Redo GN "args" command

tools/gn/setup.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_SETUP_H_
 #define TOOLS_GN_SETUP_H_
 
 #include <vector>
 
 #include "base/basictypes.h"
@@ skipping 40 matching lines @@
   // After a successful run, setting this will additionally cause the public
   // headers to be checked. Defaults to false.
   void set_check_public_headers(bool s) {
     check_public_headers_ = s;
   }
 
   BuildSettings& build_settings() { return build_settings_; }
   Builder* builder() { return builder_.get(); }
   LoaderImpl* loader() { return loader_.get(); }
 
+  // Name of the file in the root build directory that contains the build
+  // arguements.
+  static const char kBuildArgFileName[];
+
  protected:
   CommonSetup();
   CommonSetup(const CommonSetup& other);
 
   // Performs the two sets of operations to run the generation before and after
   // the message loop is run.
   void RunPreMessageLoop();
   bool RunPostMessageLoop();
 
   BuildSettings build_settings_;
@@ skipping 27 matching lines @@
 
   // Runs the load, returning true on success. On failure, prints the error
   // and returns false. This includes both RunPreMessageLoop() and
   // RunPostMessageLoop().
   bool Run();
 
   Scheduler& scheduler() { return scheduler_; }
 
   virtual Scheduler* GetScheduler() OVERRIDE;
 
+  // Returns the file used to store the build arguments. Note that the path
+  // might not exist.
+  SourceFile GetBuildArgFile() const;
+
+  // Sets whether the build arguments should be filled during setup from the
+  // command line/build argument file. This will be true by default. The use
+  // case for setting it to false is when editing build arguments, we don't
+  // want to rely on them being valid.
+  void set_fill_arguments(bool fa) { fill_arguments_ = fa; }
+
  private:
   // Fills build arguments. Returns true on success.
   bool FillArguments(const base::CommandLine& cmdline);
 
+  // Fills the build arguments from the command line or from the build arg file.
+  bool FillArgsFromCommandLine(const std::string& args);
+  bool FillArgsFromFile();
+
+  // Given an already-loaded args_input_file_, parses and saves the resulting
+  // arguments. Backend for the different FillArgs variants.
+  bool FillArgsFromArgsInputFile();
+
+  // Writes the build arguments to the build arg file.
+  bool SaveArgsToFile();
+
   // Fills the root directory into the settings. Returns true on success.
   bool FillSourceDir(const base::CommandLine& cmdline);
 
   // Fills the build directory given the value the user has specified.
   // Must happen after FillSourceDir so we can resolve source-relative
   // paths.
   bool FillBuildDir(const std::string& build_dir);
 
   // Fills the python path portion of the command line. On failure, sets
   // it to just "python".
@@ skipping 11 matching lines @@
   BuildSettings empty_build_settings_;
   Settings empty_settings_;
   Scope dotfile_scope_;
 
   // State for invoking the dotfile.
   base::FilePath dotfile_name_;
   scoped_ptr<InputFile> dotfile_input_file_;
   std::vector<Token> dotfile_tokens_;
   scoped_ptr<ParseNode> dotfile_root_;
 
+  // Set to true when we should populate the build arguments from the command
+  // line or build argument file. See setter above.
+  bool fill_arguments_;
+
   // State for invoking the command line args. We specifically want to keep
   // this around for the entire run so that Values can blame to the command
   // line when we issue errors about them.
   scoped_ptr<InputFile> args_input_file_;
   std::vector<Token> args_tokens_;
   scoped_ptr<ParseNode> args_root_;
 
   DISALLOW_COPY_AND_ASSIGN(Setup);
 };
 
@@ skipping 20 matching lines @@
   void RunPreMessageLoop();
   bool RunPostMessageLoop();
 
   virtual Scheduler* GetScheduler() OVERRIDE;
 
  private:
   Scheduler* scheduler_;
 };
 
 #endif  // TOOLS_GN_SETUP_H_