Merge branch 'master' into debug-exploratory-PR

src/libutil/url.cc

@@ -1,6 +1,7 @@
 #include "url.hh"
 #include "url-parts.hh"
 #include "util.hh"
+#include "split.hh"
 
 namespace nix {
 
@@ -136,4 +137,21 @@ bool ParsedURL::operator ==(const ParsedURL & other) const
         && fragment == other.fragment;
 }
 
+/**
+ * Parse a URL scheme of the form '(applicationScheme\+)?transportScheme'
+ * into a tuple '(applicationScheme, transportScheme)'
+ *
+ * > parseUrlScheme("http") == ParsedUrlScheme{ {}, "http"}
+ * > parseUrlScheme("tarball+http") == ParsedUrlScheme{ {"tarball"}, "http"}
+ */
+ParsedUrlScheme parseUrlScheme(std::string_view scheme)
+{
+    auto application = splitPrefixTo(scheme, '+');
+    auto transport = scheme;
+    return ParsedUrlScheme {
+        .application = application,
+        .transport = transport,
+    };
+}
+
 }

src/libutil/url.hh

@@ -27,4 +27,19 @@ std::map<std::string, std::string> decodeQuery(const std::string & query);
 
 ParsedURL parseURL(const std::string & url);
 
+/*
+ * Although that’s not really standardized anywhere, an number of tools
+ * use a scheme of the form 'x+y' in urls, where y is the “transport layer”
+ * scheme, and x is the “application layer” scheme.
+ *
+ * For example git uses `git+https` to designate remotes using a Git
+ * protocol over http.
+ */
+struct ParsedUrlScheme {
+    std::optional<std::string_view> application;
+    std::string_view transport;
+};
+
+ParsedUrlScheme parseUrlScheme(std::string_view scheme);
+
 }