Add initial prototype for the GN meta-buildsystem.

tools/gn/setup.h

Index: tools/gn/setup.h
diff --git a/tools/gn/setup.h b/tools/gn/setup.h
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+// 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_SETUP_H_
+#define TOOLS_GN_SETUP_H_
+
+#include <vector>
+
+#include "base/basictypes.h"
+#include "base/files/file_path.h"
+#include "base/memory/scoped_ptr.h"
+#include "tools/gn/build_settings.h"
+#include "tools/gn/scheduler.h"
+#include "tools/gn/scope.h"
+#include "tools/gn/settings.h"
+#include "tools/gn/token.h"
+#include "tools/gn/toolchain.h"
+
+class CommandLine;
+class InputFile;
+class ParseNode;
+
+// Helper class to setup the build settings and environment for the various
+// commands to run.
+class Setup {
+ public:
+  Setup();
+  ~Setup();
+
+  // Configures the build for the current command line. On success returns
+  // true. On failure, prints the error and returns false.
+  bool DoSetup();
+
+  // Runs the load, returning true on success. On failure, prints the error
+  // and returns false.
+  bool Run();
+
+  BuildSettings& build_settings() { return build_settings_; }
+  Scheduler& scheduler() { return scheduler_; }
+
+ private:
+  // Fills the root directory into the settings. Returns true on success.
+  bool FillSourceDir(const CommandLine& cmdline);
+
+  // Run config file.
+  bool RunConfigFile();
+
+  bool FillOtherConfig(const CommandLine& cmdline);
+
+  BuildSettings build_settings_;
+  Scheduler scheduler_;
+
+  // State for invoking the dotfile.
+  // TODO(brettw) this seems a bit excessive, maybe we can get this down
+  // somehow?
+  base::FilePath dotfile_name_;
+  scoped_ptr<InputFile> dotfile_input_file_;
+  std::vector<Token> dotfile_tokens_;
+  scoped_ptr<ParseNode> dotfile_root_;
+  BuildSettings dotfile_build_settings_;
+  Toolchain dotfile_toolchain_;
+  Settings dotfile_settings_;
+  Scope dotfile_scope_;
+
+  DISALLOW_COPY_AND_ASSIGN(Setup);
+};
+
+#endif  // TOOLS_GN_SETUP_H_