mirror of
https://github.com/janeczku/calibre-web
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120 lines
3.5 KiB
Python
120 lines
3.5 KiB
Python
""":mod:`wand.compat` --- Compatibility layer
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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This module provides several subtle things to support
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multiple Python versions (2.6, 2.7, 3.2--3.5) and VM implementations
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(CPython, PyPy).
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"""
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import contextlib
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import io
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import sys
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import types
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__all__ = ('PY3', 'binary', 'binary_type', 'encode_filename', 'file_types',
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'nested', 'string_type', 'text', 'text_type', 'xrange')
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#: (:class:`bool`) Whether it is Python 3.x or not.
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PY3 = sys.version_info >= (3,)
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#: (:class:`type`) Type for representing binary data. :class:`str` in Python 2
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#: and :class:`bytes` in Python 3.
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binary_type = bytes if PY3 else str
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#: (:class:`type`) Type for text data. :class:`basestring` in Python 2
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#: and :class:`str` in Python 3.
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string_type = str if PY3 else basestring # noqa
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#: (:class:`type`) Type for representing Unicode textual data.
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#: :class:`unicode` in Python 2 and :class:`str` in Python 3.
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text_type = str if PY3 else unicode # noqa
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def binary(string, var=None):
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"""Makes ``string`` to :class:`str` in Python 2.
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Makes ``string`` to :class:`bytes` in Python 3.
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:param string: a string to cast it to :data:`binary_type`
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:type string: :class:`bytes`, :class:`str`, :class:`unicode`
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:param var: an optional variable name to be used for error message
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:type var: :class:`str`
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"""
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if isinstance(string, text_type):
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return string.encode()
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elif isinstance(string, binary_type):
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return string
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if var:
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raise TypeError('{0} must be a string, not {1!r}'.format(var, string))
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raise TypeError('expected a string, not ' + repr(string))
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if PY3:
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def text(string):
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if isinstance(string, bytes):
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return string.decode('utf-8')
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return string
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else:
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def text(string):
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"""Makes ``string`` to :class:`str` in Python 3.
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Does nothing in Python 2.
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:param string: a string to cast it to :data:`text_type`
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:type string: :class:`bytes`, :class:`str`, :class:`unicode`
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"""
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return string
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#: The :func:`xrange()` function. Alias for :func:`range()` in Python 3.
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xrange = range if PY3 else xrange # noqa
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#: (:class:`type`, :class:`tuple`) Types for file objects that have
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#: ``fileno()``.
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file_types = io.RawIOBase if PY3 else (io.RawIOBase, types.FileType)
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def encode_filename(filename):
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"""If ``filename`` is a :data:`text_type`, encode it to
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:data:`binary_type` according to filesystem's default encoding.
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"""
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if isinstance(filename, text_type):
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return filename.encode(sys.getfilesystemencoding())
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return filename
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try:
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nested = contextlib.nested
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except AttributeError:
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# http://hg.python.org/cpython/file/v2.7.6/Lib/contextlib.py#l88
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@contextlib.contextmanager
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def nested(*managers):
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exits = []
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vars = []
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exc = (None, None, None)
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try:
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for mgr in managers:
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exit = mgr.__exit__
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enter = mgr.__enter__
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vars.append(enter())
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exits.append(exit)
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yield vars
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except:
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exc = sys.exc_info()
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finally:
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while exits:
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exit = exits.pop()
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try:
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if exit(*exc):
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exc = (None, None, None)
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except:
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exc = sys.exc_info()
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if exc != (None, None, None):
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# PEP 3109
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e = exc[0](exc[1])
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e.__traceback__ = e[2]
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raise e
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