Add support for reading .gypi files.

tools/gn/input_file_manager.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_INPUT_FILE_MANAGER_H_
 #define TOOLS_GN_INPUT_FILE_MANAGER_H_
 
 #include <set>
 #include <utility>
 #include <vector>
@@ skipping 46 matching lines @@
                      Err* err);
 
   // Loads and parses the given file synchronously, returning the root block
   // corresponding to the parsed result. On error, return NULL and the given
   // Err is set.
   const ParseNode* SyncLoadFile(const LocationRange& origin,
                                 const BuildSettings* build_settings,
                                 const SourceFile& file_name,
                                 Err* err);
 
+  // Creates an entry to manage the memory associated with keeping a parsed
+  // set of code in memory.
+  //
+  // The values pointed to by the parameters will be filled with pointers to
+  // the file, tokens, and parse node that this class created. The calling
+  // code is responsible for populating these values and maintaining
+  // threadsafety. This class' only job is to hold onto the memory and delete
+  // it when the program exits.
+  //
+  // This solves the problem that sometimes we need to execute something
+  // dynamic and save the result, but the values all have references to the
+  // nodes and file that created it. Either we need to reset the origin of
+  // the values and lose context for error reporting, or somehow keep the
+  // associated parse nodes, tokens, and file data in memory. This function
+  // allows the latter.
+  void AddDynamicInput(InputFile** file,
+                       std::vector<Token>** tokens,
+                       scoped_ptr<ParseNode>** parse_root);
+
+  // Does not count dynamic input.
   int GetInputFileCount() const;
 
   // Fills the vector with all input files.
   void GetAllPhysicalInputFileNames(std::vector<base::FilePath>* result) const;
 
  private:
   friend class base::RefCountedThreadSafe<InputFileManager>;
 
   struct InputFileData {
     InputFileData(const SourceFile& file_name);
@@ skipping 34 matching lines @@
                 const SourceFile& name,
                 InputFile* file,
                 Err* err);
 
   mutable base::Lock lock_;
 
   // Maps repo-relative filenames to the corresponding owned pointer.
   typedef base::hash_map<SourceFile, InputFileData*> InputFileMap;
   InputFileMap input_files_;
 
+  // Tracks all dynamic inputs. The data are holders for memory management
+  // purposes and should not be read or modified by this class. The values
+  // will be vended out to the code creating the dynamic input, who is in
+  // charge of the threadsafety requirements.
+  //
+  // See AddDynamicInput().
+  //
+  // Owning pointers.
+  std::vector<InputFileData*> dynamic_inputs_;
+
   DISALLOW_COPY_AND_ASSIGN(InputFileManager);
 };
 
 #endif  // TOOLS_GN_INPUT_FILE_MANAGER_H_