Add initial prototype for the GN meta-buildsystem.

tools/gn/target_generator.h

Index: tools/gn/target_generator.h
diff --git a/tools/gn/target_generator.h b/tools/gn/target_generator.h
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+++ b/tools/gn/target_generator.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_TARGET_GENERATOR_H_
+#define TOOLS_GN_TARGET_GENERATOR_H_
+
+#include <string>
+#include <vector>
+
+#include "base/basictypes.h"
+#include "base/gtest_prod_util.h"
+#include "base/memory/scoped_ptr.h"
+#include "tools/gn/source_dir.h"
+#include "tools/gn/target.h"
+
+class BuildSettings;
+class Err;
+class Location;
+class Scope;
+class Token;
+class Value;
+
+// Creates Target objects from a Scope (the result of a script execution).
+class TargetGenerator {
+ public:
+  TargetGenerator(Target* target,
+                  Scope* scope,
+                  const Token& function_token,
+                  const std::vector<Value>& args,
+                  const std::string& output_type,
+                  Err* err);
+  ~TargetGenerator();
+
+  void Run();
+
+  // The function token is the token of the function name of the generator for
+  // this target. err() will be set on failure.
+  static void GenerateTarget(Scope* scope,
+                             const Token& function_token,
+                             const std::vector<Value>& args,
+                             const std::string& output_type,
+                             Err* err);
+
+ private:
+  // Sets err_ on failure.
+  Target::OutputType GetOutputType() const;
+
+  // Reads configs from the given var name, and uses the given setting on the
+  // target to save them
+  void FillGenericConfigs(const char* var_name,
+                          void (Target::*setter)(std::vector<const Config*>*));
+
+  void FillConfigs();
+  void FillAllDependentConfigs();
+  void FillDirectDependentConfigs();
+  void FillSources();
+  void FillData();
+  void FillDependencies();
+  void FillDestDir();
+  void FillScript();
+  void FillScriptArgs();
+  void FillOutputs();
+
+  const BuildSettings* GetBuildSettings() const;
+
+  Target* target_;
+  Scope* scope_;
+  const Token& function_token_;
+  std::vector<Value> args_;
+  std::string output_type_;
+  Err* err_;
+
+  // Sources are relative to this. This comes from the input file which doesn't
+  // get freed so we don't acautlly have to make a copy.
+  const SourceDir& input_directory_;
+
+  FRIEND_TEST_ALL_PREFIXES(TargetGenerator, ResolveInputPath);
+
+  DISALLOW_COPY_AND_ASSIGN(TargetGenerator);
+};
+
+#endif  // TOOLS_GN_TARGET_GENERATOR_H_