160 lines
4.8 KiB
Python
160 lines
4.8 KiB
Python
from __future__ import absolute_import, division, unicode_literals
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from types import ModuleType
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try:
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from collections.abc import Mapping
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except ImportError:
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from collections import Mapping
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from six import text_type, PY3
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if PY3:
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import xml.etree.ElementTree as default_etree
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else:
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try:
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import xml.etree.cElementTree as default_etree
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except ImportError:
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import xml.etree.ElementTree as default_etree
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__all__ = ["default_etree", "MethodDispatcher", "isSurrogatePair",
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"surrogatePairToCodepoint", "moduleFactoryFactory",
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"supports_lone_surrogates"]
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# Platforms not supporting lone surrogates (\uD800-\uDFFF) should be
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# caught by the below test. In general this would be any platform
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# using UTF-16 as its encoding of unicode strings, such as
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# Jython. This is because UTF-16 itself is based on the use of such
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# surrogates, and there is no mechanism to further escape such
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# escapes.
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try:
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_x = eval('"\\uD800"') # pylint:disable=eval-used
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if not isinstance(_x, text_type):
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# We need this with u"" because of http://bugs.jython.org/issue2039
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_x = eval('u"\\uD800"') # pylint:disable=eval-used
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assert isinstance(_x, text_type)
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except Exception:
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supports_lone_surrogates = False
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else:
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supports_lone_surrogates = True
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class MethodDispatcher(dict):
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"""Dict with 2 special properties:
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On initiation, keys that are lists, sets or tuples are converted to
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multiple keys so accessing any one of the items in the original
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list-like object returns the matching value
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md = MethodDispatcher({("foo", "bar"):"baz"})
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md["foo"] == "baz"
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A default value which can be set through the default attribute.
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"""
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def __init__(self, items=()):
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_dictEntries = []
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for name, value in items:
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if isinstance(name, (list, tuple, frozenset, set)):
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for item in name:
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_dictEntries.append((item, value))
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else:
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_dictEntries.append((name, value))
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dict.__init__(self, _dictEntries)
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assert len(self) == len(_dictEntries)
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self.default = None
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def __getitem__(self, key):
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return dict.get(self, key, self.default)
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def __get__(self, instance, owner=None):
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return BoundMethodDispatcher(instance, self)
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class BoundMethodDispatcher(Mapping):
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"""Wraps a MethodDispatcher, binding its return values to `instance`"""
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def __init__(self, instance, dispatcher):
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self.instance = instance
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self.dispatcher = dispatcher
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def __getitem__(self, key):
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# see https://docs.python.org/3/reference/datamodel.html#object.__get__
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# on a function, __get__ is used to bind a function to an instance as a bound method
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return self.dispatcher[key].__get__(self.instance)
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def get(self, key, default):
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if key in self.dispatcher:
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return self[key]
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else:
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return default
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def __iter__(self):
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return iter(self.dispatcher)
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def __len__(self):
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return len(self.dispatcher)
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def __contains__(self, key):
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return key in self.dispatcher
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# Some utility functions to deal with weirdness around UCS2 vs UCS4
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# python builds
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def isSurrogatePair(data):
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return (len(data) == 2 and
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ord(data[0]) >= 0xD800 and ord(data[0]) <= 0xDBFF and
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ord(data[1]) >= 0xDC00 and ord(data[1]) <= 0xDFFF)
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def surrogatePairToCodepoint(data):
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char_val = (0x10000 + (ord(data[0]) - 0xD800) * 0x400 +
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(ord(data[1]) - 0xDC00))
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return char_val
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# Module Factory Factory (no, this isn't Java, I know)
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# Here to stop this being duplicated all over the place.
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def moduleFactoryFactory(factory):
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moduleCache = {}
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def moduleFactory(baseModule, *args, **kwargs):
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if isinstance(ModuleType.__name__, type("")):
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name = "_%s_factory" % baseModule.__name__
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else:
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name = b"_%s_factory" % baseModule.__name__
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kwargs_tuple = tuple(kwargs.items())
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try:
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return moduleCache[name][args][kwargs_tuple]
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except KeyError:
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mod = ModuleType(name)
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objs = factory(baseModule, *args, **kwargs)
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mod.__dict__.update(objs)
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if "name" not in moduleCache:
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moduleCache[name] = {}
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if "args" not in moduleCache[name]:
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moduleCache[name][args] = {}
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if "kwargs" not in moduleCache[name][args]:
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moduleCache[name][args][kwargs_tuple] = {}
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moduleCache[name][args][kwargs_tuple] = mod
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return mod
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return moduleFactory
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def memoize(func):
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cache = {}
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def wrapped(*args, **kwargs):
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key = (tuple(args), tuple(kwargs.items()))
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if key not in cache:
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cache[key] = func(*args, **kwargs)
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return cache[key]
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return wrapped
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