Initial source commit to grit-i18n project.

grit/extern/FP.py

+#!/usr/bin/python
+# Copyright (c) 2006-2008 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.
+
+try:
+  import hashlib
+  _new_md5 = hashlib.md5
+except ImportError:
+  import md5
+  _new_md5 = md5.new
+
+"""64-bit fingerprint support for strings.
+
+Usage:
+    from extern import FP
+    print 'Fingerprint is %ld' % FP.FingerPrint('Hello world!')
+"""
+
+
+def UnsignedFingerPrint(str, encoding='utf-8'):
+  """Generate a 64-bit fingerprint by taking the first half of the md5
+  of the string."""
+  hex128 = _new_md5(str).hexdigest()
+  int64 = long(hex128[:16], 16)
+  return int64
+
+def FingerPrint(str, encoding='utf-8'):
+  fp = UnsignedFingerPrint(str, encoding=encoding)
+  # interpret fingerprint as signed longs
+  if fp & 0x8000000000000000L:
+    fp = - ((~fp & 0xFFFFFFFFFFFFFFFFL) + 1)
+  return fp
+