implement parsing human-readable names from URLs

Based off of commit 257b768436a0e8ab7887f9b790c5b92a7fe51ef5

Upstream-PR: https://github.com/NixOS/nix/pull/8678
Co-authored-by: Felix Uhl <felix.uhl@outlook.com>
Change-Id: Idcb7f6191ca3310ef9dc854197f7798260c3f71d

1 files changed, 26 insertions, 0 deletions

diff --git a/src/libutil/url-name.hh b/src/libutil/url-name.hh
new file mode 100644
index 000000000..3a3f88e76
--- /dev/null
+++ b/src/libutil/url-name.hh
@@ -0,0 +1,26 @@
+#pragma once
+///@file url-name.hh, for some hueristic-ish URL parsing.
+
+#include <string>
+#include <optional>
+
+#include "url.hh"
+#include "url-parts.hh"
+#include "util.hh"
+#include "split.hh"
+
+namespace nix {
+
+/**
+ * Try to extract a reasonably unique and meaningful, human-readable
+ * name of a flake output from a parsed URL.
+ * When nullopt is returned, the callsite should use information available
+ * to it outside of the URL to determine a useful name.
+ * This is a heuristic approach intended for user interfaces.
+ * @return nullopt if the extracted name is not useful to identify a
+ * flake output, for example because it is empty or "default".
+ * Otherwise returns the extracted name.
+ */
+std::optional<std::string> getNameFromURL(ParsedURL const & url);
+
+}