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Viewing changes to Lib/lib2to3/fixes/fix_filter.py

  • Committer: Bazaar Package Importer
  • Author(s): Matthias Klose
  • Date: 2009-02-13 12:51:00 UTC
  • Revision ID: james.westby@ubuntu.com-20090213125100-uufgcb9yeqzujpqw
Tags: upstream-2.6.1
Import upstream version 2.6.1

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Lib/lib2to3/fixes/fix_filter.py
 
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# Copyright 2007 Google, Inc. All Rights Reserved.
 
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# Licensed to PSF under a Contributor Agreement.
 
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"""Fixer that changes filter(F, X) into list(filter(F, X)).
 
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We avoid the transformation if the filter() call is directly contained
 
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in iter(<>), list(<>), tuple(<>), sorted(<>), ...join(<>), or
 
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for V in <>:.
 
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NOTE: This is still not correct if the original code was depending on
 
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filter(F, X) to return a string if X is a string and a tuple if X is a
 
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tuple.  That would require type inference, which we don't do.  Let
 
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Python 2.6 figure it out.
 
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"""
 
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# Local imports
 
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from ..pgen2 import token
 
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from .. import fixer_base
 
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from ..fixer_util import Name, Call, ListComp, in_special_context
 
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class FixFilter(fixer_base.ConditionalFix):
 
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    PATTERN = """
 
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    filter_lambda=power<
 
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        'filter'
 
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        trailer<
 
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            '('
 
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            arglist<
 
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                lambdef< 'lambda'
 
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                         (fp=NAME | vfpdef< '(' fp=NAME ')'> ) ':' xp=any
 
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                >
 
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                ','
 
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                it=any
 
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            >
 
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            ')'
 
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        >
 
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    >
 
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    |
 
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    power<
 
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        'filter'
 
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        trailer< '(' arglist< none='None' ',' seq=any > ')' >
 
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    >
 
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    |
 
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    power<
 
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        'filter'
 
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        args=trailer< '(' [any] ')' >
 
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    >
 
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    """
 
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    skip_on = "future_builtins.filter"
 
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    def transform(self, node, results):
 
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        if self.should_skip(node):
 
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            return
 
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        if "filter_lambda" in results:
 
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            new = ListComp(results.get("fp").clone(),
 
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                           results.get("fp").clone(),
 
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                           results.get("it").clone(),
 
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                           results.get("xp").clone())
 
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        elif "none" in results:
 
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            new = ListComp(Name("_f"),
 
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                           Name("_f"),
 
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                           results["seq"].clone(),
 
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                           Name("_f"))
 
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        else:
 
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            if in_special_context(node):
 
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                return None
 
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            new = node.clone()
 
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            new.set_prefix("")
 
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            new = Call(Name("list"), [new])
 
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        new.set_prefix(node.get_prefix())
 
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        return new