copy _compat.py from flask in here (and adapt docstring)

flask/_compat.py

@@ -3,11 +3,107 @@
     flask._compat
     ~~~~~~~~~~~~~
 
-    Some py2/py3 compatibility support that is not yet available in
-    "six" 1.3.0.
-    There are bugs open for "six" for all this stuff, so we can remove it
-    again from here as soon as we require a new enough "six" release.
+    Some py2/py3 compatibility support based on a stripped down
+    version of six so we don't have to depend on a specific version
+    of it.
 
     :copyright: (c) 2013 by Armin Ronacher.
     :license: BSD, see LICENSE for more details.
 """
+import sys
+
+PY2 = sys.version_info[0] == 2
+PYPY = hasattr(sys, 'pypy_translation_info')
+_identity = lambda x: x
+
+
+if not PY2:
+    unichr = chr
+    range_type = range
+    text_type = str
+    string_types = (str,)
+
+    iterkeys = lambda d: iter(d.keys())
+    itervalues = lambda d: iter(d.values())
+    iteritems = lambda d: iter(d.items())
+
+    import pickle
+    from io import BytesIO, StringIO
+    NativeStringIO = StringIO
+
+    def reraise(tp, value, tb=None):
+        if value.__traceback__ is not tb:
+            raise value.with_traceback(tb)
+        raise value
+
+    ifilter = filter
+    imap = map
+    izip = zip
+    intern = sys.intern
+
+    implements_iterator = _identity
+    implements_to_string = _identity
+    encode_filename = _identity
+    get_next = lambda x: x.__next__
+
+else:
+    unichr = unichr
+    text_type = unicode
+    range_type = xrange
+    string_types = (str, unicode)
+
+    iterkeys = lambda d: d.iterkeys()
+    itervalues = lambda d: d.itervalues()
+    iteritems = lambda d: d.iteritems()
+
+    import cPickle as pickle
+    from cStringIO import StringIO as BytesIO, StringIO
+    NativeStringIO = BytesIO
+
+    exec('def reraise(tp, value, tb=None):\n raise tp, value, tb')
+
+    from itertools import imap, izip, ifilter
+    intern = intern
+
+    def implements_iterator(cls):
+        cls.next = cls.__next__
+        del cls.__next__
+        return cls
+
+    def implements_to_string(cls):
+        cls.__unicode__ = cls.__str__
+        cls.__str__ = lambda x: x.__unicode__().encode('utf-8')
+        return cls
+
+    get_next = lambda x: x.next
+
+    def encode_filename(filename):
+        if isinstance(filename, unicode):
+            return filename.encode('utf-8')
+        return filename
+
+
+def with_metaclass(meta, *bases):
+    # This requires a bit of explanation: the basic idea is to make a
+    # dummy metaclass for one level of class instanciation that replaces
+    # itself with the actual metaclass.  Because of internal type checks
+    # we also need to make sure that we downgrade the custom metaclass
+    # for one level to something closer to type (that's why __call__ and
+    # __init__ comes back from type etc.).
+    #
+    # This has the advantage over six.with_metaclass in that it does not
+    # introduce dummy classes into the final MRO.
+    class metaclass(meta):
+        __call__ = type.__call__
+        __init__ = type.__init__
+        def __new__(cls, name, this_bases, d):
+            if this_bases is None:
+                return type.__new__(cls, name, (), d)
+            return meta(name, bases, d)
+    return metaclass('temporary_class', None, {})
+
+
+try:
+    from urllib.parse import quote_from_bytes as url_quote
+except ImportError:
+    from urllib import quote as url_quote