Add backwards compatibility with json_pointer<basic_json>

include/nlohmann/detail/json_pointer.hpp

@@ -28,8 +28,24 @@ class json_pointer
     NLOHMANN_BASIC_JSON_TPL_DECLARATION
     friend class basic_json;
 
+    template<typename>
+    friend class json_pointer;
+
+    template<typename T>
+    struct string_t_helper
+    {
+        using type = T;
+    };
+
+    NLOHMANN_BASIC_JSON_TPL_DECLARATION
+    struct string_t_helper<NLOHMANN_BASIC_JSON_TPL>
+    {
+        using type = StringType;
+    };
+
   public:
-    using string_t = RefStringType;
+    // for backwards compatibility accept BasicJsonType
+    using string_t = typename string_t_helper<RefStringType>::type;
 
     /// @brief create JSON pointer
     /// @sa https://json.nlohmann.me/api/json_pointer/json_pointer/
@@ -794,6 +810,21 @@ class json_pointer
         return result;
     }
 
+    // can't use conversion operator because of ambiguity
+    json_pointer<string_t> convert() const&
+    {
+        json_pointer<string_t> result;
+        result.reference_tokens = reference_tokens;
+        return result;
+    }
+
+    json_pointer<string_t> convert()&&
+    {
+        json_pointer<string_t> result;
+        result.reference_tokens = std::move(reference_tokens);
+        return result;
+    }
+
     /*!
     @brief compares two JSON pointers for equality
 

include/nlohmann/detail/meta/type_traits.hpp

@@ -54,6 +54,11 @@ struct is_basic_json_context :
     || std::is_same<BasicJsonContext, std::nullptr_t>::value >
 {};
 
+template<typename> struct is_json_pointer : std::false_type {};
+
+template<typename RefStringType>
+struct is_json_pointer<json_pointer<RefStringType>> : std::true_type {};
+
 //////////////////////
 // json_ref helpers //
 //////////////////////

include/nlohmann/json.hpp

@@ -129,7 +129,11 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
 {
   private:
     template<detail::value_t> friend struct detail::external_constructor;
-    friend ::nlohmann::json_pointer<StringType>;
+
+    template<typename>
+    friend class ::nlohmann::json_pointer;
+    // can be restored when json_pointer backwards compatibility is removed
+    // friend ::nlohmann::json_pointer<StringType>;
 
     template<typename BasicJsonType, typename InputType>
     friend class ::nlohmann::detail::parser;
@@ -2221,6 +2225,14 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
         JSON_THROW(type_error::create(306, detail::concat("cannot use value() with ", type_name()), this));
     }
 
+    template<class ValueType, class BasicJsonType, typename std::enable_if<
+                 detail::is_getable<basic_json_t, ValueType>::value, int>::type = 0>
+    JSON_HEDLEY_DEPRECATED_FOR(3.10.6, basic_json::json_pointer or nlohmann::json_pointer<basic_json::string_t>) // NOLINT(readability/alt_tokens)
+    ValueType value(const ::nlohmann::json_pointer<BasicJsonType>& ptr, const ValueType& default_value) const
+    {
+        return value(ptr.convert(), default_value);
+    }
+
     /// @brief access specified object element via JSON Pointer with default value
     /// @sa https://json.nlohmann.me/api/basic_json/value/
     /// overload for a default value of type const char*
@@ -2230,6 +2242,14 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
         return value(ptr, string_t(default_value));
     }
 
+    template<typename BasicJsonType>
+    JSON_HEDLEY_DEPRECATED_FOR(3.10.6, basic_json::json_pointer or nlohmann::json_pointer<basic_json::string_t>) // NOLINT(readability/alt_tokens)
+    JSON_HEDLEY_NON_NULL(3)
+    string_t value(const typename ::nlohmann::json_pointer<BasicJsonType>& ptr, const char* default_value) const
+    {
+        return value(ptr.convert(), default_value);
+    }
+
     /// @brief access the first element
     /// @sa https://json.nlohmann.me/api/basic_json/front/
     reference front()
@@ -2492,7 +2512,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     /// @brief check the existence of an element in a JSON object
     /// @sa https://json.nlohmann.me/api/basic_json/contains/
     template < typename KeyT, typename std::enable_if <
-                   !std::is_same<typename std::decay<KeyT>::type, json_pointer>::value, int >::type = 0 >
+                   !detail::is_json_pointer<typename std::decay<KeyT>::type>::value, int >::type = 0 >
     bool contains(KeyT && key) const
     {
         return is_object() && m_value.object->find(std::forward<KeyT>(key)) != m_value.object->end();
@@ -2505,6 +2525,13 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
         return ptr.contains(this);
     }
 
+    template<typename BasicJsonType>
+    JSON_HEDLEY_DEPRECATED_FOR(3.10.6, basic_json::json_pointer or nlohmann::json_pointer<basic_json::string_t>) // NOLINT(readability/alt_tokens)
+    bool contains(const typename ::nlohmann::json_pointer<BasicJsonType> ptr) const
+    {
+        return ptr.contains(this);
+    }
+
     /// @}
 
 
@@ -4193,6 +4220,13 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
         return ptr.get_unchecked(this);
     }
 
+    template<typename BasicJsonType>
+    JSON_HEDLEY_DEPRECATED_FOR(3.10.6, basic_json::json_pointer or nlohmann::json_pointer<basic_json::string_t>) // NOLINT(readability/alt_tokens)
+    reference operator[](const ::nlohmann::json_pointer<BasicJsonType>& ptr)
+    {
+        return ptr.get_unchecked(this);
+    }
+
     /// @brief access specified element via JSON Pointer
     /// @sa https://json.nlohmann.me/api/basic_json/operator%5B%5D/
     const_reference operator[](const json_pointer& ptr) const
@@ -4200,6 +4234,13 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
         return ptr.get_unchecked(this);
     }
 
+    template<typename BasicJsonType>
+    JSON_HEDLEY_DEPRECATED_FOR(3.10.6, basic_json::json_pointer or nlohmann::json_pointer<basic_json::string_t>) // NOLINT(readability/alt_tokens)
+    const_reference operator[](const ::nlohmann::json_pointer<BasicJsonType>& ptr) const
+    {
+        return ptr.get_unchecked(this);
+    }
+
     /// @brief access specified element via JSON Pointer
     /// @sa https://json.nlohmann.me/api/basic_json/at/
     reference at(const json_pointer& ptr)
@@ -4207,6 +4248,13 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
         return ptr.get_checked(this);
     }
 
+    template<typename BasicJsonType>
+    JSON_HEDLEY_DEPRECATED_FOR(3.10.6, basic_json::json_pointer or nlohmann::json_pointer<basic_json::string_t>) // NOLINT(readability/alt_tokens)
+    reference at(const ::nlohmann::json_pointer<BasicJsonType>& ptr)
+    {
+        return ptr.get_checked(this);
+    }
+
     /// @brief access specified element via JSON Pointer
     /// @sa https://json.nlohmann.me/api/basic_json/at/
     const_reference at(const json_pointer& ptr) const
@@ -4214,6 +4262,13 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
         return ptr.get_checked(this);
     }
 
+    template<typename BasicJsonType>
+    JSON_HEDLEY_DEPRECATED_FOR(3.10.6, basic_json::json_pointer or nlohmann::json_pointer<basic_json::string_t>) // NOLINT(readability/alt_tokens)
+    const_reference at(const ::nlohmann::json_pointer<BasicJsonType>& ptr) const
+    {
+        return ptr.get_checked(this);
+    }
+
     /// @brief return flattened JSON value
     /// @sa https://json.nlohmann.me/api/basic_json/flatten/
     basic_json flatten() const

single_include/nlohmann/json.hpp

@@ -3183,6 +3183,11 @@ struct is_basic_json_context :
     || std::is_same<BasicJsonContext, std::nullptr_t>::value >
 {};
 
+template<typename> struct is_json_pointer : std::false_type {};
+
+template<typename RefStringType>
+struct is_json_pointer<json_pointer<RefStringType>> : std::true_type {};
+
 //////////////////////
 // json_ref helpers //
 //////////////////////
@@ -12488,8 +12493,24 @@ class json_pointer
     NLOHMANN_BASIC_JSON_TPL_DECLARATION
     friend class basic_json;
 
+    template<typename>
+    friend class json_pointer;
+
+    template<typename T>
+    struct string_t_helper
+    {
+        using type = T;
+    };
+
+    NLOHMANN_BASIC_JSON_TPL_DECLARATION
+    struct string_t_helper<NLOHMANN_BASIC_JSON_TPL>
+    {
+        using type = StringType;
+    };
+
   public:
-    using string_t = RefStringType;
+    // for backwards compatibility accept BasicJsonType
+    using string_t = typename string_t_helper<RefStringType>::type;
 
     /// @brief create JSON pointer
     /// @sa https://json.nlohmann.me/api/json_pointer/json_pointer/
@@ -13254,6 +13275,21 @@ class json_pointer
         return result;
     }
 
+    // can't use conversion operator because of ambiguity
+    json_pointer<string_t> convert() const&
+    {
+        json_pointer<string_t> result;
+        result.reference_tokens = reference_tokens;
+        return result;
+    }
+
+    json_pointer<string_t> convert()&&
+    {
+        json_pointer<string_t> result;
+        result.reference_tokens = std::move(reference_tokens);
+        return result;
+    }
+
     /*!
     @brief compares two JSON pointers for equality
 
@@ -17529,7 +17565,11 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
 {
   private:
     template<detail::value_t> friend struct detail::external_constructor;
-    friend ::nlohmann::json_pointer<StringType>;
+
+    template<typename>
+    friend class ::nlohmann::json_pointer;
+    // can be restored when json_pointer backwards compatibility is removed
+    // friend ::nlohmann::json_pointer<StringType>;
 
     template<typename BasicJsonType, typename InputType>
     friend class ::nlohmann::detail::parser;
@@ -19621,6 +19661,14 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
         JSON_THROW(type_error::create(306, detail::concat("cannot use value() with ", type_name()), this));
     }
 
+    template<class ValueType, class BasicJsonType, typename std::enable_if<
+                 detail::is_getable<basic_json_t, ValueType>::value, int>::type = 0>
+    JSON_HEDLEY_DEPRECATED_FOR(3.10.6, basic_json::json_pointer or nlohmann::json_pointer<basic_json::string_t>) // NOLINT(readability/alt_tokens)
+    ValueType value(const ::nlohmann::json_pointer<BasicJsonType>& ptr, const ValueType& default_value) const
+    {
+        return value(ptr.convert(), default_value);
+    }
+
     /// @brief access specified object element via JSON Pointer with default value
     /// @sa https://json.nlohmann.me/api/basic_json/value/
     /// overload for a default value of type const char*
@@ -19630,6 +19678,14 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
         return value(ptr, string_t(default_value));
     }
 
+    template<typename BasicJsonType>
+    JSON_HEDLEY_DEPRECATED_FOR(3.10.6, basic_json::json_pointer or nlohmann::json_pointer<basic_json::string_t>) // NOLINT(readability/alt_tokens)
+    JSON_HEDLEY_NON_NULL(3)
+    string_t value(const typename ::nlohmann::json_pointer<BasicJsonType>& ptr, const char* default_value) const
+    {
+        return value(ptr.convert(), default_value);
+    }
+
     /// @brief access the first element
     /// @sa https://json.nlohmann.me/api/basic_json/front/
     reference front()
@@ -19892,7 +19948,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     /// @brief check the existence of an element in a JSON object
     /// @sa https://json.nlohmann.me/api/basic_json/contains/
     template < typename KeyT, typename std::enable_if <
-                   !std::is_same<typename std::decay<KeyT>::type, json_pointer>::value, int >::type = 0 >
+                   !detail::is_json_pointer<typename std::decay<KeyT>::type>::value, int >::type = 0 >
     bool contains(KeyT && key) const
     {
         return is_object() && m_value.object->find(std::forward<KeyT>(key)) != m_value.object->end();
@@ -19905,6 +19961,13 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
         return ptr.contains(this);
     }
 
+    template<typename BasicJsonType>
+    JSON_HEDLEY_DEPRECATED_FOR(3.10.6, basic_json::json_pointer or nlohmann::json_pointer<basic_json::string_t>) // NOLINT(readability/alt_tokens)
+    bool contains(const typename ::nlohmann::json_pointer<BasicJsonType> ptr) const
+    {
+        return ptr.contains(this);
+    }
+
     /// @}
 
 
@@ -21593,6 +21656,13 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
         return ptr.get_unchecked(this);
     }
 
+    template<typename BasicJsonType>
+    JSON_HEDLEY_DEPRECATED_FOR(3.10.6, basic_json::json_pointer or nlohmann::json_pointer<basic_json::string_t>) // NOLINT(readability/alt_tokens)
+    reference operator[](const ::nlohmann::json_pointer<BasicJsonType>& ptr)
+    {
+        return ptr.get_unchecked(this);
+    }
+
     /// @brief access specified element via JSON Pointer
     /// @sa https://json.nlohmann.me/api/basic_json/operator%5B%5D/
     const_reference operator[](const json_pointer& ptr) const
@@ -21600,6 +21670,13 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
         return ptr.get_unchecked(this);
     }
 
+    template<typename BasicJsonType>
+    JSON_HEDLEY_DEPRECATED_FOR(3.10.6, basic_json::json_pointer or nlohmann::json_pointer<basic_json::string_t>) // NOLINT(readability/alt_tokens)
+    const_reference operator[](const ::nlohmann::json_pointer<BasicJsonType>& ptr) const
+    {
+        return ptr.get_unchecked(this);
+    }
+
     /// @brief access specified element via JSON Pointer
     /// @sa https://json.nlohmann.me/api/basic_json/at/
     reference at(const json_pointer& ptr)
@@ -21607,6 +21684,13 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
         return ptr.get_checked(this);
     }
 
+    template<typename BasicJsonType>
+    JSON_HEDLEY_DEPRECATED_FOR(3.10.6, basic_json::json_pointer or nlohmann::json_pointer<basic_json::string_t>) // NOLINT(readability/alt_tokens)
+    reference at(const ::nlohmann::json_pointer<BasicJsonType>& ptr)
+    {
+        return ptr.get_checked(this);
+    }
+
     /// @brief access specified element via JSON Pointer
     /// @sa https://json.nlohmann.me/api/basic_json/at/
     const_reference at(const json_pointer& ptr) const
@@ -21614,6 +21698,13 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
         return ptr.get_checked(this);
     }
 
+    template<typename BasicJsonType>
+    JSON_HEDLEY_DEPRECATED_FOR(3.10.6, basic_json::json_pointer or nlohmann::json_pointer<basic_json::string_t>) // NOLINT(readability/alt_tokens)
+    const_reference at(const ::nlohmann::json_pointer<BasicJsonType>& ptr) const
+    {
+        return ptr.get_checked(this);
+    }
+
     /// @brief return flattened JSON value
     /// @sa https://json.nlohmann.me/api/basic_json/flatten/
     basic_json flatten() const

test/src/unit-json_pointer.cpp

@@ -660,4 +660,40 @@ TEST_CASE("JSON pointers")
         CHECK(j[ptr] == j["object"]["/"]);
         CHECK(ptr.to_string() == "/object/~1");
     }
+
+    SECTION("backwards compatibility and mixing")
+    {
+        json j = R"(
+        {
+            "foo": ["bar", "baz"]
+        }
+        )"_json;
+
+        using nlohmann::ordered_json;
+        using json_ptr_str = nlohmann::json_pointer<std::string>;
+        using json_ptr_j = nlohmann::json_pointer<json>;
+        using json_ptr_oj = nlohmann::json_pointer<ordered_json>;
+
+        CHECK(std::is_same<json_ptr_str::string_t, json::json_pointer::string_t>::value);
+        CHECK(std::is_same<json_ptr_str::string_t, ordered_json::json_pointer::string_t>::value);
+        CHECK(std::is_same<json_ptr_str::string_t, json_ptr_j::string_t>::value);
+        CHECK(std::is_same<json_ptr_str::string_t, json_ptr_oj::string_t>::value);
+
+        json_ptr_str ptr{"/foo/0"};
+        json_ptr_j ptr_j{"/foo/0"};
+        json_ptr_oj ptr_oj{"/foo/0"};
+
+        CHECK(j.contains(ptr));
+        CHECK(j.contains(ptr_j));
+        CHECK(j.contains(ptr_oj));
+
+        CHECK(j.at(ptr) == j.at(ptr_j));
+        CHECK(j.at(ptr) == j.at(ptr_oj));
+
+        CHECK(j[ptr] == j[ptr_j]);
+        CHECK(j[ptr] == j[ptr_oj]);
+
+        CHECK(j.value(ptr, "x") == j.value(ptr_j, "x"));
+        CHECK(j.value(ptr, "x") == j.value(ptr_oj, "x"));
+    }
 }