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"""Fixer that changes map(F, ...) into list(map(F, ...)) unless there |
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exists a 'from future_builtins import map' statement in the top-level |
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namespace. |
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As a special case, map(None, X) is changed into list(X). (This is |
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necessary because the semantics are changed in this case -- the new |
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map(None, X) is equivalent to [(x,) for x in X].) |
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We avoid the transformation (except for the special case mentioned |
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above) if the map() call is directly contained in iter(<>), list(<>), |
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tuple(<>), sorted(<>), ...join(<>), or for V in <>:. |
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NOTE: This is still not correct if the original code was depending on |
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map(F, X, Y, ...) to go on until the longest argument is exhausted, |
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substituting None for missing values -- like zip(), it now stops as |
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soon as the shortest argument is exhausted. |
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""" |
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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, ArgList, Call, ListComp, in_special_context |
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from ..pygram import python_symbols as syms |
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from ..pytree import Node |
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class FixMap(fixer_base.ConditionalFix): |
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BM_compatible = True |
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PATTERN = """ |
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map_none=power< |
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'map' |
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trailer< '(' arglist< 'None' ',' arg=any [','] > ')' > |
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[extra_trailers=trailer*] |
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> |
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| |
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map_lambda=power< |
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'map' |
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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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[extra_trailers=trailer*] |
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> |
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power< |
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'map' args=trailer< '(' [any] ')' > |
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[extra_trailers=trailer*] |
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> |
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""" |
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skip_on = 'future_builtins.map' |
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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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trailers = [] |
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if 'extra_trailers' in results: |
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for t in results['extra_trailers']: |
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trailers.append(t.clone()) |
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if node.parent.type == syms.simple_stmt: |
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self.warning(node, "You should use a for loop here") |
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new = node.clone() |
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new.prefix = "" |
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new = Call(Name("list"), [new]) |
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elif "map_lambda" in results: |
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new = ListComp(results["xp"].clone(), |
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results["fp"].clone(), |
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results["it"].clone()) |
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new = Node(syms.power, [new] + trailers, prefix="") |
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else: |
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if "map_none" in results: |
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new = results["arg"].clone() |
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new.prefix = "" |
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else: |
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if "args" in results: |
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args = results["args"] |
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if args.type == syms.trailer and \ |
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args.children[1].type == syms.arglist and \ |
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args.children[1].children[0].type == token.NAME and \ |
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args.children[1].children[0].value == "None": |
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self.warning(node, "cannot convert map(None, ...) " |
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"with multiple arguments because map() " |
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"now truncates to the shortest sequence") |
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return |
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new = Node(syms.power, [Name("map"), args.clone()]) |
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new.prefix = "" |
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if in_special_context(node): |
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return None |
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new = Node(syms.power, [Name("list"), ArgList([new])] + trailers) |
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new.prefix = "" |
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new.prefix = node.prefix |
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return new |
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