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

     2 

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

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

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

     6 

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

     8 # Author: Collin Winter

     9 

    10 # Local imports

    11 from .. import pytree

    12 from ..pgen2 import token

    13 from .. import fixer_base

    14 from ..fixer_util import Name, Call, ArgList, Attr, is_tuple

    15 

    16 class FixThrow(fixer_base.BaseFix):

    17 

    18     PATTERN = """

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

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

    21     >

    22     |

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

    24     """

    25 

    26     def transform(self, node, results):

    27         syms = self.syms

    28 

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

    30         if exc.type is token.STRING:

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

    32             return

    33 

    34         # Leave "g.throw(E)" alone

    35         val = results.get("val")

    36         if val is None:

    37             return

    38 

    39         val = val.clone()

    40         if is_tuple(val):

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

    42         else:

    43             val.set_prefix("")

    44             args = [val]

    45 

    46         throw_args = results["args"]

    47 

    48         if "tb" in results:

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

    50             tb.set_prefix("")

    51 

    52             e = Call(exc, args)

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

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

    55         else:

    56             throw_args.replace(Call(exc, args))