Fixes for Win toolchain isolate

infra/bots/win_toolchain_utils.py

Index: infra/bots/win_toolchain_utils.py
diff --git a/infra/bots/win_toolchain_utils.py b/infra/bots/win_toolchain_utils.py
new file mode 100644
index 0000000000000000000000000000000000000000..43f62863cde3de8a457830d6339c50bc8bc47e4e
--- /dev/null
+++ b/infra/bots/win_toolchain_utils.py
@@ -0,0 +1,53 @@
+#!/usr/bin/env python
+#
+# Copyright 2016 Google Inc.
+#
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+
+"""Utilities for manipulating the win_toolchain.json file."""
+
+
+import json
+
+
+PLACEHOLDER = '<(TOOLCHAIN_BASE_DIR)'
+
+
+def _replace_prefix(val, before, after):
+  """Replace the given prefix with the given string."""
+  if val.startswith(before):
+    return val.replace(before, after, 1)
+  return val
+
+
+def _replace(val, before, after):
+  """Replace occurrences of one string with another within the data."""
+  if isinstance(val, basestring):
+    return _replace_prefix(val, before, after)
+  elif isinstance(val, (list, tuple)):
+    return [_replace(elem, before, after) for elem in val]
+  elif isinstance(val, dict):
+    return {_replace(k, before, after):
+            _replace(v, before, after) for k, v in val.iteritems()}
+  raise Exception('Cannot replace variable: %s' % val)
+
+
+def _replace_in_file(filename, before, after):
+  """Replace occurrences of one string with another within the file."""
+  with open(filename) as f:
+    contents = json.load(f)
+  new_contents = _replace(contents, before, after)
+  with open(filename, 'w') as f:
+    json.dump(new_contents, f)
+
+
+def abstract(win_toolchain_json, old_path):
+  """Replace absolute paths in win_toolchain.json with placeholders."""
+  _replace_in_file(win_toolchain_json, old_path, PLACEHOLDER)
+
+
+def resolve(win_toolchain_json, new_path):
+  """Replace placeholders in win_toolchain.json with absolute paths."""
+  _replace_in_file(win_toolchain_json, PLACEHOLDER, new_path)