Generalize the CellSet type into a general-purpose Set

js/Set.js

@@ -0,0 +1,69 @@
+return {
+	make: make
+};
+
+function make(type) {
+	if(type == undefined) {
+		var id = function(x) {return x;};
+		type = {toKey: id, ofKey: id};
+	}
+
+	function Set(s) {
+		this.elements = {};
+		if(Array.isArray(s)) {
+			s.forEach(this.add.bind(this));
+		} else if(s != undefined) {
+			this.add(s);
+		}
+	}
+
+	Set.prototype.add = function(e) { this.elements[type.toKey(e)] = true; };
+	Set.prototype.remove = function(e) { delete this.elements[type.toKey(e)]; };
+	Set.prototype.contains = function(e) { return !!this.elements[type.toKey(e)]; };
+	Set.prototype.size = function() { return Object.keys(this.elements).length; };
+
+	Set.prototype.toList = function() {
+		var result = [];
+		for(var k in this.elements) {
+			result.push(type.ofKey(k));
+		}
+		return Array.from(result).sort();
+	}
+
+	Set.prototype.iter = function(f) { this.toList().forEach(f); };
+	Set.prototype.map = function(f) { return this.toList().map(f); };
+
+	Set.prototype.equals = function(set) {
+		var sorted = [this.toList(), set.toList()];
+		return sorted[0].length == sorted[1].length &&
+			sorted[0].every(function(x) {return x == sorted[1].shift();});
+	}
+
+	Set.prototype.subset = function(predicate) {
+		var newSet = new Set();
+		this.iter(function(e) {
+			if(predicate(e)) {
+				newSet.add(e);
+			}
+		});
+		return newSet;
+	};
+
+	Set.prototype.difference = function(set) {
+		return this.subset(function(e) {return !set.contains(e);});
+	}
+
+	Set.prototype.intersection = function(set) {
+		return this.subset(function(e) {return set.contains(e);});
+	}
+
+	Set.union = function(sets) {
+		var newSet = new Set();
+		for(var i = 0; i < sets.length; i++) {
+			sets[i].iter(newSet.add.bind(newSet));
+		}
+		return newSet;
+	}
+
+	return Set;
+}