Merge pull request #1765 from crazyjul/fix/items-with-alt-string

Allow items() to be used with custom string

include/nlohmann/detail/iterators/iteration_proxy.hpp

@@ -12,6 +12,11 @@ namespace nlohmann
 {
 namespace detail
 {
+template<typename string_type>
+void int_to_string( string_type& target, int value )
+{
+ target = std::to_string(value);
+}
 template <typename IteratorType> class iteration_proxy_value
 {
  public:
@@ -20,6 +25,7 @@ template <typename IteratorType> class iteration_proxy_value
  using pointer = value_type * ;
  using reference = value_type & ;
  using iterator_category = std::input_iterator_tag;
+ using string_type = typename std::remove_cv< typename std::remove_reference<decltype( std::declval<IteratorType>().key() ) >::type >::type;
 
  private:
  /// the iterator
@@ -29,9 +35,9 @@ template <typename IteratorType> class iteration_proxy_value
  /// last stringified array index
  mutable std::size_t array_index_last = 0;
  /// a string representation of the array index
- mutable std::string array_index_str = "0";
+ mutable string_type array_index_str = "0";
  /// an empty string (to return a reference for primitive values)
- const std::string empty_str = "";
+ const string_type empty_str = "";
 
  public:
  explicit iteration_proxy_value(IteratorType it) noexcept : anchor(it) {}
@@ -64,7 +70,7 @@ template <typename IteratorType> class iteration_proxy_value
  }
 
  /// return key of the iterator
- const std::string& key() const
+ const string_type& key() const
  {
  assert(anchor.m_object != nullptr);
 
@@ -75,7 +81,7 @@ template <typename IteratorType> class iteration_proxy_value
  {
  if (array_index != array_index_last)
  {
- array_index_str = std::to_string(array_index);
+ int_to_string( array_index_str, array_index );
  array_index_last = array_index;
  }
  return array_index_str;

single_include/nlohmann/json.hpp

@@ -3186,6 +3186,11 @@ namespace nlohmann
 {
 namespace detail
 {
+template<typename string_type>
+void int_to_string( string_type& target, int value )
+{
+ target = std::to_string(value);
+}
 template <typename IteratorType> class iteration_proxy_value
 {
  public:
@@ -3194,6 +3199,7 @@ template <typename IteratorType> class iteration_proxy_value
  using pointer = value_type * ;
  using reference = value_type & ;
  using iterator_category = std::input_iterator_tag;
+ using string_type = typename std::remove_cv< typename std::remove_reference<decltype( std::declval<IteratorType>().key() ) >::type >::type;
 
  private:
  /// the iterator
@@ -3203,9 +3209,9 @@ template <typename IteratorType> class iteration_proxy_value
  /// last stringified array index
  mutable std::size_t array_index_last = 0;
  /// a string representation of the array index
- mutable std::string array_index_str = "0";
+ mutable string_type array_index_str = "0";
  /// an empty string (to return a reference for primitive values)
- const std::string empty_str = "";
+ const string_type empty_str = "";
 
  public:
  explicit iteration_proxy_value(IteratorType it) noexcept : anchor(it) {}
@@ -3238,7 +3244,7 @@ template <typename IteratorType> class iteration_proxy_value
  }
 
  /// return key of the iterator
- const std::string& key() const
+ const string_type& key() const
  {
  assert(anchor.m_object != nullptr);
 
@@ -3249,7 +3255,7 @@ template <typename IteratorType> class iteration_proxy_value
  {
  if (array_index != array_index_last)
  {
- array_index_str = std::to_string(array_index);
+ int_to_string( array_index_str, array_index );
  array_index_last = array_index;
  }
  return array_index_str;

test/src/unit-alt-string.cpp

@@ -154,6 +154,11 @@ class alt_string
  friend bool ::operator<(const char*, const alt_string&);
 };
 
+void int_to_string( alt_string& target, int value )
+{
+ target = std::to_string(value).c_str();
+}
+
 using alt_json = nlohmann::basic_json <
  std::map,
  std::vector,
@@ -232,6 +237,35 @@ TEST_CASE("alternative string type")
  CHECK(dump == R"({"foo":"bar"})");
  }
 
+ SECTION("items")
+ {
+ auto doc = alt_json::parse("{\"foo\": \"bar\"}");
+
+ for ( auto item : doc.items() )
+ {
+ CHECK( item.key() == "foo" );
+ CHECK( item.value() == "bar" );
+ }
+
+ auto doc_array = alt_json::parse("[\"foo\", \"bar\"]");
+
+ for ( auto item : doc_array.items() )
+ {
+ if (item.key() == "0" )
+ {
+ CHECK( item.value() == "foo" );
+ }
+ else if (item.key() == "1" )
+ {
+ CHECK( item.value() == "bar" );
+ }
+ else
+ {
+ CHECK( false );
+ }
+ }
+ }
+
  SECTION("equality")
  {
  alt_json doc;