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