tag/Handler: pass StringView to OnTag() and OnPair()

Eliminates a number of allocations, because callers don't need to copy
the strings to a newly allocated buffer only to null-terminate them.
And most callers don't need to have a null-terminated string.

8 files changed, 15 insertions, 8 deletions

diff --git a/src/decoder/plugins/AdPlugDecoderPlugin.cxx b/src/decoder/plugins/AdPlugDecoderPlugin.cxx
index c082f6f2f..ba1d9c013 100644
--- a/src/decoder/plugins/AdPlugDecoderPlugin.cxx
+++ b/src/decoder/plugins/AdPlugDecoderPlugin.cxx
@@ -24,6 +24,7 @@
 #include "fs/Path.hxx"
 #include "util/Domain.hxx"
 #include "util/Macros.hxx"
+#include "util/StringView.hxx"
 #include "Log.hxx"
 
 #include <adplug/adplug.h>
@@ -85,7 +86,7 @@ adplug_scan_tag(TagType type, const std::string &value,
 		TagHandler &handler) noexcept
 {
 	if (!value.empty())
-		handler.OnTag(type, value.c_str());
+		handler.OnTag(type, {value.data(), value.size()});
 }
 
 static bool
diff --git a/src/decoder/plugins/DsdiffDecoderPlugin.cxx b/src/decoder/plugins/DsdiffDecoderPlugin.cxx
index 1e4d9799c..a46d678bf 100644
--- a/src/decoder/plugins/DsdiffDecoderPlugin.cxx
+++ b/src/decoder/plugins/DsdiffDecoderPlugin.cxx
@@ -33,6 +33,7 @@
 #include "CheckAudioFormat.hxx"
 #include "util/bit_reverse.h"
 #include "util/ByteOrder.hxx"
+#include "util/StringView.hxx"
 #include "tag/Handler.hxx"
 #include "DsdLib.hxx"
 #include "Log.hxx"
@@ -205,15 +206,14 @@ dsdiff_handle_native_tag(DecoderClient *client, InputStream &is,
 	if (length == 0 || length > MAX_LENGTH)
 		return;
 
-	char string[MAX_LENGTH + 1];
+	char string[MAX_LENGTH];
 	char *label;
 	label = string;
 
 	if (!decoder_read_full(client, is, label, (size_t)length))
 		return;
 
-	string[length] = '\0';
-	handler.OnTag(type, label);
+	handler.OnTag(type, {label, length});
 	return;
 }
 
diff --git a/src/decoder/plugins/FfmpegMetaData.cxx b/src/decoder/plugins/FfmpegMetaData.cxx
index 265722f49..61b2a9245 100644
--- a/src/decoder/plugins/FfmpegMetaData.cxx
+++ b/src/decoder/plugins/FfmpegMetaData.cxx
@@ -24,6 +24,7 @@
 #include "tag/Table.hxx"
 #include "tag/Handler.hxx"
 #include "tag/Id3MusicBrainz.hxx"
+#include "util/StringView.hxx"
 
 extern "C" {
 #include <libavutil/dict.h>
diff --git a/src/decoder/plugins/GmeDecoderPlugin.cxx b/src/decoder/plugins/GmeDecoderPlugin.cxx
index 64f0a1ad4..2b2ea38f3 100644
--- a/src/decoder/plugins/GmeDecoderPlugin.cxx
+++ b/src/decoder/plugins/GmeDecoderPlugin.cxx
@@ -29,6 +29,7 @@
 #include "fs/FileSystem.hxx"
 #include "util/ScopeExit.hxx"
 #include "util/StringFormat.hxx"
+#include "util/StringView.hxx"
 #include "util/UriUtil.hxx"
 #include "util/Domain.hxx"
 #include "Log.hxx"
@@ -220,7 +221,7 @@ ScanGmeInfo(const gme_info_t &info, unsigned song_num, int track_count,
 		handler.OnDuration(SongTime::FromMS(info.play_length));
 
 	if (track_count > 1)
-		handler.OnTag(TAG_TRACK, StringFormat<16>("%u", song_num + 1));
+		handler.OnTag(TAG_TRACK, StringFormat<16>("%u", song_num + 1).c_str());
 
 	if (info.song != nullptr) {
 		if (track_count > 1) {
@@ -229,7 +230,7 @@ ScanGmeInfo(const gme_info_t &info, unsigned song_num, int track_count,
 				StringFormat<1024>("%s (%u/%d)",
 						   info.song, song_num + 1,
 						   track_count);
-			handler.OnTag(TAG_TITLE, tag_title);
+			handler.OnTag(TAG_TITLE, tag_title.c_str());
 		} else
 			handler.OnTag(TAG_TITLE, info.song);
 	}
diff --git a/src/decoder/plugins/MikmodDecoderPlugin.cxx b/src/decoder/plugins/MikmodDecoderPlugin.cxx
index e023dd2c4..1a62dc501 100644
--- a/src/decoder/plugins/MikmodDecoderPlugin.cxx
+++ b/src/decoder/plugins/MikmodDecoderPlugin.cxx
@@ -24,6 +24,7 @@
 #include "fs/Path.hxx"
 #include "util/Domain.hxx"
 #include "util/RuntimeError.hxx"
+#include "util/StringView.hxx"
 #include "Log.hxx"
 
 #include <mikmod.h>
diff --git a/src/decoder/plugins/ModplugDecoderPlugin.cxx b/src/decoder/plugins/ModplugDecoderPlugin.cxx
index d3d91efe1..96696ad1d 100644
--- a/src/decoder/plugins/ModplugDecoderPlugin.cxx
+++ b/src/decoder/plugins/ModplugDecoderPlugin.cxx
@@ -24,6 +24,7 @@
 #include "util/WritableBuffer.hxx"
 #include "util/Domain.hxx"
 #include "util/RuntimeError.hxx"
+#include "util/StringView.hxx"
 #include "Log.hxx"
 
 #include <libmodplug/modplug.h>
diff --git a/src/decoder/plugins/SidplayDecoderPlugin.cxx b/src/decoder/plugins/SidplayDecoderPlugin.cxx
index 3d34b4436..71e530e34 100644
--- a/src/decoder/plugins/SidplayDecoderPlugin.cxx
+++ b/src/decoder/plugins/SidplayDecoderPlugin.cxx
@@ -31,6 +31,7 @@
 #endif
 #include "util/Macros.hxx"
 #include "util/StringFormat.hxx"
+#include "util/StringView.hxx"
 #include "util/Domain.hxx"
 #include "util/ByteOrder.hxx"
 #include "Log.hxx"
@@ -460,7 +461,7 @@ ScanSidTuneInfo(const SidTuneInfo &info, unsigned track, unsigned n_tracks,
 		const auto tag_title =
 			StringFormat<1024>("%s (%u/%u)",
 					   title, track, n_tracks);
-		handler.OnTag(TAG_TITLE, tag_title);
+		handler.OnTag(TAG_TITLE, tag_title.c_str());
 	} else
 		handler.OnTag(TAG_TITLE, title);
 
@@ -475,7 +476,7 @@ ScanSidTuneInfo(const SidTuneInfo &info, unsigned track, unsigned n_tracks,
 		handler.OnTag(TAG_DATE, date);
 
 	/* track */
-	handler.OnTag(TAG_TRACK, StringFormat<16>("%u", track));
+	handler.OnTag(TAG_TRACK, StringFormat<16>("%u", track).c_str());
 }
 
 static bool
diff --git a/src/decoder/plugins/SndfileDecoderPlugin.cxx b/src/decoder/plugins/SndfileDecoderPlugin.cxx
index 08cbb88c1..315af0589 100644
--- a/src/decoder/plugins/SndfileDecoderPlugin.cxx
+++ b/src/decoder/plugins/SndfileDecoderPlugin.cxx
@@ -24,6 +24,7 @@
 #include "tag/Handler.hxx"
 #include "util/Domain.hxx"
 #include "util/ScopeExit.hxx"
+#include "util/StringView.hxx"
 #include "Log.hxx"
 
 #include <exception>