"""Module to handle keywords and sets of keywords"""




import types, itertools




class Keyword(str) :
	"""Keyword is a case insensitive string with the spaces omitted,
		that is Keyword(Foo Bar) == Keyword(foobar)"""

	def __init__(self, s) :
		t = ""
		for x in s.split() :
			# FIXME : speed up the hashing by xor'ing the parts on which self is split
			# instead of performing this string concatenation
			t += x
		self.hash = hash(t.lower())
		str.__init__(self)

	def __hash__(self) :
		return self.hash

	def __eq__(self, other) :
		if not isinstance(other, Keyword) :
			other = Keyword(other)
		return self.hash == other.hash # Use direct hash comparison to save a call to self.__hash__()




class Set(set) :
	"""Mutable set of keywords. Besides keywords, it can operate on ordinary strings as well,
		which get implicitly converted into the Keyword instances"""

	def __init__(self, *args) :
		xargs = []
		for x in args :
			if isinstance(x, Keyword) :
				xargs.append(x)
			else :
				xargs.append(Keyword(x))
		set.__init__(self, xargs)

	def __contains__(self, x) :
		if isinstance(x, Keyword) :
			return set.__contains__(self, x)
		else :
			return set.__contains__(self, Keyword(x))