util/UriExtract: migrate uri_get_scheme() to std::string_view

src/util/UriExtract.cxx

@@ -82,17 +82,17 @@ uri_after_scheme(const char *uri) noexcept
 bool
 uri_has_scheme(const char *uri) noexcept
 {
-	return !uri_get_scheme(uri).IsNull();
+	return !uri_get_scheme(uri).empty();
 }
 
-StringView
-uri_get_scheme(const char *uri) noexcept
+std::string_view
+uri_get_scheme(std::string_view uri) noexcept
 {
-	const char *end = strstr(uri, "://");
-	if (end == nullptr)
-		return nullptr;
+	auto end = uri.find("://");
+	if (end == std::string_view::npos)
+		return {};
 
-	return {uri, end};
+	return uri.substr(0, end);
 }
 
 bool

src/util/UriExtract.hxx

@@ -32,7 +32,7 @@
 
 #include "Compiler.h"
 
-struct StringView;
+#include <string_view>
 
 /**
  * Checks whether the specified URI has a scheme in the form
@@ -46,8 +46,8 @@ uri_has_scheme(const char *uri) noexcept;
  * Returns the scheme name of the specified URI, or an empty string.
  */
 gcc_pure
-StringView
-uri_get_scheme(const char *uri) noexcept;
+std::string_view
+uri_get_scheme(std::string_view uri) noexcept;
 
 gcc_pure
 bool