rambda/_ts-toolbelt/src/Number/NumberOf.ts

Lightweight faster alternative to Ramda

import {IterationMap} from '../Iteration/IterationOf'
import {SelectKeys} from '../Object/SelectKeys'
import {Numbers} from './_Internal'
import {Key} from '../Iteration/Key'

type NumberToIterationMap = {
    0 : ['-1', '1', '0', 0, '0']
    1 : ['0', '2', '1', 1, '+'],
    2 : ['1', '3', '2', 2, '+'],
    3 : ['2', '4', '3', 3, '+'],
    4 : ['3', '5', '4', 4, '+'],
    5 : ['4', '6', '5', 5, '+'],
    6 : ['5', '7', '6', 6, '+'],
    7 : ['6', '8', '7', 7, '+'],
    8 : ['7', '9', '8', 8, '+'],
    9 : ['8', '10', '9', 9, '+'],
    10: ['9', '11', '10', 10, '+'],
    11: ['10', '12', '11', 11, '+'],
    12: ['11', '13', '12', 12, '+'],
    13: ['12', '14', '13', 13, '+'],
    14: ['13', '15', '14', 14, '+'],
    15: ['14', '16', '15', 15, '+'],
    16: ['15', '17', '16', 16, '+'],
    17: ['16', '18', '17', 17, '+'],
    18: ['17', '19', '18', 18, '+'],
    19: ['18', '20', '19', 19, '+'],
    20: ['19', '21', '20', 20, '+'],
    21: ['20', '22', '21', 21, '+'],
    22: ['21', '23', '22', 22, '+'],
    23: ['22', '24', '23', 23, '+'],
    24: ['23', '25', '24', 24, '+'],
    25: ['24', '26', '25', 25, '+'],
    26: ['25', '27', '26', 26, '+'],
    27: ['26', '28', '27', 27, '+'],
    28: ['27', '29', '28', 28, '+'],
    29: ['28', '30', '29', 29, '+'],
    30: ['29', '31', '30', 30, '+'],
    31: ['30', '32', '31', 31, '+'],
    32: ['31', '33', '32', 32, '+'],
    33: ['32', '34', '33', 33, '+'],
    34: ['33', '35', '34', 34, '+'],
    35: ['34', '36', '35', 35, '+'],
    36: ['35', '37', '36', 36, '+'],
    37: ['36', '38', '37', 37, '+'],
    38: ['37', '39', '38', 38, '+'],
    39: ['38', '40', '39', 39, '+'],
    40: ['39', '__', '40', 40, '+'],
}

/** Transform a **`number`** into a **`Number`**
 * @param N to stringify
 * @returns **`string`**
 * @example
 * ```ts
 * import {N} from 'ts-toolbelt'
 *
 * type test0 = N.StringOf<5>  //  '5'
 * type test1 = N.StringOf<-5> // '-5'
 * ```
 */
export type NumberOf<N extends number> =
    N extends keyof NumberToIterationMap
    ? Key<NumberToIterationMap[N]>
    : N extends Numbers['number']['-'] // expensive with negative numbers
      ? Key<IterationMap[SelectKeys<IterationMap, [any, any, any, N, any]>]>
    : string // out of range