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feat: Web Streams API (ReadableStream + WritableStream + TransformStream) — closes #237 #301

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Merged
proggeramlug merged 2 commits into from
Apr 29, 2026
Merged

feat: Web Streams API (ReadableStream + WritableStream + TransformStream) — closes #237 #301

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e24e9e8
feat(stdlib): web streams api (ReadableStream + WritableStream + Tran…
TheHypnoo Apr 29, 2026
278074c
Merge branch 'main' into fix/issue-237-web-streams
TheHypnoo Apr 29, 2026
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231 changes: 231 additions & 0 deletions crates/perry-codegen/src/lower_call.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3359,6 +3359,13 @@ pub(super) fn lower_fetch_native_method(
let promise = blk.call(I64, "js_response_blob", &[(DOUBLE, &recv_handle)]);
return Ok(Some(nanbox_pointer_inline(blk, &promise)));
}
// Issue #237: response.body — returns ReadableStream over the
// buffered body bytes. Property access lowers as a zero-arg
// method call here, same as response.headers above.
"body" => {
let h = ctx.block().call(DOUBLE, "js_response_body", &[(DOUBLE, &recv_handle)]);
return Ok(Some(h));
}
_ => return Ok(None),
}
}
Expand Down Expand Up @@ -3430,6 +3437,230 @@ pub(super) fn lower_fetch_native_method(
);
return Ok(Some(new_handle));
}
// Issue #237: blob.stream() — returns ReadableStream over the
// blob's bytes. Single-chunk; closes after one read.
"stream" => {
let h = ctx.block().call(DOUBLE, "js_blob_stream", &[(DOUBLE, &recv_handle)]);
return Ok(Some(h));
}
_ => return Ok(None),
}
}

// ─────────────────────────────────────────────────────────────────
// Web Streams API (issue #237)
// The receivers are numeric registry-id handles carried as f64,
// mirroring the Blob/Response handle ABI. Locals are tagged
// (module, class_name) by `register_native_instance` in
// `destructuring.rs`.
// ─────────────────────────────────────────────────────────────────

if module == "readable_stream" {
let recv_handle = lower_expr(ctx, recv)?;
match method {
"getReader" => {
let h = ctx.block().call(DOUBLE, "js_readable_stream_get_reader", &[(DOUBLE, &recv_handle)]);
return Ok(Some(h));
}
"cancel" => {
let reason = if !args.is_empty() {
lower_expr(ctx, &args[0])?
} else {
double_literal(f64::from_bits(crate::nanbox::TAG_UNDEFINED))
};
let blk = ctx.block();
let promise = blk.call(I64, "js_readable_stream_cancel", &[(DOUBLE, &recv_handle), (DOUBLE, &reason)]);
return Ok(Some(nanbox_pointer_inline(blk, &promise)));
}
"tee" => {
let h = ctx.block().call(DOUBLE, "js_readable_stream_tee", &[(DOUBLE, &recv_handle)]);
return Ok(Some(h));
}
"pipeTo" => {
let dest = if !args.is_empty() {
lower_expr(ctx, &args[0])?
} else {
double_literal(f64::from_bits(crate::nanbox::TAG_UNDEFINED))
};
let blk = ctx.block();
let promise = blk.call(I64, "js_readable_stream_pipe_to", &[(DOUBLE, &recv_handle), (DOUBLE, &dest)]);
return Ok(Some(nanbox_pointer_inline(blk, &promise)));
}
"pipeThrough" => {
// pipeThrough(transform) — transform has .readable / .writable.
// We need both sub-handles. Lower the transform once, then
// call js_transform_stream_writable / _readable to extract.
let transform = if !args.is_empty() {
lower_expr(ctx, &args[0])?
} else {
double_literal(f64::from_bits(crate::nanbox::TAG_UNDEFINED))
};
let writable = ctx.block().call(DOUBLE, "js_transform_stream_writable", &[(DOUBLE, &transform)]);
let readable = ctx.block().call(DOUBLE, "js_transform_stream_readable", &[(DOUBLE, &transform)]);
let new_h = ctx.block().call(
DOUBLE,
"js_readable_stream_pipe_through",
&[(DOUBLE, &recv_handle), (DOUBLE, &writable), (DOUBLE, &readable)],
);
return Ok(Some(new_h));
}
"locked" => {
let v = ctx.block().call(DOUBLE, "js_readable_stream_locked", &[(DOUBLE, &recv_handle)]);
return Ok(Some(v));
}
// ReadableStreamDefaultController on the same handle:
"enqueue" => {
let chunk = if !args.is_empty() {
lower_expr(ctx, &args[0])?
} else {
double_literal(f64::from_bits(crate::nanbox::TAG_UNDEFINED))
};
let v = ctx.block().call(DOUBLE, "js_readable_stream_controller_enqueue", &[(DOUBLE, &recv_handle), (DOUBLE, &chunk)]);
return Ok(Some(v));
}
"close" => {
let v = ctx.block().call(DOUBLE, "js_readable_stream_controller_close", &[(DOUBLE, &recv_handle)]);
return Ok(Some(v));
}
"error" => {
let reason = if !args.is_empty() {
lower_expr(ctx, &args[0])?
} else {
double_literal(f64::from_bits(crate::nanbox::TAG_UNDEFINED))
};
let v = ctx.block().call(DOUBLE, "js_readable_stream_controller_error", &[(DOUBLE, &recv_handle), (DOUBLE, &reason)]);
return Ok(Some(v));
}
"desiredSize" => {
let v = ctx.block().call(DOUBLE, "js_readable_stream_controller_desired_size", &[(DOUBLE, &recv_handle)]);
return Ok(Some(v));
}
_ => return Ok(None),
}
}

if module == "readable_stream_reader" {
let recv_handle = lower_expr(ctx, recv)?;
match method {
"read" => {
let blk = ctx.block();
let promise = blk.call(I64, "js_reader_read", &[(DOUBLE, &recv_handle)]);
return Ok(Some(nanbox_pointer_inline(blk, &promise)));
}
"releaseLock" => {
let v = ctx.block().call(DOUBLE, "js_reader_release_lock", &[(DOUBLE, &recv_handle)]);
return Ok(Some(v));
}
"cancel" => {
let reason = if !args.is_empty() {
lower_expr(ctx, &args[0])?
} else {
double_literal(f64::from_bits(crate::nanbox::TAG_UNDEFINED))
};
let blk = ctx.block();
let promise = blk.call(I64, "js_reader_cancel", &[(DOUBLE, &recv_handle), (DOUBLE, &reason)]);
return Ok(Some(nanbox_pointer_inline(blk, &promise)));
}
"closed" => {
let blk = ctx.block();
let promise = blk.call(I64, "js_reader_closed", &[(DOUBLE, &recv_handle)]);
return Ok(Some(nanbox_pointer_inline(blk, &promise)));
}
_ => return Ok(None),
}
}

if module == "writable_stream" {
let recv_handle = lower_expr(ctx, recv)?;
match method {
"getWriter" => {
let h = ctx.block().call(DOUBLE, "js_writable_stream_get_writer", &[(DOUBLE, &recv_handle)]);
return Ok(Some(h));
}
"abort" => {
let reason = if !args.is_empty() {
lower_expr(ctx, &args[0])?
} else {
double_literal(f64::from_bits(crate::nanbox::TAG_UNDEFINED))
};
let blk = ctx.block();
let promise = blk.call(I64, "js_writable_stream_abort", &[(DOUBLE, &recv_handle), (DOUBLE, &reason)]);
return Ok(Some(nanbox_pointer_inline(blk, &promise)));
}
"close" => {
let blk = ctx.block();
let promise = blk.call(I64, "js_writable_stream_close", &[(DOUBLE, &recv_handle)]);
return Ok(Some(nanbox_pointer_inline(blk, &promise)));
}
"locked" => {
let v = ctx.block().call(DOUBLE, "js_writable_stream_locked", &[(DOUBLE, &recv_handle)]);
return Ok(Some(v));
}
_ => return Ok(None),
}
}

if module == "writable_stream_writer" {
let recv_handle = lower_expr(ctx, recv)?;
match method {
"write" => {
let chunk = if !args.is_empty() {
lower_expr(ctx, &args[0])?
} else {
double_literal(f64::from_bits(crate::nanbox::TAG_UNDEFINED))
};
let blk = ctx.block();
let promise = blk.call(I64, "js_writer_write", &[(DOUBLE, &recv_handle), (DOUBLE, &chunk)]);
return Ok(Some(nanbox_pointer_inline(blk, &promise)));
}
"close" => {
let blk = ctx.block();
let promise = blk.call(I64, "js_writer_close", &[(DOUBLE, &recv_handle)]);
return Ok(Some(nanbox_pointer_inline(blk, &promise)));
}
"abort" => {
let reason = if !args.is_empty() {
lower_expr(ctx, &args[0])?
} else {
double_literal(f64::from_bits(crate::nanbox::TAG_UNDEFINED))
};
let blk = ctx.block();
let promise = blk.call(I64, "js_writer_abort", &[(DOUBLE, &recv_handle), (DOUBLE, &reason)]);
return Ok(Some(nanbox_pointer_inline(blk, &promise)));
}
"releaseLock" => {
let v = ctx.block().call(DOUBLE, "js_writer_release_lock", &[(DOUBLE, &recv_handle)]);
return Ok(Some(v));
}
"closed" => {
let blk = ctx.block();
let promise = blk.call(I64, "js_writer_closed", &[(DOUBLE, &recv_handle)]);
return Ok(Some(nanbox_pointer_inline(blk, &promise)));
}
"ready" => {
let blk = ctx.block();
let promise = blk.call(I64, "js_writer_ready", &[(DOUBLE, &recv_handle)]);
return Ok(Some(nanbox_pointer_inline(blk, &promise)));
}
"desiredSize" => {
let v = ctx.block().call(DOUBLE, "js_writer_desired_size", &[(DOUBLE, &recv_handle)]);
return Ok(Some(v));
}
_ => return Ok(None),
}
}

if module == "transform_stream" {
let recv_handle = lower_expr(ctx, recv)?;
match method {
"readable" => {
let v = ctx.block().call(DOUBLE, "js_transform_stream_readable", &[(DOUBLE, &recv_handle)]);
return Ok(Some(v));
}
"writable" => {
let v = ctx.block().call(DOUBLE, "js_transform_stream_writable", &[(DOUBLE, &recv_handle)]);
return Ok(Some(v));
}
_ => return Ok(None),
}
}
Expand Down
104 changes: 104 additions & 0 deletions crates/perry-codegen/src/lower_call/builtin.rs
View file
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Original file line number Diff line number Diff line change
Expand Up @@ -361,6 +361,110 @@ pub(super) fn lower_builtin_new(
Ok(Some(handle))
}

// Issue #237: Web Streams API constructors. Source / sink / transform
// objects accept `start` / `pull` / `cancel` / `write` / `close` /
// `abort` / `transform` / `flush` callbacks; missing ones are passed
// as TAG_UNDEFINED so the runtime can no-op cleanly.
"ReadableStream" => {
let mut start = double_literal(f64::from_bits(crate::nanbox::TAG_UNDEFINED));
let mut pull = double_literal(f64::from_bits(crate::nanbox::TAG_UNDEFINED));
let mut cancel = double_literal(f64::from_bits(crate::nanbox::TAG_UNDEFINED));
let mut hwm = double_literal(1.0);
if !args.is_empty() {
if let Some(props) = extract_options_fields(ctx, &args[0]) {
for (k, vexpr) in &props {
match k.as_str() {
"start" => { start = lower_expr(ctx, vexpr)?; }
"pull" => { pull = lower_expr(ctx, vexpr)?; }
"cancel" => { cancel = lower_expr(ctx, vexpr)?; }
_ => { let _ = lower_expr(ctx, vexpr)?; }
}
}
} else {
let _ = lower_expr(ctx, &args[0])?;
}
}
if args.len() >= 2 {
if let Some(qprops) = extract_options_fields(ctx, &args[1]) {
for (k, vexpr) in &qprops {
if k == "highWaterMark" { hwm = lower_expr(ctx, vexpr)?; }
}
}
}
let h = ctx.block().call(
DOUBLE,
"js_readable_stream_new",
&[(DOUBLE, &start), (DOUBLE, &pull), (DOUBLE, &cancel), (DOUBLE, &hwm)],
);
Ok(Some(h))
}

"WritableStream" => {
let mut write = double_literal(f64::from_bits(crate::nanbox::TAG_UNDEFINED));
let mut close = double_literal(f64::from_bits(crate::nanbox::TAG_UNDEFINED));
let mut abort = double_literal(f64::from_bits(crate::nanbox::TAG_UNDEFINED));
let mut hwm = double_literal(1.0);
if !args.is_empty() {
if let Some(props) = extract_options_fields(ctx, &args[0]) {
for (k, vexpr) in &props {
match k.as_str() {
"write" => { write = lower_expr(ctx, vexpr)?; }
"close" => { close = lower_expr(ctx, vexpr)?; }
"abort" => { abort = lower_expr(ctx, vexpr)?; }
_ => { let _ = lower_expr(ctx, vexpr)?; }
}
}
} else {
let _ = lower_expr(ctx, &args[0])?;
}
}
if args.len() >= 2 {
if let Some(qprops) = extract_options_fields(ctx, &args[1]) {
for (k, vexpr) in &qprops {
if k == "highWaterMark" { hwm = lower_expr(ctx, vexpr)?; }
}
}
}
let h = ctx.block().call(
DOUBLE,
"js_writable_stream_new",
&[(DOUBLE, &write), (DOUBLE, &close), (DOUBLE, &abort), (DOUBLE, &hwm)],
);
Ok(Some(h))
}

"TransformStream" => {
let mut transform = double_literal(f64::from_bits(crate::nanbox::TAG_UNDEFINED));
let mut flush = double_literal(f64::from_bits(crate::nanbox::TAG_UNDEFINED));
let mut hwm = double_literal(1.0);
if !args.is_empty() {
if let Some(props) = extract_options_fields(ctx, &args[0]) {
for (k, vexpr) in &props {
match k.as_str() {
"transform" => { transform = lower_expr(ctx, vexpr)?; }
"flush" => { flush = lower_expr(ctx, vexpr)?; }
_ => { let _ = lower_expr(ctx, vexpr)?; }
}
}
} else {
let _ = lower_expr(ctx, &args[0])?;
}
}
if args.len() >= 2 {
if let Some(qprops) = extract_options_fields(ctx, &args[1]) {
for (k, vexpr) in &qprops {
if k == "highWaterMark" { hwm = lower_expr(ctx, vexpr)?; }
}
}
}
let h = ctx.block().call(
DOUBLE,
"js_transform_stream_new",
&[(DOUBLE, &transform), (DOUBLE, &flush), (DOUBLE, &hwm)],
);
Ok(Some(h))
}

"Promise" => {
// `new Promise((resolve, reject) => { ... })` — the runtime's
// `js_promise_new_with_executor` takes the closure, allocates
Expand Down
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