mirror of https://github.com/python/cpython
93 lines
2.9 KiB
Python
93 lines
2.9 KiB
Python
# 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 basefix
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from .util import Name, Call, ListComp, does_tree_import, in_special_context
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from ..pygram import python_symbols as syms
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class FixMap(basefix.BaseFix):
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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'
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args=trailer< '(' [any] ')' >
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>
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"""
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def start_tree(self, *args):
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super(FixMap, self).start_tree(*args)
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self._future_map_found = None
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def has_future_map(self, node):
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if self._future_map_found is not None:
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return self._future_map_found
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self._future_map_found = does_tree_import('future_builtins', 'map', node)
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return self._future_map_found
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def transform(self, node, results):
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if self.has_future_map(node):
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# If a future map has been imported for this file, we won't
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# be making any modifications
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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.set_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.get("xp").clone(),
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results.get("fp").clone(),
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results.get("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 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
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