export interface Encoder<Output extends string | Uint8Array = string | Uint8Array> {
    /**
     * Whether this encoder might call the provided callbacks asynchronously
     */
    isAsync: boolean;
    /**
     * Whether some data has been written since the last finish() or finishSync() call
     */
    isEmpty: boolean;
    /**
     * Write a string to be encoded.
     *
     * This operation can be synchronous or asynchronous depending on the encoder implementation.
     *
     * If specified, the callback will be invoked when the operation finishes, unless the operation is
     * asynchronous and finish() or finishSync() is called in the meantime.
     */
    write(data: string, callback?: (additionalEncodedBytesCount: number) => void): void;
    /**
     * Waits for pending data to be encoded and resets the encoder state.
     *
     * This operation can be synchronous or asynchronous depending on the encoder implementation.
     *
     * The callback will be invoked when the operation finishes, unless the operation is asynchronous
     * and another call to finish() or finishSync() occurs in the meantime.
     */
    finish(callback: (result: EncoderResult<Output>) => void): void;
    /**
     * Resets the encoder state then returns the encoded data and any potential pending data directly,
     * discarding all pending write operations and finish() callbacks.
     */
    finishSync(): EncoderResult<Output> & {
        pendingData: string;
    };
    /**
     * Returns a rough estimation of the bytes count if the data was encoded.
     */
    estimateEncodedBytesCount(data: string): number;
}
export interface EncoderResult<Output extends string | Uint8Array = string | Uint8Array> {
    output: Output;
    outputBytesCount: number;
    /**
     * An encoding type supported by HTTP Content-Encoding, if applicable.
     * See https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Encoding#directives
     */
    encoding?: 'deflate';
    /**
     * Total bytes count of the input strings encoded to UTF-8.
     */
    rawBytesCount: number;
}
export declare function createIdentityEncoder(): Encoder<string>;