source: node_modules/ramda/es/reduceRight.js

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Last change on this file was d24f17c, checked in by Aleksandar Panovski <apano77@…>, 15 months ago

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[d24f17c]1import _curry3 from "./internal/_curry3.js";
2/**
3 * Returns a single item by iterating through the list, successively calling
4 * the iterator function and passing it an accumulator value and the current
5 * value from the array, and then passing the result to the next call.
6 *
7 * Similar to [`reduce`](#reduce), except moves through the input list from the
8 * right to the left.
9 *
10 * The iterator function receives two values: *(value, acc)*, while the arguments'
11 * order of `reduce`'s iterator function is *(acc, value)*. `reduceRight` may use [`reduced`](#reduced)
12 * to short circuit the iteration.
13 *
14 * Note: `R.reduceRight` does not skip deleted or unassigned indices (sparse
15 * arrays), unlike the native `Array.prototype.reduceRight` method. For more details
16 * on this behavior, see:
17 * https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/reduceRight#Description
18 *
19 * Be cautious of mutating and returning the accumulator. If you reuse it across
20 * invocations, it will continue to accumulate onto the same value. The general
21 * recommendation is to always return a new value. If you can't do so for
22 * performance reasons, then be sure to reinitialize the accumulator on each
23 * invocation.
24 *
25 * @func
26 * @memberOf R
27 * @since v0.1.0
28 * @category List
29 * @sig ((a, b) -> b) -> b -> [a] -> b
30 * @param {Function} fn The iterator function. Receives two values, the current element from the array
31 * and the accumulator.
32 * @param {*} acc The accumulator value.
33 * @param {Array} list The list to iterate over.
34 * @return {*} The final, accumulated value.
35 * @see R.reduce, R.addIndex, R.reduced
36 * @example
37 *
38 * R.reduceRight(R.subtract, 0, [1, 2, 3, 4]) // => (1 - (2 - (3 - (4 - 0)))) = -2
39 * // - -2
40 * // / \ / \
41 * // 1 - 1 3
42 * // / \ / \
43 * // 2 - ==> 2 -1
44 * // / \ / \
45 * // 3 - 3 4
46 * // / \ / \
47 * // 4 0 4 0
48 *
49 * @symb R.reduceRight(f, a, [b, c, d]) = f(b, f(c, f(d, a)))
50 */
51
52var reduceRight =
53/*#__PURE__*/
54_curry3(function reduceRight(fn, acc, list) {
55 var idx = list.length - 1;
56
57 while (idx >= 0) {
58 acc = fn(list[idx], acc);
59
60 if (acc && acc['@@transducer/reduced']) {
61 acc = acc['@@transducer/value'];
62 break;
63 }
64
65 idx -= 1;
66 }
67
68 return acc;
69});
70
71export default reduceRight;
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