Add ReadableStream::from(async_iterable)

CHANGELOG.md

@@ -2,8 +2,9 @@
 
 ## Unreleased
 
+* Added `ReadableStream::from(async_iterable)` and `try_from(async_iterable)`. ([#23](https://github.com/MattiasBuelens/wasm-streams/pull/23))
 * Stop calling `byobRequest.respond(0)` on cancel ([#16](https://github.com/MattiasBuelens/wasm-streams/pull/16))
-* ⚠ **Breaking change:** The system modules (`readable::sys`, `writable::sys` and `transform::sys`) now re-export directly from [the `web-sys` crate](https://docs.rs/web-sys/latest/web_sys/). This should make it easier to use `from_raw()`, `as_raw()` and `into_raw()`. ([#22](https://github.com/MattiasBuelens/wasm-streams/pull/22/))
+* ⚠ **Breaking change:** The system modules (`readable::sys`, `writable::sys` and `transform::sys`) now re-export directly from [the `web-sys` crate](https://docs.rs/web-sys/latest/web_sys/). This should make it easier to use `from_raw()`, `as_raw()` and `into_raw()`. ([#22](https://github.com/MattiasBuelens/wasm-streams/pull/22))
 
 ## v0.3.0 (2022-10-16)
 

src/readable/mod.rs

@@ -2,6 +2,7 @@
 //! [readable streams](https://developer.mozilla.org/en-US/docs/Web/API/ReadableStream).
 use futures_util::io::AsyncRead;
 use futures_util::Stream;
+use js_sys::Object;
 use wasm_bindgen::prelude::*;
 use wasm_bindgen::JsCast;
 
@@ -72,7 +73,7 @@ impl ReadableStream {
  let strategy = QueuingStrategy::new(0.0);
  let raw = sys::ReadableStreamExt::new_with_into_underlying_source(source, strategy)
  .unchecked_into();
- Self { raw }
+ Self::from_raw(raw)
  }
 
  /// Creates a new `ReadableStream` from an [`AsyncRead`].
@@ -95,7 +96,44 @@ impl ReadableStream {
  let raw = sys::ReadableStreamExt::new_with_into_underlying_byte_source(source)
  .expect_throw("readable byte streams not supported")
  .unchecked_into();
- Self { raw }
+ Self::from_raw(raw)
+ }
+
+ /// Creates a new `ReadableStream` wrapping the provided [iterable] or [async iterable].
+ ///
+ /// This can be used to adapt various kinds of objects into a readable stream,
+ /// such as an [array], an [async generator] or a [Node.js readable stream][Readable].
+ ///
+ /// **Panics** if `ReadableStream.from()` is not supported by the browser,
+ /// or if the given object is not a valid iterable or async iterable.
+ /// For a non-panicking variant, use [`try_from`](Self::try_from).
+ ///
+ /// [iterable]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols#the_iterable_protocol
+ /// [async iterable]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols#the_async_iterator_and_async_iterable_protocols
+ /// [array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array
+ /// [async generator]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/AsyncGenerator
+ /// [Readable]: https://nodejs.org/api/stream.html#class-streamreadable
+ pub fn from(async_iterable: Object) -> Self {
+ Self::try_from(async_iterable).unwrap_throw()
+ }
+
+ /// Try to create a new `ReadableStream` wrapping the provided [iterable] or [async iterable].
+ ///
+ /// This can be used to adapt various kinds of objects into a readable stream,
+ /// such as an [array], an [async generator] or a [Node.js readable stream][Readable].
+ ///
+ /// If `ReadableStream.from()` is not supported by the browser,
+ /// or if the given object is not a valid iterable or async iterable,
+ /// then this returns an error.
+ ///
+ /// [iterable]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols#the_iterable_protocol
+ /// [async iterable]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols#the_async_iterator_and_async_iterable_protocols
+ /// [array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array
+ /// [async generator]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/AsyncGenerator
+ /// [Readable]: https://nodejs.org/api/stream.html#class-streamreadable
+ pub fn try_from(async_iterable: Object) -> Result<Self, js_sys::Error> {
+ let raw = sys::ReadableStreamExt::from_async_iterable(&async_iterable)?.unchecked_into();
+ Ok(Self::from_raw(raw))
  }
 
  /// Acquires a reference to the underlying [JavaScript stream](sys::ReadableStream).

src/readable/sys.rs

@@ -47,6 +47,9 @@ extern "C" {
 
  #[wasm_bindgen(method, catch, js_class = ReadableStream, js_name = tee)]
  pub(crate) fn try_tee(this: &ReadableStreamExt) -> Result<Array, Error>;
+
+ #[wasm_bindgen(catch, static_method_of = ReadableStreamExt, js_class = ReadableStream, js_name = from)]
+ pub(crate) fn from_async_iterable(async_iterable: &Object) -> Result<ReadableStreamExt, Error>;
 }
 
 #[wasm_bindgen]

src/writable/mod.rs

@@ -55,7 +55,7 @@ impl WritableStream {
  // Use the default queuing strategy (with a HWM of 1 chunk).
  // We shouldn't set HWM to 0, since that would break piping to the writable stream.
  let raw = sys::WritableStreamExt::new_with_into_underlying_sink(sink).unchecked_into();
- WritableStream { raw }
+ Self::from_raw(raw)
  }
 
  /// Acquires a reference to the underlying [JavaScript stream](sys::WritableStream).

tests/tests/readable_stream.rs

@@ -298,3 +298,28 @@ async fn test_readable_stream_into_stream_then_into_async_read() {
  assert_eq!(async_read.read(&mut buf).await.unwrap(), 0);
  assert_eq!(&buf, &[4, 5, 6]);
 }
+
+#[wasm_bindgen_test]
+async fn test_readable_stream_from_js_array() {
+ let js_array =
+ js_sys::Array::from_iter([JsValue::from_str("Hello"), JsValue::from_str("world!")]);
+ let mut readable = match ReadableStream::try_from(js_array.unchecked_into()) {
+ Ok(readable) => readable,
+ Err(err) => {
+ // ReadableStream.from() is not yet supported in all browsers.
+ assert_eq!(err.name(), "TypeError");
+ assert_eq!(
+ err.message().as_string().unwrap(),
+ "ReadableStream.from is not a function"
+ );
+ return;
+ }
+ };
+ assert!(!readable.is_locked());
+
+ let mut reader = readable.get_reader();
+ assert_eq!(reader.read().await.unwrap(), Some(JsValue::from("Hello")));
+ assert_eq!(reader.read().await.unwrap(), Some(JsValue::from("world!")));
+ assert_eq!(reader.read().await.unwrap(), None);
+ reader.closed().await.unwrap();
+}