[gn] Consolidate exec_script calls to speed up generation

tools/process_gypis.py

+#!/usr/bin/env python
+# Copyright 2016, the Dart project authors.  Please see the AUTHORS file
+# for details. All rights reserved. Use of this source code is governed by a
+# BSD-style license that can be found in the LICENSE file.
+
+import gn_helpers
+import os.path
+import sys
+
+# Given a list of dart package names read in the set of runtime and sdk library
+# sources into variables in a gn scope.
+
+
+def LoadPythonDictionary(path):
+  file_string = open(path).read()
+  try:
+    file_data = eval(file_string, {'__builtins__': None}, None)
+  except SyntaxError, e:
+    e.filename = path
+    raise
+  except Exception, e:
+    raise Exception('Unexpected error while reading %s: %s' %
+                    (path, str(e)))
+
+  assert isinstance(
+    file_data, dict), '%s does not eval to a dictionary' % path
+  return file_data
+
+
+def main():
+  dart_root_dir = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
+  runtime_dir = os.path.join(dart_root_dir, 'runtime')
+  runtime_lib_dir = os.path.join(runtime_dir, 'lib')
+  sdk_lib_dir = os.path.join(dart_root_dir, 'sdk', 'lib')
+  libs = sys.argv[1:]
+  data = {}
+  data['allsources'] = []
+
+  for lib in libs:
+    runtime_path = os.path.join(runtime_lib_dir, lib + '_sources.gypi')
+    sdk_path = os.path.join(sdk_lib_dir, lib, lib + '_sources.gypi')
+    runtime_dict = LoadPythonDictionary(runtime_path)
+    for source in runtime_dict['sources']:
+      data['allsources'].append(source)
+    data[lib + '_runtime_sources'] = runtime_dict['sources']
+    sdk_dict = LoadPythonDictionary(sdk_path)
+    data[lib + '_sdk_sources'] = sdk_dict['sources']
+
+  vm_sources_path = os.path.join(runtime_dir, 'vm', 'vm_sources.gypi')
+  vm_sources_dict = LoadPythonDictionary(vm_sources_path)
+  data['vm_sources'] = vm_sources_dict['sources']
+
+  platform_sources_base = os.path.join(runtime_dir, 'platform', 'platform_')
+  platform_headers_dict = LoadPythonDictionary(
+      platform_sources_base + 'headers.gypi')
+  platform_sources_dict = LoadPythonDictionary(
+      platform_sources_base + 'sources.gypi')
+  data['platform_sources'] = platform_headers_dict[
+      'sources'] + platform_sources_dict['sources']
+
+  bin_io_sources_path = os.path.join(runtime_dir, 'bin', 'io_sources.gypi')
+  bin_io_sources_dict = LoadPythonDictionary(bin_io_sources_path)
+  data['bin_io_sources'] = bin_io_sources_dict['sources']
+
+  print gn_helpers.ToGNString(data)
+  return 0
+
+if __name__ == '__main__':
+  sys.exit(main())