"""
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.
    """
    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 ):
        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()

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