36 lines
1.3 KiB
JavaScript
36 lines
1.3 KiB
JavaScript
const require_lazy = require("../_internal/lazy.js");
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//#region src/fp/array/map.ts
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/**
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* Creates a function that builds a new array by calling `callback` on every
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* element, equivalent to `Array.prototype.map`. Use it with {@link pipe}.
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*
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* The returned function is **lazy-capable**: inside a {@link pipe} it is fused
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* with adjacent lazy functions and runs element-by-element, so a trailing
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* `take` can terminate the walk early without mapping the rest of the input.
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*
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* @template T - The type of elements in the input array.
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* @template U - The type of elements in the output array.
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* @param callback - Called with `(value, index)` for each element; its return
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* value becomes the corresponding element of the output array.
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* @returns A function that maps a `readonly T[]` to a new `U[]`.
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*
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* @example
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* import { pipe, map } from 'es-toolkit/fp';
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*
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* pipe([1, 2, 3], map(x => x * 2)); // => [2, 4, 6]
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*
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* @example
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* // The index is available as the second argument.
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* pipe([10, 20, 30], map((value, index) => value + index)); // => [10, 21, 32]
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*/
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function map(callback) {
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function mapEager(array) {
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return array.map(callback);
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}
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const mapLazy = require_lazy.createLazyFunction((value, index, emit) => {
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emit(callback(value, index));
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});
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return require_lazy.combineEagerAndLazyFunctions(mapEager, mapLazy);
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}
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//#endregion
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exports.map = map;
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