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Split

2022-05-20 11

题目来源(type-challenges)

问题 

type case1 = Split<'Hi! How are you?', 'z'> // ['Hi! How are you?']
type case2 = Split<'Hi! How are you?', ' '> // ['Hi!', 'How', 'are', 'you?']
type case3 = Split<'Hi! How are you?', ''> // ['H', 'i', '!', ' ', 'H', 'o', 'w', ' ', 'a', 'r', 'e', ' ', 'y', 'o', 'u', '?']
type case4 = Split<'', ''> // []
type case5 = Split<'', 'z'> // ['']
type case6 = Split<string, 'whatever'> // string[]

解答 

type Split<S extends string, SEP extends string> =
string extends S
? string[]
: S extends `${infer A}${SEP}${infer B}`
  ? [A, ...Split<B, SEP>]
  : S extends ''
    ? SEP extends '' ? [] : [S]
    : [S]

拆分

  1. string extends S S extends '' SEP extends '' 是为了通过测试用例没必要算上去
  2. 正常核心代码就 S extends${infer A}${SEP}${infer B}``
cd ..