Small perfomance optimization in Directives and Tag methods

src/directives.cpp

@@ -3,15 +3,19 @@
 namespace YAML {
 Directives::Directives() : version{true, 1, 2}, tags{} {}
 
-const std::string Directives::TranslateTagHandle(
+std::string Directives::TranslateTagHandle(
     const std::string& handle) const {
+  std::string result;
   auto it = tags.find(handle);
   if (it == tags.end()) {
     if (handle == "!!")
-      return "tag:yaml.org,2002:";
-    return handle;
+      result = "tag:yaml.org,2002:";
+    else
+      result = handle;
+  } else {
+    result = it->second;
   }
 
-  return it->second;
+  return result;
 }
 }  // namespace YAML

src/directives.h

@@ -19,7 +19,7 @@ struct Version {
 struct Directives {
   Directives();
 
-  const std::string TranslateTagHandle(const std::string& handle) const;
+  std::string TranslateTagHandle(const std::string& handle) const;
 
   Version version;
   std::map<std::string, std::string> tags;

src/tag.cpp

@@ -29,22 +29,31 @@ Tag::Tag(const Token& token)
   }
 }
 
-const std::string Tag::Translate(const Directives& directives) {
+std::string Tag::Translate(const Directives& directives) {
+  std::string result;
+
   switch (type) {
     case VERBATIM:
-      return value;
+      result = value;
+      break;
     case PRIMARY_HANDLE:
-      return directives.TranslateTagHandle("!") + value;
+      result = directives.TranslateTagHandle("!") + value;
+      break;
     case SECONDARY_HANDLE:
-      return directives.TranslateTagHandle("!!") + value;
+      result = directives.TranslateTagHandle("!!") + value;
+      break;
     case NAMED_HANDLE:
-      return directives.TranslateTagHandle("!" + handle + "!") + value;
+      result = directives.TranslateTagHandle("!" + handle + "!") + value;
+      break;
     case NON_SPECIFIC:
       // TODO:
-      return "!";
+      result = "!";
+      break;
     default:
       assert(false);
+      throw std::runtime_error("yaml-cpp: internal error, bad tag type");
   }
-  throw std::runtime_error("yaml-cpp: internal error, bad tag type");
+
+  return result;
 }
 }  // namespace YAML

src/tag.h

@@ -23,7 +23,7 @@ struct Tag {
   };
 
   Tag(const Token& token);
-  const std::string Translate(const Directives& directives);
+  std::string Translate(const Directives& directives);
 
   TYPE type;
   std::string handle, value;