test_op_overloading.js

"use strict";

function assert(actual, expected, message) {
    if (arguments.length == 1)
        expected = true;

    if (actual === expected)
        return;

    if (actual !== null && expected !== null
    &&  typeof actual == 'object' && typeof expected == 'object'
    &&  actual.toString() === expected.toString())
        return;

    throw Error("assertion failed: got |" + actual + "|" +
                ", expected |" + expected + "|" +
                (message ? " (" + message + ")" : ""));
}

/* operators overloading with Operators.create() */
function test_operators_create() {
    class Vec2
    {
        constructor(x, y) {
            this.x = x;
            this.y = y;
        }
        static mul_scalar(p1, a) {
            var r = new Vec2();
            r.x = p1.x * a;
            r.y = p1.y * a;
            return r;
        }
        toString() {
            return "Vec2(" + this.x + "," + this.y + ")";
        }
    }
    
    Vec2.prototype[Symbol.operatorSet] = Operators.create(
    {
        "+"(p1, p2) {
            var r = new Vec2();
            r.x = p1.x + p2.x;
            r.y = p1.y + p2.y;
            return r;
        },
        "-"(p1, p2) {
            var r = new Vec2();
            r.x = p1.x - p2.x;
            r.y = p1.y - p2.y;
            return r;
        },
        "=="(a, b) {
            return a.x == b.x && a.y == b.y;
        },
        "<"(a, b) {
            var r;
            /* lexicographic order */
            if (a.x == b.x)
                r = (a.y < b.y);
            else
                r = (a.x < b.x);
            return r;
        },
        "++"(a) {
            var r = new Vec2();
            r.x = a.x + 1;
            r.y = a.y + 1;
            return r;
        }
    },
    {
        left: Number,
        "*"(a, b) {
            return Vec2.mul_scalar(b, a);
        }
    },
    {
        right: Number,
        "*"(a, b) {
            return Vec2.mul_scalar(a, b);
        }
    });

    var a = new Vec2(1, 2);
    var b = new Vec2(3, 4);
    var r;

    r = a * 2 + 3 * b;
    assert(r.x === 11 && r.y === 16);
    assert(a == a, true);
    assert(a == b, false);
    assert(a != a, false);
    assert(a < b, true);
    assert(a <= b, true);
    assert(b < a, false);
    assert(b <= a, false);
    assert(a <= a, true);
    assert(a >= a, true);
    a++;
    assert(a.x === 2 && a.y === 3);
    r = ++a;
    assert(a.x === 3 && a.y === 4);
    assert(r === a);
}

/* operators overloading thru inheritance */
function test_operators()
{
    var Vec2;

    function mul_scalar(p1, a) {
        var r = new Vec2();
        r.x = p1.x * a;
        r.y = p1.y * a;
        return r;
    }

    var vec2_ops = Operators({
        "+"(p1, p2) {
            var r = new Vec2();
            r.x = p1.x + p2.x;
            r.y = p1.y + p2.y;
            return r;
        },
        "-"(p1, p2) {
            var r = new Vec2();
            r.x = p1.x - p2.x;
            r.y = p1.y - p2.y;
            return r;
        },
        "=="(a, b) {
            return a.x == b.x && a.y == b.y;
        },
        "<"(a, b) {
            var r;
            /* lexicographic order */
            if (a.x == b.x)
                r = (a.y < b.y);
            else
                r = (a.x < b.x);
            return r;
        },
        "++"(a) {
            var r = new Vec2();
            r.x = a.x + 1;
            r.y = a.y + 1;
            return r;
        }
    },
    {
        left: Number,
        "*"(a, b) {
            return mul_scalar(b, a);
        }
    },
    {
        right: Number,
        "*"(a, b) {
            return mul_scalar(a, b);
        }
    });

    Vec2 = class Vec2 extends vec2_ops
    {
        constructor(x, y) {
            super();
            this.x = x;
            this.y = y;
        }
        toString() {
            return "Vec2(" + this.x + "," + this.y + ")";
        }
    }
    
    var a = new Vec2(1, 2);
    var b = new Vec2(3, 4);
    var r;

    r = a * 2 + 3 * b;
    assert(r.x === 11 && r.y === 16);
    assert(a == a, true);
    assert(a == b, false);
    assert(a != a, false);
    assert(a < b, true);
    assert(a <= b, true);
    assert(b < a, false);
    assert(b <= a, false);
    assert(a <= a, true);
    assert(a >= a, true);
    a++;
    assert(a.x === 2 && a.y === 3);
    r = ++a;
    assert(a.x === 3 && a.y === 4);
    assert(r === a);
}

function test_default_op()
{
    assert(Object(1) + 2, 3);
    assert(Object(1) + true, 2);
    assert(-Object(1), -1);
}

test_operators_create();
test_operators();
test_default_op();