tag/Handler: convert to class with virtual methods

src/decoder/plugins/FfmpegMetaData.cxx

@@ -43,46 +43,42 @@ static constexpr struct tag_table ffmpeg_tags[] = {
 static void
 FfmpegScanTag(TagType type,
 	      AVDictionary *m, const char *name,
-	      const TagHandler &handler, void *handler_ctx)
+	      TagHandler &handler) noexcept
 {
 	AVDictionaryEntry *mt = nullptr;
 
 	while ((mt = av_dict_get(m, name, mt, 0)) != nullptr)
-		tag_handler_invoke_tag(handler, handler_ctx,
-				       type, mt->value);
+		handler.OnTag(type, mt->value);
 }
 
 static void
-FfmpegScanPairs(AVDictionary *dict,
-		const TagHandler &handler, void *handler_ctx)
+FfmpegScanPairs(AVDictionary *dict, TagHandler &handler) noexcept
 {
 	AVDictionaryEntry *i = nullptr;
 
 	while ((i = av_dict_get(dict, "", i, AV_DICT_IGNORE_SUFFIX)) != nullptr)
-		tag_handler_invoke_pair(handler, handler_ctx,
-					i->key, i->value);
+		handler.OnPair(i->key, i->value);
 }
 
 void
-FfmpegScanDictionary(AVDictionary *dict,
-		     const TagHandler &handler, void *handler_ctx)
+FfmpegScanDictionary(AVDictionary *dict, TagHandler &handler) noexcept
 {
-	if (handler.tag != nullptr) {
+	if (handler.WantTag()) {
 		for (unsigned i = 0; i < TAG_NUM_OF_ITEM_TYPES; ++i)
 			FfmpegScanTag(TagType(i), dict, tag_item_names[i],
-				      handler, handler_ctx);
+				      handler);
 
 		for (const struct tag_table *i = ffmpeg_tags;
 		     i->name != nullptr; ++i)
 			FfmpegScanTag(i->type, dict, i->name,
-				      handler, handler_ctx);
+				      handler);
 
 		for (const struct tag_table *i = musicbrainz_txxx_tags;
 		     i->name != nullptr; ++i)
 			FfmpegScanTag(i->type, dict, i->name,
-				      handler, handler_ctx);
+				      handler);
 	}
 
-	if (handler.pair != nullptr)
-		FfmpegScanPairs(dict, handler, handler_ctx);
+	if (handler.WantPair())
+		FfmpegScanPairs(dict, handler);
 }