'use strict'
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/**
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* Expose `arrayFlatten`.
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*/
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module.exports = flatten
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module.exports.from = flattenFrom
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module.exports.depth = flattenDepth
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module.exports.fromDepth = flattenFromDepth
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/**
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* Flatten an array.
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*
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* @param {Array} array
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* @return {Array}
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*/
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function flatten (array) {
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if (!Array.isArray(array)) {
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throw new TypeError('Expected value to be an array')
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}
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return flattenFrom(array)
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}
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/**
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* Flatten an array-like structure.
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*
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* @param {Array} array
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* @return {Array}
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*/
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function flattenFrom (array) {
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return flattenDown(array, [])
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}
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/**
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* Flatten an array-like structure with depth.
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*
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* @param {Array} array
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* @param {number} depth
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* @return {Array}
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*/
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function flattenDepth (array, depth) {
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if (!Array.isArray(array)) {
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throw new TypeError('Expected value to be an array')
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}
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return flattenFromDepth(array, depth)
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}
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/**
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* Flatten an array-like structure with depth.
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*
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* @param {Array} array
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* @param {number} depth
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* @return {Array}
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*/
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function flattenFromDepth (array, depth) {
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if (typeof depth !== 'number') {
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throw new TypeError('Expected the depth to be a number')
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}
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return flattenDownDepth(array, [], depth)
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}
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/**
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* Flatten an array indefinitely.
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*
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* @param {Array} array
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* @param {Array} result
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* @return {Array}
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*/
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function flattenDown (array, result) {
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for (var i = 0; i < array.length; i++) {
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var value = array[i]
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if (Array.isArray(value)) {
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flattenDown(value, result)
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} else {
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result.push(value)
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}
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}
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return result
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}
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/**
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* Flatten an array with depth.
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*
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* @param {Array} array
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* @param {Array} result
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* @param {number} depth
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* @return {Array}
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*/
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function flattenDownDepth (array, result, depth) {
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depth--
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for (var i = 0; i < array.length; i++) {
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var value = array[i]
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if (depth > -1 && Array.isArray(value)) {
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flattenDownDepth(value, result, depth)
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} else {
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result.push(value)
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}
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}
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return result
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}
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