
-                }
-
-                // do not keep a reference into tree.children across the
-                // push_back below, as it may reallocate
-                const std::size_t next = tree.children.size();
-                const auto inserted = tree.children[id].emplace(std::move(reference_token), next);
-                id = inserted.first->second;
-                if (inserted.second)
-                {
-                    tree.children.emplace_back();
-                    tree.is_array.push_back(false);
+                    array_parents.insert(prefix);
                 }
+                prefix.push_back(std::move(reference_token));
             }
         }
 
@@ -20998,7 +20909,7 @@ class json_pointer
             // 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.
-            json_pointer(element.first).get_and_create(result, tree) = element.second;
+            json_pointer(element.first).get_and_create(result, array_parents) = element.second;
         }
 
         return result;

tests/src/unit-bson.cpp

@@ -46,9 +46,7 @@ class huge_binary_t : public std::vector<std::uint8_t>
     }
 };
 
-using huge_binary_json = nlohmann::basic_json <
-                         std::map, std::vector, std::string, bool, std::int64_t, std::uint64_t,
-                         double, std::allocator, nlohmann::adl_serializer, huge_binary_t, void >;
+using huge_binary_json = nlohmann::json::with_binary_t<huge_binary_t>;
 
 // a string type that can be made to report a size beyond INT32_MAX without
 // allocating that much memory, so BSON length overflow can be tested for
@@ -96,9 +94,7 @@ class huge_string_t : public std::string
     bool pretend_huge = false;
 };
 
-using huge_string_json = nlohmann::basic_json <
-                         std::map, std::vector, huge_string_t, bool, std::int64_t, std::uint64_t,
-                         double, std::allocator, nlohmann::adl_serializer, std::vector<std::uint8_t>, void >;
+using huge_string_json = nlohmann::json::with_string_t<huge_string_t>;
 } // namespace
 
 TEST_CASE("BSON")

tests/src/unit-custom-base-class.cpp

@@ -400,20 +400,7 @@ class base_class_with_hidden_members
     std::size_t m_size = 42;
 };
 
-using json_with_hidden_base_members =
-    nlohmann::basic_json <
-    std::map,
-    std::vector,
-    std::string,
-    bool,
-    std::int64_t,
-    std::uint64_t,
-    double,
-    std::allocator,
-    nlohmann::adl_serializer,
-    std::vector<std::uint8_t>,
-    base_class_with_hidden_members
-    >;
+using json_with_hidden_base_members = nlohmann::json::with_base_class_t<base_class_with_hidden_members>;
 
 TEST_CASE("JSON Node as_base_class")
 {
@@ -459,19 +446,7 @@ struct const_member_base
     const int id = 7; // NOLINT(misc-non-private-member-variables-in-classes)
 };
 
-using json_with_const_base = nlohmann::basic_json <
-                             std::map,
-                             std::vector,
-                             std::string,
-                             bool,
-                             std::int64_t,
-                             std::uint64_t,
-                             double,
-                             std::allocator,
-                             nlohmann::adl_serializer,
-                             std::vector<std::uint8_t>,
-                             const_member_base
-                             >;
+using json_with_const_base = nlohmann::json::with_base_class_t<const_member_base>;
 
 // build an array nested @a depth levels deep, with the innermost value 1;
 // every level is constructed (never assigned), since const_member_base does

tests/src/unit-custom-binary-type.cpp

@@ -26,15 +26,11 @@ namespace
 
 // a BinaryType whose value type is signed: the elements must still be
 // processed as the numbers 0..255
-using char_binary_json = nlohmann::basic_json <
-                         std::map, std::vector, std::string, bool, std::int64_t, std::uint64_t,
-                         double, std::allocator, nlohmann::adl_serializer, std::vector<char>, void >;
+using char_binary_json = nlohmann::json::with_binary_t<std::vector<char>>;
 
 #ifdef JSON_HAS_CPP_17
     // a BinaryType whose value type is not an integer type at all
-    using byte_binary_json = nlohmann::basic_json <
-    std::map, std::vector, std::string, bool, std::int64_t, std::uint64_t,
-    double, std::allocator, nlohmann::adl_serializer, std::vector<std::byte>, void >;
+    using byte_binary_json = nlohmann::json::with_binary_t<std::vector<std::byte>>;
 #endif
 
 } // namespace

tests/src/unit-json_pointer.cpp

@@ -939,114 +939,3 @@ TEST_CASE("unescaping keeps a '~' that does not start an escape sequence")
     nlohmann::detail::unescape(s);
     CHECK(s == "~/~");
 }
-
-TEST_CASE("flatten of structured values")
-{
-    SECTION("values nested too deeply for the call stack (#5393)")
-    {
-        // flatten() used to recurse once per nesting level
-        const std::size_t depth = 100000;
-        for (const bool objects :
-                {
-                    false, true
-                })
-        {
-            CAPTURE(objects)
-            std::string text;
-            std::string path;
-            for (std::size_t i = 0; i < depth; ++i)
-            {
-                text += objects ? "{\"a\":" : "[";
-                path += objects ? "/a" : "/0";
-            }
-            text += "0";
-            text += std::string(depth, objects ? '}' : ']');
-            const auto value = json::parse(text);
-
-            const auto flat = value.flatten();
-            REQUIRE(flat.size() == 1);
-            REQUIRE(flat.begin().key().size() == path.size());
-            CHECK(flat.begin().key() == path);
-            CHECK(flat.begin().value() == 0);
-
-            // unflatten() is linear in the depth, so the value roundtrips
-            CHECK(flat.unflatten() == value);
-        }
-    }
-
-    SECTION("unflatten of a deeply nested pointer")
-    {
-        const std::size_t depth = 100000;
-        for (const bool objects :
-                {
-                    false, true
-                })
-        {
-            CAPTURE(objects)
-            std::string path;
-            for (std::size_t i = 0; i < depth; ++i)
-            {
-                path += objects ? "/a" : "/0";
-            }
-
-            json flat = json::object();
-            flat[path] = 1;
-            const json value = flat.unflatten();
-
-            // walk down iteratively
-            std::size_t levels = 0;
-            const json* current = &value;
-            while (objects ? current->is_object() : current->is_array())
-            {
-                REQUIRE(current->size() == 1);
-                current = objects ? &current->at("a") : &current->at(0);
-                ++levels;
-            }
-            CHECK(levels == depth);
-            CHECK(*current == 1);
-        }
-    }
-
-    SECTION("unflatten does not depend on the iteration order")
-    {
-        // the "0" key comes after its sibling in iteration order
-        const nlohmann::ordered_json flat_array = nlohmann::ordered_json::parse(R"({"/a/1": 2, "/a/0": 1})");
-        CHECK(flat_array.unflatten() == nlohmann::ordered_json::parse(R"({"a": [1, 2]})"));
-
-        const nlohmann::ordered_json flat_object = nlohmann::ordered_json::parse(R"({"/b/1": 2})");
-        CHECK(flat_object.unflatten() == nlohmann::ordered_json::parse(R"({"b": {"1": 2}})"));
-    }
-
-    SECTION("objects and arrays interleaved")
-    {
-        const json value =
-        {
-            {"a", {1, {{"b", json::array()}, {"c", json::object()}}, json::array({{{"x~/", {true, nullptr}}}})}},
-            {"a/b", {{"~", 1}}},
-            {"z", "s"}
-        };
-
-        const json expected =
-        {
-            {"/a/0", 1},
-            {"/a/1/b", nullptr},
-            {"/a/1/c", nullptr},
-            {"/a/2/0/x~0~1/0", true},
-            {"/a/2/0/x~0~1/1", nullptr},
-            {"/a~1b/~0", 1},
-            {"/z", "s"}
-        };
-
-        CHECK(value.flatten() == expected);
-    }
-
-    SECTION("order of the entries of an ordered_json")
-    {
-        const auto value = nlohmann::ordered_json::parse(
-                               R"({"z":"s","a/b":{"~":1,"k":[]},"a":[1,{"c":{},"b":[]},[{"x~/":[true,null],"w":2}]]})");
-
-        const auto flat = value.flatten();
-        CHECK(flat.dump() ==
-              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})");
-    }
-}

tests/src/unit-msgpack.cpp

@@ -2201,10 +2201,7 @@ struct huge_array : std::vector<T, A>
     }
 };
 
-using huge_array_json = nlohmann::basic_json <
-                        std::map, huge_array, std::string, bool, std::int64_t, std::uint64_t,
-                        double, std::allocator, nlohmann::adl_serializer,
-                        std::vector<std::uint8_t>, void >;
+using huge_array_json = nlohmann::json::with_array_t<huge_array>;
 
 TEST_CASE("MessagePack Size above uint32 for array")
 {
@@ -2249,18 +2246,7 @@ template<typename K, typename V,
     }
 };
 
-using huge_object_json = nlohmann::basic_json <
-                         huge_map,
-                         std::vector,
-                         std::string,
-                         bool,
-                         std::int64_t,
-                         std::uint64_t,
-                         double,
-                         std::allocator,
-                         nlohmann::adl_serializer,
-                         std::vector<std::uint8_t>,
-                         void >;
+using huge_object_json = nlohmann::json::with_object_t<huge_map>;
 
 TEST_CASE("MessagePack Size above uint32 for object")
 {
@@ -2295,18 +2281,7 @@ struct huge_string : std::string
     }
 };
 
-using huge_string_json = nlohmann::basic_json <
-                         std::map,
-                         std::vector,
-                         huge_string,
-                         bool,
-                         std::int64_t,
-                         std::uint64_t,
-                         double,
-                         std::allocator,
-                         nlohmann::adl_serializer,
-                         std::vector<std::uint8_t>,
-                         void >;
+using huge_string_json = nlohmann::json::with_string_t<huge_string>;
 
 TEST_CASE("MessagePack Size above uint32 for string")
 {
@@ -2329,18 +2304,7 @@ struct huge_binary : std::vector<std::uint8_t>
     }
 };
 
-using huge_binary_json = nlohmann::basic_json <
-                         std::map,
-                         std::vector,
-                         std::string,
-                         bool,
-                         std::int64_t,
-                         std::uint64_t,
-                         double,
-                         std::allocator,
-                         nlohmann::adl_serializer,
-                         huge_binary,
-                         void >;
+using huge_binary_json = nlohmann::json::with_binary_t<huge_binary>;
 
 TEST_CASE("MessagePack Size above uint32 for binary")
 {
@@ -2390,14 +2354,10 @@ class beyond_uint32_string_t : public std::string
     }
 };
 
-using beyond_uint32_string_json = nlohmann::basic_json <
-                                  std::map, std::vector, beyond_uint32_string_t, bool, std::int64_t, std::uint64_t,
-                                  double, std::allocator, nlohmann::adl_serializer, std::vector<std::uint8_t>, void >;
+using beyond_uint32_string_json = nlohmann::json::with_string_t<beyond_uint32_string_t>;
 #endif
 
-using beyond_uint32_binary_json = nlohmann::basic_json <
-                                  std::map, std::vector, std::string, bool, std::int64_t, std::uint64_t,
-                                  double, std::allocator, nlohmann::adl_serializer, beyond_uint32_binary_t, void >;
+using beyond_uint32_binary_json = nlohmann::json::with_binary_t<beyond_uint32_binary_t>;
 } // namespace
 
 TEST_CASE("MessagePack lengths beyond UINT32_MAX cannot be serialized")

tests/src/unit-ordered_json2.cpp

@@ -217,16 +217,7 @@ void int_to_string(alt_string& target, std::size_t value)
     target = std::to_string(value).c_str();
 }
 
-using alt_json = nlohmann::basic_json <
-                 std::map,
-                 std::vector,
-                 alt_string,
-                 bool,
-                 std::int64_t,
-                 std::uint64_t,
-                 double,
-                 std::allocator,
-                 nlohmann::adl_serializer >;
+using alt_json = nlohmann::json::with_string_t<alt_string>;
 
 bool operator<(const char* op1, const alt_string& op2) noexcept
 {