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108 lines
3.8 KiB
108 lines
3.8 KiB
"""Fixer for 'raise E, V'
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From Armin Ronacher's ``python-modernize``.
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raise -> raise
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raise E -> raise E
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raise E, 5 -> raise E(5)
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raise E, 5, T -> raise E(5).with_traceback(T)
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raise E, None, T -> raise E.with_traceback(T)
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raise (((E, E'), E''), E'''), 5 -> raise E(5)
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raise "foo", V, T -> warns about string exceptions
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raise E, (V1, V2) -> raise E(V1, V2)
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raise E, (V1, V2), T -> raise E(V1, V2).with_traceback(T)
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CAVEATS:
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1) "raise E, V, T" cannot be translated safely in general. If V
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is not a tuple or a (number, string, None) literal, then:
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raise E, V, T -> from future.utils import raise_
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raise_(E, V, T)
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"""
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# Author: Collin Winter, Armin Ronacher, Mark Huang
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# Local imports
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from lib2to3 import pytree, fixer_base
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from lib2to3.pgen2 import token
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from lib2to3.fixer_util import Name, Call, is_tuple, Comma, Attr, ArgList
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from libfuturize.fixer_util import touch_import_top
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class FixRaise(fixer_base.BaseFix):
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BM_compatible = True
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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 == token.STRING:
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msg = "Python 3 does not support string exceptions"
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self.cannot_convert(node, msg)
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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 = u" "
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if "tb" in results:
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tb = results["tb"].clone()
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else:
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tb = None
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if "val" in results:
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val = results["val"].clone()
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if is_tuple(val):
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# Assume that exc is a subclass of Exception and call exc(*val).
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args = [c.clone() for c in val.children[1:-1]]
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exc = Call(exc, args)
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elif val.type in (token.NUMBER, token.STRING):
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# Handle numeric and string literals specially, e.g.
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# "raise Exception, 5" -> "raise Exception(5)".
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val.prefix = u""
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exc = Call(exc, [val])
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elif val.type == token.NAME and val.value == u"None":
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# Handle None specially, e.g.
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# "raise Exception, None" -> "raise Exception".
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pass
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else:
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# val is some other expression. If val evaluates to an instance
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# of exc, it should just be raised. If val evaluates to None,
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# a default instance of exc should be raised (as above). If val
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# evaluates to a tuple, exc(*val) should be called (as
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# above). Otherwise, exc(val) should be called. We can only
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# tell what to do at runtime, so defer to future.utils.raise_(),
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# which handles all of these cases.
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touch_import_top(u"future.utils", u"raise_", node)
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exc.prefix = u""
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args = [exc, Comma(), val]
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if tb is not None:
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args += [Comma(), tb]
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return Call(Name(u"raise_"), args, prefix=node.prefix)
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if tb is not None:
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tb.prefix = ""
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exc_list = Attr(exc, Name('with_traceback')) + [ArgList([tb])]
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else:
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exc_list = [exc]
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return pytree.Node(syms.raise_stmt,
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[Name(u"raise")] + exc_list,
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prefix=node.prefix)
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