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#!/usr/bin/env python3
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#
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# byteify-strings.py - transform string literals to be Python 3 safe
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#
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# Copyright 2015 Gregory Szorc <gregory.szorc@gmail.com>
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#
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# This software may be used and distributed according to the terms of the
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# GNU General Public License version 2 or any later version.
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from __future__ import absolute_import, print_function
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import argparse
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import contextlib
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import errno
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import os
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import sys
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import tempfile
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import token
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import tokenize
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def adjusttokenpos(t, ofs):
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"""Adjust start/end column of the given token"""
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return t._replace(start=(t.start[0], t.start[1] + ofs),
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end=(t.end[0], t.end[1] + ofs))
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def replacetokens(tokens, opts):
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"""Transform a stream of tokens from raw to Python 3.
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Returns a generator of possibly rewritten tokens.
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The input token list may be mutated as part of processing. However,
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its changes do not necessarily match the output token stream.
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"""
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sysstrtokens = set()
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# The following utility functions access the tokens list and i index of
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# the for i, t enumerate(tokens) loop below
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def _isop(j, *o):
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"""Assert that tokens[j] is an OP with one of the given values"""
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try:
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return tokens[j].type == token.OP and tokens[j].string in o
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except IndexError:
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return False
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def _findargnofcall(n):
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"""Find arg n of a call expression (start at 0)
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Returns index of the first token of that argument, or None if
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there is not that many arguments.
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Assumes that token[i + 1] is '('.
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"""
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nested = 0
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for j in range(i + 2, len(tokens)):
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if _isop(j, ')', ']', '}'):
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# end of call, tuple, subscription or dict / set
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nested -= 1
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if nested < 0:
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return None
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elif n == 0:
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# this is the starting position of arg
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return j
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elif _isop(j, '(', '[', '{'):
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nested += 1
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elif _isop(j, ',') and nested == 0:
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n -= 1
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return None
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def _ensuresysstr(j):
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"""Make sure the token at j is a system string
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Remember the given token so the string transformer won't add
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the byte prefix.
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Ignores tokens that are not strings. Assumes bounds checking has
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already been done.
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"""
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k = j
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currtoken = tokens[k]
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while currtoken.type in (token.STRING, token.NEWLINE, tokenize.NL):
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k += 1
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if (
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currtoken.type == token.STRING
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and currtoken.string.startswith(("'", '"'))
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):
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sysstrtokens.add(currtoken)
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try:
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currtoken = tokens[k]
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except IndexError:
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break
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def _isitemaccess(j):
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"""Assert the next tokens form an item access on `tokens[j]` and that
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`tokens[j]` is a name.
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"""
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try:
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return (
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tokens[j].type == token.NAME
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and _isop(j + 1, '[')
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and tokens[j + 2].type == token.STRING
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and _isop(j + 3, ']')
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)
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except IndexError:
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return False
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def _ismethodcall(j, *methodnames):
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"""Assert the next tokens form a call to `methodname` with a string
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as first argument on `tokens[j]` and that `tokens[j]` is a name.
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"""
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try:
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return (
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tokens[j].type == token.NAME
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and _isop(j + 1, '.')
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and tokens[j + 2].type == token.NAME
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and tokens[j + 2].string in methodnames
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and _isop(j + 3, '(')
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and tokens[j + 4].type == token.STRING
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)
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except IndexError:
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return False
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coldelta = 0 # column increment for new opening parens
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coloffset = -1 # column offset for the current line (-1: TBD)
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parens = [(0, 0, 0, -1)] # stack of (line, end-column, column-offset, type)
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ignorenextline = False # don't transform the next line
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insideignoreblock = False # don't transform until turned off
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for i, t in enumerate(tokens):
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# Compute the column offset for the current line, such that
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# the current line will be aligned to the last opening paren
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# as before.
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if coloffset < 0:
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lastparen = parens[-1]
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if t.start[1] == lastparen[1]:
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coloffset = lastparen[2]
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elif (
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t.start[1] + 1 == lastparen[1]
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and lastparen[3] not in (token.NEWLINE, tokenize.NL)
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):
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# fix misaligned indent of s/util.Abort/error.Abort/
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coloffset = lastparen[2] + (lastparen[1] - t.start[1])
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else:
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coloffset = 0
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# Reset per-line attributes at EOL.
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if t.type in (token.NEWLINE, tokenize.NL):
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yield adjusttokenpos(t, coloffset)
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coldelta = 0
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coloffset = -1
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if not insideignoreblock:
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ignorenextline = (
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tokens[i - 1].type == token.COMMENT
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and tokens[i - 1].string == "# no-py3-transform"
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)
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continue
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if t.type == token.COMMENT:
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if t.string == "# py3-transform: off":
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insideignoreblock = True
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if t.string == "# py3-transform: on":
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insideignoreblock = False
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if ignorenextline or insideignoreblock:
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yield adjusttokenpos(t, coloffset)
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continue
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# Remember the last paren position.
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if _isop(i, '(', '[', '{'):
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parens.append(t.end + (coloffset + coldelta, tokens[i + 1].type))
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elif _isop(i, ')', ']', '}'):
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parens.pop()
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# Convert most string literals to byte literals. String literals
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# in Python 2 are bytes. String literals in Python 3 are unicode.
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# Most strings in Mercurial are bytes and unicode strings are rare.
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# Rather than rewrite all string literals to use ``b''`` to indicate
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# byte strings, we apply this token transformer to insert the ``b``
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# prefix nearly everywhere.
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if t.type == token.STRING and t not in sysstrtokens:
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s = t.string
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# Preserve docstrings as string literals. This is inconsistent
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# with regular unprefixed strings. However, the
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# "from __future__" parsing (which allows a module docstring to
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# exist before it) doesn't properly handle the docstring if it
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# is b''' prefixed, leading to a SyntaxError. We leave all
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# docstrings as unprefixed to avoid this. This means Mercurial
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# components touching docstrings need to handle unicode,
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# unfortunately.
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if s[0:3] in ("'''", '"""'):
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# If it's assigned to something, it's not a docstring
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if not _isop(i - 1, '='):
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yield adjusttokenpos(t, coloffset)
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continue
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# If the first character isn't a quote, it is likely a string
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# prefixing character (such as 'b', 'u', or 'r'. Ignore.
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if s[0] not in ("'", '"'):
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yield adjusttokenpos(t, coloffset)
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continue
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# String literal. Prefix to make a b'' string.
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yield adjusttokenpos(t._replace(string='b%s' % t.string),
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coloffset)
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coldelta += 1
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continue
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# This looks like a function call.
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if t.type == token.NAME and _isop(i + 1, '('):
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fn = t.string
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# *attr() builtins don't accept byte strings to 2nd argument.
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if fn in (
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'getattr', 'setattr', 'hasattr', 'safehasattr', 'wrapfunction',
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'wrapclass', 'addattr'
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) and (opts['allow-attr-methods'] or not _isop(i - 1, '.')):
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arg1idx = _findargnofcall(1)
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if arg1idx is not None:
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_ensuresysstr(arg1idx)
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# .encode() and .decode() on str/bytes/unicode don't accept
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# byte strings on Python 3.
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elif fn in ('encode', 'decode') and _isop(i - 1, '.'):
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for argn in range(2):
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argidx = _findargnofcall(argn)
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if argidx is not None:
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_ensuresysstr(argidx)
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# It changes iteritems/values to items/values as they are not
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# present in Python 3 world.
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elif opts['dictiter'] and fn in ('iteritems', 'itervalues'):
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yield adjusttokenpos(t._replace(string=fn[4:]), coloffset)
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continue
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if t.type == token.NAME and t.string in opts['treat-as-kwargs']:
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if _isitemaccess(i):
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_ensuresysstr(i + 2)
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if _ismethodcall(i, 'get', 'pop', 'setdefault', 'popitem'):
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_ensuresysstr(i + 4)
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# Looks like "if __name__ == '__main__'".
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if (t.type == token.NAME and t.string == '__name__'
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and _isop(i + 1, '==')):
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_ensuresysstr(i + 2)
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# Emit unmodified token.
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yield adjusttokenpos(t, coloffset)
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def process(fin, fout, opts):
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tokens = tokenize.tokenize(fin.readline)
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tokens = replacetokens(list(tokens), opts)
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fout.write(tokenize.untokenize(tokens))
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def tryunlink(fname):
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try:
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os.unlink(fname)
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except OSError as err:
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if err.errno != errno.ENOENT:
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raise
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@contextlib.contextmanager
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def editinplace(fname):
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n = os.path.basename(fname)
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d = os.path.dirname(fname)
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fp = tempfile.NamedTemporaryFile(prefix='.%s-' % n, suffix='~', dir=d,
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delete=False)
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try:
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yield fp
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fp.close()
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if os.name == 'nt':
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tryunlink(fname)
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os.rename(fp.name, fname)
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finally:
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fp.close()
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tryunlink(fp.name)
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def main():
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ap = argparse.ArgumentParser()
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ap.add_argument('--version', action='version',
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version='Byteify strings 1.0')
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ap.add_argument('-i', '--inplace', action='store_true', default=False,
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help='edit files in place')
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ap.add_argument('--dictiter', action='store_true', default=False,
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help='rewrite iteritems() and itervalues()'),
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ap.add_argument('--allow-attr-methods', action='store_true',
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default=False,
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help='also handle attr*() when they are methods'),
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ap.add_argument('--treat-as-kwargs', nargs="+", default=[],
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help="ignore kwargs-like objects"),
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ap.add_argument('files', metavar='FILE', nargs='+', help='source file')
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args = ap.parse_args()
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opts = {
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'dictiter': args.dictiter,
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'treat-as-kwargs': set(args.treat_as_kwargs),
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'allow-attr-methods': args.allow_attr_methods,
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}
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for fname in args.files:
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if args.inplace:
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with editinplace(fname) as fout:
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with open(fname, 'rb') as fin:
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process(fin, fout, opts)
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else:
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with open(fname, 'rb') as fin:
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fout = sys.stdout.buffer
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process(fin, fout, opts)
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if __name__ == '__main__':
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if sys.version_info.major < 3:
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print('This script must be run under Python 3.')
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sys.exit(3)
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main()
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