From ea48e3a5b5f1051c251184792417326c513bf00f Mon Sep 17 00:00:00 2001
From: Carlo Nucera <carlo.nucera@protonmail.com>
Date: Thu, 2 Jul 2020 11:29:33 -0400
Subject: [PATCH] Abstract common parsing functionality

---
 src/libutil/hash.cc   | 37 +++----------------------------------
 src/libutil/parser.hh | 22 ++++++++++++++++++++++
 2 files changed, 25 insertions(+), 34 deletions(-)

diff --git a/src/libutil/hash.cc b/src/libutil/hash.cc
index 75f8f319c..7d6b8d96e 100644
--- a/src/libutil/hash.cc
+++ b/src/libutil/hash.cc
@@ -147,22 +147,7 @@ Hash Hash::parseSRI(std::string_view original) {
 Hash Hash::parseAnyPrefixed(std::string_view original)
 {
     auto rest = original;
-
-    bool isSRI = false;
-
-    // Parse the has type before the separater, if there was one.
-    std::optional<HashType> optParsedType;
-    {
-        auto hashRaw = splitPrefix(rest, ':');
-
-        if (!hashRaw) {
-            hashRaw = splitPrefix(rest, '-');
-            if (hashRaw)
-                isSRI = true;
-        }
-        if (hashRaw)
-            optParsedType = parseHashType(*hashRaw);
-    }
+    auto [optParsedType, isSRI] = getParsedTypeAndSRI(rest);
 
     // Either the string or user must provide the type, if they both do they
     // must agree.
@@ -175,23 +160,7 @@ Hash Hash::parseAnyPrefixed(std::string_view original)
 Hash Hash::parseAny(std::string_view original, std::optional<HashType> optType)
 {
     auto rest = original;
-
-    bool isSRI = false;
-    HashType hashType;
-
-    // Parse the has type before the separater, if there was one.
-    std::optional<HashType> optParsedType;
-    {
-        auto hashRaw = splitPrefix(rest, ':');
-
-        if (!hashRaw) {
-            hashRaw = splitPrefix(rest, '-');
-            if (hashRaw)
-                isSRI = true;
-        }
-        if (hashRaw)
-            optParsedType = parseHashType(*hashRaw);
-    }
+    auto [optParsedType, isSRI] = getParsedTypeAndSRI(rest);
 
     // Either the string or user must provide the type, if they both do they
     // must agree.
@@ -200,7 +169,7 @@ Hash Hash::parseAny(std::string_view original, std::optional<HashType> optType)
     else if (optParsedType && optType && *optParsedType != *optType)
         throw BadHash("hash '%s' should have type '%s'", original, printHashType(*optType));
 
-    hashType = optParsedType ? *optParsedType : *optType;
+    HashType hashType = optParsedType ? *optParsedType : *optType;
     return Hash(rest, hashType, isSRI);
 }
 
diff --git a/src/libutil/parser.hh b/src/libutil/parser.hh
index d3bfafe75..d20e4dfc6 100644
--- a/src/libutil/parser.hh
+++ b/src/libutil/parser.hh
@@ -21,4 +21,26 @@ static inline std::optional<std::string_view> splitPrefix(std::string_view & str
     return std::nullopt;
 }
 
+// Mutates the string to eliminate the prefixes when found
+std::pair<std::optional<HashType>, bool> getParsedTypeAndSRI(std::string_view & rest) {
+    bool isSRI = false;
+
+    // Parse the has type before the separater, if there was one.
+    std::optional<HashType> optParsedType;
+    {
+        auto hashRaw = splitPrefix(rest, ':');
+
+        if (!hashRaw) {
+            hashRaw = splitPrefix(rest, '-');
+            if (hashRaw)
+                isSRI = true;
+        }
+        if (hashRaw)
+            optParsedType = parseHashType(*hashRaw);
+    }
+
+    return std::make_pair(optParsedType, isSRI);
+}
+
+
 }