/**
 * StringBuf - Cross-Platform String Buffer
 *
 * Efficient string builder that accumulates UTF-8 encoded bytes into a single
 * `Uint8Array`. Designed for hot paths that build large XML / text payloads
 * (XLSX worksheet writers, streaming DOCX writer) where naïve `string +=`
 * concatenation triggers O(n²) re-allocations.
 *
 * Works identically in Node.js and Browser environments — uses only
 * `TextEncoder` and `Uint8Array`.
 */
interface StringBufOptions {
    /** Initial capacity in bytes (default: 16384). */
    size?: number;
    /**
     * Encoding label, accepted for API symmetry. Only UTF-8 is supported by
     * `TextEncoder`, so this option is ignored.
     */
    encoding?: string;
}
/**
 * Efficient string builder backed by a growable `Uint8Array`.
 */
declare class StringBuf {
    private _buf;
    private _inPos;
    private _buffer;
    constructor(options?: StringBufOptions);
    get length(): number;
    get capacity(): number;
    get buffer(): Uint8Array;
    /** Return a snapshot of the bytes written so far. Cached until next mutation. */
    toBuffer(): Uint8Array;
    reset(position?: number): void;
    private _grow;
    /** Append a string, encoded as UTF-8. */
    addText(text: string): void;
    /** Append the contents of another StringBuf without re-encoding. */
    addStringBuf(inBuf: StringBuf): void;
}
export { StringBuf };
export type { StringBufOptions };