Lib/lib2to3/fixes/fix_sys_exc.py

   1 """Fixer for sys.exc_{type, value, traceback}
   2
   3 sys.exc_type -> sys.exc_info()[0]
   4 sys.exc_value -> sys.exc_info()[1]
   5 sys.exc_traceback -> sys.exc_info()[2]
   6 """
   7
   8 # By Jeff Balogh and Benjamin Peterson
   9
  10 # Local imports
  11 from .. import fixer_base
  12 from ..fixer_util import Attr, Call, Name, Number, Subscript, Node, syms
  13
  14 class FixSysExc(fixer_base.BaseFix):
  15     # This order matches the ordering of sys.exc_info().
  16     exc_info = ["exc_type", "exc_value", "exc_traceback"]
  17     PATTERN = """
  18               power< 'sys' trailer< dot='.' attribute=(%s) > >
  19               """ % '|'.join("'%s'" % e for e in exc_info)
  20
  21     def transform(self, node, results):
  22         sys_attr = results["attribute"][0]
  23         index = Number(self.exc_info.index(sys_attr.value))
  24
  25         call = Call(Name(u"exc_info"), prefix=sys_attr.prefix)
  26         attr = Attr(Name(u"sys"), call)
  27         attr[1].children[0].prefix = results["dot"].prefix
  28         attr.append(Subscript(index))
  29         return Node(syms.power, attr, prefix=node.prefix)