Don't unnecessarily copy strings

base/strings/string_split.cc

Index: base/strings/string_split.cc
diff --git a/base/strings/string_split.cc b/base/strings/string_split.cc
index 4253e2f8f86b7ed393dfdf66193b91b489176bf8..623766b09aef2f6f0d98d2324369b244870495e4 100644
--- a/base/strings/string_split.cc
+++ b/base/strings/string_split.cc
@@ -128,10 +128,10 @@ bool AppendStringKeyValue(StringPiece input,
   return true;
 }
 
-template <typename Str>
+template <typename Str, typename OutputStringType>
 void SplitStringUsingSubstrT(BasicStringPiece<Str> input,
                              BasicStringPiece<Str> delimiter,
-                             std::vector<Str>* result) {
+                             std::vector<OutputStringType>* result) {
   using Piece = BasicStringPiece<Str>;
   using size_type = typename Piece::size_type;
 
@@ -143,12 +143,12 @@ void SplitStringUsingSubstrT(BasicStringPiece<Str> input,
       // No delimiter, use the rest of the string.
       Piece term = TrimString(input.substr(begin_index),
                               WhitespaceForType<Str>(), TRIM_ALL);
-      result->push_back(term.as_string());
+      result->push_back(PieceToOutputType<Str, OutputStringType>(term));
       return;
     }
     Piece term = TrimString(input.substr(begin_index, end_index - begin_index),
                             WhitespaceForType<Str>(), TRIM_ALL);
-    result->push_back(term.as_string());
+    result->push_back(PieceToOutputType<Str, OutputStringType>(term));
     begin_index = end_index + delimiter.size();
   }
 }
@@ -237,4 +237,19 @@ void SplitStringUsingSubstr(StringPiece input,
   SplitStringUsingSubstrT(input, delimiter, result);
 }
 
+std::vector<StringPiece16> SplitStringPieceUsingSubstr(
+    StringPiece16 input,
+    StringPiece16 delimiter) {

[mef, 2015/12/28 17:29:55]

Would it make sense to take a pointer to an output vector as a parameter to
avoid copying it on the return?

[brettw, 2015/12/29 04:07:14]

Return value optimization should take care of this: there should be no copy when
used in most cases.

[mef, 2015/12/30 19:36:58]

Acknowledged.

+  std::vector<StringPiece16> result;
+  SplitStringUsingSubstrT(input, delimiter, &result);
+  return result;
+}
+
+std::vector<StringPiece> SplitStringPieceUsingSubstr(StringPiece input,
+                                                     StringPiece delimiter) {
+  std::vector<StringPiece> result;
+  SplitStringUsingSubstrT(input, delimiter, &result);
+  return result;
+}
+
 }  // namespace base