Add initial prototype for the GN meta-buildsystem.

tools/gn/output_stream.h

+// Copyright (c) 2013 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 TOOLS_GN_OUTPUT_STREAM_H_
+#define TOOLS_GN_OUTPUT_STREAM_H_
+
+class OutputStream {
+ public:
+
+
+
+  OutputStream& WriteBuffer(const char* buf, size_t len);
+  OutputStream& WriteInt(int i);
+
+  // Write a literal.
+  // This template expansion prevents having to look for nulls.
+  template<size_t size> OutputStream& Write(const char (&buf)[size]) {
+    return WriteBuffer(buf, size);
+  }
+
+  // Write a literal string.
+  OutputStream& Write(const std::string& str) {
+    return WriteBuffer(str.c_str(), str.size());
+  }
+
+  // Quotes if necessary, and does necessary escaping. If more than one
+  // input is provided, the results will be concatenated together (useful
+  // for constructing paths without a temporary buffer).
+  OutputStream& WritePath(const std::string& s);
+  OutputStream& WritePath(const std::string& s0,
+                          const std::string& s1);
+  OutputStream& WritePath(const std::string& s0,
+                          const std::string& s1,
+                          const std::string& s2);
+
+  OutputStream& EndLine() {
+    return WriteBuffer("\n", 1);
+  }
+};
+
+#endif  // TOOLS_GN_OUTPUT_STREAM_H_