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105 lines
3.3 KiB
Python
105 lines
3.3 KiB
Python
"""
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Tools to open .py files as Unicode, using the encoding specified within the file,
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as per PEP 263.
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Much of the code is taken from the tokenize module in Python 3.2.
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"""
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import io
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from io import TextIOWrapper, BytesIO
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from pathlib import Path
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import re
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from tokenize import open, detect_encoding
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cookie_re = re.compile(r"coding[:=]\s*([-\w.]+)", re.UNICODE)
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cookie_comment_re = re.compile(r"^\s*#.*coding[:=]\s*([-\w.]+)", re.UNICODE)
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def source_to_unicode(txt, errors='replace', skip_encoding_cookie=True):
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"""Converts a bytes string with python source code to unicode.
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Unicode strings are passed through unchanged. Byte strings are checked
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for the python source file encoding cookie to determine encoding.
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txt can be either a bytes buffer or a string containing the source
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code.
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"""
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if isinstance(txt, str):
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return txt
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if isinstance(txt, bytes):
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buffer = BytesIO(txt)
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else:
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buffer = txt
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try:
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encoding, _ = detect_encoding(buffer.readline)
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except SyntaxError:
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encoding = "ascii"
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buffer.seek(0)
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with TextIOWrapper(buffer, encoding, errors=errors, line_buffering=True) as text:
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text.mode = 'r'
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if skip_encoding_cookie:
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return u"".join(strip_encoding_cookie(text))
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else:
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return text.read()
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def strip_encoding_cookie(filelike):
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"""Generator to pull lines from a text-mode file, skipping the encoding
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cookie if it is found in the first two lines.
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"""
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it = iter(filelike)
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try:
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first = next(it)
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if not cookie_comment_re.match(first):
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yield first
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second = next(it)
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if not cookie_comment_re.match(second):
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yield second
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except StopIteration:
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return
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yield from it
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def read_py_file(filename, skip_encoding_cookie=True):
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"""Read a Python file, using the encoding declared inside the file.
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Parameters
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----------
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filename : str
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The path to the file to read.
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skip_encoding_cookie : bool
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If True (the default), and the encoding declaration is found in the first
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two lines, that line will be excluded from the output.
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Returns
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-------
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A unicode string containing the contents of the file.
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"""
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filepath = Path(filename)
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with open(filepath) as f: # the open function defined in this module.
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if skip_encoding_cookie:
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return "".join(strip_encoding_cookie(f))
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else:
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return f.read()
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def read_py_url(url, errors='replace', skip_encoding_cookie=True):
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"""Read a Python file from a URL, using the encoding declared inside the file.
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Parameters
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----------
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url : str
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The URL from which to fetch the file.
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errors : str
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How to handle decoding errors in the file. Options are the same as for
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bytes.decode(), but here 'replace' is the default.
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skip_encoding_cookie : bool
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If True (the default), and the encoding declaration is found in the first
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two lines, that line will be excluded from the output.
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Returns
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-------
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A unicode string containing the contents of the file.
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"""
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# Deferred import for faster start
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from urllib.request import urlopen
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response = urlopen(url)
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buffer = io.BytesIO(response.read())
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return source_to_unicode(buffer, errors, skip_encoding_cookie)
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