General purpose memoization

memoize.js

/**
 * A general-purpose function to enable a function to use memoization. The function must use explicit, string-serializable parameters
 * @param func {Function} to be memoized
 * @parma context {Object} the context for the memoized function to execute within
 */
function memoize(func, context) {
    function memoizeArg (argPos) {
        var cache = {};
        return function() {
            if (argPos == 0) {
                if (!(arguments[argPos] in cache)) {
                    cache[arguments[argPos]] = func.apply(context, arguments);
                }
                return cache[arguments[argPos]];
            }
            else {
                if (!(arguments[argPos] in cache)) {
                    cache[arguments[argPos]] = memoizeArg(argPos - 1);
                }
                return cache[arguments[argPos]].apply(this, arguments);
            }
        }
    }
    // JScript doesn't grok the arity property, but uses length instead
    var arity = func.arity || func.length;
    return memoizeArg(arity - 1);
}