| """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, 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 basefix |
| from .util import Name, Call, Attr, ArgList, is_tuple |
| |
| class FixRaise(basefix.BaseFix): |
| |
| 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 is token.STRING: |
| self.cannot_convert(node, "Python 3 does not support string exceptions") |
| 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.set_prefix(" ") |
| |
| if "val" not in results: |
| # One-argument raise |
| new = pytree.Node(syms.raise_stmt, [Name("raise"), exc]) |
| new.set_prefix(node.get_prefix()) |
| return new |
| |
| val = results["val"].clone() |
| if is_tuple(val): |
| args = [c.clone() for c in val.children[1:-1]] |
| else: |
| val.set_prefix("") |
| args = [val] |
| |
| if "tb" in results: |
| tb = results["tb"].clone() |
| tb.set_prefix("") |
| |
| e = Call(exc, args) |
| with_tb = Attr(e, Name('with_traceback')) + [ArgList([tb])] |
| new = pytree.Node(syms.simple_stmt, [Name("raise")] + with_tb) |
| new.set_prefix(node.get_prefix()) |
| return new |
| else: |
| return pytree.Node(syms.raise_stmt, |
| [Name("raise"), Call(exc, args)], |
| prefix=node.get_prefix()) |