83 lines
2.5 KiB
Python
83 lines
2.5 KiB
Python
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"""Fixer for 'raise E, V, T'
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raise -> raise
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raise E -> raise E
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raise E, V -> raise E(V)
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raise E, V, T -> raise E(V).with_traceback(T)
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raise (((E, E'), E''), E'''), V -> raise E(V)
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raise "foo", V, T -> warns about string exceptions
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CAVEATS:
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1) "raise E, V" will be incorrectly translated if V is an exception
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instance. The correct Python 3 idiom is
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raise E from V
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but since we can't detect instance-hood by syntax alone and since
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any client code would have to be changed as well, we don't automate
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this.
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"""
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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, Attr, ArgList, is_tuple
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class FixRaise(fixer_base.BaseFix):
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PATTERN = """
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raise_stmt< 'raise' exc=any [',' val=any [',' tb=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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# Python 2 supports
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# raise ((((E1, E2), E3), E4), E5), V
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# as a synonym for
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# raise E1, V
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# Since Python 3 will not support this, we recurse down any tuple
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# literals, always taking the first element.
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if is_tuple(exc):
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while is_tuple(exc):
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# exc.children[1:-1] is the unparenthesized tuple
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# exc.children[1].children[0] is the first element of the tuple
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exc = exc.children[1].children[0].clone()
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exc.prefix = " "
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if "val" not in results:
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# One-argument raise
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new = pytree.Node(syms.raise_stmt, [Name(u"raise"), exc])
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new.prefix = node.prefix
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return new
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val = results["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 = u""
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args = [val]
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if "tb" in results:
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tb = results["tb"].clone()
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tb.prefix = u""
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e = Call(exc, args)
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with_tb = Attr(e, Name(u'with_traceback')) + [ArgList([tb])]
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new = pytree.Node(syms.simple_stmt, [Name(u"raise")] + with_tb)
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new.prefix = node.prefix
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return new
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else:
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return pytree.Node(syms.raise_stmt,
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[Name(u"raise"), Call(exc, args)],
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prefix=node.prefix)
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