declare type Splitter = "-" | "_" | "/" | ".";
declare type FirstOfString<S extends string> = S extends `${infer F}${string}` ? F : never;
declare type RemoveFirstOfString<S extends string> = S extends `${string}${infer R}` ? R : never;
declare type IsUpper<S extends string> = S extends Uppercase<S> ? true : false;
declare type IsLower<S extends string> = S extends Lowercase<S> ? true : false;
declare type SameLetterCase<X extends string, Y extends string> = IsUpper<X> extends IsUpper<Y> ? true : IsLower<X> extends IsLower<Y> ? true : false;
declare type CapitalizedWords<T extends readonly string[], Accumulator extends string = ""> = T extends readonly [infer F extends string, ...infer R extends string[]] ? CapitalizedWords<R, `${Accumulator}${Capitalize<F>}`> : Accumulator;
declare type JoinLowercaseWords<T extends readonly string[], Joiner extends string, Accumulator extends string = ""> = T extends readonly [infer F extends string, ...infer R extends string[]] ? Accumulator extends "" ? JoinLowercaseWords<R, Joiner, `${Accumulator}${Lowercase<F>}`> : JoinLowercaseWords<R, Joiner, `${Accumulator}${Joiner}${Lowercase<F>}`> : Accumulator;
declare type LastOfArray<T extends any[]> = T extends [...any, infer R] ? R : never;
declare type RemoveLastOfArray<T extends any[]> = T extends [...infer F, any] ? F : never;
declare type SplitByCase<T, Separator extends string = Splitter, Accumulator extends unknown[] = []> = string extends Separator ? string[] : T extends `${infer F}${infer R}` ? [LastOfArray<Accumulator>] extends [never] ? SplitByCase<R, Separator, [F]> : LastOfArray<Accumulator> extends string ? R extends "" ? SplitByCase<R, Separator, [...RemoveLastOfArray<Accumulator>, `${LastOfArray<Accumulator>}${F}`]> : SameLetterCase<F, FirstOfString<R>> extends true ? F extends Separator ? FirstOfString<R> extends Separator ? SplitByCase<R, Separator, [...Accumulator, ""]> : IsUpper<FirstOfString<R>> extends true ? SplitByCase<RemoveFirstOfString<R>, Separator, [...Accumulator, FirstOfString<R>]> : SplitByCase<R, Separator, [...Accumulator, ""]> : SplitByCase<R, Separator, [...RemoveLastOfArray<Accumulator>, `${LastOfArray<Accumulator>}${F}`]> : IsLower<F> extends true ? SplitByCase<RemoveFirstOfString<R>, Separator, [...RemoveLastOfArray<Accumulator>, `${LastOfArray<Accumulator>}${F}`, FirstOfString<R>]> : SplitByCase<R, Separator, [...Accumulator, F]> : never : Accumulator extends [] ? T extends "" ? [] : string[] : Accumulator;
declare type PascalCase<T> = string extends T ? string : string[] extends T ? string : T extends string ? SplitByCase<T> extends readonly string[] ? CapitalizedWords<SplitByCase<T>> : never : T extends readonly string[] ? CapitalizedWords<T> : never;
declare type CamelCase<T> = string extends T ? string : string[] extends T ? string : Uncapitalize<PascalCase<T>>;
declare type JoinByCase<T, Joiner extends string> = string extends T ? string : string[] extends T ? string : T extends string ? SplitByCase<T> extends readonly string[] ? JoinLowercaseWords<SplitByCase<T>, Joiner> : never : T extends readonly string[] ? JoinLowercaseWords<T, Joiner> : never;

declare function isUppercase(char?: string): boolean | undefined;
declare function splitByCase<T extends string>(string_: T): SplitByCase<T>;
declare function splitByCase<T extends string, Separator extends readonly string[]>(string_: T, separators: Separator): SplitByCase<T, Separator[number]>;
declare function upperFirst<S extends string>(string_: S): Capitalize<S>;
declare function lowerFirst<S extends string>(string_: S): Uncapitalize<S>;
declare function pascalCase(): "";
declare function pascalCase<T extends string | readonly string[]>(string_: T): PascalCase<T>;
declare function camelCase(): "";
declare function camelCase<T extends string | readonly string[]>(string_: T): CamelCase<T>;
declare function kebabCase(): "";
declare function kebabCase<T extends string | readonly string[]>(string_: T): JoinByCase<T, "-">;
declare function kebabCase<T extends string | readonly string[], Joiner extends string>(string_: T, joiner: Joiner): JoinByCase<T, Joiner>;
declare function snakeCase(): "";
declare function snakeCase<T extends string | readonly string[]>(string_: T): JoinByCase<T, "_">;

export { camelCase, isUppercase, kebabCase, lowerFirst, pascalCase, snakeCase, splitByCase, upperFirst };