00147-hard-c-printf-parser.ts

// ============= Test Cases =============
import type { Equal, Expect } from './test-utils'

type cases = [
  Expect<Equal<ParsePrintFormat<''>, []>>,
  Expect<Equal<ParsePrintFormat<'Any string.'>, []>>,
  Expect<Equal<ParsePrintFormat<'The result is %d.'>, ['dec']>>,
  Expect<Equal<ParsePrintFormat<'The result is %%d.'>, []>>,
  Expect<Equal<ParsePrintFormat<'The result is %%%d.'>, ['dec']>>,
  Expect<Equal<ParsePrintFormat<'The result is %f.'>, ['float']>>,
  Expect<Equal<ParsePrintFormat<'The result is %h.'>, ['hex']>>,
  Expect<Equal<ParsePrintFormat<'The result is %q.'>, []>>,
  Expect<Equal<ParsePrintFormat<'Hello %s: score is %d.'>, ['string', 'dec']>>,
  Expect<Equal<ParsePrintFormat<'The result is %'>, []>>
]

// ============= Your Code Here =============
type ControlsMap = {
  c: 'char'
  s: 'string'
  d: 'dec'
  o: 'oct'
  h: 'hex'
  f: 'float'
  p: 'pointer'
}

type ParsePrintFormat<T extends string> =
  T extends `${string}%${infer Head}${infer Tail}`
    ? Head extends keyof ControlsMap
      ? [ControlsMap[Head], ...ParsePrintFormat<Tail>]
      : ParsePrintFormat<Tail>
    : []

type Test = ParsePrintFormat<'The result is %d.'>