string_view support for object access

cmake/ci.cmake

@@ -470,6 +470,7 @@ add_custom_target(ci_test_coverage
     COMMAND CXX=${GCC_TOOL} ${CMAKE_COMMAND}
         -DCMAKE_BUILD_TYPE=Debug -GNinja -DCMAKE_CXX_FLAGS="--coverage;-fprofile-arcs;-ftest-coverage"
         -DJSON_BuildTests=ON -DJSON_MultipleHeaders=ON
+        -DCMAKE_CXX_STANDARD=17 -DCMAKE_CXX_STANDARD_REQUIRED=ON
         -S${PROJECT_SOURCE_DIR} -B${PROJECT_BINARY_DIR}/build_coverage
     COMMAND ${CMAKE_COMMAND} --build ${PROJECT_BINARY_DIR}/build_coverage
     COMMAND cd ${PROJECT_BINARY_DIR}/build_coverage && ${CMAKE_CTEST_COMMAND} --parallel ${N} --output-on-failure

doc/mkdocs/docs/api/basic_json/at.md

@@ -6,8 +6,10 @@ reference at(size_type idx);
 const_reference at(size_type idx) const;
 
 // (2)
-reference at(const typename object_t::key_type& key);
-const_reference at(const typename object_t::key_type& key) const;
+template<typename KeyT>
+reference at(KeyT && key);
+template<typename KeyT>
+const_reference at(KeyT && key) const;
 
 // (3)
 reference at(const json_pointer& ptr);
@@ -18,6 +20,12 @@ const_reference at(const json_pointer& ptr) const;
 2. Returns a reference to the element at with specified key `key`, with bounds checking.
 3. Returns a reference to the element at with specified JSON pointer `ptr`, with bounds checking.
 
+## Template parameters
+
+`KeyT`
+:   A type for an object key other than `basic_json::json_pointer`. This can also be a string literal or a string view
+    (C++17).
+
 ## Parameters
 
 `idx` (in)
@@ -167,5 +175,5 @@ Strong exception safety: if an exception occurs, the original value stays intact
 ## Version history
 
 1. Added in version 1.0.0.
-2. Added in version 1.0.0.
+2. Added in version 1.0.0; `KeyT` template added in version 3.10.0.
 3. Added in version 2.0.0.

doc/mkdocs/docs/api/basic_json/contains.md

@@ -11,7 +11,8 @@ value is not an object, `#!cpp false` is returned.
 ## Template parameters
 
 `KeyT`
-:   A type for an object key other than `basic_json::json_pointer`.
+:   A type for an object key other than `basic_json::json_pointer`. This can also be a string literal or a string view 
+    (C++17).
 
 ## Parameters
 

doc/mkdocs/docs/api/basic_json/count.md

@@ -2,7 +2,7 @@
 
 ```cpp
 template<typename KeyT>
-size_type count(KeyT&& key) const;
+size_type count(KeyT && key) const;
 ```
 
 Returns the number of elements with key `key`. If `ObjectType` is the default `std::map` type, the return value will
@@ -11,7 +11,7 @@ always be `0` (`key` was not found) or `1` (`key` was found).
 ## Template parameters
 
 `KeyT`
-:   A type for an object key.
+:   A type for an object key. This can also be a string literal or a string view (C++17).
 
 ## Parameters
 

doc/mkdocs/docs/api/basic_json/erase.md

@@ -10,7 +10,9 @@ iterator erase(iterator first, iterator last);
 const_iterator erase(const_iterator first, const_iterator last);
 
 // (3)
-size_type erase(const typename object_t::key_type& key);
+template<typename KeyT>
+size_type erase(KeyT && key);
+size_type erase(const std::string_view& key); // since C++17
 
 // (4)
 void erase(const size_type idx);
@@ -31,6 +33,11 @@ void erase(const size_type idx);
 
 4. Removes an element from a JSON array by index.
 
+## Template parameters
+
+`KeyT`
+:   A type convertible to an object key. This can also be a string literal.
+
 ## Parameters
 
 `pos` (in)
@@ -175,3 +182,4 @@ Strong exception safety: if an exception occurs, the original value stays intact
 
 - Added in version 1.0.0.
 - Added support for binary types in version 3.8.0.
+- Added `KeyT` template and overload for `std::string_view` in version 3.10.0.

doc/mkdocs/docs/api/basic_json/find.md

@@ -2,10 +2,10 @@
 
 ```cpp
 template<typename KeyT>
-iterator find(KeyT&& key);
+iterator find(KeyT && key);
 
 template<typename KeyT>
-const_iterator find(KeyT&& key) const
+const_iterator find(KeyT && key) const
 ```
 
 Finds an element in a JSON object with key equivalent to `key`. If the element is not found or the JSON value is not an
@@ -14,7 +14,7 @@ object, `end()` is returned.
 ## Template parameters
 
 `KeyT`
-:   A type for an object key.
+:   A type for an object key. This can also be a string literal or a string view (C++17).
 
 ## Parameters
 

doc/mkdocs/docs/api/basic_json/operator[].md

@@ -6,12 +6,16 @@ reference operator[](size_type idx);
 const_reference operator[](size_type idx) const;
 
 // (2)
-reference operator[](const typename object_t::key_type& key);
-const_reference operator[](const typename object_t::key_type& key) const;
+template<typename KeyT>
+reference operator[](KeyT && key);
+template<typename KeyT>
+const_reference operator[](KeyT && key) const;
 template<typename T>
 reference operator[](T* key);
 template<typename T>
 const_reference operator[](T* key) const;
+reference operator[](const std::string_view& key); // since C++17
+const_reference operator[](const std::string_view& key) const; // since C++17
 
 // (3)
 reference operator[](const json_pointer& ptr);
@@ -24,6 +28,10 @@ const_reference operator[](const json_pointer& ptr) const;
 
 ## Template parameters
 
+`KeyT`
+:   A type for an object key other than `basic_json::json_pointer`. This can also be a string literal or a string view
+    (C++17).
+
 `T`
 :   string literal convertible to `object_t::key_type`
 
@@ -187,5 +195,6 @@ Strong exception safety: if an exception occurs, the original value stays intact
 ## Version history
 
 1. Added in version 1.0.0.
-2. Added in version 1.0.0. Overloads for `T* key` added in version 1.1.0.
+2. Added in version 1.0.0. Overloads for `T* key` added in version 1.1.0. Template and overload for `std::string_view`
+   added in version 3.10.0.
 3. Added in version 2.0.0.

doc/mkdocs/docs/api/basic_json/value.md

@@ -2,8 +2,8 @@
 
 ```cpp
 // (1)
-template<class ValueType>
-ValueType value(const typename object_t::key_type& key,
+template<class KeyType, class ValueType>
+ValueType value(const KeyType& key,
                 const ValueType& default_value) const;
 
 // (2)
@@ -41,6 +41,8 @@ Unlike [`operator[]`](operator[].md), this function does not implicitly add an e
 
 ## Template parameters
 
+`KeyType`
+:   A type for an object key. This can also be a string literal or a string view (C++17).
 `ValueType` 
 :   type compatible to JSON values, for instance `#!cpp int` for JSON integer numbers, `#!cpp bool` for JSON booleans,
     or `#!cpp std::vector` types for JSON arrays. Note the type of the expected value at `key`/`ptr` and the default
@@ -118,4 +120,4 @@ changes to any JSON value.
 ## Version history
 
 1. Added in version 1.0.0.
-2. Added in version 2.0.2.
+2. Added in version 2.0.2. `KeyType` template parameter added in 3.10.0.