tag/Handler: pass std::span to OnPicture()

src/tag/Handler.cxx

@@ -36,7 +36,7 @@ NullTagHandler::OnPair(StringView, StringView) noexcept
 }
 
 void
-NullTagHandler::OnPicture(const char *, ConstBuffer<void>) noexcept
+NullTagHandler::OnPicture(const char *, std::span<const std::byte>) noexcept
 {
 }
 

src/tag/Handler.hxx

@@ -24,7 +24,9 @@
 #include "Chrono.hxx"
 #include "util/Compiler.h"
 
-template<typename T> struct ConstBuffer;
+#include <cstddef>
+#include <span>
+
 struct StringView;
 struct AudioFormat;
 class TagBuilder;
@@ -116,7 +118,7 @@ public:
 	 * invalidated after this method returns
 	 */
 	virtual void OnPicture(const char *mime_type,
-			       ConstBuffer<void> buffer) noexcept = 0;
+			       std::span<const std::byte> buffer) noexcept = 0;
 };
 
 class NullTagHandler : public TagHandler {
@@ -129,7 +131,7 @@ public:
 	void OnPair(StringView key, StringView value) noexcept override;
 	void OnAudioFormat(AudioFormat af) noexcept override;
 	void OnPicture(const char *mime_type,
-		       ConstBuffer<void> buffer) noexcept override;
+		       std::span<const std::byte> buffer) noexcept override;
 };
 
 /**

src/tag/Id3Picture.cxx

@@ -20,37 +20,35 @@
 #include "Id3Picture.hxx"
 #include "Handler.hxx"
 #include "util/ByteOrder.hxx"
-#include "util/ConstBuffer.hxx"
 #include "util/StringView.hxx"
 
 #include <cstdint>
 #include <string>
 
 static StringView
-ReadString(ConstBuffer<uint8_t> &src) noexcept
+ReadString(std::span<const std::byte> &src) noexcept
 {
-	if (src.size < 4)
+	if (src.size() < 4)
 		return nullptr;
 
-	const size_t length = *(const PackedBE32 *)src.data;
-	src.skip_front(4);
+	const size_t length = *(const PackedBE32 *)(const void *)src.data();
+	src = src.subspan(4);
 
-	if (src.size < length)
+	if (src.size() < length)
 		return nullptr;
 
-	StringView result((const char *)src.data, length);
-	src.skip_front(length);
+	const std::string_view result{(const char *)src.data(), length};
+	src = src.subspan(length);
 	return result;
 }
 
 void
-ScanId3Apic(ConstBuffer<void> _buffer, TagHandler &handler) noexcept
+ScanId3Apic(std::span<const std::byte> buffer, TagHandler &handler) noexcept
 {
-	auto buffer = ConstBuffer<uint8_t>::FromVoid(_buffer);
-	if (buffer.size < 4)
+	if (buffer.size() < 4)
 		return;
 
-	buffer.skip_front(4); /* picture type */
+	buffer = buffer.subspan(4); /* picture type */
 
 	const auto mime_type = ReadString(buffer);
 	if (mime_type.IsNull())
@@ -60,18 +58,18 @@ ScanId3Apic(ConstBuffer<void> _buffer, TagHandler &handler) noexcept
 	if (ReadString(buffer).IsNull())
 		return;
 
-	if (buffer.size < 20)
+	if (buffer.size() < 20)
 		return;
 
-	buffer.skip_front(16);
+	buffer = buffer.subspan(16);
 
-	const size_t image_size = *(const PackedBE32 *)buffer.data;
-	buffer.skip_front(4);
+	const size_t image_size = *(const PackedBE32 *)(const void *)buffer.data();
+	buffer = buffer.subspan(4);
 
-	if (buffer.size < image_size)
+	if (buffer.size() < image_size)
 		return;
 
-	ConstBuffer<void> image(buffer.data, image_size);
+	const auto image = buffer.first(image_size);
 
 	// TODO: don't copy MIME type, pass StringView to TagHandler::OnPicture()
 	handler.OnPicture(std::string(mime_type.data, mime_type.size).c_str(),

src/tag/Id3Picture.hxx

@@ -20,13 +20,14 @@
 #ifndef MPD_TAG_ID3_PICTURE_HXX
 #define MPD_TAG_ID3_PICTURE_HXX
 
-template<typename T> struct ConstBuffer;
+#include <span>
+
 class TagHandler;
 
 /**
  * Scan an "APIC" value and call TagHandler::OnPicture().
  */
 void
-ScanId3Apic(ConstBuffer<void> buffer, TagHandler &handler) noexcept;
+ScanId3Apic(std::span<const std::byte> buffer, TagHandler &handler) noexcept;
 
 #endif

src/tag/Id3Scan.cxx

@@ -308,7 +308,8 @@ tag_id3_handle_apic(const struct id3_tag *id3_tag,
 		if (data == nullptr || size == 0)
 			continue;
 
-		handler.OnPicture(mime_type, {data, size});
+		handler.OnPicture(mime_type,
+				  std::as_bytes(std::span{data, size}));
 	}
 }