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printf 2 #14427

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ethereal-sheep opened this issue Aug 12, 2022 · 2 comments · May be fixed by #14428
Open

printf 2 #14427

ethereal-sheep opened this issue Aug 12, 2022 · 2 comments · May be fixed by #14428
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new-challenge Propose a new challenge, a PR will be auto generated

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@ethereal-sheep
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ethereal-sheep commented Aug 12, 2022 •
edited

Please follow the template and fill the info. A PR will be auto-generated and always reflect on your changes.

Detailed solution/guide is not required, but please be sure the challenge is solvable.

Info

Basic info of your challenge questions,

difficulty:  hard
title: printf 2
tags: template-literal

Question

printf is a c function which prints a format string with some arguments to stdout.

For this challenge, your task is to implement the Printf type which takes a format string as the first generic argument, and an array of arguments as the second generic argument.

Printf must follow a couple of rules.

  1. %d | %s | %b wildcards must be replaced with the appropriate type arguments.
    1.1 %d replaced with number
    1.2 %s replaced with string
    1.3 %b replaced with boolean
  2. %% must be escaped to a single %.
  3. Number of wildcards and arguments must be the same; else never.

Example:

type str = Printf<'%s %s', ['Hello', 'World']> // str: 'Hello World'

Template

type Printf<Fs extends string, Args extends any[]> = any

Test Cases

import type { Equal, Expect } from '@type-challenges/utils'

type cases = [
  Expect<Equal<Printf<'%s %s', ['Hello', 'World']>, 'Hello World'>>,
  Expect<Equal<Printf<'%s %d %s %b', ['All', 3, 'types', true]>, 'All 3 types true'>>,
  Expect<Equal<Printf<'Invalid', [true]>, never>>,
  Expect<Equal<Printf<'Invalid %b', []>, never>>,
  Expect<Equal<Printf<'Bad Order %d %s %b', [true, 1, 's']>, never>>,
  Expect<Equal<Printf<'Valid %%%b', [true]>, 'Valid %true'>>,
  Expect<Equal<Printf<'Convoluted %d%d%%%d%%%d %d', [1,2,3,4,5]>, 'Convoluted 12%3%4 5'>>,
  Expect<Equal<Printf<'Seems Wrong %%s %%d %%b', []>, 'Seems Wrong %s %d %b'>>,
  Expect<Equal<Printf<'Nothing happens %s %s %s', ['%s', '%s', '%s']>, 'Nothing happens %s %s %s'>>,
]

Solution:

type Printf<Fs extends string, Ts extends any[]> = 
  Fs extends `${infer Fl}%${infer C extends 's' | 'd' | 'b'}${infer Fr}` ?
    C extends 's' ?
      Ts extends [infer Tl extends string, ...infer Tr extends any[]] ?
        `${Fl}${Tl}${Printf<Fr, Tr>}` : never :
    C extends 'd' ?
      Ts extends [infer Tl extends number, ...infer Tr extends any[]] ?
        `${Fl}${Tl}${Printf<Fr, Tr>}` : never :
    C extends 'b' ?
      Ts extends [infer Tl extends boolean, ...infer Tr extends any[]] ?
        `${Fl}${Tl}${Printf<Fr, Tr>}` : never : 
    never :
  Fs extends `${infer Fl}%%${infer Fr}` ?      
     `${Fl}%${Printf<Fr, Ts>}` : 
  Fs extends `${infer Fl}${infer Fr}` ?      
     `${Fl}${Printf<Fr, Ts>}` : 
  Ts extends [any] ? never :
  Fs
@ethereal-sheep ethereal-sheep added the new-challenge Propose a new challenge, a PR will be auto generated label Aug 12, 2022
@github-actions github-actions bot linked a pull request Aug 12, 2022 that will close this issue
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github-actions bot commented Aug 12, 2022 •
edited

#14428 - Pull Request updated.

2022-09-01T09:57:35.710Z Preview in Playground

github-actions bot pushed a commit that referenced this issue Aug 12, 2022
@ethereal-sheep
feat(question): add #14427 - printf 2
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github-actions bot pushed a commit that referenced this issue Sep 1, 2022
@ethereal-sheep
feat(question): add #14427 - printf 2
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@ethereal-sheep
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Updated testcases.

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#14427 - printf 2 type-challenges/type-challenges
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