mapping: Use member equality operators and document

Signed-off-by: Simon Rozman <simon@rozman.si>

include/stdex/mapping.hpp

@@ -18,12 +18,43 @@ namespace stdex
 		T from; // index in source string
 		T to;   // index in destination string
 
+		///
+		/// Constructs a zero to zero mapping
+		///
 		inline mapping() : from(0), to(0) {}
+
+		///
+		/// Constructs an id mapping
+		///
+		/// \param[in] x  Mapping from and to value
+		///
 		inline mapping(_In_ T x) : from(x), to(x) {}
+
+		///
+		/// Constructs a mapping
+		///
+		/// \param[in] _from  Mapping from value
+		/// \param[in] _to    Mapping to value
+		///
 		inline mapping(_In_ T _from, _In_ T _to) : from(_from), to(_to) {}
 
-		friend bool operator ==(_In_ stdex::mapping<T> const& a, _In_ stdex::mapping<T> const& b) noexcept { return a.from == b.from && a.to == b.to; }
+		///
-		friend bool operator !=(_In_ stdex::mapping<T> const& a, _In_ stdex::mapping<T> const& b) noexcept { return !(a == b); }
+		/// Are mappings identical?
+		///
+		/// \param[in] other  Other mapping to compare against
+		///
+		/// \returns true if mappings are identical or false otherwise
+		///
+		inline bool operator==(const mapping& other) const { return from == other.from && to == other.to; }
+
+		///
+		/// Are mappings different?
+		///
+		/// \param[in] other  Other mapping to compare against
+		///
+		/// \returns true if mappings are different or false otherwise
+		///
+		inline bool operator!=(const mapping& other) const { return !operator==(other); }
 	};
 
 	template <class T, class _Alloc = std::allocator<mapping<T>>>