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from __future__ import absolute_import, division, unicode_literals

import sys

from types import ModuleType

from six import text_type

try:

import xml.etree.cElementTree as default_etree

except ImportError:

import xml.etree.ElementTree as default_etree

__all__ = ["default_etree", "MethodDispatcher", "isSurrogatePair",

"surrogatePairToCodepoint", "moduleFactoryFactory",

"supports_lone_surrogates", "PY27"]

PY27 = sys.version_info[0] == 2 and sys.version_info[1] >= 7

# Platforms not supporting lone surrogates (\uD800-\uDFFF) should be

# caught by the below test. In general this would be any platform

# using UTF-16 as its encoding of unicode strings, such as

# Jython. This is because UTF-16 itself is based on the use of such

# surrogates, and there is no mechanism to further escape such

# escapes.

try:

_x = eval('"\\uD800"') # pylint:disable=eval-used

if not isinstance(_x, text_type):

# We need this with u"" because of http://bugs.jython.org/issue2039

_x = eval('u"\\uD800"') # pylint:disable=eval-used

assert isinstance(_x, text_type)

except: # pylint:disable=bare-except

supports_lone_surrogates = False

else:

supports_lone_surrogates = True

class MethodDispatcher(dict):

"""Dict with 2 special properties:

On initiation, keys that are lists, sets or tuples are converted to

multiple keys so accessing any one of the items in the original

list-like object returns the matching value

md = MethodDispatcher({("foo", "bar"):"baz"})

md["foo"] == "baz"

A default value which can be set through the default attribute.

"""

def __init__(self, items=()):

# Using _dictEntries instead of directly assigning to self is about

# twice as fast. Please do careful performance testing before changing

# anything here.

_dictEntries = []

for name, value in items:

if isinstance(name, (list, tuple, frozenset, set)):

for item in name:

_dictEntries.append((item, value))

else:

_dictEntries.append((name, value))

dict.__init__(self, _dictEntries)

assert len(self) == len(_dictEntries)

self.default = None

def __getitem__(self, key):

return dict.get(self, key, self.default)

# Some utility functions to deal with weirdness around UCS2 vs UCS4

# python builds

def isSurrogatePair(data):

return (len(data) == 2 and

ord(data[0]) >= 0xD800 and ord(data[0]) <= 0xDBFF and

ord(data[1]) >= 0xDC00 and ord(data[1]) <= 0xDFFF)

def surrogatePairToCodepoint(data):

char_val = (0x10000 + (ord(data[0]) - 0xD800) * 0x400 +

(ord(data[1]) - 0xDC00))

return char_val

# Module Factory Factory (no, this isn't Java, I know)

# Here to stop this being duplicated all over the place.

def moduleFactoryFactory(factory):

moduleCache = {}

def moduleFactory(baseModule, *args, **kwargs):

if isinstance(ModuleType.__name__, type("")):

name = "_%s_factory" % baseModule.__name__

else:

name = b"_%s_factory" % baseModule.__name__

kwargs_tuple = tuple(kwargs.items())

try:

return moduleCache[name][args][kwargs_tuple]

except KeyError:

mod = ModuleType(name)

objs = factory(baseModule, *args, **kwargs)

mod.__dict__.update(objs)

if "name" not in moduleCache:

moduleCache[name] = {}

if "args" not in moduleCache[name]:

moduleCache[name][args] = {}

if "kwargs" not in moduleCache[name][args]:

moduleCache[name][args][kwargs_tuple] = {}

moduleCache[name][args][kwargs_tuple] = mod

return mod

return moduleFactory

def memoize(func):

cache = {}

def wrapped(*args, **kwargs):

key = (tuple(args), tuple(kwargs.items()))

if key not in cache:

cache[key] = func(*args, **kwargs)

return cache[key]

return wrapped