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import type { Num, U } from './index.ts';
/** * Returns the length of the given string S. * @example * ```ts * Length<'abc'> => 3 * ``` */export type Length<S extends string> = LengthHelper<S, 0>;
type LengthHelper<S extends string, Result extends number> = S extends ''  ? Result  : S extends `${string}${string}${string}${string}${string}${string}${string}${string}${string}${string}${infer Rest}`  ? LengthHelper<Rest, Num.Add<Result, 10>>  : S extends `${string}${string}${string}${string}${string}${infer Rest}`  ? LengthHelper<Rest, Num.Add<Result, 5>>  : S extends `${string}${infer Rest}`  ? LengthHelper<Rest, Num.Add<Result, 1>>  : Result;
/** * Convenience type to represent the concatenation of two string types. * @example * ```ts * Append<'abc', 'def'> => 'abcdef' * Append<'abc', 'd' | 'e'> => 'abcd' | 'abce' * ``` */export type Append<Start extends string, End extends string> = `${Start}${End}`;
/** * Convenience type to represent the concatenation of three string types. * @example * ```ts * AppendTwo<'abc', 'def', 'ghi'> => 'abcdefghi' * AppendTwo<'abc', 'd' | 'e', 'fgh'> => 'abcdfgh' | 'abcefgh' * ``` */export type AppendTwo<  Start extends string,  Middle extends string,  End extends string> = `${Start}${Middle}${End}`;
/** * Returns false if the given string is empty, true otherwise. * @example * ```ts * IsNonEmptyString<''> => false * IsNonEmptyString<'abc'> => true * ``` */export type IsNonEmptyString<S extends string> = '' extends S ? false : true;
/** * Returns never if the given string is empty, otherwise the given string. * @example * ```ts * NonEmptyString<''> => never * NonEmptyString<'abc'> => 'abc' * ``` */export type NonEmptyString<S extends string> = '' extends S ? never : unknown;
/** * If the given string does not start with the given `Start` type, returns false. * Otherwise, returns a tuple containing the matched start and the rest. * @example * ```ts * StartsWith<'abcd', 'ab'> => ['ab', 'cd'] * StartsWith<'abcd', 'd'> => false * StartsWith<'abcd', 'ab' | 'bc'> => ['ab', 'cd'] * StartsWith<'abcd', 'ab' | 'a'> => ['ab', 'cd'] | ['a', 'bcd'] * ``` */export type StartsWith<  S extends string,  Start extends string & NonEmptyString<Start>> = S extends Append<Start, infer Rest>  ? S extends Append<infer StartInstance, Rest>    ? [StartInstance, Rest]    : false  : false;
/** * If the given string does not end with the given `End` type, returns false. * Otherwise, returns a tuple containing the start and the matched end. * @example * ```ts * EndsWith<'abcd', 'cd'> => ['ab', 'cd'] * EndsWith<'abcd', 'a'> => false * EndsWith<'abcd', 'cd' | 'de'> => ['ab', 'cd'] * EndsWith<'abcd', 'cd' | 'd'> => ['ab', 'cd'] | ['abc', 'd'] * ``` */export type EndsWith<  S extends string,  End extends string & NonEmptyString<End>> = S extends Append<infer Start, End>  ? S extends Append<Start, infer EndInstance>    ? [Start, EndInstance]    : false  : false;
/** * Returns false if the given string does not contain the given `Middle` type, * or a 3-tuple containing the start, the matched middle, and the rest. * @example * ```ts * SplitAt<'abcd', 'bc'> => ['a', 'bc', 'd'] * SplitAt<'abcd', 'ef'> => false * SplitAt<'abcd', 'b' | 'c'> => ['a', 'b', 'cd'] | ['ab', 'c', 'd'] * ``` */export type SplitAt<  S extends string,  Middle extends string & NonEmptyString<Middle>> = S extends AppendTwo<infer Start, Middle, infer End>  ? S extends AppendTwo<Start, infer MiddleInstance, End>    ? [Start, MiddleInstance, End]    : false  : ['', '', S];
/** * Returns a string containing all the elements that do not match the given Sub type. * @example * ```ts * FilterNot<'abcd', 'b'> => 'acd' * FilterNot<'abcd', 'b' | 'd'> => 'ac' * ``` */export type FilterNot<  S extends string,  Sub extends string & NonEmptyString<Sub>> = FilterNotHelper<S, Sub, ''>;
type FilterNotHelper<  S extends string,  Sub extends string & NonEmptyString<Sub>,  Result extends string> = S extends ''  ? Result  : S extends Append<Sub, infer Rest>  ? FilterNotHelper<Rest, Sub, Result>  : S extends Append<infer First, infer Rest>  ? FilterNotHelper<Rest, Sub, Append<Result, First>>  : '';
/** * Returns a string containing all the elements that match the given Sub type. * @example * ```ts * Filter<'abcd', 'b'> => 'b' * Filter<'abcd', 'b' | 'd'> => 'bd' * ``` */
export type Filter<  S extends string,  Sub extends string & NonEmptyString<Sub>> = FilterHelper<S, Sub, ''>;
type FilterHelper<  S extends string,  Sub extends string & NonEmptyString<Sub>,  Result extends string> = S extends ''  ? Result  : StartsWith<S, Sub> extends [infer SubInstance, infer Rest]  ? FilterHelper<string & Rest, Sub, Append<Result, string & SubInstance>>  : S extends Append<string, infer Rest>  ? FilterHelper<Rest, Sub, Result>  : '';
/** * Replaces, in the given string, all matches with Sub with the given Repl. * @example * ```ts * ReplaceAll<'abcba', 'b', '_'> => 'a_c_a' * ReplaceAll<'abcba', 'b' | 'c', '_'> => 'a___a' * ``` */export type ReplaceAll<  S extends string,  Sub extends string & NonEmptyString<Sub>,  Repl extends string> = S extends ''  ? ''  : S extends Append<Sub, infer Rest>  ? Append<Repl, ReplaceAll<Rest, Sub, Repl>>  : S extends Append<infer Start, infer Rest>  ? Append<Start, ReplaceAll<Rest, Sub, Repl>>  : never;
/** * Replaces, in the given string, the first match with Sub with the given Repl. * Returns never if there was no match. * @example * ```ts * ReplaceFirst<'abcba', 'b', '_'> => 'a_cba' * ReplaceFirst<'abcba', 'b' | 'c', '_'> => 'a_cba' * ``` */export type ReplaceFirst<  S extends string,  Sub extends string & NonEmptyString<Sub>,  Repl extends string> = S extends ''  ? never  : S extends Append<Sub, infer Rest>  ? Append<Repl, Rest>  : S extends Append<infer Start, infer Rest>  ? Append<Start, ReplaceFirst<Rest, Sub, Repl>>  : never;
/** * Replaces, in the given string, the last match with Sub with the given Repl. * Returns never if there was no match. * @example * ```ts * ReplaceLast<'abcba', 'b', '_'> => 'abc_a' * ReplaceLast<'abcba', 'b' | 'c', '_'> => 'abc_a' * ``` */export type ReplaceLast<  S extends string,  Sub extends string & NonEmptyString<Sub>,  Repl extends string> = ReplaceLastHelper<S, Sub, Repl, false>;
type ReplaceLastHelper<  S extends string,  Sub extends string & NonEmptyString<Sub>,  Repl extends string,  Replaced extends boolean> = S extends ''  ? Replaced extends true    ? ''    : never  : StartsWith<S, Sub> extends [infer SubInstance, infer Rest]  ? ReplaceLastHelper<string & Rest, Sub, Repl, true> extends infer Result    ? Append<        Result extends Rest ? string & Repl : string & SubInstance,        string & Result      >    : never  : S extends Append<infer Start, infer Rest>  ? Append<Start, ReplaceLastHelper<Rest, Sub, Repl, Replaced>>  : never;
/** * Returns the amount of times the given `Sub` type is encountered in the given string. * @example * ```ts * Count<'abcba', 'c'> => 1 * Count<'abcba', 'a' | 'c'> => 3 * Count<'abcba', 'q'> => 0 * ``` */export type Count<  S extends string,  Sub extends string & NonEmptyString<Sub>> = CountHelper<S, Sub, 0>;
type CountHelper<  S extends string,  Sub extends string & NonEmptyString<Sub>,  Result extends number> = S extends ''  ? Result  : S extends Append<Sub, infer Rest>  ? CountHelper<Rest, Sub, Num.Inc<Result>>  : S extends Append<string, infer Rest>  ? CountHelper<Rest, Sub, Result>  : Result;
/** * Returns true if the given string contains the given Amount (default 1) of Sub types. * @example * ```ts * Contains<'abcba', 'b'> => true * Contains<'abcba', 'b', 2> => true * Contains<'abcba', 'b', 3> => false * Contains<'abcba', 'q'> => false * ``` */export type Contains<  S extends string,  Sub extends string & NonEmptyString<Sub>,  Amount extends number = 1> = Amount extends 0  ? true  : S extends Append<Sub, infer Rest>  ? Contains<Rest, Sub, Num.Decr<Amount>>  : S extends Append<string, infer Rest>  ? Contains<Rest, Sub, Amount>  : false;
/** * Returns true if the given string does not contain the given Amount (default 1) of Sub types. * @example * ```ts * NotContains<'abcba', 'b'> => false * NotContains<'abcba', 'b', 2> => false * NotContains<'abcba', 'b', 3> => true * NotContains<'abcba', 'q'> => true * ``` */export type NotContains<  S extends string,  Sub extends string & NonEmptyString<Sub>,  Amount extends number = 1> = Contains<S, Sub, Amount> extends false ? true : false;
export type RepeatTimes<  S extends string,  Sub extends string & NonEmptyString<Sub>> = RepeatTimesHelper<S, Sub, [0, '']>;
type RepeatTimesHelper<  S extends string,  Sub extends string & NonEmptyString<Sub>,  Result extends [number, string]> = S extends ''  ? [...Result, S]  : StartsWith<S, Sub> extends [infer SubInstance, infer Rest]  ? RepeatTimesHelper<      string & Rest,      Sub,      [Num.Inc<Result[0]>, Append<Result[1], string & SubInstance>]    >  : [...Result, S];
/** * Returns a tuple containing the matched part and the rest of the given string if the string * start repeats the given Sub at least N times. * @example * ```ts * RepeatAtLeastTimes<'aabc', 'a', 0> => ['', 'aabc'] * RepeatAtLeastTimes<'aabc', 'a', 1> => ['a', 'abc'] * RepeatAtLeastTimes<'aabc', 'a', 3> => false * RepeatAtLeastTimes<'aabc', 'a' | 'b', 3> => ['aab', 'c'] * ``` */export type RepeatAtLeastTimes<  S extends string,  Sub extends string & NonEmptyString<Sub>,  N extends number> = RepeatAtLeastTimesHelper<S, Sub, N, ''>;
type RepeatAtLeastTimesHelper<  S extends string,  Sub extends string & NonEmptyString<Sub>,  N extends number,  Processed extends string> = N extends 0  ? [Processed, S]  : S extends ''  ? false  : StartsWith<S, Sub> extends [infer SubInstance, infer Rest]  ? RepeatAtLeastTimesHelper<      string & Rest,      Sub,      Num.Decr<N>,      Append<Processed, string & SubInstance>    >  : false;
/** * Returns a tuple containing the matched part and the rest of the given string if the string * start repeats the given Sub at most N times. * @example * ```ts * RepeatAtMostTimes<'aabc', 'a', 0> => false * RepeatAtMostTimes<'aabc', 'a', 1> => false * RepeatAtMostTimes<'aabc', 'a', 3> => ['aa', 'bc'] * RepeatAtMostTimes<'aabc', 'a' | 'b', 3> => ['aab', 'c'] * ``` */export type RepeatAtMostTimes<  S extends string,  Sub extends string & NonEmptyString<Sub>,  N extends number> = RepeatAtMostTimesHelper<S, Sub, N, ''>;
type RepeatAtMostTimesHelper<  S extends string,  Sub extends string & NonEmptyString<Sub>,  N extends number,  Processed extends string> = S extends Append<Sub, infer Rest>  ? N extends 0    ? false    : S extends Append<infer SubInstance, Rest>    ? RepeatAtMostTimesHelper<        Rest,        Sub,        Num.Decr<N>,        Append<Processed, SubInstance>      >    : never  : [Processed, S];
/** * Returns a tuple containing the matched part and the rest of the given string if the string * start repeats the given Sub exactly N times. * @example * ```ts * RepeatExactTimes<'aabc', 'a', 0> => false * RepeatExactTimes<'aabc', 'a', 1> => false * RepeatExactTimes<'aabc', 'a', 2> => ['aa', 'bc'] * RepeatExactTimes<'aabc', 'a', 3> => false * RepeatExactTimes<'aabc', 'a' | 'b', 3> => ['aab', 'c'] * ``` */export type RepeatExactTimes<  S extends string,  Sub extends string & NonEmptyString<Sub>,  N extends number> = RepeatExactTimesHelper<S, Sub, N, ''>;
type RepeatExactTimesHelper<  S extends string,  Sub extends string & NonEmptyString<Sub>,  N extends number,  Processed extends string> = S extends Append<Sub, infer Rest>  ? N extends 0    ? false    : S extends Append<infer SubInstance, Rest>    ? RepeatExactTimesHelper<        Rest,        Sub,        Num.Decr<N>,        Append<Processed, SubInstance>      >    : never  : N extends 0  ? [Processed, S]  : false;
/** * Returns the first N characters of the given string, or false if the string does * not have enough characters. * @example * ```ts * TakeStrict<'abcd', 2> => 'ab' * TakeStrict<'abcd', 5> => false * ``` */export type TakeStrict<S extends string, N extends number> = TakeStrictHelper<  S,  N,  ''>;
type TakeStrictHelper<  S extends string,  N extends number,  Result extends string> = N extends 0  ? Result  : S extends Append<infer First, infer Rest>  ? TakeStrictHelper<Rest, Num.Decr<N>, Append<Result, First>>  : false;
/** * Returns the first N characters of the given string, or the given * string if it does not have enough characters. * @example * ```ts * Take<'abcd', 2> => 'ab' * Take<'abcd', 5> => 'abcd' * ``` */export type Take<S extends string, N extends number> = TakeHelper<S, N, ''>;
type TakeHelper<  S extends string,  N extends number,  Result extends string> = N extends 0  ? Result  : S extends Append<infer First, infer Rest>  ? TakeHelper<Rest, Num.Decr<N>, Append<Result, First>>  : Result;
/** * Returns part of the string as long as its parts match Sub. * @example * ```ts * TakeWhile<'aabc', 'a'> => 'aa' * TakeWhile<'aabc', 'a' | 'b'> => 'aab' * TakeWhile<'aabc', 'q'> => '' * ``` */export type TakeWhile<  S extends string,  Sub extends string & NonEmptyString<Sub>> = TakeWhileHelper<S, Sub, ''>;
type TakeWhileHelper<  S extends string,  Sub extends string & NonEmptyString<Sub>,  Result extends string> = StartsWith<S, Sub> extends [infer SubInstance, infer Rest]  ? TakeWhileHelper<string & Rest, Sub, Append<Result, string & SubInstance>>  : Result;
/** * Skips part of the string as long as its parts match Sub. * @example * ```ts * DropWhile<'aabc', 'a'> => 'bc' * DropWhile<'aabc', 'a' | 'b'> => 'c' * DropWhile<'aabc', 'q'> => 'aabc' * ``` */export type DropWhile<S extends string, Sub extends string> = S extends Append<  Sub,  infer Rest>  ? DropWhile<Rest, Sub>  : S;
/** * Returns the given string reversed. * @example * ```ts * Reverse<'abcd'> => 'dcba' * ``` */export type Reverse<S extends string> = ReverseHelper<S, ''>;
type ReverseHelper<S extends string, Result extends string> = S extends Append<  infer First,  infer Rest>  ? ReverseHelper<Rest, Append<First, Result>>  : Result;
/** * Returns the given string without the first N characters, or false if the * string has less characters. * @example * ```ts * DropStrict<'abcd', 2> => 'cd' * DropStrict<'abcd', 5> => false * ``` */export type DropStrict<S extends string, N extends number> = N extends 0  ? S  : S extends Append<string, infer Rest>  ? DropStrict<Rest, Num.Decr<N>>  : false;
/** * Returns the given string without the first N characters, or an empty string if the * string has less characters. * @example * ```ts * Drop<'abcd', 2> => 'cd' * Drop<'abcd', 5> => '' * ``` */export type Drop<S extends string, N extends number> = N extends 0  ? S  : S extends Append<string, infer Rest>  ? Drop<Rest, Num.Decr<N>>  : S;
/** * Returns the first character of the given string, or false if the string is empty. * @example * ```ts * First<'abc'> => 'a' * First<''> => false * ``` */export type First<S extends string> = S extends Append<infer First, string>  ? First  : false;
/** * Returns all but the first character of the given string, or false if the string is empty. * @example * ```ts * Tail<'abcd'> => 'bcd' * Tail<''> => false * ``` */export type Tail<S extends string> = S extends Append<string, infer Rest>  ? Rest  : false;
/** * Returns all but the last character of the given string, or false if the string is empty. * @example * ```ts * Init<'abcd'> => 'abc' * Init<''> => false * ``` */export type Init<S extends string> = InitHelper<S, ''>;
type InitHelper<S extends string, Result extends string> = S extends Append<  infer First,  infer Rest>  ? U.Extends<Rest, '', Result, InitHelper<Rest, Append<Result, First>>>  : false;
/** * Returns the last character of the given string, or false if the string if empty. * @example * ```ts * Last<'abcd'> => 'd' * Last<''> => false * ``` */export type Last<S extends string> = S extends Append<infer First, infer Rest>  ? U.Extends<Rest, '', First, Last<Rest>>  : false;
/** * Returns the character in the given string at the given Index, or false if the index * is out of bounds. * @example * ```ts * CharAt<'abcd', 1> => 'b' * CharAt<'abcd', 5> => false * ``` */export type CharAt<S extends string, Index extends number> = S extends Append<  infer Start,  infer Rest>  ? U.Extends<Index, 0, Start, CharAt<Rest, Num.Decr<Index>>>  : false;