@phosphor/algorithm
Version:
PhosphorJS - Algorithms and Iterators
84 lines (83 loc) • 2.52 kB
JavaScript
;
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");
/**
* Transform the values of an iterable with a mapping function.
*
* @param object - The iterable or array-like object of interest.
*
* @param fn - The mapping function to invoke for each value.
*
* @returns An iterator which yields the transformed values.
*
* #### Example
* ```typescript
* import { map, toArray } from '@phosphor/algorithm';
*
* let data = [1, 2, 3];
*
* let stream = map(data, value => value * 2);
*
* toArray(stream); // [2, 4, 6]
* ```
*/
function map(object, fn) {
return new MapIterator(iter_1.iter(object), fn);
}
exports.map = map;
/**
* An iterator which transforms values using a mapping function.
*/
var MapIterator = /** @class */ (function () {
/**
* Construct a new map iterator.
*
* @param source - The iterator of values of interest.
*
* @param fn - The mapping function to invoke for each value.
*/
function MapIterator(source, fn) {
this._index = 0;
this._source = source;
this._fn = fn;
}
/**
* Get an iterator over the object's values.
*
* @returns An iterator which yields the object's values.
*/
MapIterator.prototype.iter = function () {
return this;
};
/**
* Create an independent clone of the iterator.
*
* @returns A new independent clone of the iterator.
*/
MapIterator.prototype.clone = function () {
var result = new MapIterator(this._source.clone(), this._fn);
result._index = this._index;
return result;
};
/**
* Get the next value from the iterator.
*
* @returns The next value from the iterator, or `undefined`.
*/
MapIterator.prototype.next = function () {
var value = this._source.next();
if (value === undefined) {
return undefined;
}
return this._fn.call(undefined, value, this._index++);
};
return MapIterator;
}());
exports.MapIterator = MapIterator;