/**
 * Repeats a string using a fast doubling technique.
 *
 * @param input - The string to repeat.
 * @param count - The number of times to repeat the string.
 * @returns The repeated string, or an empty string when count is not positive or not finite.
 *
 * Special behavior: Non-integer counts are floored; non-finite or non-positive counts return "".
 */
export declare function fastRepeat(input: string, count: number): string;
/**
 * Pads the left side of a string to a target length using a fast repeat.
 *
 * @param input - The string to pad.
 * @param length - The desired total length of the result.
 * @param char - The padding character (defaults to a space).
 * @returns The padded string, or the original string if already long enough.
 *
 * Special behavior: Uses code unit length and does not trim or normalize input.
 */
export declare function fastPadLeft(input: string, length: number, char?: string): string;
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