Add a compatibility file.

parso/_compatibility.py

@@ -0,0 +1,68 @@
+"""
+To ensure compatibility from Python ``2.6`` - ``3.3``, a module has been
+created. Clearly there is huge need to use conforming syntax.
+"""
+import sys
+
+# Cannot use sys.version.major and minor names, because in Python 2.6 it's not
+# a namedtuple.
+py_version = int(str(sys.version_info[0]) + str(sys.version_info[1]))
+
+# unicode function
+try:
+    unicode = unicode
+except NameError:
+    unicode = str
+
+
+def use_metaclass(meta, *bases):
+    """ Create a class with a metaclass. """
+    if not bases:
+        bases = (object,)
+    return meta("HackClass", bases, {})
+
+
+try:
+    encoding = sys.stdout.encoding
+    if encoding is None:
+        encoding = 'utf-8'
+except AttributeError:
+    encoding = 'ascii'
+
+
+def u(string):
+    """Cast to unicode DAMMIT!
+    Written because Python2 repr always implicitly casts to a string, so we
+    have to cast back to a unicode (and we now that we always deal with valid
+    unicode, because we check that in the beginning).
+    """
+    if py_version >= 30:
+        return str(string)
+
+    if not isinstance(string, unicode):
+        return unicode(str(string), 'UTF-8')
+    return string
+
+
+try:
+    FileNotFoundError = FileNotFoundError
+except NameError:
+    FileNotFoundError = IOError
+
+
+def utf8_repr(func):
+    """
+    ``__repr__`` methods in Python 2 don't allow unicode objects to be
+    returned. Therefore cast them to utf-8 bytes in this decorator.
+    """
+    def wrapper(self):
+        result = func(self)
+        if isinstance(result, unicode):
+            return result.encode('utf-8')
+        else:
+            return result
+
+    if py_version >= 30:
+        return func
+    else:
+        return wrapper