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/**
* Like `Array#splice`, but smarter for giant arrays.
*
* `Array#splice` takes all items to be inserted as individual argument which
* causes a stack overflow in V8 when trying to insert 100k items for instance.
*
* Otherwise, this does not return the removed items, and takes `items` as an
* array instead of rest parameters.
*
* @template {unknown} T
* Item type.
* @param {Array<T>} list
* List to operate on.
* @param {number} start
* Index to remove/insert at (can be negative).
* @param {number} remove
* Number of items to remove.
* @param {Array<T>} items
* Items to inject into `list`.
* @returns {void}
* Nothing.
*/
export function splice(list, start, remove, items) {
const end = list.length
let chunkStart = 0
/** @type {Array<unknown>} */
let parameters
// Make start between zero and `end` (included).
if (start < 0) {
start = -start > end ? 0 : end + start
} else {
start = start > end ? end : start
}
remove = remove > 0 ? remove : 0
// No need to chunk the items if there’s only a couple (10k) items.
if (items.length < 10000) {
parameters = Array.from(items)
parameters.unshift(start, remove)
// @ts-expect-error Hush, it’s fine.
list.splice(...parameters)
} else {
// Delete `remove` items starting from `start`
if (remove) list.splice(start, remove)
// Insert the items in chunks to not cause stack overflows.
while (chunkStart < items.length) {
parameters = items.slice(chunkStart, chunkStart + 10000)
parameters.unshift(start, 0)
// @ts-expect-error Hush, it’s fine.
list.splice(...parameters)
chunkStart += 10000
start += 10000
}
}
}
/**
* Append `items` (an array) at the end of `list` (another array).
* When `list` was empty, returns `items` instead.
*
* This prevents a potentially expensive operation when `list` is empty,
* and adds items in batches to prevent V8 from hanging.
*
* @template {unknown} T
* Item type.
* @param {Array<T>} list
* List to operate on.
* @param {Array<T>} items
* Items to add to `list`.
* @returns {Array<T>}
* Either `list` or `items`.
*/
export function push(list, items) {
if (list.length > 0) {
splice(list, list.length, 0, items)
return list
}
return items
}
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