Add initial prototype for the GN meta-buildsystem.

tools/gn/output_file.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_FILE_H_
+#define TOOLS_GN_OUTPUT_FILE_H_
+
+#include <string>
+
+#include "tools/gn/build_settings.h"
+#include "tools/gn/source_file.h"
+
+// A simple wrapper around a string that indicates the string is a path
+// relative to the output directory.
+class OutputFile {
+ public:
+  OutputFile() : value_() {}
+  explicit OutputFile(const base::StringPiece& str)
+      : value_(str.data(), str.size()) {
+  }
+
+  std::string& value() { return value_; }
+  const std::string& value() const { return value_; }
+
+  // Converts to a SourceFile by prepending the build directory to the file.
+  SourceFile GetSourceFile(const BuildSettings* build_settings) const {
+    return SourceFile(build_settings->build_dir().value() + value_);
+  }
+
+  bool operator==(const OutputFile& other) const {
+    return value_ == other.value_;
+  }
+  bool operator!=(const OutputFile& other) const {
+    return value_ != other.value_;
+  }
+
+ private:
+  std::string value_;
+};
+
+#endif