Don't unnecessarily copy strings

base/strings/string_split.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef BASE_STRINGS_STRING_SPLIT_H_
 #define BASE_STRINGS_STRING_SPLIT_H_
 
 #include <string>
 #include <utility>
 #include <vector>
@@ skipping 83 matching lines @@
 // TODO(brettw) this should probably be changed and expanded to provide a
 // mirror of the SplitString[Piece] API above, just with the different
 // delimiter handling.
 BASE_EXPORT void SplitStringUsingSubstr(StringPiece16 input,
                                         StringPiece16 delimiter,
                                         std::vector<string16>* result);
 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_