circ.js

require('lib/test');

// Circular reference detection.
function checkCircularRefs(obj, parents)
{
    var val;
    parents = parents || [];
    for (var key in obj)
    {
        if (!obj.hasOwnProperty(key)) continue;
        var val = obj[key];
        if (typeof(val) === 'object') {
            if (parents.indexOf(val) !== -1)
            {
                throw new Error("Circular reference detected");
            }
            parents.push(val);
            checkCircularRefs(val, parents);
            parents.pop();
        }
    }
}

// should throw
assertThrows(function () {
    var a = [];
    a.push(a);
    checkCircularRefs(a);
});

// should not throw
(function () {
    var a = [],
        b = [],
        c = [],
        d = [],
        e = [];
        g = [];
    a.push(b, c);
    b.push(d, e);
    c.push(g);
    d.push(c, g);
    checkCircularRefs(a);
})();

// should throw
assertThrows(function () {
    var a = [],
        b = [],
        c = [],
        d = [],
        e = [];
        g = [];
    a.push(b, c);
    b.push(d, e);
    c.push(g);
    d.push(a);
    checkCircularRefs(a);
});

// 2nd paragraph

// should not throw
(function () {
    var a = [],
        b = [],
        c = [],
        d = [],
        e = [];
        g = [];
    a.push(b, c);
    b.push(d, e);
    c.push(g);
    g.push(d);
    checkCircularRefs(a);
})();

// should throw
assertThrows(function () {
    var a = [],
        b = [],
        c = [],
        d = [],
        e = [];
        g = [];
    a.push(b, c);
    b.push(d, e);
    c.push(g);
    d.push(a);
    g.push(d);
    checkCircularRefs(a);
});