# Copyright 2007 Google, Inc. All Rights Reserved.
# Licensed to PSF under a Contributor Agreement.

"""Fixer that changes filter(F, X) into list(filter(F, X)).

We avoid the transformation if the filter() call is directly contained
in iter(<>), list(<>), tuple(<>), sorted(<>), ...join(<>), or
for V in <>:.

NOTE: This is still not correct if the original code was depending on
filter(F, X) to return a string if X is a string and a tuple if X is a
tuple. That would require type inference, which we don't do. Let
Python 2.6 figure it out.
"""

# Local imports
from ..pgen2 import token
from .. import fixer_base
from ..fixer_util import Name, Call, ListComp, in_special_context

class FixFilter(fixer_base.ConditionalFix):
BM_compatible = True

PATTERN = """
filter_lambda=power<
'filter'
trailer<
'('
arglist<
lambdef< 'lambda'
(fp=NAME | vfpdef< '(' fp=NAME ')'> ) ':' xp=any
>
','
it=any
>
')'
>
>
|
power<
'filter'
trailer< '(' arglist< none='None' ',' seq=any > ')' >
>
|
power<
'filter'
args=trailer< '(' [any] ')' >
>
"""

skip_on = "future_builtins.filter"

def transform(self, node, results):
if self.should_skip(node):
return

if "filter_lambda" in results:
new = ListComp(results.get("fp").clone(),
results.get("fp").clone(),
results.get("it").clone(),
results.get("xp").clone())

elif "none" in results:
new = ListComp(Name(u"_f"),
Name(u"_f"),
results["seq"].clone(),
Name(u"_f"))

else:
if in_special_context(node):
return None
new = node.clone()
new.prefix = u""
new = Call(Name(u"list"), [new])
new.prefix = node.prefix
return new