@phosphor/algorithm/lib/stride.js

PhosphorJS - Algorithms and Iterators

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
/*-----------------------------------------------------------------------------
| Copyright (c) 2014-2017, PhosphorJS Contributors
|
| Distributed under the terms of the BSD 3-Clause License.
|
| The full license is in the file LICENSE, distributed with this software.
|----------------------------------------------------------------------------*/
var iter_1 = require("./iter");
/**
 * Iterate over an iterable using a stepped increment.
 *
 * @param object - The iterable or array-like object of interest.
 *
 * @param step - The distance to step on each iteration. A value
 *   of less than `1` will behave the same as a value of `1`.
 *
 * @returns An iterator which traverses the iterable step-wise.
 *
 * #### Example
 * ```typescript
 * import { stride, toArray } from '@phosphor/algorithm';
 *
 * let data = [1, 2, 3, 4, 5, 6];
 *
 * let stream = stride(data, 2);
 *
 * toArray(stream);  // [1, 3, 5];
 * ```
 */
function stride(object, step) {
    return new StrideIterator(iter_1.iter(object), step);
}
exports.stride = stride;
/**
 * An iterator which traverses a source iterator step-wise.
 */
var StrideIterator = /** @class */ (function () {
    /**
     * Construct a new stride iterator.
     *
     * @param source - The iterator of values of interest.
     *
     * @param step - The distance to step on each iteration. A value
     *   of less than `1` will behave the same as a value of `1`.
     */
    function StrideIterator(source, step) {
        this._source = source;
        this._step = step;
    }
    /**
     * Get an iterator over the object's values.
     *
     * @returns An iterator which yields the object's values.
     */
    StrideIterator.prototype.iter = function () {
        return this;
    };
    /**
     * Create an independent clone of the iterator.
     *
     * @returns A new independent clone of the iterator.
     */
    StrideIterator.prototype.clone = function () {
        return new StrideIterator(this._source.clone(), this._step);
    };
    /**
     * Get the next value from the iterator.
     *
     * @returns The next value from the iterator, or `undefined`.
     */
    StrideIterator.prototype.next = function () {
        var value = this._source.next();
        for (var n = this._step - 1; n > 0; --n) {
            this._source.next();
        }
        return value;
    };
    return StrideIterator;
}());
exports.StrideIterator = StrideIterator;