File Explorer

1# Copyright 2007 Google, Inc. All Rights Reserved.2# Licensed to PSF under a Contributor Agreement.3 4"""Fixer that changes map(F, ...) into list(map(F, ...)) unless there5exists a 'from future_builtins import map' statement in the top-level6namespace.7 8As a special case, map(None, X) is changed into list(X).  (This is9necessary because the semantics are changed in this case -- the new10map(None, X) is equivalent to [(x,) for x in X].)11 12We avoid the transformation (except for the special case mentioned13above) if the map() call is directly contained in iter(<>), list(<>),14tuple(<>), sorted(<>), ...join(<>), or for V in <>:.15 16NOTE: This is still not correct if the original code was depending on17map(F, X, Y, ...) to go on until the longest argument is exhausted,18substituting None for missing values -- like zip(), it now stops as19soon as the shortest argument is exhausted.20"""21 22# Local imports23from ..pgen2 import token24from .. import fixer_base25from ..fixer_util import Name, ArgList, Call, ListComp, in_special_context26from ..pygram import python_symbols as syms27from ..pytree import Node28 29 30class FixMap(fixer_base.ConditionalFix):31    BM_compatible = True32 33    PATTERN = """34    map_none=power<35        'map'36        trailer< '(' arglist< 'None' ',' arg=any [','] > ')' >37        [extra_trailers=trailer*]38    >39    |40    map_lambda=power<41        'map'42        trailer<43            '('44            arglist<45                lambdef< 'lambda'46                         (fp=NAME | vfpdef< '(' fp=NAME ')'> ) ':' xp=any47                >48                ','49                it=any50            >51            ')'52        >53        [extra_trailers=trailer*]54    >55    |56    power<57        'map' args=trailer< '(' [any] ')' >58        [extra_trailers=trailer*]59    >60    """61 62    skip_on = 'future_builtins.map'63 64    def transform(self, node, results):65        if self.should_skip(node):66            return67 68        trailers = []69        if 'extra_trailers' in results:70            for t in results['extra_trailers']:71                trailers.append(t.clone())72 73        if node.parent.type == syms.simple_stmt:74            self.warning(node, "You should use a for loop here")75            new = node.clone()76            new.prefix = ""77            new = Call(Name("list"), [new])78        elif "map_lambda" in results:79            new = ListComp(results["xp"].clone(),80                           results["fp"].clone(),81                           results["it"].clone())82            new = Node(syms.power, [new] + trailers, prefix="")83 84        else:85            if "map_none" in results:86                new = results["arg"].clone()87                new.prefix = ""88            else:89                if "args" in results:90                    args = results["args"]91                    if args.type == syms.trailer and \92                       args.children[1].type == syms.arglist and \93                       args.children[1].children[0].type == token.NAME and \94                       args.children[1].children[0].value == "None":95                        self.warning(node, "cannot convert map(None, ...) "96                                     "with multiple arguments because map() "97                                     "now truncates to the shortest sequence")98                        return99 100                    new = Node(syms.power, [Name("map"), args.clone()])101                    new.prefix = ""102 103                if in_special_context(node):104                    return None105 106            new = Node(syms.power, [Name("list"), ArgList([new])] + trailers)107            new.prefix = ""108 109        new.prefix = node.prefix110        return new111