Add support for reading .gypi files.

build/gn_helpers.py

Index: build/gn_helpers.py
diff --git a/build/gn_helpers.py b/build/gn_helpers.py
new file mode 100644
index 0000000000000000000000000000000000000000..04a7612f5bbd2cae0553e21f3bb545bd2ed9af5c
--- /dev/null
+++ b/build/gn_helpers.py
@@ -0,0 +1,47 @@
+# Copyright 2014 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.
+
+"""Helper functions useful when writing scripts that are run from GN's
+exec_script function."""
+import sys

[Dirk Pranke, 2014/04/04 23:01:11]

nit: I don't think you need this import any more.

+
+
+class GNException(Exception):
+  pass
+
+
+def PrintDict(value):
+  """Writes a python dictionary as a GN scope."""

[Dirk Pranke, 2014/04/04 23:01:11]

nit: delete this function (no longer needed)?

+
+
+def ToGNString(value, allow_dicts = True):
+  """Prints the given value to stdout.
+
+  allow_dicts indicates if this function will allow converting dictionaries
+  to GN scopes. This is only possible at the top level, you can't nest a
+  GN scope in a list, so this should be set to False for recursive calls."""
+  if isinstance(value, str):
+    if value.find('\n') >= 0:
+      raise GNException("Trying to print a string with a newline in it.")
+    return '"' + value.replace('"', '\\"') + '"'
+
+  if isinstance(value, list):
+    return '[ %s ]' % ', '.join(ToGNString(v) for v in value)
+
+  if isinstance(value, dict):
+    if not allow_dicts:
+      raise GNException("Attempting to recursively print a dictionary.")
+    result = ""
+    for key in value:
+      if not isinstance(key, str):
+        raise GNException("Dictionary key is not a string.")
+      result += "%s = %s\n" % (key, ToGNString(value[key], False))
+    return result
+
+  if isinstance(value, int):
+    return str(value)
+
+  raise GNException("Unsupported type when printing to GN.")
+
+