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Viewing changes to Epsilon/epsilon/unrepr.py

  • Committer: Jean-Paul Calderone
  • Date: 2014-06-29 20:33:04 UTC
  • mfrom: (2749.1.1 remove-epsilon-1325289)
  • Revision ID: exarkun@twistedmatrix.com-20140629203304-gdkmbwl1suei4m97
merge lp:~exarkun/divmod.org/remove-epsilon-1325289

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Epsilon/epsilon/unrepr.py
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import compiler
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def unrepr(s):
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    """
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    Convert a string produced by python's repr() into the
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    corresponding data structure, without calling eval().
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    """
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    return Builder().build(getObj(s))
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def getObj(s):
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    s="a="+s
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    return compiler.parse(s).getChildren()[1].getChildren()[0].getChildren()[1]
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class UnknownType(Exception):
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    pass
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class Builder:
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    def build(self, o):
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        m = getattr(self, 'build_'+o.__class__.__name__, None)
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        if m is None:
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            raise UnknownType(o.__class__.__name__)
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        return m(o)
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    def build_List(self, o):
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        return map(self.build, o.getChildren())
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    def build_Const(self, o):
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        return o.value
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    def build_Dict(self, o):
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        d = {}
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        i = iter(map(self.build, o.getChildren()))
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        for el in i:
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            d[el] = i.next()
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        return d
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    def build_Tuple(self, o):
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        return tuple(self.build_List(o))
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    def build_Name(self, o):
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        if o.name == 'None':
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            return None
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        raise UnknownType('Name')
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    def build_Add(self, o):
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        real, imag = map(self.build_Const, o.getChildren())
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        try:
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            real = float(real)
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        except TypeError:
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            raise UnknownType('Add')
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        if not isinstance(imag, complex) or imag.real != 0.0:
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            raise UnknownType('Add')
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        return real+imag