638 lines
22 KiB
Python
638 lines
22 KiB
Python
# $Id: io.py 9427 2023-07-07 06:50:09Z 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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__docformat__ = 'reStructuredText'
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import codecs
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import locale
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import os
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import re
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import sys
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import warnings
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from docutils import TransformSpec
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# Guess the locale's preferred encoding.
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# If no valid guess can be made, _locale_encoding is set to `None`:
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#
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# TODO: check whether this is set correctly with every OS and Python version
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# or whether front-end tools need to call `locale.setlocale()`
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# before importing this module
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try:
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# Return locale encoding also in UTF-8 mode
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with warnings.catch_warnings():
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warnings.simplefilter("ignore")
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_locale_encoding = (locale.getlocale()[1]
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or locale.getdefaultlocale()[1])
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_locale_encoding = _locale_encoding.lower()
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except: # noqa any other problems determining the locale -> use None
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_locale_encoding = None
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try:
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codecs.lookup(_locale_encoding)
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except (LookupError, TypeError):
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_locale_encoding = None
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class InputError(OSError): pass
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class OutputError(OSError): 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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def error_string(err):
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"""Return string representation of Exception `err`.
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"""
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return f'{err.__class__.__name__}: {err}'
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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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Docutils input objects must provide a `read()` method that
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returns the source, typically as `str` instance.
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Inheriting `TransformSpec` allows input objects to add
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"transforms" and "unknown_reference_resolvers" to the "Transformer".
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(Optional for custom input objects since Docutils 0.19.)
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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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"""Return input as `str`. Define in subclasses."""
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raise NotImplementedError
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def decode(self, data):
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"""
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Decode `data` if required.
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Return Unicode `str` instances unchanged (nothing to decode).
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If `self.encoding` is None, determine encoding from data
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or try UTF-8 and the locale's preferred encoding.
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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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Raise UnicodeError if unsuccessful.
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Provisional: encoding detection will be removed in Docutils 1.0.
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"""
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if self.encoding and self.encoding.lower() == 'unicode':
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assert isinstance(data, str), ('input encoding is "unicode" '
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'but `data` is no `str` instance')
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if isinstance(data, str):
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# nothing to decode
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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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encoding_candidates = [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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# `data` declares its encoding with "magic comment" or BOM,
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encoding_candidates = [data_encoding]
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else:
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# Apply heuristics if the encoding is not specified.
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# Start with UTF-8, because that only matches
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# data that *IS* UTF-8:
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encoding_candidates = ['utf-8']
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# If UTF-8 fails, fall back to the locale's preferred encoding:
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fallback = locale.getpreferredencoding(do_setlocale=False)
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if fallback and fallback.lower() != 'utf-8':
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encoding_candidates.append(fallback)
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for enc in encoding_candidates:
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try:
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decoded = str(data, enc, self.error_handler)
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self.successful_encoding = enc
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return decoded
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except (UnicodeError, LookupError) as err:
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# keep exception instance for use outside of the "for" loop.
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error = err
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raise UnicodeError(
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'Unable to decode input data. Tried the following encodings: '
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f'{", ".join(repr(enc) for enc in encoding_candidates)}.\n'
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f'({error_string(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_UTF32_BE, 'utf-32'),
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(codecs.BOM_UTF32_LE, 'utf-32'),
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(codecs.BOM_UTF8, 'utf-8-sig'),
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(codecs.BOM_UTF16_BE, 'utf-16'),
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(codecs.BOM_UTF16_LE, 'utf-16'),
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)
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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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def isatty(self):
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"""Return True, if the input source is connected to a TTY device."""
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try:
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return self.source.isatty()
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except AttributeError:
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return False
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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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Docutils output objects must provide a `write()` method that
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expects and handles one argument (the output).
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Inheriting `TransformSpec` allows output objects to add
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"transforms" and "unknown_reference_resolvers" to the "Transformer".
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(Optional for custom output objects since Docutils 0.19.)
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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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"""Write `data`. Define in subclasses."""
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raise NotImplementedError
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def encode(self, data):
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"""
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Encode and return `data`.
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If `data` is a `bytes` instance, it is returned unchanged.
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Otherwise it is encoded with `self.encoding`.
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Provisional: If `self.encoding` is set to the pseudo encoding name
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"unicode", `data` must be a `str` instance and is returned unchanged.
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"""
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if self.encoding and self.encoding.lower() == 'unicode':
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assert isinstance(data, str), ('output encoding is "unicode" '
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'but `data` is no `str` instance')
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return data
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if not isinstance(data, str):
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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 ErrorOutput:
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"""
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Wrapper class for file-like error streams with
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failsafe de- and encoding of `str`, `bytes`, `unicode` and
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`Exception` instances.
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"""
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def __init__(self, destination=None, encoding=None,
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encoding_errors='backslashreplace',
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decoding_errors='replace'):
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"""
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:Parameters:
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- `destination`: a file-like object,
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a string (path to a file),
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`None` (write to `sys.stderr`, default), or
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evaluating to `False` (write() requests are ignored).
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- `encoding`: `destination` text encoding. Guessed if None.
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- `encoding_errors`: how to treat encoding errors.
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"""
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if destination is None:
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destination = sys.stderr
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elif not destination:
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destination = False
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# if `destination` is a file name, open it
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elif isinstance(destination, str):
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destination = open(destination, 'w')
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self.destination = destination
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"""Where warning output is sent."""
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self.encoding = (encoding or getattr(destination, 'encoding', None)
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or _locale_encoding or 'ascii')
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"""The output character encoding."""
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self.encoding_errors = encoding_errors
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"""Encoding error handler."""
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self.decoding_errors = decoding_errors
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"""Decoding error handler."""
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def write(self, data):
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"""
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Write `data` to self.destination. Ignore, if self.destination is False.
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`data` can be a `bytes`, `str`, or `Exception` instance.
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"""
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if not self.destination:
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return
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if isinstance(data, Exception):
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data = str(data)
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try:
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self.destination.write(data)
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except UnicodeEncodeError:
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self.destination.write(data.encode(self.encoding,
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self.encoding_errors))
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except TypeError:
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if isinstance(data, str): # destination may expect bytes
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self.destination.write(data.encode(self.encoding,
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self.encoding_errors))
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elif self.destination in (sys.stderr, sys.stdout):
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# write bytes to raw stream
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self.destination.buffer.write(data)
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else:
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self.destination.write(str(data, self.encoding,
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self.decoding_errors))
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def close(self):
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"""
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Close the error-output stream.
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Ignored if the destination is` sys.stderr` or `sys.stdout` or has no
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close() method.
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"""
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if self.destination in (sys.stdout, sys.stderr):
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return
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try:
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self.destination.close()
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except AttributeError:
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pass
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def isatty(self):
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"""Return True, if the destination is connected to a TTY device."""
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try:
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return self.destination.isatty()
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except AttributeError:
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return False
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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, mode='r'):
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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 for reading.
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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 is read only ('r').
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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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try:
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self.source = open(source_path, mode,
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encoding=self.encoding,
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errors=self.error_handler)
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except OSError 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 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, return as `str`.
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"""
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try:
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if not self.encoding and hasattr(self.source, 'buffer'):
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# read as binary data
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data = self.source.buffer.read()
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# decode with heuristics
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data = self.decode(data)
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# normalize newlines
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data = '\n'.join(data.splitlines()+[''])
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else:
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data = self.source.read()
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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 readlines(self):
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"""
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Return lines of a single file as list of 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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"""Output for single, simple file-like objects."""
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default_destination_path = '<file>'
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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 handle_io_errors is not None:
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warnings.warn('io.FileOutput: init argument "handle_io_errors" '
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'is ignored and will be removed in '
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'Docutils 2.0.', DeprecationWarning, stacklevel=2)
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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
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if '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 OSError 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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"""Write `data` to a single file, also return it.
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`data` can be a `str` or `bytes` instance.
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If writing `bytes` fails, an attempt is made to write to
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the low-level interface ``self.destination.buffer``.
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If `data` is a `str` instance and `self.encoding` and
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`self.destination.encoding` are set to different values, `data`
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is encoded to a `bytes` instance using `self.encoding`.
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Provisional: future versions may raise an error if `self.encoding`
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and `self.destination.encoding` are set to different values.
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"""
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if not self.opened:
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self.open()
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if (isinstance(data, str)
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and check_encoding(self.destination, self.encoding) is False):
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if os.linesep != '\n':
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data = data.replace('\n', os.linesep) # fix endings
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data = self.encode(data)
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try:
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self.destination.write(data)
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except TypeError as err:
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if 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(
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f'Encoding of {self.destination_path} '
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f'({self.destination.encoding}) differs \n'
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f' from specified encoding ({self.encoding})')
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else:
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raise err
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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: '
|
|
f'{self.encoding}.\n({error_string(err)})')
|
|
finally:
|
|
if self.autoclose:
|
|
self.close()
|
|
return data
|
|
|
|
def close(self):
|
|
if self.destination not in (sys.stdout, sys.stderr):
|
|
self.destination.close()
|
|
self.opened = False
|
|
|
|
|
|
class BinaryFileOutput(FileOutput):
|
|
"""
|
|
A version of docutils.io.FileOutput which writes to a binary file.
|
|
"""
|
|
# Used by core.publish_cmdline_to_binary() which in turn is used by
|
|
# tools/rst2odt.py but not by core.rst2odt().
|
|
mode = 'wb'
|
|
|
|
|
|
class StringInput(Input):
|
|
"""Input from a `str` or `bytes` instance."""
|
|
|
|
default_source_path = '<string>'
|
|
|
|
def read(self):
|
|
"""Return the source as `str` instance.
|
|
|
|
Decode, if required (see `Input.decode`).
|
|
"""
|
|
return self.decode(self.source)
|
|
|
|
|
|
class StringOutput(Output):
|
|
"""Output to a `bytes` or `str` instance.
|
|
|
|
Provisional.
|
|
"""
|
|
|
|
default_destination_path = '<string>'
|
|
|
|
def write(self, data):
|
|
"""Store `data` in `self.destination`, and return it.
|
|
|
|
If `self.encoding` is set to the pseudo encoding name "unicode",
|
|
`data` must be a `str` instance and is stored/returned unchanged
|
|
(cf. `Output.encode`).
|
|
|
|
Otherwise, `data` can be a `bytes` or `str` instance and is
|
|
stored/returned as a `bytes` instance
|
|
(`str` data is encoded with `self.encode()`).
|
|
|
|
Attention: the `output_encoding`_ setting may affect the content
|
|
of the output (e.g. an encoding declaration in HTML or XML or the
|
|
representation of characters as LaTeX macro vs. literal character).
|
|
"""
|
|
self.destination = self.encode(data)
|
|
return self.destination
|
|
|
|
|
|
class NullInput(Input):
|
|
|
|
"""Degenerate input: read nothing."""
|
|
|
|
default_source_path = 'null input'
|
|
|
|
def read(self):
|
|
"""Return an empty string."""
|
|
return ''
|
|
|
|
|
|
class NullOutput(Output):
|
|
|
|
"""Degenerate output: write nothing."""
|
|
|
|
default_destination_path = 'null output'
|
|
|
|
def write(self, data):
|
|
"""Do nothing, return None."""
|
|
pass
|
|
|
|
|
|
class DocTreeInput(Input):
|
|
|
|
"""
|
|
Adapter for document tree input.
|
|
|
|
The document tree must be passed in the ``source`` parameter.
|
|
"""
|
|
|
|
default_source_path = 'doctree input'
|
|
|
|
def read(self):
|
|
"""Return the document tree."""
|
|
return self.source
|