Enum.py

#!/usr/bin/env python
# -*- encoding: UTF-8 -*-
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#   
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#   
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>

class Enum:

    """Create an enumerated type, then add var/value pairs to it.
    The constructor and the method .ints(names) take a list of variable names,
    and assign them consecutive integers as values.    The method .strs(names)
    assigns each variable name to itself (that is variable 'v' has value 'v').
    The method .vals(a=99, b=200) allows you to assign any value to variables.
    A 'list of variable names' can also be a string, which will be .split().
    The method .end() returns one more than the maximum int value.
    Example: opcodes = Enum("add sub load store").vals(illegal=255)."""
  
    def __init__(self, names=[]): self.ints(names)

    def set(self, var, val):
        """Set var to the value val in the enum."""
        if var in vars(self).keys(): raise AttributeError("duplicate var in enum")
        if val in vars(self).values(): raise ValueError("duplicate value in enum")
        vars(self)[var] = val
        return self
  
    def strs(self, names):
        """Set each of the names to itself (as a string) in the enum."""
        for var in self._parse(names): self.set(var, var)
        return self

    def ints(self, names):
        """Set each of the names to the next highest int in the enum."""
        for var in self._parse(names): self.set(var, self.end())
        return self

    def vals(self, **entries):
        """Set each of var=val pairs in the enum."""
        for (var, val) in entries.items(): self.set(var, val)
        return self

    def end(self):
        """One more than the largest int value in the enum, or 0 if none."""
        try: return max([x for x in vars(self).values() if type(x)==type(0)]) + 1
        except ValueError: return 0
    
    def _parse(self, names):
        ### If names is a string, parse it as a list of names.
        if type(names) == type(""): return names.split()
        else: return names