Add infra_libs as a bootstrap dependency.

infra_libs/infra_types/infra_types.py

-# 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.
-
-import collections
-import operator
-
-
-def freeze(obj):
-  """Takes a generic object ``obj``, and returns an immutable version of it.
-
-  Supported types:
-    * dict / OrderedDict -> FrozenDict
-    * list -> tuple
-    * set -> frozenset
-    * any object with a working __hash__ implementation (assumes that hashable
-      means immutable)
-
-  Will raise TypeError if you pass an object which is not hashable.
-  """
-  if isinstance(obj, dict):
-    return FrozenDict((freeze(k), freeze(v)) for k, v in obj.iteritems())
-  elif isinstance(obj, (list, tuple)):
-    return tuple(freeze(i) for i in obj)
-  elif isinstance(obj, set):
-    return frozenset(freeze(i) for i in obj)
-  else:
-    hash(obj)
-    return obj
-
-
-def thaw(obj):
-  """Takes an object from freeze() and returns a mutable copy of it."""
-  if isinstance(obj, FrozenDict):
-    return collections.OrderedDict(
-        (thaw(k), thaw(v)) for k, v in obj.iteritems())
-  elif isinstance(obj, tuple):
-    return list(thaw(i) for i in obj)
-  elif isinstance(obj, frozenset):
-    return set(thaw(i) for i in obj)
-  else:
-    return obj
-
-
-class FrozenDict(collections.Mapping):
-  """An immutable OrderedDict.
-
-  Modified From: http://stackoverflow.com/a/2704866
-  """
-  def __init__(self, *args, **kwargs):
-    self._d = collections.OrderedDict(*args, **kwargs)
-
-    # Calculate the hash immediately so that we know all the items are
-    # hashable too.
-    self._hash = reduce(operator.xor,
-                        (hash(i) for i in enumerate(self._d.iteritems())), 0)
-
-  def __eq__(self, other):
-    if not isinstance(other, collections.Mapping):
-      return NotImplemented
-    if self is other:
-      return True
-    if len(self) != len(other):
-      return False
-    for k, v in self.iteritems():
-      if k not in other or other[k] != v:
-        return False
-    return True
-
-  def __iter__(self):
-    return iter(self._d)
-
-  def __len__(self):
-    return len(self._d)
-
-  def __getitem__(self, key):
-    return self._d[key]
-
-  def __hash__(self):
-    return self._hash
-
-  def __repr__(self):
-    return 'FrozenDict(%r)' % (self._d.items(),)