path: root/cli/js/streams/readable-stream.ts

// Forked from https://github.com/stardazed/sd-streams/tree/8928cf04b035fd02fb1340b7eb541c76be37e546
// Copyright (c) 2018-Present by Arthur Langereis - @zenmumbler MIT

/**
 * streams/readable-stream - ReadableStream class implementation
 * Part of Stardazed
 * (c) 2018-Present by Arthur Langereis - @zenmumbler
 * https://github.com/stardazed/sd-streams
 */

/* eslint prefer-const: "off" */
// TODO remove this, surpressed because of
//   284:7   error    'branch1' is never reassigned. Use 'const' instead  prefer-const

import * as rs from "./readable-internals.ts";
import * as shared from "./shared-internals.ts";
import {
  QueuingStrategy,
  QueuingStrategySizeCallback,
  UnderlyingSource,
  UnderlyingByteSource
} from "../dom_types.ts";

import {
  ReadableStreamDefaultController,
  setUpReadableStreamDefaultControllerFromUnderlyingSource
} from "./readable-stream-default-controller.ts";
import { ReadableStreamDefaultReader } from "./readable-stream-default-reader.ts";

import {
  ReadableByteStreamController,
  setUpReadableByteStreamControllerFromUnderlyingSource
} from "./readable-byte-stream-controller.ts";
import { SDReadableStreamBYOBReader } from "./readable-stream-byob-reader.ts";

export class SDReadableStream<OutputType>
  implements rs.SDReadableStream<OutputType> {
  [shared.state_]: rs.ReadableStreamState;
  [shared.storedError_]: shared.ErrorResult;
  [rs.reader_]: rs.SDReadableStreamReader<OutputType> | undefined;
  [rs.readableStreamController_]: rs.SDReadableStreamControllerBase<OutputType>;

  constructor(
    underlyingSource: UnderlyingByteSource,
    strategy?: { highWaterMark?: number; size?: undefined }
  );
  constructor(
    underlyingSource?: UnderlyingSource<OutputType>,
    strategy?: QueuingStrategy<OutputType>
  );
  constructor(
    underlyingSource: UnderlyingSource<OutputType> | UnderlyingByteSource = {},
    strategy:
      | QueuingStrategy<OutputType>
      | { highWaterMark?: number; size?: undefined } = {}
  ) {
    rs.initializeReadableStream(this);

    const sizeFunc = strategy.size;
    const stratHWM = strategy.highWaterMark;
    const sourceType = underlyingSource.type;

    if (sourceType === undefined) {
      const sizeAlgorithm = shared.makeSizeAlgorithmFromSizeFunction(sizeFunc);
      const highWaterMark = shared.validateAndNormalizeHighWaterMark(
        stratHWM === undefined ? 1 : stratHWM
      );
      setUpReadableStreamDefaultControllerFromUnderlyingSource(
        this,
        underlyingSource as UnderlyingSource<OutputType>,
        highWaterMark,
        sizeAlgorithm
      );
    } else if (String(sourceType) === "bytes") {
      if (sizeFunc !== undefined) {
        throw new RangeError(
          "bytes streams cannot have a strategy with a `size` field"
        );
      }
      const highWaterMark = shared.validateAndNormalizeHighWaterMark(
        stratHWM === undefined ? 0 : stratHWM
      );
      setUpReadableByteStreamControllerFromUnderlyingSource(
        (this as unknown) as rs.SDReadableStream<ArrayBufferView>,
        underlyingSource as UnderlyingByteSource,
        highWaterMark
      );
    } else {
      throw new RangeError(
        "The underlying source's `type` field must be undefined or 'bytes'"
      );
    }
  }

  get locked(): boolean {
    return rs.isReadableStreamLocked(this);
  }

  getReader(): rs.SDReadableStreamDefaultReader<OutputType>;
  getReader(options: { mode?: "byob" }): rs.SDReadableStreamBYOBReader;
  getReader(options?: {
    mode?: "byob";
  }):
    | rs.SDReadableStreamDefaultReader<OutputType>
    | rs.SDReadableStreamBYOBReader {
    if (!rs.isReadableStream(this)) {
      throw new TypeError();
    }
    if (options === undefined) {
      options = {};
    }
    const { mode } = options;
    if (mode === undefined) {
      return new ReadableStreamDefaultReader(this);
    } else if (String(mode) === "byob") {
      return new SDReadableStreamBYOBReader(
        (this as unknown) as rs.SDReadableStream<ArrayBufferView>
      );
    }
    throw RangeError("mode option must be undefined or `byob`");
  }

  cancel(reason: shared.ErrorResult): Promise<void> {
    if (!rs.isReadableStream(this)) {
      return Promise.reject(new TypeError());
    }
    if (rs.isReadableStreamLocked(this)) {
      return Promise.reject(new TypeError("Cannot cancel a locked stream"));
    }
    return rs.readableStreamCancel(this, reason);
  }

  tee(): Array<SDReadableStream<OutputType>> {
    return readableStreamTee(this, false);
  }

  /* TODO reenable these methods when we bring in writableStreams and transport types
  pipeThrough<ResultType>(
    transform: rs.GenericTransformStream<OutputType, ResultType>,
    options: PipeOptions = {}
  ): rs.SDReadableStream<ResultType> {
    const { readable, writable } = transform;
    if (!rs.isReadableStream(this)) {
      throw new TypeError();
    }
    if (!ws.isWritableStream(writable)) {
      throw new TypeError("writable must be a WritableStream");
    }
    if (!rs.isReadableStream(readable)) {
      throw new TypeError("readable must be a ReadableStream");
    }
    if (options.signal !== undefined && !shared.isAbortSignal(options.signal)) {
      throw new TypeError("options.signal must be an AbortSignal instance");
    }
    if (rs.isReadableStreamLocked(this)) {
      throw new TypeError("Cannot pipeThrough on a locked stream");
    }
    if (ws.isWritableStreamLocked(writable)) {
      throw new TypeError("Cannot pipeThrough to a locked stream");
    }

    const pipeResult = pipeTo(this, writable, options);
    pipeResult.catch(() => {});

    return readable;
  }

  pipeTo(
    dest: ws.WritableStream<OutputType>,
    options: PipeOptions = {}
  ): Promise<void> {
    if (!rs.isReadableStream(this)) {
      return Promise.reject(new TypeError());
    }
    if (!ws.isWritableStream(dest)) {
      return Promise.reject(
        new TypeError("destination must be a WritableStream")
      );
    }
    if (options.signal !== undefined && !shared.isAbortSignal(options.signal)) {
      return Promise.reject(
        new TypeError("options.signal must be an AbortSignal instance")
      );
    }
    if (rs.isReadableStreamLocked(this)) {
      return Promise.reject(new TypeError("Cannot pipe from a locked stream"));
    }
    if (ws.isWritableStreamLocked(dest)) {
      return Promise.reject(new TypeError("Cannot pipe to a locked stream"));
    }

    return pipeTo(this, dest, options);
  }
  */
}

export function createReadableStream<OutputType>(
  startAlgorithm: rs.StartAlgorithm,
  pullAlgorithm: rs.PullAlgorithm<OutputType>,
  cancelAlgorithm: rs.CancelAlgorithm,
  highWaterMark?: number,
  sizeAlgorithm?: QueuingStrategySizeCallback<OutputType>
): SDReadableStream<OutputType> {
  if (highWaterMark === undefined) {
    highWaterMark = 1;
  }
  if (sizeAlgorithm === undefined) {
    sizeAlgorithm = (): number => 1;
  }
  // Assert: ! IsNonNegativeNumber(highWaterMark) is true.

  const stream = Object.create(SDReadableStream.prototype) as SDReadableStream<
    OutputType
  >;
  rs.initializeReadableStream(stream);
  const controller = Object.create(
    ReadableStreamDefaultController.prototype
  ) as ReadableStreamDefaultController<OutputType>;
  rs.setUpReadableStreamDefaultController(
    stream,
    controller,
    startAlgorithm,
    pullAlgorithm,
    cancelAlgorithm,
    highWaterMark,
    sizeAlgorithm
  );
  return stream;
}

export function createReadableByteStream<OutputType>(
  startAlgorithm: rs.StartAlgorithm,
  pullAlgorithm: rs.PullAlgorithm<OutputType>,
  cancelAlgorithm: rs.CancelAlgorithm,
  highWaterMark?: number,
  autoAllocateChunkSize?: number
): SDReadableStream<OutputType> {
  if (highWaterMark === undefined) {
    highWaterMark = 0;
  }
  // Assert: ! IsNonNegativeNumber(highWaterMark) is true.
  if (autoAllocateChunkSize !== undefined) {
    if (
      !shared.isInteger(autoAllocateChunkSize) ||
      autoAllocateChunkSize <= 0
    ) {
      throw new RangeError(
        "autoAllocateChunkSize must be a positive, finite integer"
      );
    }
  }

  const stream = Object.create(SDReadableStream.prototype) as SDReadableStream<
    OutputType
  >;
  rs.initializeReadableStream(stream);
  const controller = Object.create(
    ReadableByteStreamController.prototype
  ) as ReadableByteStreamController;
  rs.setUpReadableByteStreamController(
    (stream as unknown) as SDReadableStream<ArrayBufferView>,
    controller,
    startAlgorithm,
    (pullAlgorithm as unknown) as rs.PullAlgorithm<ArrayBufferView>,
    cancelAlgorithm,
    highWaterMark,
    autoAllocateChunkSize
  );
  return stream;
}

export function readableStreamTee<OutputType>(
  stream: SDReadableStream<OutputType>,
  cloneForBranch2: boolean
): [SDReadableStream<OutputType>, SDReadableStream<OutputType>] {
  if (!rs.isReadableStream(stream)) {
    throw new TypeError();
  }

  const reader = new ReadableStreamDefaultReader(stream);
  let closedOrErrored = false;
  let canceled1 = false;
  let canceled2 = false;
  let reason1: shared.ErrorResult;
  let reason2: shared.ErrorResult;
  let branch1: SDReadableStream<OutputType>;
  let branch2: SDReadableStream<OutputType>;

  let cancelResolve: (reason: shared.ErrorResult) => void;
  const cancelPromise = new Promise<void>(resolve => (cancelResolve = resolve));

  const pullAlgorithm = (): Promise<void> => {
    return rs
      .readableStreamDefaultReaderRead(reader)
      .then(({ value, done }) => {
        if (done && !closedOrErrored) {
          if (!canceled1) {
            rs.readableStreamDefaultControllerClose(
              branch1![
                rs.readableStreamController_
              ] as ReadableStreamDefaultController<OutputType>
            );
          }
          if (!canceled2) {
            rs.readableStreamDefaultControllerClose(
              branch2![
                rs.readableStreamController_
              ] as ReadableStreamDefaultController<OutputType>
            );
          }
          closedOrErrored = true;
        }
        if (closedOrErrored) {
          return;
        }
        const value1 = value;
        let value2 = value;
        if (!canceled1) {
          rs.readableStreamDefaultControllerEnqueue(
            branch1![
              rs.readableStreamController_
            ] as ReadableStreamDefaultController<OutputType>,
            value1!
          );
        }
        if (!canceled2) {
          if (cloneForBranch2) {
            value2 = shared.cloneValue(value2);
          }
          rs.readableStreamDefaultControllerEnqueue(
            branch2![
              rs.readableStreamController_
            ] as ReadableStreamDefaultController<OutputType>,
            value2!
          );
        }
      });
  };

  const cancel1Algorithm = (reason: shared.ErrorResult): Promise<void> => {
    canceled1 = true;
    reason1 = reason;
    if (canceled2) {
      const cancelResult = rs.readableStreamCancel(stream, [reason1, reason2]);
      cancelResolve(cancelResult);
    }
    return cancelPromise;
  };

  const cancel2Algorithm = (reason: shared.ErrorResult): Promise<void> => {
    canceled2 = true;
    reason2 = reason;
    if (canceled1) {
      const cancelResult = rs.readableStreamCancel(stream, [reason1, reason2]);
      cancelResolve(cancelResult);
    }
    return cancelPromise;
  };

  const startAlgorithm = (): undefined => undefined;
  branch1 = createReadableStream(
    startAlgorithm,
    pullAlgorithm,
    cancel1Algorithm
  );
  branch2 = createReadableStream(
    startAlgorithm,
    pullAlgorithm,
    cancel2Algorithm
  );

  reader[rs.closedPromise_].promise.catch(error => {
    if (!closedOrErrored) {
      rs.readableStreamDefaultControllerError(
        branch1![
          rs.readableStreamController_
        ] as ReadableStreamDefaultController<OutputType>,
        error
      );
      rs.readableStreamDefaultControllerError(
        branch2![
          rs.readableStreamController_
        ] as ReadableStreamDefaultController<OutputType>,
        error
      );
      closedOrErrored = true;
    }
  });

  return [branch1, branch2];
}