"""Values to match result-trees even when implementations change

These values match the "logical" values of the result-trees
as they apply to SimpleParse's usage, rather than the particular
concrete results returned by the engine.  So, for instance, you
can say "returns no children" (NullResults) for result-tuples or
"whatever failure position" for failure return values.
"""

class _NullResults:
	def __cmp__( self, other ):
		if other == [] or other == None:
			return 0
		else:
			return -1
	def __repr__( self ):
		return "<Null Children>"
NullResult = _NullResults()
class _AnyInt:
	def __cmp__( self, other ):
		if type(other) == type(1):
			return 0
		else:
			return -1
	def __repr__( self ):
		return "<Any Integer>"
AnyInt = _AnyInt()