Make iterators real iterators (#77)

They were missing the iterator_category and thus could not be used with
some standard algorithms.

include/toml++/toml_array.h

@@ -38,6 +38,7 @@ TOML_IMPL_NAMESPACE_START
 			using reference = value_type&;
 			using pointer = value_type*;
 			using difference_type = ptrdiff_t;
+			using iterator_category = typename std::iterator_traits<raw_iterator>::iterator_category;
 
 			array_iterator() noexcept = default;
 			array_iterator(const array_iterator&) noexcept = default;

include/toml++/toml_common.h

@@ -16,6 +16,7 @@ TOML_DISABLE_WARNINGS
 #include <cstring>
 #include <cfloat>
 #include <climits>
+#include <iterator>
 #include <limits>
 #include <memory>
 #include <string_view>

include/toml++/toml_table.h

@@ -75,6 +75,8 @@ TOML_IMPL_NAMESPACE_START
 			using value_type = table_proxy_pair<IsConst>;
 			using reference = value_type&;
 			using pointer = value_type*;
+			using difference_type = typename std::iterator_traits<raw_iterator>::difference_type;
+			using iterator_category = typename std::iterator_traits<raw_iterator>::iterator_category;
 
 			table_iterator& operator++() noexcept // ++pre
 			{

tests/meson.build

@@ -21,6 +21,7 @@ test_sources = [
 	'manipulating_values.cpp',
 	'unicode.cpp',
 	'user_feedback.cpp',
+	'using_iterators.cpp',
 	'windows_compat.cpp'
 ]
 

tests/using_iterators.cpp

@@ -0,0 +1,55 @@
+#include "tests.h"
+
+TOML_DISABLE_WARNINGS
+#include <algorithm>
+TOML_ENABLE_WARNINGS
+
+TEST_CASE("Using std::distance, std::count_if, etc. with Iterators")
+{
+	constexpr auto data = R"(array=[1,"Foo",true]
+string="Bar"
+number=5)"sv;
+	parsing_should_succeed(FILE_LINE_ARGS, data, [](auto&& table)
+	{
+		const auto table_begin = table.begin();
+		const auto table_end = table.end();
+
+		auto count_table_lambda = [table_begin, table_end](node_type type) noexcept
+		{
+			return std::count_if(table_begin, table_end, [type](const auto& pair) noexcept
+			{
+				return pair.second.type() == type;
+			});
+		};
+
+		CHECK(std::distance(table_begin, table_end) == 3);
+		CHECK(count_table_lambda(node_type::table) == 0);
+		CHECK(count_table_lambda(node_type::integer) == 1);
+		CHECK(count_table_lambda(node_type::string) == 1);
+		CHECK(std::next(table_begin, 3) == table_end);
+
+		const auto array_iter = std::find_if(table_begin, table_end, [](const auto& pair) noexcept
+		{
+			return pair.second.is_array();
+		});
+
+		REQUIRE(array_iter != table_end);
+		const auto& array = array_iter->second.as_array();
+		const auto array_begin = array->begin();
+		const auto array_end = array->end();
+
+		auto count_array_lambda = [array_begin, array_end](node_type type) noexcept
+		{
+			return std::count_if(array_begin, array_end, [type](const auto& node) noexcept
+			{
+				return node.type() == type;
+			});
+		};
+
+		CHECK(std::distance(array_begin, array_end) == 3);
+		CHECK(count_array_lambda(node_type::table) == 0);
+		CHECK(count_array_lambda(node_type::integer) == 1);
+		CHECK(count_array_lambda(node_type::string) == 1);
+		CHECK(std::next(array_begin, 2) != array_end);
+	});
+}

toml.hpp

@@ -613,6 +613,7 @@ TOML_DISABLE_WARNINGS
 #include <cstring>
 #include <cfloat>
 #include <climits>
+#include <iterator>
 #include <limits>
 #include <memory>
 #include <string_view>
@@ -3433,6 +3434,7 @@ TOML_IMPL_NAMESPACE_START
 			using reference = value_type&;
 			using pointer = value_type*;
 			using difference_type = ptrdiff_t;
+			using iterator_category = typename std::iterator_traits<raw_iterator>::iterator_category;
 
 			array_iterator() noexcept = default;
 			array_iterator(const array_iterator&) noexcept = default;
@@ -4047,6 +4049,8 @@ TOML_IMPL_NAMESPACE_START
 			using value_type = table_proxy_pair<IsConst>;
 			using reference = value_type&;
 			using pointer = value_type*;
+			using difference_type = typename std::iterator_traits<raw_iterator>::difference_type;
+			using iterator_category = typename std::iterator_traits<raw_iterator>::iterator_category;
 
 			table_iterator& operator++() noexcept // ++pre
 			{