Don't unnecessarily copy strings

base/strings/string_split.h

Index: base/strings/string_split.h
diff --git a/base/strings/string_split.h b/base/strings/string_split.h
index 2a0c79561b85cca9561bbc80cf8e709e7ed2eace..ec9f24604a6339051f9aa9086b3460c71e983559 100644
--- a/base/strings/string_split.h
+++ b/base/strings/string_split.h
@@ -101,6 +101,29 @@ BASE_EXPORT void SplitStringUsingSubstr(StringPiece input,
                                         StringPiece delimiter,
                                         std::vector<std::string>* result);
 
+// Like SplitStringUsingSubstr above except it returns a vector of StringPieces
+// which reference the original buffer without copying. Although you have to be
+// careful to keep the original string unmodified, this provides an efficient
+// way to iterate through tokens in a string.
+//
+// To iterate through all newline-separated tokens in an input string:
+//
+//   for (const auto& cur :
+//        base::SplitStringUsingSubstr(input, "\r\n",
+//                                     base::KEEP_WHITESPACE,
+//                                     base::SPLIT_WANT_NONEMPTY)) {
+//     ...
+BASE_EXPORT std::vector<StringPiece16> SplitStringPieceUsingSubstr(
+    StringPiece16 input,
+    StringPiece16 delimiter,
+    WhitespaceHandling whitespace,
+    SplitResult result_type);
+BASE_EXPORT std::vector<StringPiece> SplitStringPieceUsingSubstr(
+    StringPiece input,
+    StringPiece delimiter,
+    WhitespaceHandling whitespace,
+    SplitResult result_type);
+
 }  // namespace base
 
 #endif  // BASE_STRINGS_STRING_SPLIT_H_