482 lines
16 KiB
Python
482 lines
16 KiB
Python
# $Id: io.py 8394 2019-09-18 10:13:17Z milde $
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# Author: David Goodger <goodger@python.org>
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# Copyright: This module has been placed in the public domain.
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"""
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I/O classes provide a uniform API for low-level input and output. Subclasses
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exist for a variety of input/output mechanisms.
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"""
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from __future__ import print_function
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__docformat__ = 'reStructuredText'
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import sys
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import os
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import re
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import codecs
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from docutils import TransformSpec
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from docutils.utils.error_reporting import locale_encoding, ErrorString, ErrorOutput
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if sys.version_info >= (3, 0):
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unicode = str # noqa
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class InputError(IOError): pass
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class OutputError(IOError): pass
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def check_encoding(stream, encoding):
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"""Test, whether the encoding of `stream` matches `encoding`.
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Returns
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:None: if `encoding` or `stream.encoding` are not a valid encoding
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argument (e.g. ``None``) or `stream.encoding is missing.
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:True: if the encoding argument resolves to the same value as `encoding`,
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:False: if the encodings differ.
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"""
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try:
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return codecs.lookup(stream.encoding) == codecs.lookup(encoding)
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except (LookupError, AttributeError, TypeError):
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return None
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class Input(TransformSpec):
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"""
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Abstract base class for input wrappers.
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"""
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component_type = 'input'
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default_source_path = None
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def __init__(self, source=None, source_path=None, encoding=None,
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error_handler='strict'):
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self.encoding = encoding
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"""Text encoding for the input source."""
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self.error_handler = error_handler
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"""Text decoding error handler."""
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self.source = source
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"""The source of input data."""
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self.source_path = source_path
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"""A text reference to the source."""
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if not source_path:
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self.source_path = self.default_source_path
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self.successful_encoding = None
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"""The encoding that successfully decoded the source data."""
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def __repr__(self):
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return '%s: source=%r, source_path=%r' % (self.__class__, self.source,
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self.source_path)
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def read(self):
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raise NotImplementedError
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def decode(self, data):
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"""
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Decode a string, `data`, heuristically.
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Raise UnicodeError if unsuccessful.
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The client application should call ``locale.setlocale`` at the
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beginning of processing::
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locale.setlocale(locale.LC_ALL, '')
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"""
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if self.encoding and self.encoding.lower() == 'unicode':
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assert isinstance(data, unicode), (
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'input encoding is "unicode" '
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'but input is not a unicode object')
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if isinstance(data, unicode):
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# Accept unicode even if self.encoding != 'unicode'.
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return data
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if self.encoding:
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# We believe the user/application when the encoding is
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# explicitly given.
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encodings = [self.encoding]
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else:
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data_encoding = self.determine_encoding_from_data(data)
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if data_encoding:
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# If the data declares its encoding (explicitly or via a BOM),
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# we believe it.
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encodings = [data_encoding]
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else:
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# Apply heuristics only if no encoding is explicitly given and
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# no BOM found. Start with UTF-8, because that only matches
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# data that *IS* UTF-8:
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encodings = ['utf-8', 'latin-1']
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if locale_encoding:
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encodings.insert(1, locale_encoding)
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for enc in encodings:
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try:
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decoded = unicode(data, enc, self.error_handler)
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self.successful_encoding = enc
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# Return decoded, removing BOMs.
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return decoded.replace(u'\ufeff', u'')
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except (UnicodeError, LookupError) as err:
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error = err # in Python 3, the <exception instance> is
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# local to the except clause
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raise UnicodeError(
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'Unable to decode input data. Tried the following encodings: '
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'%s.\n(%s)' % (', '.join([repr(enc) for enc in encodings]),
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ErrorString(error)))
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coding_slug = re.compile(br"coding[:=]\s*([-\w.]+)")
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"""Encoding declaration pattern."""
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byte_order_marks = ((codecs.BOM_UTF8, 'utf-8'),
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(codecs.BOM_UTF16_BE, 'utf-16-be'),
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(codecs.BOM_UTF16_LE, 'utf-16-le'),)
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"""Sequence of (start_bytes, encoding) tuples for encoding detection.
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The first bytes of input data are checked against the start_bytes strings.
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A match indicates the given encoding."""
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def determine_encoding_from_data(self, data):
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"""
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Try to determine the encoding of `data` by looking *in* `data`.
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Check for a byte order mark (BOM) or an encoding declaration.
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"""
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# check for a byte order mark:
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for start_bytes, encoding in self.byte_order_marks:
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if data.startswith(start_bytes):
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return encoding
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# check for an encoding declaration pattern in first 2 lines of file:
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for line in data.splitlines()[:2]:
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match = self.coding_slug.search(line)
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if match:
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return match.group(1).decode('ascii')
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return None
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class Output(TransformSpec):
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"""
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Abstract base class for output wrappers.
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"""
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component_type = 'output'
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default_destination_path = None
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def __init__(self, destination=None, destination_path=None,
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encoding=None, error_handler='strict'):
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self.encoding = encoding
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"""Text encoding for the output destination."""
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self.error_handler = error_handler or 'strict'
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"""Text encoding error handler."""
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self.destination = destination
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"""The destination for output data."""
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self.destination_path = destination_path
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"""A text reference to the destination."""
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if not destination_path:
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self.destination_path = self.default_destination_path
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def __repr__(self):
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return ('%s: destination=%r, destination_path=%r'
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% (self.__class__, self.destination, self.destination_path))
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def write(self, data):
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"""`data` is a Unicode string, to be encoded by `self.encode`."""
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raise NotImplementedError
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def encode(self, data):
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if self.encoding and self.encoding.lower() == 'unicode':
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assert isinstance(data, unicode), (
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'the encoding given is "unicode" but the output is not '
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'a Unicode string')
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return data
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if not isinstance(data, unicode):
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# Non-unicode (e.g. bytes) output.
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return data
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else:
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return data.encode(self.encoding, self.error_handler)
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class FileInput(Input):
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"""
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Input for single, simple file-like objects.
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"""
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def __init__(self, source=None, source_path=None,
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encoding=None, error_handler='strict',
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autoclose=True,
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mode='r' if sys.version_info >= (3, 0) else 'rU'):
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"""
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:Parameters:
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- `source`: either a file-like object (which is read directly), or
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`None` (which implies `sys.stdin` if no `source_path` given).
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- `source_path`: a path to a file, which is opened and then read.
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- `encoding`: the expected text encoding of the input file.
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- `error_handler`: the encoding error handler to use.
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- `autoclose`: close automatically after read (except when
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`sys.stdin` is the source).
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- `mode`: how the file is to be opened (see standard function
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`open`). The default 'rU' provides universal newline support
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for text files with Python 2.x.
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"""
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Input.__init__(self, source, source_path, encoding, error_handler)
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self.autoclose = autoclose
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self._stderr = ErrorOutput()
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if source is None:
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if source_path:
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# Specify encoding in Python 3
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if sys.version_info >= (3, 0):
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kwargs = {'encoding': self.encoding,
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'errors': self.error_handler}
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else:
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kwargs = {}
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try:
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self.source = open(source_path, mode, **kwargs)
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except IOError as error:
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raise InputError(error.errno, error.strerror, source_path)
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else:
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self.source = sys.stdin
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elif (sys.version_info >= (3, 0) and
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check_encoding(self.source, self.encoding) is False):
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# TODO: re-open, warn or raise error?
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raise UnicodeError('Encoding clash: encoding given is "%s" '
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'but source is opened with encoding "%s".' %
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(self.encoding, self.source.encoding))
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if not source_path:
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try:
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self.source_path = self.source.name
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except AttributeError:
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pass
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def read(self):
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"""
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Read and decode a single file and return the data (Unicode string).
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"""
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try:
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if self.source is sys.stdin and sys.version_info >= (3, 0):
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# read as binary data to circumvent auto-decoding
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data = self.source.buffer.read()
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# normalize newlines
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data = b'\n'.join(data.splitlines()) + b'\n'
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else:
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data = self.source.read()
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except (UnicodeError, LookupError) as err: # (in Py3k read() decodes)
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if not self.encoding and self.source_path:
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# re-read in binary mode and decode with heuristics
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b_source = open(self.source_path, 'rb')
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data = b_source.read()
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b_source.close()
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# normalize newlines
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data = b'\n'.join(data.splitlines()) + b'\n'
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else:
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raise
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finally:
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if self.autoclose:
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self.close()
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return self.decode(data)
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def readlines(self):
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"""
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Return lines of a single file as list of Unicode strings.
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"""
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return self.read().splitlines(True)
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def close(self):
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if self.source is not sys.stdin:
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self.source.close()
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class FileOutput(Output):
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"""
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Output for single, simple file-like objects.
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"""
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mode = 'w'
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"""The mode argument for `open()`."""
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# 'wb' for binary (e.g. OpenOffice) files (see also `BinaryFileOutput`).
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# (Do not use binary mode ('wb') for text files, as this prevents the
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# conversion of newlines to the system specific default.)
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def __init__(self, destination=None, destination_path=None,
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encoding=None, error_handler='strict', autoclose=True,
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handle_io_errors=None, mode=None):
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"""
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:Parameters:
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- `destination`: either a file-like object (which is written
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directly) or `None` (which implies `sys.stdout` if no
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`destination_path` given).
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- `destination_path`: a path to a file, which is opened and then
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written.
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- `encoding`: the text encoding of the output file.
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- `error_handler`: the encoding error handler to use.
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- `autoclose`: close automatically after write (except when
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`sys.stdout` or `sys.stderr` is the destination).
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- `handle_io_errors`: ignored, deprecated, will be removed.
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- `mode`: how the file is to be opened (see standard function
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`open`). The default is 'w', providing universal newline
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support for text files.
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"""
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Output.__init__(self, destination, destination_path,
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encoding, error_handler)
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self.opened = True
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self.autoclose = autoclose
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if mode is not None:
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self.mode = mode
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self._stderr = ErrorOutput()
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if destination is None:
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if destination_path:
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self.opened = False
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else:
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self.destination = sys.stdout
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elif (# destination is file-type object -> check mode:
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mode and hasattr(self.destination, 'mode')
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and mode != self.destination.mode):
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print('Warning: Destination mode "%s" differs from specified '
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'mode "%s"' % (self.destination.mode, mode),
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file=self._stderr)
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if not destination_path:
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try:
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self.destination_path = self.destination.name
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except AttributeError:
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pass
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def open(self):
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# Specify encoding in Python 3.
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if sys.version_info >= (3, 0) and 'b' not in self.mode:
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kwargs = {'encoding': self.encoding,
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'errors': self.error_handler}
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else:
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kwargs = {}
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try:
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self.destination = open(self.destination_path, self.mode, **kwargs)
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except IOError as error:
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raise OutputError(error.errno, error.strerror,
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self.destination_path)
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self.opened = True
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def write(self, data):
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"""Encode `data`, write it to a single file, and return it.
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With Python 3 or binary output mode, `data` is returned unchanged,
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except when specified encoding and output encoding differ.
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"""
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if not self.opened:
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self.open()
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if ('b' not in self.mode and sys.version_info < (3, 0)
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or check_encoding(self.destination, self.encoding) is False
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):
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data = self.encode(data)
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if sys.version_info >= (3, 0) and os.linesep != '\n':
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data = data.replace(b'\n', bytes(os.linesep, 'ascii')) # fix endings
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try:
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self.destination.write(data)
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except TypeError as e:
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if sys.version_info >= (3, 0) and isinstance(data, bytes):
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try:
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self.destination.buffer.write(data)
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except AttributeError:
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if check_encoding(self.destination,
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self.encoding) is False:
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raise ValueError('Encoding of %s (%s) differs \n'
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' from specified encoding (%s)' %
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(self.destination_path or 'destination',
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self.destination.encoding, self.encoding))
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else:
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raise e
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except (UnicodeError, LookupError) as err:
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raise UnicodeError(
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'Unable to encode output data. output-encoding is: '
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'%s.\n(%s)' % (self.encoding, ErrorString(err)))
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finally:
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if self.autoclose:
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self.close()
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return data
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def close(self):
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if self.destination not in (sys.stdout, sys.stderr):
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self.destination.close()
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self.opened = False
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class BinaryFileOutput(FileOutput):
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"""
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A version of docutils.io.FileOutput which writes to a binary file.
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"""
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# Used by core.publish_cmdline_to_binary() which in turn is used by
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# rst2odt (OpenOffice writer)
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mode = 'wb'
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class StringInput(Input):
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"""
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Direct string input.
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"""
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default_source_path = '<string>'
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def read(self):
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"""Decode and return the source string."""
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return self.decode(self.source)
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class StringOutput(Output):
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"""
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Direct string output.
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"""
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default_destination_path = '<string>'
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def write(self, data):
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"""Encode `data`, store it in `self.destination`, and return it."""
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self.destination = self.encode(data)
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return self.destination
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class NullInput(Input):
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"""
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Degenerate input: read nothing.
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"""
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default_source_path = 'null input'
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def read(self):
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"""Return a null string."""
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return u''
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class NullOutput(Output):
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"""
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Degenerate output: write nothing.
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"""
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default_destination_path = 'null output'
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def write(self, data):
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"""Do nothing ([don't even] send data to the bit bucket)."""
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pass
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class DocTreeInput(Input):
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"""
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Adapter for document tree input.
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The document tree must be passed in the ``source`` parameter.
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"""
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default_source_path = 'doctree input'
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def read(self):
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"""Return the document tree."""
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return self.source
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