Streams: Implement stream pipe-to (#35650)

* implement PipeTo, stub pipe_to

Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com>

* define a data structure to manage the piping

Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com>

* implement propagation of errors forward and backward, stub shutdown and shutdown with action

Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com>

* adding more fine-grain shutdown variants to state

Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com>

* implement progagate closing backward and forward

Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com>

* implement shutdown and actions

Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com>

* implement reading and writing

Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com>

* implement shutdown continuation and finalize

Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com>

* fix typo

Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com>

* add can_gc arguments

Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com>

* implement writer close with error propagation

Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com>

* move and document wait on pending write

Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com>

* more docs

Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com>

* write pending reads as part of shutdown

Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com>

* turn on piping test suite

Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com>

* add comment about using Rust api
improve comment on result
add comment on backpressure

Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com>

* fix multiple propagations

Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com>

* fix writing of chunks

Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com>

* fix error and close propagation
update test expectations

Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com>

* fix warnings

Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com>

* improve docs
remove redundant logic in pending writes

Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com>

* fix clippy

Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com>

* remove unnecessary expansion of visibility of enqueued value to_jsval

Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com>

* remove unnecessary conditional accessing of streams when propagating states

Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com>

* improve docs

Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com>

* remove unused result var

Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com>

* fix typo

Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com>

* remove redundant logic dealing with closed sources with pending writes

Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com>

* add doc links for shutdown actions

Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com>

* add comments on the need to return early when shutting down before checking close and error states

Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com>

* fmt

Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com>

* Update test expectations

Signed-off-by: Taym Haddadi <haddadi.taym@gmail.com>

* fix can_gc

Signed-off-by: Taym Haddadi <haddadi.taym@gmail.com>

---------

Signed-off-by: gterzian <2792687+gterzian@users.noreply.github.com>
Signed-off-by: Taym Haddadi <haddadi.taym@gmail.com>
Co-authored-by: Taym Haddadi <haddadi.taym@gmail.com>

components/script/dom/writablestreamdefaultwriter.rs

@@ -263,7 +263,7 @@ impl WritableStreamDefaultWriter {
     }
 
     /// <https://streams.spec.whatwg.org/#writable-stream-default-writer-write>
-    fn write(
+    pub(crate) fn write(
         &self,
         cx: SafeJSContext,
         global: &GlobalScope,
@@ -377,6 +377,52 @@ impl WritableStreamDefaultWriter {
         // Set this.[[stream]] to undefined.
         self.stream.set(None);
     }
+
+    /// <https://streams.spec.whatwg.org/#writable-stream-default-writer-close-with-error-propagation>
+    pub(crate) fn close_with_error_propagation(
+        &self,
+        cx: SafeJSContext,
+        global: &GlobalScope,
+        can_gc: CanGc,
+    ) -> Rc<Promise> {
+        // Let stream be writer.[[stream]].
+        let Some(stream) = self.stream.get() else {
+            // Assert: stream is not undefined.
+            unreachable!("Stream should be set.");
+        };
+
+        // Let state be stream.[[state]].
+        // Used via stream method calls.
+
+        // If ! WritableStreamCloseQueuedOrInFlight(stream) is true
+        // or state is "closed",
+        if stream.close_queued_or_in_flight() || stream.is_closed() {
+            // return a promise resolved with undefined.
+            let promise = Promise::new(global, can_gc);
+            promise.resolve_native(&(), can_gc);
+            return promise;
+        }
+
+        // If state is "errored",
+        if stream.is_errored() {
+            // return a promise rejected with stream.[[storedError]].
+            rooted!(in(*cx) let mut error = UndefinedValue());
+            stream.get_stored_error(error.handle_mut());
+            let promise = Promise::new(global, can_gc);
+            promise.reject_native(&error.handle(), can_gc);
+            return promise;
+        }
+
+        // Assert: state is "writable" or "erroring".
+        assert!(stream.is_writable() || stream.is_erroring());
+
+        // Return ! WritableStreamDefaultWriterClose(writer).
+        self.close(cx, global, can_gc)
+    }
+
+    pub(crate) fn get_stream(&self) -> Option<DomRoot<WritableStream>> {
+        self.stream.get()
+    }
 }
 
 impl WritableStreamDefaultWriterMethods<crate::DomTypeHolder> for WritableStreamDefaultWriter {