load("lexer.js");


// This should only contain hat definition attributes, not runtime things.
function Hat(name, hatid) {
	this.name = name;
	this.hatid = hatid;
	this.magic = [];
}

function Place(type, id) {
	this.type = type;
	this.id = id;
	this.toString = function() {
		return "<" + type + " " + id + ">";
	}
}

function Move(source, dest) {
	this.source = source;
	this.dest = dest;
	this.toString = function() {
		return source + " to " + dest;
	}
}

function Program(text) {
	this.hats = [];
	this.ids = [];
	this.next_hatid = 42;
	this.next_gensym = 0;
	this.stream = new Stream(text);

	this.intern_hat = function(name) {
		if (!this.hats[name]) {
			this.hats[name] = new Hat(name, this.next_hatid);
			this.ids[this.next_hatid] = this.hats[name];
			this.next_hatid++;
		}
		return this.hats[name];
	}

	this.get_by_hatid = function(id) {
		if (this.ids[id])
			return this.ids[id];
		else
			throw 'unknown hatid' + id;
	}

	this.next = function(constraints) {
		var token = this.stream.next();
		for (var i in constraints) {
			if (constraints[i] != token[i])
				this.stream.error("Expected token with " + i + " '" + constraints[i] + "', but found " + token);
		}
		return token;
	}

	this.back = function() {
		this.stream.back();
	}

	this.gensym = function() {
		return this.next_gensym++;
	}

	this.parse_thyself = function() {
		var token;
		while (1) {
			token = this.next();
			if (token.text == "hat") {
				var name = this.next({type: "IDENTIFIER"}).text;
				this.next({text: ":"});
				var hat = this.intern_hat(name);
				while (1) {
					token = this.next();
					if (token.text=="init" || token.text=="in" || token.text=="out")
						hat.magic[token.text] = this.parse_magic().magic;
					else {
						this.back();
						break;
					}
				}
			}

			else if (token.type == "EOF")
				return;
			else
				this.stream.error("Unexpected token " + token + " at toplevel");
		}
	}

	this.parse_magic = function() {
		var left=null, op=null, right=null;
		var leftmost=null, magic=[], leftmagic, rightmagic;
		var token;

		while (1) {
			token = this.next();
			rightmagic = [];
			if (token.text == "[") {
				submagic = this.parse_magic();
				right = submagic.leftmost;
				rightmagic = submagic.magic;
				this.next({text: "]"});
			}
			else if (token.text=="apply") {
				right = new Place("apply", this.gensym());
			}
			else if (token.type=="IDENTIFIER") {
				right = new Place("hat", token.text);
			}
			else if (token.type=="NUMBER") {
				right = new Place("number", Number(token.text));
			}
			else if (token.text=="~") {
				right = new Place("number", -Number(this.next({type: "NUMBER"}).text));
			}
			else if (token.text=="@") {
				token = this.next();
				if (token.type == "NUMBER")
					right = new Place("stack", Number(token.text))
				else {
					right = new Place("stack", 0);
					this.back();
				}
			}
			else if (token.text=="\\") {
				right = new Place("hatid", this.next({type: "IDENTIFIER"}).text);
			}

			else {
				this.stream.error("Unexpected end of magic; expecting identifier or grouping, found " + token);
			}


			if (op) {
				if (op == "->") {
					magic.push(new Move(left, right));
					magic = magic.concat(rightmagic);
				}

				else {
					magic = magic.concat(rightmagic);
					magic.push(new Move(right, left));
				}
			}
			else {
				leftmost = right;
				magic = rightmagic;
			}

			left = right;


			token = this.next();
			if (token.type != "ARROW") {
				this.back();
				if (op) {
					return {leftmost: leftmost, magic: magic};
				}
				else {
					this.stream.error("Unexpected end of magic; expecting arrow, found " + token);
				}
			}

			op = token.text;
		}
	}
}