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| """Fixer for 'raise E, V, T' | |
| raise -> raise | |
| raise E -> raise E | |
| raise E, V -> raise E(V) | |
| raise E, V, T -> raise E(V).with_traceback(T) | |
| raise E, None, T -> raise E.with_traceback(T) | |
| raise (((E, E'), E''), E'''), V -> raise E(V) | |
| raise "foo", V, T -> warns about string exceptions | |
| CAVEATS: | |
| 1) "raise E, V" will be incorrectly translated if V is an exception | |
| instance. The correct Python 3 idiom is | |
| raise E from V | |
| but since we can't detect instance-hood by syntax alone and since | |
| any client code would have to be changed as well, we don't automate | |
| this. | |
| """ | |
| # Author: Collin Winter | |
| # Local imports | |
| from .. import pytree | |
| from ..pgen2 import token | |
| from .. import fixer_base | |
| from ..fixer_util import Name, Call, Attr, ArgList, is_tuple | |
| class FixRaise(fixer_base.BaseFix): | |
| BM_compatible = True | |
| PATTERN = """ | |
| raise_stmt< 'raise' exc=any [',' val=any [',' tb=any]] > | |
| """ | |
| def transform(self, node, results): | |
| syms = self.syms | |
| exc = results["exc"].clone() | |
| if exc.type == token.STRING: | |
| msg = "Python 3 does not support string exceptions" | |
| self.cannot_convert(node, msg) | |
| return | |
| # Python 2 supports | |
| # raise ((((E1, E2), E3), E4), E5), V | |
| # as a synonym for | |
| # raise E1, V | |
| # Since Python 3 will not support this, we recurse down any tuple | |
| # literals, always taking the first element. | |
| if is_tuple(exc): | |
| while is_tuple(exc): | |
| # exc.children[1:-1] is the unparenthesized tuple | |
| # exc.children[1].children[0] is the first element of the tuple | |
| exc = exc.children[1].children[0].clone() | |
| exc.prefix = " " | |
| if "val" not in results: | |
| # One-argument raise | |
| new = pytree.Node(syms.raise_stmt, [Name("raise"), exc]) | |
| new.prefix = node.prefix | |
| return new | |
| val = results["val"].clone() | |
| if is_tuple(val): | |
| args = [c.clone() for c in val.children[1:-1]] | |
| else: | |
| val.prefix = "" | |
| args = [val] | |
| if "tb" in results: | |
| tb = results["tb"].clone() | |
| tb.prefix = "" | |
| e = exc | |
| # If there's a traceback and None is passed as the value, then don't | |
| # add a call, since the user probably just wants to add a | |
| # traceback. See issue #9661. | |
| if val.type != token.NAME or val.value != "None": | |
| e = Call(exc, args) | |
| with_tb = Attr(e, Name('with_traceback')) + [ArgList([tb])] | |
| new = pytree.Node(syms.simple_stmt, [Name("raise")] + with_tb) | |
| new.prefix = node.prefix | |
| return new | |
| else: | |
| return pytree.Node(syms.raise_stmt, | |
| [Name("raise"), Call(exc, args)], | |
| prefix=node.prefix) | |