mirror of https://github.com/python/cpython
91 lines
3.0 KiB
Python
91 lines
3.0 KiB
Python
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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 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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# 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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from ..pygram import python_symbols as syms
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class FixMap(fixer_base.ConditionalFix):
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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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>
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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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>
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power<
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'map' trailer< '(' [arglist=any] ')' >
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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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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 = u""
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new = Call(Name(u"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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else:
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if "map_none" in results:
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new = results["arg"].clone()
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else:
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if "arglist" in results:
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args = results["arglist"]
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if args.type == syms.arglist and \
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args.children[0].type == token.NAME and \
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args.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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if in_special_context(node):
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return None
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new = node.clone()
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new.prefix = u""
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new = Call(Name(u"list"), [new])
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new.prefix = node.prefix
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return new
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