50 lines
1.7 KiB
JavaScript
50 lines
1.7 KiB
JavaScript
const require_windowed = require("../../array/windowed.js");
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const require_lazy = require("../_internal/lazy.js");
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//#region src/fp/array/windowed.ts
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/**
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* Creates a function that returns sliding windows from an array.
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*
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* By default only full windows are returned. Pass partialWindows: true to include shorter
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* trailing windows. The full-window form is lazy-capable inside {@link pipe}.
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*
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* @template T - The type of elements in the array.
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* @param size - The size of each window. Must be a positive integer.
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* @param step - The step between window starts. Defaults to 1.
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* @param options - Window options.
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* @returns A function that maps a readonly array to sliding windows.
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* @throws {Error} When size or step is not a positive integer.
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*
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* @example
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* import { pipe, windowed } from 'es-toolkit/fp';
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*
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* pipe([1, 2, 3, 4], windowed(2));
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* // => [[1, 2], [2, 3], [3, 4]]
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*/
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function windowed(size, step, options) {
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const resolvedStep = step ?? 1;
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const partialWindows = options?.partialWindows ?? false;
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function windowedEager(array) {
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return require_windowed.windowed(array, size, step, options);
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}
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if (partialWindows || !Number.isInteger(size) || size <= 0 || !Number.isInteger(resolvedStep) || resolvedStep <= 0) return windowedEager;
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const windowedLazy = (emit) => {
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const buffer = [];
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let index = 0;
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return (value) => {
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buffer.push(value);
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if (buffer.length > size) buffer.shift();
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if (buffer.length === size) {
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if ((index - size + 1) % resolvedStep === 0) {
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const shouldContinue = emit(buffer.slice());
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index++;
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return shouldContinue;
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}
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}
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index++;
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return true;
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};
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};
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return require_lazy.combineEagerAndLazyFunctions(windowedEager, windowedLazy);
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}
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//#endregion
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exports.windowed = windowed;
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