"""Fixer for generator.throw(E, V, T).

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g.throw(E) -> g.throw(E)

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g.throw(E, V) -> g.throw(E(V))

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g.throw(E, V, T) -> g.throw(E(V).with_traceback(T))

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g.throw("foo"[, V[, T]]) will warn about string exceptions."""

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# Author: Collin Winter

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# Local imports

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from .. import pytree

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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, ArgList, Attr, is_tuple

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class FixThrow(fixer_base.BaseFix):

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BM_compatible = True

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PATTERN = """

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power< any trailer< '.' 'throw' >

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trailer< '(' args=arglist< exc=any ',' val=any [',' tb=any] > ')' >

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>

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|

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power< any trailer< '.' 'throw' > trailer< '(' exc=any ')' > >

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"""

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def transform(self, node, results):

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syms = self.syms

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exc = results["exc"].clone()

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if exc.type is token.STRING:

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self.cannot_convert(node, "Python 3 does not support string exceptions")

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return

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# Leave "g.throw(E)" alone

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val = results.get("val")

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if val is None:

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return

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val = val.clone()

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if is_tuple(val):

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args = [c.clone() for c in val.children[1:-1]]

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else:

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val.prefix = ""

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args = [val]

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throw_args = results["args"]

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if "tb" in results:

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tb = results["tb"].clone()

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tb.prefix = ""

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e = Call(exc, args)

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with_tb = Attr(e, Name('with_traceback')) + [ArgList([tb])]

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throw_args.replace(pytree.Node(syms.power, with_tb))

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else:

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throw_args.replace(Call(exc, args))

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