Merge branch 'tag-compare' of https://github.com/geneticdrift/MPD

src/decoder/Bridge.cxx

@@ -239,6 +239,10 @@ DecoderBridge::UpdateStreamTag(InputStream *is) noexcept
 		/* discard the song tag; we don't need it */
 		song_tag.reset();
 
+	if (stream_tag && tag && *stream_tag == *tag)
+		/* not changed */
+		return false;
+
 	stream_tag = std::move(tag);
 	return true;
 }

src/player/Thread.cxx

@@ -904,13 +904,15 @@ PlayerControl::LockUpdateSongTag(DetachedSong &song,
 		   streams may change tags dynamically */
 		return;
 
-	song.SetTag(new_tag);
+	if (new_tag != song.GetTag()) {
+		song.SetTag(new_tag);
 
-	LockSetTaggedSong(song);
+		LockSetTaggedSong(song);
 
-	/* the main thread will update the playlist version when he
-	   receives this event */
-	listener.OnPlayerTagModified();
+		/* the main thread will update the playlist version when he
+		   receives this event */
+		listener.OnPlayerTagModified();
+	}
 }
 
 inline void

src/tag/Item.hxx

@@ -5,6 +5,7 @@
 #define MPD_TAG_ITEM_HXX
 
 #include <cstdint>
+#include <cstring>
 
 enum TagType : uint8_t;
 
@@ -22,6 +23,15 @@ struct TagItem {
 	 */
 	char value[1];
 
+	bool operator==(const TagItem &other) const noexcept {
+		return (this == &other) ? true :
+			type == other.type && std::strcmp(value, other.value) == 0;
+	}
+
+private:
+	/* making the constructor private
+	   to only allow construction by TagPoolItem. */
+	friend struct TagPoolItem;
 	TagItem() = default;
 	TagItem(const TagItem &other) = delete;
 	TagItem &operator=(const TagItem &other) = delete;

src/tag/Tag.cxx

@@ -7,6 +7,15 @@
 
 #include <cassert>
 
+bool
+Tag::operator==(const Tag &other) const noexcept {
+	return (this == &other) ? true :
+		duration == other.duration
+		&& has_playlist == other.has_playlist
+		&& num_items == other.num_items
+		&& std::equal(begin(), end(), other.begin(), other.end());
+}
+
 void
 Tag::Clear() noexcept
 {

src/tag/Tag.hxx

@@ -65,6 +65,8 @@ struct Tag {
 		return *this;
 	}
 
+	bool operator==(const Tag &other) const noexcept;
+
 	/**
 	 * Similar to the move operator, but move only the #TagItem
 	 * array.

src/util/DereferenceIterator.hxx

@@ -82,6 +82,10 @@ public:
 		return DereferenceIterator{original - n};
 	}
 
+	constexpr auto operator-(const DereferenceIterator<IT, VT>& other) const noexcept {
+		return std::distance(other.original, original);
+	}
+
 	/* this is a template to allow comparisons with sentinel end
 	   iterators */
 	template<typename IT2>

src/util/TerminatedArray.hxx

@@ -101,6 +101,10 @@ public:
 			return iterator{cursor - n};
 		}
 
+		constexpr auto operator-(const iterator& other) const noexcept {
+			return std::distance(other.cursor, cursor);
+		}
+
 		reference operator*() const noexcept {
 			return *cursor;
 		}