我想将字符串文字从camelCase转换为snake_case,例如:
type CamelCaseStr = "helloWorldAgain"
type _ = ToSnakeCase<CamelCaseStr> // "hello_world_again"
这是我的解决方案:
type str = "helloWorldAgain";
type UpperCollection = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
type Chars<T extends string> = T extends `${infer Char}${infer Rest}` ? Char | Chars<Rest> : never;
type UpperLetters = Chars<UpperCollection>;
type ToSnakeCase<T extends string> =
T extends `${infer LowerStr}${UpperLetters}${infer AfterFirstBigLetter}` ?
T extends `${LowerStr}${infer WithFirstBigLetter}` ?
`${LowerStr}_${ToSnakeCase<Uncapitalize<WithFirstBigLetter>>}` :
LowerStr :
T;
type _ = ToSnakeCase<str>;
// type _ = "helloWorld_again" | "helloWorld_world_again" | "hello_again" | "hello_world_again"
我尝试提取
LowerStr
,直到第一次遇到大写字母,因此提取第一个大写的str,然后Uncapitalize
它并再次使用ToSnakeCase
。然而结果是错误的,所以我写了一些测试代码。
type TestToSnakeCase<T extends string> =
T extends `${infer LowerStr}${UpperLetters}${infer AfterFirstBigLetter}` ?
T extends `${LowerStr}${infer WithFirstBigLetter}` ?
[LowerStr, WithFirstBigLetter] :
never
: T;
type __ = TestToSnakeCase<str>;
// type __ = ["helloWorld" | "hello", "Again" | "WorldAgain"];
问题似乎已经减少到消除歧视的地步。我搜索并发现这个链接很有用,我再次尝试了。
type ShutDiscrimination<T extends string> =
[T] extends [`${infer LowerStr}${UpperLetters}${infer AfterFirstBigLetter}`] ?
[T] extends [`${LowerStr}${infer WithFirstBigLetter}`] ?
`${LowerStr}_${ShutDiscrimination<Uncapitalize<WithFirstBigLetter>>}` :
LowerStr :
T;
type ___ = ShutDiscrimination<str>;
// type ___ = "helloWorld_again" | "helloWorld_worldAgain" | "hello_again" | "hello_worldAgain"
为了解决这个问题我错过了什么关键的事情吗?我希望我能很好地表达我的想法,格式化相当麻烦:)
代码的主要问题是您直接在推断的条件子句中使用
UpperLetters
。由于 UpperLetters
只能是单个字符,因此您应该推断该字符,然后检查它是否为 extends
UpperLetters
。这将使您看到的联合变平。
type UpperLetter = "a" | "b";
type Parse<S extends string> = S extends
`${infer $Start}${infer $UpperLetter}${infer $Rest}`
? $UpperLetter extends UpperLetter ? true : false
: false;
无论如何,我自己尝试了这个问题,没有使用静态
UpperLetter
联合,通过检查Capitalize<S>
是否等于S
。在这里:
type CamelToSnakeCase<S extends string, $Acc extends string = ""> =
//
S extends `${infer $Ch}${infer $Rest}`
? S extends Capitalize<S>
? CamelToSnakeCase<$Rest, `${$Acc}_${Lowercase<$Ch>}`>
: CamelToSnakeCase<$Rest, `${$Acc}${$Ch}`>
: $Acc;
type foo = CamelToSnakeCase<"helloAwesomeWorld">; // "hello_awesome_world"
type foo2 = CamelToSnakeCase<"">; // ""
type foo3 = CamelToSnakeCase<"bruhSOCool">; // "bruh_s_o_cool"
type SnakeToCamelCase<S extends string, $Acc extends string = ""> =
//
S extends `${infer $Ch}${infer $Rest}`
? $Ch extends "_"
? $Rest extends `${infer $Ch}${infer $Rest}`
? SnakeToCamelCase<$Rest, `${$Acc}${Capitalize<$Ch>}`>
: ""
: SnakeToCamelCase<$Rest, `${$Acc}${$Ch}`>
: $Acc;
type asdf = SnakeToCamelCase<"hello_awesome_world">; // "helloAwesomeWorld"
type asdf2 = SnakeToCamelCase<"bruh_s_o_cool">; // "bruhSOCool"
type asdf3 = SnakeToCamelCase<"">; // ""
type asdf4 = SnakeToCamelCase<"so_cool_bro">; // "soCoolBro"
编辑:修复您的代码的不是工会。事实上,当我做
${infer $Ch}${infer $Rest}
时,我推断出下一个字母,然后通过Capitalize
检查它是否是大写。您正在执行 ${infer LowerStr}${UpperLetters}${infer AfterFirstBigLetter}
计算 UpperLetters
中每个分支的字符串值,这会导致 LowerStr
和 AfterFirstBigLetter
出现多种类型的问题。这是一个例子:
type UpperLetter = "A" | "B" | "C" | "D" // ..
// This is going to go through each computed type in the extends clause and come up with multiple
// answers in the union for after the various characters.
type bad = "ABCD" extends `${string}${UpperLetter}${infer $After}` ? $After : never; // "" | "D" | "BCD" | "CD"
// Now, let's fix the code by writing an infer character to force the extends clause to only have one possible combination.
// This can be done by replacing `UpperLetter` with `infer $Ch` because any `string` / `infer $Ch` and removing the leading
// `${string}` part.
type fixed = "ABCD" extends `${infer $Ch}${infer $After}` ? $Ch extends UpperLetter ? $After : never : never; // "BCD"
这是我的解决方案,灵感来自@sno2
我关注的是只有一种方法可以将“目标字符”与递归进行比较,没有
Alphabet Collection
。
export type CamelCaseToSnakeCase<
T extends string,
Joiner extends '' | '_' = ''
> = T extends `${infer Character}${infer Rest}`
? Character extends Uppercase<Character>
? `${Joiner}${Lowercase<Character>}${CamelCaseToSnakeCase<Rest, '_'>}`
: `${Character}${CamelCaseToSnakeCase<Rest, '_'>}`
: '';