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1# Copyright 2007 Google, Inc. All Rights Reserved.2# Licensed to PSF under a Contributor Agreement.3 4"""Fixer that changes filter(F, X) into list(filter(F, X)).5 6We avoid the transformation if the filter() call is directly contained7in iter(<>), list(<>), tuple(<>), sorted(<>), ...join(<>), or8for V in <>:.9 10NOTE: This is still not correct if the original code was depending on11filter(F, X) to return a string if X is a string and a tuple if X is a12tuple.  That would require type inference, which we don't do.  Let13Python 2.6 figure it out.14"""15 16# Local imports17from .. import fixer_base18from ..pytree import Node19from ..pygram import python_symbols as syms20from ..fixer_util import Name, ArgList, ListComp, in_special_context, parenthesize21 22 23class FixFilter(fixer_base.ConditionalFix):24    BM_compatible = True25 26    PATTERN = """27    filter_lambda=power<28        'filter'29        trailer<30            '('31            arglist<32                lambdef< 'lambda'33                         (fp=NAME | vfpdef< '(' fp=NAME ')'> ) ':' xp=any34                >35                ','36                it=any37            >38            ')'39        >40        [extra_trailers=trailer*]41    >42    |43    power<44        'filter'45        trailer< '(' arglist< none='None' ',' seq=any > ')' >46        [extra_trailers=trailer*]47    >48    |49    power<50        'filter'51        args=trailer< '(' [any] ')' >52        [extra_trailers=trailer*]53    >54    """55 56    skip_on = "future_builtins.filter"57 58    def transform(self, node, results):59        if self.should_skip(node):60            return61 62        trailers = []63        if 'extra_trailers' in results:64            for t in results['extra_trailers']:65                trailers.append(t.clone())66 67        if "filter_lambda" in results:68            xp = results.get("xp").clone()69            if xp.type == syms.test:70                xp.prefix = ""71                xp = parenthesize(xp)72 73            new = ListComp(results.get("fp").clone(),74                           results.get("fp").clone(),75                           results.get("it").clone(), xp)76            new = Node(syms.power, [new] + trailers, prefix="")77 78        elif "none" in results:79            new = ListComp(Name("_f"),80                           Name("_f"),81                           results["seq"].clone(),82                           Name("_f"))83            new = Node(syms.power, [new] + trailers, prefix="")84 85        else:86            if in_special_context(node):87                return None88 89            args = results['args'].clone()90            new = Node(syms.power, [Name("filter"), args], prefix="")91            new = Node(syms.power, [Name("list"), ArgList([new])] + trailers)92            new.prefix = ""93        new.prefix = node.prefix94        return new95