"""
Ordered dictionary implementation.
"""

from UserDict import UserDict

class odict(UserDict):
    """
    http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/107747

    This dictionary class extends UserDict to record the order in which items are
    added. Calling keys(), values(), items(), etc. will return results in this
    order. 

    I've added iterkeys, itervalues, iteritems
    """
    def __init__(self, dict = None):
        self._keys = []
        UserDict.__init__(self, dict)

    def __delitem__(self, key):
        UserDict.__delitem__(self, key)
        self._keys.remove(key)

    def __setitem__(self, key, item):
        UserDict.__setitem__(self, key, item)
        if key not in self._keys: self._keys.append(key)

    def clear(self):
        UserDict.clear(self)
        self._keys = []

    def copy(self):
        new = odict()
        new.update( self )
        return new

    def items(self):
        return zip(self._keys, self.values())

    def keys(self):
        return self._keys[:]

    def popitem(self):
        try:
            key = self._keys[-1]
        except IndexError:
            raise KeyError('dictionary is empty')

        val = self[key]
        del self[key]

        return (key, val)

    def setdefault(self, key, failobj = None):
        if key not in self._keys: self._keys.append(key)
        return UserDict.setdefault(self, key, failobj)

    def update(self, dict):
        UserDict.update(self, dict)
        for key in dict.keys():
            if key not in self._keys: self._keys.append(key)

    def update(self, dict):
        for (key,val) in dict.items():
            self.__setitem__(key,val)

    def values(self):
        return map(self.get, self._keys)

    def iterkeys(self):
        return iter( self._keys )

    def itervalues(self):
        for key in self._keys:
            yield self.get(key)

    def iteritems(self):
        for key in self._keys:
            yield key, self.get(key)        

    def __iter__( self ):
        for key in self._keys: 
            yield key
    
    def reverse( self ):
        self._keys.reverse()