repeat.js

var O = require("pop-observe");
var swap = require("pop-swap");

var empty = [];

module.exports = Repetition;
function Repetition(body, scope) {
    this.body = body;
    this.scope = scope;
    this.iterations = [];
    this.Iteration = scope.argument.component;
    this.id = scope.id;
    this.observer = null;
    this._value = null;
    this.value = [];
}

Object.defineProperty(Repetition.prototype, "value", {
    get: function () {
        return this._value;
    },
    set: function (value) {
        if (!Array.isArray(value)) {
            throw new Error('Value of repetition must be an array');
        }
        if (this.observer) {
            this.observer.cancel();
            this.handleValueRangeChange(empty, this._value, 0);
        }
        this._value = value;
        this.handleValueRangeChange(this._value, empty, 0);
        this.observer = O.observeRangeChange(this._value, this, "value");
    }
});

Repetition.prototype.handleValueRangeChange = function (plus, minus, index) {
    var body = this.body;
    var document = this.body.ownerDocument;

    for (var offset = index; offset < index + minus.length; offset++) {
        var iteration = this.iterations[offset];
        body.removeChild(iteration.body);
        iteration.value = null;
        iteration.index = null;
        iteration.body = null;
        if (iteration.destroy) {
            iteration.destroy();
        }
    }

    var nextIteration = this.iterations[index];
    var nextSibling = nextIteration && nextIteration.body;

    var add = [];
    for (var offset = 0; offset < plus.length; offset++) {
        var value = plus[offset];
        var iterationNode = document.createBody();
        var iterationScope = this.scope.nestComponents();

        var iteration = new this.Iteration(iterationNode, iterationScope);

        iteration.value = value;
        iteration.index = index + offset;
        iteration.body = iterationNode;

        iterationScope.hookup(this.scope.id + ":iteration", iteration);

        body.insertBefore(iterationNode, nextSibling);
        add.push(iteration);
    }

    swap(this.iterations, index, minus.length, add);

    // Update indexes
    for (var offset = index; offset < this.iterations.length; offset++) {
        this.iterations[offset].index = offset;
    }
};

Repetition.prototype.redraw = function (region) {
    for (var index = 0; index < this.iterations.length; index++) {
        var iteration = this.iterations[index];
        iteration.redraw(region);
    }
};

Repetition.prototype.destroy = function () {
    this.observer.cancel();
    this.handleValuesRangeChange([], this._value, 0);
};