/**
 * Changes the casing of a string to constant case.
 * @param string The input string to change the casing of.
 * @returns A new string with the casing changed to constant case.
 * @example
 * ```ts
 * constantCase('fooBar') // 'FOO_BAR'
 * constantCase('foo bar') // 'FOO_BAR'
 * constantCase('foo-bar') // 'FOO_BAR'
 * constantCase('fooBar42') // 'FOO_BAR42'
 * ```
 */
declare function constantCase<S extends string>(string: S): ConstantCase<S>;
/**
 * Changes the casing of a string to constant case.
 * @see {@link constantCase}.
 */
type ConstantCase<S extends string> = Uppercase<S extends `${infer S1}${infer S2}` ? `${S1 extends '-' ? '_' : S1 extends ' ' ? '_' : S1 extends '_' ? '_' : S1 extends Capitalize<S1> ? `_${Lowercase<S1>}` : S1}${ConstantCase<S2>}` : S>;

export { type ConstantCase, constantCase };