src/array/range.ts
import { AsyncIterable2 } from '../iter/asyncIterable2'
import { Iterable2 } from '../iter/iterable2'
/* eslint-disable no-redeclare, unicorn/no-new-array */
/**
* Returns an array with ranges from `from` up to (but not including) `to`.
*
* Right bound is Exclusive (not Inclusive), to comply with lodash _.range
*
* @example
* range(3) // [0, 1, 2]
* range(3, 6) // [ 3, 4, 5 ]
* range(1, 10, 2) // [ 1, 3, 5, 7, 9 ]
*/
export function _range(toExcl: number): number[]
export function _range(fromIncl: number, toExcl: number, step?: number): number[]
export function _range(fromIncl: number, toExcl?: number, step = 1): number[] {
if (toExcl === undefined) {
return Array.from(new Array(fromIncl), (_, i) => i)
}
return Array.from(
{ length: Math.ceil((toExcl - fromIncl) / step) },
(_, i) => i * step + fromIncl,
)
}
/**
* Like _range, but returns an Iterable2.
*/
export function _rangeIterable(toExcl: number): Iterable2<number>
export function _rangeIterable(fromIncl: number, toExcl: number, step?: number): Iterable2<number>
export function _rangeIterable(fromIncl: number, toExcl?: number, step = 1): Iterable2<number> {
if (toExcl === undefined) {
toExcl = fromIncl
fromIncl = 0
}
return Iterable2.of({
*[Symbol.iterator]() {
for (let i = fromIncl; i < toExcl; i += step) {
yield i
}
},
})
}
/**
* Like _range, but returns an AsyncIterable2.
*/
export function _rangeAsyncIterable(toExcl: number): AsyncIterable2<number>
export function _rangeAsyncIterable(
fromIncl: number,
toExcl: number,
step?: number,
): AsyncIterable2<number>
export function _rangeAsyncIterable(
fromIncl: number,
toExcl?: number,
step = 1,
): AsyncIterable2<number> {
if (toExcl === undefined) {
toExcl = fromIncl
fromIncl = 0
}
return AsyncIterable2.of({
async *[Symbol.asyncIterator]() {
for (let i = fromIncl; i < toExcl; i += step) {
yield i
}
},
})
}