/* See /sys/src/9/port/latin1.c */

function Compose(parent){
	var mode = false;
	var buf = [];

	var handle = function(){
		if(buf.length < 2) return;
		if(buf[0] == "X"){
			if(buf.length < 5) return;
			handleX();
		}else{
			for(var k in Composetab){
				if(buf[0] == k.charAt(0)){
					if(k.length == 1)
						var c = buf[1];
					else if(k.charAt(1) != buf[1])
						continue;
					else if(buf.length < 3)
						return;
					else
						var c = buf[2];
					/* parent.take so[si.find(c)] */
					var i = Composetab[k].from.indexOf(c);
					if(i < 0)
						return reset();
					else{
						parent.take(Composetab[k].to[i]);
						return reset();
					}
				}
			}
			return reset();
		}
	}

	var handleX = function(){
		var xdigits = "0123456789ABCDEF";
		var i, x, c = 0;

		if(buf.length != 5) return reset();

		for(i = 1; i < 5; ++i){
			x = xdigits.indexOf(buf[i].toUpperCase());
			if(x < 0) return reset();
			c |= x << ((4 - i) * 4);
		}
		parent.take(String.fromCharCode(c));
	}

	this.set = function(){
		mode = true;
	}

	/* XXX Why can't I call ``this.reset()'' directly? */
	var reset = function(){
		mode = false;
		buf = [];
	}
	this.reset = reset;

	this.getmode = function(){
		return mode;
	}

	this.push = function(c){
		if(mode){
			buf.push(c);
			handle();
		}else{
			throw("Not in compose mode!");
		}
	}
}