# Copyright 2007 Google, Inc. All Rights Reserved.

# Licensed to PSF under a Contributor Agreement.

"""Fixer for dict methods.

d.keys() -> list(d.keys())

d.items() -> list(d.items())

d.values() -> list(d.values())

d.iterkeys() -> iter(d.keys())

d.iteritems() -> iter(d.items())

d.itervalues() -> iter(d.values())

Except in certain very specific contexts: the iter() can be dropped

when the context is list(), sorted(), iter() or for...in; the list()

can be dropped when the context is list() or sorted() (but not iter()

or for...in!). Special contexts that apply to both: list(), sorted(), tuple()

set(), any(), all(), sum().

Note: iter(d.keys()) could be written as iter(d) but since the

original d.iterkeys() was also redundant we don't fix this.  And there

are (rare) contexts where it makes a difference (e.g. when passing it

as an argument to a function that introspects the argument).

"""

# Local imports

from .. import pytree

from .. import patcomp

from ..pgen2 import token

from .. import fixer_base

from ..fixer_util import Name, Call, LParen, RParen, ArgList, Dot

from .. import fixer_util

iter_exempt = fixer_util.consuming_calls | set(["iter"])

class FixDict(fixer_base.BaseFix):

    PATTERN = """

    power< head=any+

         trailer< '.' method=('keys'|'items'|'values'|

                              'iterkeys'|'iteritems'|'itervalues') >

         parens=trailer< '(' ')' >

         tail=any*

    >

    """

    def transform(self, node, results):

        head = results["head"]

        method = results["method"][0] # Extract node for method name

        tail = results["tail"]

        syms = self.syms

        method_name = method.value

        isiter = method_name.startswith("iter")

        if isiter:

            method_name = method_name[4:]

        assert method_name in ("keys", "items", "values"), repr(method)

        head = [n.clone() for n in head]

        tail = [n.clone() for n in tail]

        special = not tail and self.in_special_context(node, isiter)

        args = head + [pytree.Node(syms.trailer,

                                   [Dot(),

                                    Name(method_name,

                                         prefix=method.get_prefix())]),

                       results["parens"].clone()]

        new = pytree.Node(syms.power, args)

        if not special:

            new.set_prefix("")

            new = Call(Name(isiter and "iter" or "list"), [new])

        if tail:

            new = pytree.Node(syms.power, [new] + tail)

        new.set_prefix(node.get_prefix())

        return new

    P1 = "power< func=NAME trailer< '(' node=any ')' > any* >"

    p1 = patcomp.compile_pattern(P1)

    P2 = """for_stmt< 'for' any 'in' node=any ':' any* >

            | comp_for< 'for' any 'in' node=any any* >

         """

    p2 = patcomp.compile_pattern(P2)

    def in_special_context(self, node, isiter):

        if node.parent is None:

            return False

        results = {}

        if (node.parent.parent is not None and

               self.p1.match(node.parent.parent, results) and

               results["node"] is node):

            if isiter:

                # iter(d.iterkeys()) -> iter(d.keys()), etc.

                return results["func"].value in iter_exempt

            else:

                # list(d.keys()) -> list(d.keys()), etc.

                return results["func"].value in fixer_util.consuming_calls

        if not isiter:

            return False

        # for ... in d.iterkeys() -> for ... in d.keys(), etc.

        return self.p2.match(node.parent, results) and results["node"] is node