// io — stream interface (Plan 9 Bio / Hare io::stream shape).
//
// No closures, no methods. A `stream` is a struct of function
// pointers plus a `ctx: *void`. The error channel is the return
// value of read/write/close — Hare-shaped tagged unions instead of
// errno-style integer sentinels.

// eof — read past the end of the stream. Hare uses the `done`
// singleton for EOF; ww doesn't have `done` yet so we ship a
// named-void variant tag.
package io;

export type eof = void;

// closed — operation attempted on a stream that has already been
// closed. ww-specific: Hare's io collapses this into the wider
// errors union, but our stream vtable has no handle-ownership
// semantics, so a distinct tag is honest. Named void.
export type closed = void;

// underread — an I/O handle hit eof partway through a fixed-size
// read. Payload is the byte count actually delivered. Mirrors
// Hare's `io::underread = !size`; ww uses i32 because the
// underlying buffer-length type is i32 today.
export type underread = !i32;

export type stream = struct {
	ctx:    *void,
	read:   fn(s: *stream, buf: []u8) (i32 | eof | closed),
	write:  fn(s: *stream, buf: []u8) (i32 | closed),
	close:  fn(s: *stream) (void | closed),
};

export fn read(s: *stream, buf: []u8) (i32 | eof | closed) = {
	return s.read(s, buf);
};

export fn write(s: *stream, buf: []u8) (i32 | closed) = {
	return s.write(s, buf);
};

export fn close(s: *stream) (void | closed) = {
	return s.close(s);
};