"use strict";

const VARIABLES = {"x": 0, "y": 1, "z": 2};

function newOperation(action, symbol) {
    function Operation(...args) {
        this.operands = args;
    }

    Operation.prototype.toString = function () {
        return this.operands.join(" ") + " " + symbol;
    };

    Operation.prototype.evaluate = function (...args) {
        return action(...this.operands.map(operand => (operand.evaluate(...args))));
    };

    return Operation;
}

function Const(x) {
    this.value = x;
}

Const.prototype.toString = function () {
    return this.value.toString();
};

Const.prototype.evaluate = function () {
    return this.value;
};

function Variable(s) {
    this.name = s;
    this.index = VARIABLES[s];
}

Variable.prototype.toString = function () {
    return this.name;
};
Variable.prototype.evaluate = function (...args) {
    return args[this.index];
};

const Add = newOperation((a, b) => a + b, "+");
const Subtract = newOperation((a, b) => a - b, "-");
const Multiply = newOperation((a, b) => a * b, "*");
const Divide = newOperation((a, b) => a / b, "/");
const Negate = newOperation(a => -a, "negate");
const Min3 = newOperation((a, b, c) => Math.min(a, b, c), "min3");
const Max5 = newOperation((a, b, c, d, e) => Math.max(a, b, c, d, e), "max5");