[d24f17c] | 1 | import _curry3 from "./internal/_curry3.js";
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| 2 | /**
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| 3 | * The `mapAccumRight` function behaves like a combination of map and reduce; it
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| 4 | * applies a function to each element of a list, passing an accumulating
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| 5 | * parameter from right to left, and returning a final value of this
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| 6 | * accumulator together with the new list.
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| 7 | *
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| 8 | * Similar to [`mapAccum`](#mapAccum), except moves through the input list from
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| 9 | * the right to the left.
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| 10 | *
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| 11 | * The iterator function receives two arguments, *acc* and *value*, and should
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| 12 | * return a tuple *[acc, value]*.
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| 13 | *
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| 14 | * @func
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| 15 | * @memberOf R
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| 16 | * @since v0.10.0
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| 17 | * @category List
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| 18 | * @sig ((acc, x) -> (acc, y)) -> acc -> [x] -> (acc, [y])
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| 19 | * @param {Function} fn The function to be called on every element of the input `list`.
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| 20 | * @param {*} acc The accumulator value.
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| 21 | * @param {Array} list The list to iterate over.
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| 22 | * @return {*} The final, accumulated value.
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| 23 | * @see R.addIndex, R.mapAccum
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| 24 | * @example
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| 25 | *
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| 26 | * const digits = ['1', '2', '3', '4'];
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| 27 | * const appender = (a, b) => [b + a, b + a];
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| 28 | *
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| 29 | * R.mapAccumRight(appender, 5, digits); //=> ['12345', ['12345', '2345', '345', '45']]
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| 30 | * @symb R.mapAccumRight(f, a, [b, c, d]) = [
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| 31 | * f(f(f(a, d)[0], c)[0], b)[0],
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| 32 | * [
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| 33 | * f(a, d)[1],
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| 34 | * f(f(a, d)[0], c)[1],
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| 35 | * f(f(f(a, d)[0], c)[0], b)[1]
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| 36 | * ]
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| 37 | * ]
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| 38 | */
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| 39 |
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| 40 | var mapAccumRight =
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| 41 | /*#__PURE__*/
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| 42 | _curry3(function mapAccumRight(fn, acc, list) {
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| 43 | var idx = list.length - 1;
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| 44 | var result = [];
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| 45 | var tuple = [acc];
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| 46 |
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| 47 | while (idx >= 0) {
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| 48 | tuple = fn(tuple[0], list[idx]);
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| 49 | result[idx] = tuple[1];
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| 50 | idx -= 1;
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| 51 | }
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| 52 |
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| 53 | return [tuple[0], result];
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| 54 | });
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| 55 |
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| 56 | export default mapAccumRight; |
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