xref: /interface/sdk-js/api/@ohos.util.stream.d.ts

/*
 * Copyright (c) 2024 Huawei Device Co., Ltd.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
 
 /**
 * @file
 * @kit ArkTS
 */
 import { Callback } from './@ohos.base';
 import emitter from './@ohos.events.emitter';
 
 /**
  * The stream module provides a comprehensive set of stream processing capabilities, including four types of streams:
  * - Writable: streams designed for writing data to.
  * - Readable: streams designed for reading data from.
  * - Duplex: streams that are both readable and writable.
  * - Transform: a specialized type of duplex stream that can modify or transform data as it's being written and read.
  *
  * @namespace stream
  * @syscap SystemCapability.Utils.Lang
  * @crossplatform
  * @atomicservice
  * @since 12
  */
declare namespace stream {
  /**
   * Streams to which data can be written.
   *
   * @syscap SystemCapability.Utils.Lang
   * @crossplatform
   * @atomicservice
   * @since 12
   */
  class Writable {
    /**
     * The Writable constructor.
     *
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    constructor();
    /**
     * writes a chunk to Writable and invokes callback when the chunk is flushed. The return value indicates
     * whether the internal buffer of the Writable reaches the hightWaterMark. If true is returned, the buffer
     * does not reach the hightWaterMark. If false is returned, the buffer has been reached. The write function
     * should be called after the drain event is triggered. If the write function is called continuously,
     * the chunk is still added to the buffer until the memory overflows
     *
     * @param { string | Uint8Array } [chunk] - Data to be written.
     * @param { string } [encoding] - Encoding type.
     * @param { Function } [callback] - Callback after writing.
     * @returns { boolean } Write success returns true, write failure returns false.
     * @throws { BusinessError } 401 - Parameter error. Possible causes:
     *     1.Mandatory parameters are left unspecified;
     *     2.Incorrect parameter types;
     *     3.Parameter verification failed.
     * @throws { BusinessError } 10200035 - The doWrite method has not been implemented.
     * @throws { BusinessError } 10200036 - The stream has been ended.
     * @throws { BusinessError } 10200037 - The callback is invoked multiple times consecutively.
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
    */
    write(chunk?: string | Uint8Array, encoding?: string, callback?: Function): boolean;
    /**
     * Write the last chunk to Writable.
     *
     * @param { string | Uint8Array } [chunk] - Data to be written.
     * @param { string } [encoding] - Encoding type.
     * @param { Function } [callback] - Callback after writing.
     * @returns { Writable } Returns the Writable object.
     * @throws { BusinessError } 401 - Parameter error. Possible causes:
     *     1.Mandatory parameters are left unspecified;
     *     2.Incorrect parameter types;
     *     3.Parameter verification failed.
     * @throws { BusinessError } 10200035 - The doWrite method has not been implemented.
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    end(chunk?: string | Uint8Array, encoding?: string, callback?: Function): Writable;
    /**
     * Set the default encoding mode.
     *
     * @param { string } [encoding] - Encoding type.Default: utf8.
     * @returns { boolean } Setting successful returns true, setting failed returns false.
     * @throws { BusinessError } 401 - Parameter error. Possible causes:
     *     1.Mandatory parameters are left unspecified;
     *     2.Incorrect parameter types;
     *     3.Parameter verification failed.
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
    */
    setDefaultEncoding(encoding?: string): boolean;
    /**
     * After the call, all Write operations will be forced to write to the buffer instead of being flushed.
     *
     * @returns { boolean } Setting successful returns true, setting failed returns false.
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    cork(): boolean;
    /**
     * After calling, flush all buffers.
     *
     * @returns { boolean } Setting successful returns true, setting failed returns false.
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    uncork(): boolean;
    /**
     * Registering Event Messages.
     *
     * @param { string } event - Register Event.
     * @param { Callback<emitter.EventData> } callback - event callbacks.
     * @throws { BusinessError } 401 - Parameter error. Possible causes:
     *     1.Mandatory parameters are left unspecified;
     *     2.Incorrect parameter types;
     *     3.Parameter verification failed.
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    on(event: string, callback: Callback<emitter.EventData>): void;
    /**
     * Cancel event message.
     *
     * @param { string } event - Register Event.
     * @param { Callback<emitter.EventData> } callback - event callbacks.
     * @throws { BusinessError } 401 - Parameter error. Possible causes:
     *     1.Mandatory parameters are left unspecified;
     *     2.Incorrect parameter types.
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    off(event: string, callback?: Callback<emitter.EventData>): void;
    /**
     * This method is invoked by the Writable method during initialization and must not be invoked directly.
     * After the resource is initialized in the doInitialize method, the callback () method is invoked.
     *
     * @param { Function } callback - Callback when the stream has completed the initial.
     * @throws { BusinessError } 401 - Parameter error. Possible causes:
     *     1.Mandatory parameters are left unspecified;
     *     2.Incorrect parameter types.
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    doInitialize(callback: Function): void;
    /**
     * Implemented by subclass inheritance. The implementation logic of flushing chunks in the buffer must not be
     * directly called. The call is controlled by Writable.write.
     *
     * @param { string | Uint8Array } [chunk] - Data to be written.
     * @param { string } [encoding] - Encoding type.
     * @param { Function } [callback] - Callback after writing.
     * @throws { BusinessError } 401 - Parameter error. Possible causes:
     *     1.Mandatory parameters are left unspecified;
     *     2.Incorrect parameter types;
     *     3.Parameter verification failed.
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    doWrite(chunk: string | Uint8Array, encoding: string, callback: Function): void;
    /**
     * The implementation logic of flushing chunks in the buffer in batches should not be actively called.
     * The call is controlled by Writable.write.
     *
     * @param { string[] | Uint8Array[] } [chunks] - Data to be written.
     * @param { Function } [callback] - Callback after writing.
     * @throws { BusinessError } 401 - Parameter error. Possible causes:
     *     1.Mandatory parameters are left unspecified;
     *     2.Incorrect parameter types;
     *     3.Parameter verification failed.
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    doWritev(chunks: string[] | Uint8Array[], callback: Function): void;
    /**
     * Returns boolean indicating whether it is in ObjectMode.
     *
     * @type { boolean }
     * @readonly
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    readonly writableObjectMode: boolean;
    /**
     * Value of highWatermark.
     *
     * @type { number }
     * @readonly
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    readonly writableHighWatermark: number;
    /**
     * Is true if it is safe to call writable.write(), which means the stream has not been destroyed, error or end.
     *
     * @type { boolean }
     * @readonly
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    readonly writable: boolean;
    /**
     * Size of data that can be flushed, in bytes or objects.
     *
     * @type { number }
     * @readonly
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    readonly writableLength: number;
    /**
     * Number of times writable.uncork() needs to be called in order to fully uncork the stream.
     *
     * @type { number }
     * @readonly
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    readonly writableCorked: number;
    /**
     * Whether Writable.end has been called.
     *
     * @type { boolean }
     * @readonly
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    readonly writableEnded: boolean;
    /**
     * Whether Writable.end has been called and all buffers have been flushed.
     *
     * @type { boolean }
     * @readonly
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    readonly writableFinished: boolean;
  }
  /**
   * Transform stream is a Duplex stream where the output is computed in some way from the input.
   * Transform implementations must implement the doTransform() method and may also implement the doFlush() method.
   *
   * @extends Duplex
   * @syscap SystemCapability.Utils.Lang
   * @crossplatform
   * @atomicservice
   * @since 12
   */
  class Transform extends Duplex {
    /**
     * The Transform constructor.
     *
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    constructor();
    /**
     * Convert the input data. After the conversion, Transform.push can be called to send the input to the read stream.
     * Transform.push should not be called Transform.write to call.
     *
     * @param { string } chunk - Input data to be converted.
     * @param { string } encoding - If the chunk is a string, then this is the encoding type. If chunk is a buffer,
     * then this is the special value 'buffer'. Ignore it in that case.
     * @param { Function } callback - Callback after conversion.
     * @throws { BusinessError } 401 - Parameter error. Possible causes:
     *     1.Mandatory parameters are left unspecified;
     *     2.Incorrect parameter types;
     *     3.Parameter verification failed.
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    doTransform(chunk: string, encoding: string, callback: Function): void;
    /**
     * After all data is flushed to the write stream, you can use the Transform.doFlush writes some extra data, must
     * not be called directly, only called by Writable after flushing all data.
     *
     * @param { Function } callback - Callback after flush completion.
     * @throws { BusinessError } 401 - Parameter error. Possible causes:
     *     1.Mandatory parameters are left unspecified;
     *     2.Incorrect parameter types;
     *     3.Parameter verification failed.
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    doFlush(callback: Function): void;
  }

  /**
   * Return readable options.
   *
   * @interface ReadableOptions
   * @syscap SystemCapability.Utils.Lang
   * @crossplatform
   * @atomicservice
   * @since 12
   */
  interface ReadableOptions {
    /**
    * Specifies the encoding format of the data. If this parameter is provided,
    * the readable stream decodes the data into a string in the specified encoding format. Default: utf8.
    * If an invalid string is entered, a 401 exception is thrown in the Readable constructor.
    * Supported encoding formats: utf-8, ibm866, iso-8859-2, iso-8859-3, iso-8859-4, iso-8859-5, iso-8859-6,
    * iso-8859-7, iso-8859-8, iso-8859-8-i, iso-8859-10, iso-8859-13, iso-8859-14, iso-8859-15, koi8-r, koi8-u,
    * macintosh, windows-874, windows-1250, windows-1251, windows-1252, windows-1253, windows-1254, windows-1255,
    * windows-1256, windows-1257, windows-1258, x-mac-cyrillic, gbk, gb18030, big5, euc-jp, iso-2022-jp, shift_jis,
    * euc-kr, utf-16be, utf-16le.
    *
    * @type { ?string }
    * @syscap SystemCapability.Utils.Lang
    * @crossplatform
    * @atomicservice
    * @since 12
    */
    encoding?: string;
  }

  /**
   * The stream from which data can be read.
   *
   * @syscap SystemCapability.Utils.Lang
   * @crossplatform
   * @atomicservice
   * @since 12
   */
   class Readable {
    /**
     * The Readable constructor.
     *
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    constructor();
    /**
     * The Readable constructor.
     *
     * @param { ReadableOptions } options - Provide options.
     * @throws { BusinessError } 401 - Parameter error. Possible causes:
     *     1.Mandatory parameters are left unspecified;
     *     2.Incorrect parameter types;
     *     3.Parameter verification failed.
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    constructor(options: ReadableOptions);
    /**
     * Reads a buffer of a specified size from the buffer. If the available buffer is sufficient, the result
     * of the specified size is returned. Otherwise, if Readable has ended, all remaining buffers are returned.
     *
     * @param { number } size - Expected length of the data to be read.
     * @returns { string | null } If no data is available to read, null is returned.
     * @throws { BusinessError } 401 - Parameter error. Possible causes:
     *     1.Mandatory parameters are left unspecified;
     *     2.Incorrect parameter types;
     *     3.Parameter verification failed.
     * @throws { BusinessError } 10200038 - The doRead method has not been implemented.
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    read(size?: number): string | null;
    /**
     * Switch Readable to Streaming Mode.
     *
     * @returns { Readable } Return this object.
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    resume(): Readable;
    /**
     * Toggle Readable to Suspend Mode.
     *
     * @returns { Readable } Return this object.
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    pause(): Readable;
    /**
     * Sets the encoding format of the input binary data.Default: utf8.
     *
     * @param { string } [encoding] - Original Data Encoding Type.
     * @returns { boolean } Setting successful returns true, setting failed returns false.
     * @throws { BusinessError } 401 - Parameter error. Possible causes:
     *     1.Mandatory parameters are left unspecified;
     *     2.Incorrect parameter types.
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    setEncoding(encoding?: string): boolean;
    /**
     * Query whether it is in pause state.
     *
     * @returns { boolean } Pause state returns true, otherwise returns false.
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    isPaused(): boolean;
    /**
     * Concatenated a Writable to a Readable and switches the Readable to stream mode.
     *
     * @param { Writable } destination - Output writable stream.
     * @param { Object } [options] - Pipeline Options.
     * @returns { Writable } Returns the Writable object.
     * @throws { BusinessError } 401 - Parameter error. Possible causes:
     *     1.Mandatory parameters are left unspecified;
     *     2.Incorrect parameter types;
     *     3.Parameter verification failed.
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    pipe(destination: Writable, options?: Object): Writable;
    /**
     * Disconnect Writable from Readable.
     *
     * @param { Writable } [destination] - Writable Streams Needing to Be Disconnected.
     * @returns { Readable } Returns the Readable object.
     * @throws { BusinessError } 401 - Parameter error. Possible causes:
     *     1.Mandatory parameters are left unspecified;
     *     2.Incorrect parameter types;
     *     3.Parameter verification failed.
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    unpipe(destination?: Writable): Readable;
    /**
     * Registering Event Messages.
     *
     * @param { string } event - Registering Events.
     * @param { Callback<emitter.EventData> } callback - Event callback.
     * @throws { BusinessError } 401 - Parameter error. Possible causes:
     *     1.Mandatory parameters are left unspecified;
     *     2.Incorrect parameter types.
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    on(event: string, callback: Callback<emitter.EventData>): void;
    /**
     * Cancel event message.
     *
     * @param { string } event - Registering Events.
     * @param { Callback<emitter.EventData> } callback - Event callback.
     * @throws { BusinessError } 401 - Parameter error. Possible causes:
     *     1.Mandatory parameters are left unspecified;
     *     2.Incorrect parameter types.
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    off(event: string, callback?: Callback<emitter.EventData>): void;
    /**
     * It may be implemented by child classes, and if so, will be called by the Readable class methods only.
     * It must not be called directly.
     *
     * @param { Function } callback - Callback when the stream has completed the initial.
     * @throws { BusinessError } 401 - Parameter error. Possible causes:
     *     1.Mandatory parameters are left unspecified;
     *     2.Incorrect parameter types;
     *     3.Parameter verification failed.
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    doInitialize(callback: Function): void;
    /**
     * The specific implementation of data production. It must not be actively called. 
     * After data production, Readable.push should be called to push the produced data into the buffer.
     * If push is not called, doRead will not be called again.
     * 
     * @param { number } size - Expected length of the data to be read.
     * @throws { BusinessError } 401 - Parameter error. Possible causes:
     *     1.Mandatory parameters are left unspecified;
     *     2.Incorrect parameter types;
     *     3.Parameter verification failed.
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    doRead(size: number): void;
    /**
     * Adds the generated data to the buffer. The return value indicates whether the data in the buffer has not
     * reached the highWaterMark (similar to Writable.write). If the chunk is null, all data has been generated.
     *
     * @param {  Uint8Array | string | null } chunk - Binary data to be stored in the buffer.
     * @param { string } [encoding] - Binary data encoding type.
     * @returns { boolean } If true is returned, the data in the buffer reaches the highWaterMark. Otherwise, the
     * data in the buffer does not reach the highWaterMark.
     * @throws { BusinessError } 401 - Parameter error. Possible causes:
     *     1.Mandatory parameters are left unspecified;
     *     2.Incorrect parameter types.
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    push(chunk: Uint8Array | string | null, encoding?: string): boolean;
    /**
     * Returns boolean indicating whether it is in ObjectMode.
     *
     * @type { boolean }
     * @readonly
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    readonly readableObjectMode: boolean;
    /**
     * Is true if it is safe to call readable.read(), which means
     * the stream has not been destroyed or emitted 'error' or 'end'.
     *
     * @type { boolean }
     * @readonly
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    readonly readable: boolean;
    /**
     * Returns the value of highWatermark passed when creating this Readable.
     *
     * @type { number }
     * @readonly
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    readonly readableHighWatermark: number;
    /**
     * This property reflects the current state of the readable stream null/true/false.
     *
     * @type { boolean | null }
     * @readonly
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    readonly readableFlowing: boolean | null;
    /**
     * Size of the data that can be read, in bytes or objects.
     *
     * @type { number }
     * @readonly
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    readonly readableLength: number;
    /**
     * Getter for the property encoding of a given Readable stream. The encoding property can be set using the
     * readable.setEncoding() method.
     *
     * @type { string | null }
     * @readonly
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    readonly readableEncoding: string | null;
    /**
     * Whether all data has been generated.
     *
     * @type { boolean }
     * @readonly
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    readonly readableEnded: boolean;
  }
  /**
   * Duplex streams are streams that implement both the Readable streams and Writable streams interfaces.
   *
   * @extends Readable
   * @syscap SystemCapability.Utils.Lang
   * @crossplatform
   * @atomicservice
   * @since 12
   */
  class Duplex extends Readable {
    /**
    * The Duplex constructor.
     *
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    constructor();
    /**
     * writes a chunk to Writable and invokes callback when the chunk is flushed. The return value indicates
     * whether the internal buffer of the Writable reaches the hightWaterMark. If true is returned, the buffer
     * does not reach the hightWaterMark. If false is returned, the buffer has been reached. The write function
     * should be called after the drain event is triggered. If the write function is called continuously,
     * the chunk is still added to the buffer until the memory overflows
     *
     * @param { string | Uint8Array } [chunk] - Data to be written.
     * @param { string } [encoding] - Encoding type.
     * @param { Function } [callback] - Callback after writing.
     * @returns { boolean } Write success returns true, write failure returns false.
     * @throws { BusinessError } 401 - Parameter error. Possible causes:
     *     1.Mandatory parameters are left unspecified;
     *     2.Incorrect parameter types;
     *     3.Parameter verification failed.
     * @throws { BusinessError } 10200036 - The stream has been ended.
     * @throws { BusinessError } 10200037 - The callback is invoked multiple times consecutively.
     * @throws { BusinessError } 10200039 - The doTransform method has not been implemented for a class that inherits from Transform.
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    write(chunk?: string | Uint8Array, encoding?: string, callback?: Function): boolean;
    /**
     * Write the last chunk to Writable.
     *
     * @param { string | Uint8Array } [chunk] - Data to be written.
     * @param { string } [encoding] - Encoding type.
     * @param { Function } [callback] - Callback after writing.
     * @returns { Writable } Returns the Writable object.
     * @throws { BusinessError } 401 - Parameter error. Possible causes:
     *     1.Mandatory parameters are left unspecified;
     *     2.Incorrect parameter types;
     *     3.Parameter verification failed.
     * @throws { BusinessError } 10200039 - The doTransform method has not been implemented for a class that inherits from Transform.
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    end(chunk?: string | Uint8Array, encoding?: string, callback?: Function): Writable;
    /**
     * Set the default encoding mode.
     *
     * @param { string } [encoding] - Encoding type.Default: utf8.
     * @returns { boolean } Setting successful returns true, setting failed returns false.
     * @throws { BusinessError } 401 - Parameter error. Possible causes:
     *     1.Mandatory parameters are left unspecified;
     *     2.Incorrect parameter types;
     *     3.Parameter verification failed.
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    setDefaultEncoding(encoding?: string): boolean;
    /**
     * After the call, all Write operations will be forced to write to the buffer instead of being flushed.
     *
     * @returns { boolean } Setting successful returns true, setting failed returns false.
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    cork(): boolean;
    /**
     * After calling, flush all buffers.
     *
     * @returns { boolean } Setting successful returns true, setting failed returns false.
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    uncork(): boolean;
    /**
     * Implemented by subclass inheritance. The implementation logic of flushing chunks in the buffer must not be
     * directly called. The call is controlled by Writable.write.
     *
     * @param { string | Uint8Array } [chunk] - Data to be written.
     * @param { string } [encoding] - Encoding type.
     * @param { Function } [callback] - Callback after writing.
     * @throws { BusinessError } 401 - Parameter error. Possible causes:
     *     1.Mandatory parameters are left unspecified;
     *     2.Incorrect parameter types;
     *     3.Parameter verification failed.
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    doWrite(chunk: string | Uint8Array, encoding: string, callback: Function): void;
    /**
     * The implementation logic of flushing chunks in the buffer in batches should not be actively called.
     * The call is controlled by Writable.write.
     *
     * @param { string[] | Uint8Array[] } [chunks] - Data to be written.
     * @param { Function } [callback] - Callback after writing.
     * @throws { BusinessError } 401 - Parameter error. Possible causes:
     *     1.Mandatory parameters are left unspecified;
     *     2.Incorrect parameter types;
     *     3.Parameter verification failed.
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    doWritev(chunks: string[] | Uint8Array[], callback: Function): void;
    /**
     * Returns boolean indicating whether it is in ObjectMode.
     *
     * @type { boolean }
     * @readonly
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    readonly writableObjectMode: boolean;
    /**
     * Value of highWatermark.
     *
     * @type { number }
     * @readonly
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    readonly writableHighWatermark: number;
    /**
     * Is true if it is safe to call writable.write(), which means the stream has not been destroyed, error or end.
     *
     * @type { boolean }
     * @readonly
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    readonly writable: boolean;
    /**
     * Size of data that can be flushed, in bytes or objects.
     *
     * @type { number }
     * @readonly
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    readonly writableLength: number;
    /**
     * Number of times writable.uncork() needs to be called in order to fully uncork the stream.
     *
     * @type { number }
     * @readonly
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    readonly writableCorked: number;
    /**
     * Whether Writable.end has been called.
     *
     * @type { boolean }
     * @readonly
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    readonly writableEnded: boolean;
    /**
     * Whether Writable.end has been called and all buffers have been flushed.
     *
     * @type { boolean }
     * @readonly
     * @syscap SystemCapability.Utils.Lang
     * @crossplatform
     * @atomicservice
     * @since 12
     */
    readonly writableFinished: boolean;
  }
}
export default stream;