Add string_piece_util

Following functions are implemented for further performance
optimization.

* JoinStringPiece
* SplitStringPiece
* EqualsCaseInsensitiveASCII
* ToLowerASCII

To improve performance of CLParser, I will introduce above functions
into include_normalize-win32.cc.

1 files changed, 34 insertions, 0 deletions

diff --git a/src/string_piece_util.h b/src/string_piece_util.h
new file mode 100644
index 0000000..2e40b9f
--- /dev/null
+++ b/src/string_piece_util.h
@@ -0,0 +1,34 @@
+// Copyright 2017 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef NINJA_STRINGPIECE_UTIL_H_
+#define NINJA_STRINGPIECE_UTIL_H_
+
+#include <string>
+#include <vector>
+
+#include "string_piece.h"
+using namespace std;
+
+vector<StringPiece> SplitStringPiece(StringPiece input, char sep);
+
+string JoinStringPiece(const vector<StringPiece>& list, char sep);
+
+inline char ToLowerASCII(char c) {
+  return (c >= 'A' && c <= 'Z') ? (c + ('a' - 'A')) : c;
+}
+
+bool EqualsCaseInsensitiveASCII(StringPiece a, StringPiece b);
+
+#endif  // NINJA_STRINGPIECE_UTIL_H_