1 files changed, 296 insertions, 0 deletions
diff --git a/std/node/_stream/duplex_internal.ts b/std/node/_stream/duplex_internal.ts
new file mode 100644
index 000000000..bfd9749f8
--- /dev/null
+++ b/std/node/_stream/duplex_internal.ts
@@ -0,0 +1,296 @@
+// Copyright Node.js contributors. All rights reserved. MIT License.
+import type { ReadableState } from "./readable.ts";
+import { addChunk, maybeReadMore, onEofChunk } from "./readable_internal.ts";
+import type Writable from "./writable.ts";
+import type { WritableState } from "./writable.ts";
+import {
+  afterWrite,
+  AfterWriteTick,
+  afterWriteTick,
+  clearBuffer,
+  errorBuffer,
+  kOnFinished,
+  needFinish,
+  prefinish,
+} from "./writable_internal.ts";
+import { Buffer } from "../buffer.ts";
+import type Duplex from "./duplex.ts";
+import {
+  ERR_MULTIPLE_CALLBACK,
+  ERR_STREAM_PUSH_AFTER_EOF,
+  ERR_STREAM_UNSHIFT_AFTER_END_EVENT,
+} from "../_errors.ts";
+
+export function endDuplex(stream: Duplex) {
+  const state = stream._readableState;
+
+  if (!state.endEmitted) {
+    state.ended = true;
+    queueMicrotask(() => endReadableNT(state, stream));
+  }
+}
+
+function endReadableNT(state: ReadableState, stream: Duplex) {
+  // Check that we didn't get one last unshift.
+  if (
+    !state.errorEmitted && !state.closeEmitted &&
+    !state.endEmitted && state.length === 0
+  ) {
+    state.endEmitted = true;
+    stream.emit("end");
+
+    if (stream.writable && stream.allowHalfOpen === false) {
+      queueMicrotask(() => endWritableNT(state, stream));
+    } else if (state.autoDestroy) {
+      // In case of duplex streams we need a way to detect
+      // if the writable side is ready for autoDestroy as well.
+      const wState = stream._writableState;
+      const autoDestroy = !wState || (
+        wState.autoDestroy &&
+        // We don't expect the writable to ever 'finish'
+        // if writable is explicitly set to false.
+        (wState.finished || wState.writable === false)
+      );
+
+      if (autoDestroy) {
+        stream.destroy();
+      }
+    }
+  }
+}
+
+function endWritableNT(state: ReadableState, stream: Duplex) {
+  const writable = stream.writable &&
+    !stream.writableEnded &&
+    !stream.destroyed;
+  if (writable) {
+    stream.end();
+  }
+}
+
+export function errorOrDestroy(
+  // deno-lint-ignore no-explicit-any
+  this: any,
+  stream: Duplex,
+  err: Error,
+  sync = false,
+) {
+  const r = stream._readableState;
+  const w = stream._writableState;
+
+  if (w.destroyed || r.destroyed) {
+    return this;
+  }
+
+  if (r.autoDestroy || w.autoDestroy) {
+    stream.destroy(err);
+  } else if (err) {
+    // Avoid V8 leak, https://github.com/nodejs/node/pull/34103#issuecomment-652002364
+    err.stack;
+
+    if (w && !w.errored) {
+      w.errored = err;
+    }
+    if (r && !r.errored) {
+      r.errored = err;
+    }
+
+    if (sync) {
+      queueMicrotask(() => {
+        if (w.errorEmitted || r.errorEmitted) {
+          return;
+        }
+
+        w.errorEmitted = true;
+        r.errorEmitted = true;
+
+        stream.emit("error", err);
+      });
+    } else {
+      if (w.errorEmitted || r.errorEmitted) {
+        return;
+      }
+
+      w.errorEmitted = true;
+      r.errorEmitted = true;
+
+      stream.emit("error", err);
+    }
+  }
+}
+
+function finish(stream: Duplex, state: WritableState) {
+  state.pendingcb--;
+  if (state.errorEmitted || state.closeEmitted) {
+    return;
+  }
+
+  state.finished = true;
+
+  for (const callback of state[kOnFinished].splice(0)) {
+    callback();
+  }
+
+  stream.emit("finish");
+
+  if (state.autoDestroy) {
+    stream.destroy();
+  }
+}
+
+export function finishMaybe(
+  stream: Duplex,
+  state: WritableState,
+  sync?: boolean,
+) {
+  if (needFinish(state)) {
+    prefinish(stream as Writable, state);
+    if (state.pendingcb === 0 && needFinish(state)) {
+      state.pendingcb++;
+      if (sync) {
+        queueMicrotask(() => finish(stream, state));
+      } else {
+        finish(stream, state);
+      }
+    }
+  }
+}
+
+export function onwrite(stream: Duplex, er?: Error | null) {
+  const state = stream._writableState;
+  const sync = state.sync;
+  const cb = state.writecb;
+
+  if (typeof cb !== "function") {
+    errorOrDestroy(stream, new ERR_MULTIPLE_CALLBACK());
+    return;
+  }
+
+  state.writing = false;
+  state.writecb = null;
+  state.length -= state.writelen;
+  state.writelen = 0;
+
+  if (er) {
+    // Avoid V8 leak, https://github.com/nodejs/node/pull/34103#issuecomment-652002364
+    er.stack;
+
+    if (!state.errored) {
+      state.errored = er;
+    }
+
+    if (stream._readableState && !stream._readableState.errored) {
+      stream._readableState.errored = er;
+    }
+
+    if (sync) {
+      queueMicrotask(() => onwriteError(stream, state, er, cb));
+    } else {
+      onwriteError(stream, state, er, cb);
+    }
+  } else {
+    if (state.buffered.length > state.bufferedIndex) {
+      clearBuffer(stream, state);
+    }
+
+    if (sync) {
+      if (
+        state.afterWriteTickInfo !== null &&
+        state.afterWriteTickInfo.cb === cb
+      ) {
+        state.afterWriteTickInfo.count++;
+      } else {
+        state.afterWriteTickInfo = {
+          count: 1,
+          cb: (cb as (error?: Error) => void),
+          stream: stream as Writable,
+          state,
+        };
+        queueMicrotask(() =>
+          afterWriteTick(state.afterWriteTickInfo as AfterWriteTick)
+        );
+      }
+    } else {
+      afterWrite(stream as Writable, state, 1, cb as (error?: Error) => void);
+    }
+  }
+}
+
+function onwriteError(
+  stream: Duplex,
+  state: WritableState,
+  er: Error,
+  cb: (error: Error) => void,
+) {
+  --state.pendingcb;
+
+  cb(er);
+  errorBuffer(state);
+  errorOrDestroy(stream, er);
+}
+
+export function readableAddChunk(
+  stream: Duplex,
+  chunk: string | Buffer | Uint8Array | null,
+  encoding: undefined | string = undefined,
+  addToFront: boolean,
+) {
+  const state = stream._readableState;
+  let usedEncoding = encoding;
+
+  let err;
+  if (!state.objectMode) {
+    if (typeof chunk === "string") {
+      usedEncoding = encoding || state.defaultEncoding;
+      if (state.encoding !== usedEncoding) {
+        if (addToFront && state.encoding) {
+          chunk = Buffer.from(chunk, usedEncoding).toString(state.encoding);
+        } else {
+          chunk = Buffer.from(chunk, usedEncoding);
+          usedEncoding = "";
+        }
+      }
+    } else if (chunk instanceof Uint8Array) {
+      chunk = Buffer.from(chunk);
+    }
+  }
+
+  if (err) {
+    errorOrDestroy(stream, err);
+  } else if (chunk === null) {
+    state.reading = false;
+    onEofChunk(stream, state);
+  } else if (state.objectMode || (chunk.length > 0)) {
+    if (addToFront) {
+      if (state.endEmitted) {
+        errorOrDestroy(stream, new ERR_STREAM_UNSHIFT_AFTER_END_EVENT());
+      } else {
+        addChunk(stream, state, chunk, true);
+      }
+    } else if (state.ended) {
+      errorOrDestroy(stream, new ERR_STREAM_PUSH_AFTER_EOF());
+    } else if (state.destroyed || state.errored) {
+      return false;
+    } else {
+      state.reading = false;
+      if (state.decoder && !usedEncoding) {
+        //TODO(Soremwar)
+        //I don't think this cast is right
+        chunk = state.decoder.write(Buffer.from(chunk as Uint8Array));
+        if (state.objectMode || chunk.length !== 0) {
+          addChunk(stream, state, chunk, false);
+        } else {
+          maybeReadMore(stream, state);
+        }
+      } else {
+        addChunk(stream, state, chunk, false);
+      }
+    }
+  } else if (!addToFront) {
+    state.reading = false;
+    maybeReadMore(stream, state);
+  }
+
+  return !state.ended &&
+    (state.length < state.highWaterMark || state.length === 0);
+}