"""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))