util/UriExtract: uri_get_scheme() returns StringView

src/playlist/PlaylistRegistry.cxx

@@ -123,7 +123,7 @@ playlist_list_open_uri_scheme(const char *uri, Mutex &mutex,
 
 		if (playlist_plugins_enabled[i] && plugin->open_uri != nullptr &&
 		    plugin->schemes != nullptr &&
-		    StringArrayContainsCase(plugin->schemes, scheme.c_str())) {
+		    StringArrayContainsCase(plugin->schemes, scheme)) {
 			auto playlist = plugin->open_uri(uri, mutex);
 			if (playlist)
 				return playlist;

src/util/UriExtract.cxx

@@ -85,14 +85,14 @@ uri_has_scheme(const char *uri) noexcept
 	return strstr(uri, "://") != nullptr;
 }
 
-std::string
+StringView
 uri_get_scheme(const char *uri) noexcept
 {
 	const char *end = strstr(uri, "://");
 	if (end == nullptr)
-		end = uri;
+		return nullptr;
 
-	return std::string(uri, end);
+	return {uri, end};
 }
 
 const char *

src/util/UriExtract.hxx

@@ -32,7 +32,7 @@
 
 #include "Compiler.h"
 
-#include <string>
+struct StringView;
 
 /**
  * Checks whether the specified URI has a scheme in the form
@@ -46,7 +46,7 @@ uri_has_scheme(const char *uri) noexcept;
  * Returns the scheme name of the specified URI, or an empty string.
  */
 gcc_pure
-std::string
+StringView
 uri_get_scheme(const char *uri) noexcept;
 
 /**