Add helper function parseHashFormat[Opt] printHashFormat

Add hash format analogy of
parseHashTypeOpt, parseHashType, and printHashType.

Co-authored-by: Valentin Gagarin <[email protected]>

src/libutil/hash.cc

@@ -386,6 +386,41 @@ Hash compressHash(const Hash & hash, unsigned int newSize)
 }
 
 
+std::optional<HashFormat> parseHashFormatOpt(std::string_view hashFormatName)
+{
+ if (hashFormatName == "base16") return HashFormat::Base16;
+ if (hashFormatName == "base32") return HashFormat::Base32;
+ if (hashFormatName == "base64") return HashFormat::Base64;
+ if (hashFormatName == "sri") return HashFormat::SRI;
+ return std::nullopt;
+}
+
+HashFormat parseHashFormat(std::string_view hashFormatName)
+{
+ auto opt_f = parseHashFormatOpt(hashFormatName);
+ if (opt_f)
+ return *opt_f;
+ throw UsageError("unknown hash format '%1%', expect 'base16', 'base32', 'base64', or 'sri'", hashFormatName);
+}
+
+std::string_view printHashFormat(HashFormat HashFormat)
+{
+ switch (HashFormat) {
+ case HashFormat::Base64:
+ return "base64";
+ case HashFormat::Base32:
+ return "base32";
+ case HashFormat::Base16:
+ return "base16";
+ case HashFormat::SRI:
+ return "sri";
+ default:
+ // illegal hash base enum value internally, as opposed to external input
+ // which should be validated with nice error message.
+ assert(false);
+ }
+}
+
 std::optional<HashType> parseHashTypeOpt(std::string_view s)
 {
  if (s == "md5") return htMD5;

src/libutil/hash.hh

@@ -181,6 +181,21 @@ HashResult hashPath(HashType ht, const Path & path,
  */
 Hash compressHash(const Hash & hash, unsigned int newSize);
 
+/**
+ * Parse a string representing a hash format.
+ */
+HashFormat parseHashFormat(std::string_view hashFormatName);
+
+/**
+ * std::optional version of parseHashFormat that doesn't throw error.
+ */
+std::optional<HashFormat> parseHashFormatOpt(std::string_view hashFormatName);
+
+/**
+ * The reverse of parseHashFormat.
+ */
+std::string_view printHashFormat(HashFormat hashFormat);
+
 /**
  * Parse a string representing a hash type.
  */

src/libutil/tests/hash.cc

@@ -79,6 +79,21 @@ namespace nix {
  "7299aeadb6889018501d289e4900f7e4331b99dec4b5433a"
  "c7d329eeb6dd26545e96e55b874be909");
  }
+
+ /* ----------------------------------------------------------------------------
+ * parseHashFormat, parseHashFormatOpt, printHashFormat
+ * --------------------------------------------------------------------------*/
+
+ TEST(hashFormat, testRoundTripPrintParse) {
+ for (const HashFormat hashFormat: { HashFormat::Base64, HashFormat::Base32, HashFormat::Base16, HashFormat::SRI}) {
+ ASSERT_EQ(parseHashFormat(printHashFormat(hashFormat)), hashFormat);
+ ASSERT_EQ(*parseHashFormatOpt(printHashFormat(hashFormat)), hashFormat);
+ }
+ }
+
+ TEST(hashFormat, testParseHashFormatOptException) {
+ ASSERT_EQ(parseHashFormatOpt("sha0042"), std::nullopt);
+ }
 }
 
 namespace rc {