io interface (first pass)

examples/programs/io/main.bro

@@ -0,0 +1,124 @@
+io :: import "@std/io"
+
+_read_ok func(_ ?*mut anyopaque, _ io.ReadStream, buffer []mut u8) usize ! io.ReadError {
+	if buffer.len == 0 {
+		return 0
+	}
+	buffer[0] = 'o'
+	if buffer.len == 1 {
+		return 1
+	}
+	buffer[1] = 'k'
+	return 2
+}
+
+_read_too_much func(_ ?*mut anyopaque, _ io.ReadStream, buffer []mut u8) usize ! io.ReadError {
+	return buffer.len + 1
+}
+
+_read_eof func(_ ?*mut anyopaque, _ io.ReadStream, _ []mut u8) usize ! io.ReadError {
+	return 0
+}
+
+_write_short func(_ ?*mut anyopaque, _ io.WriteStream, bytes []u8) usize ! io.WriteError {
+	if bytes.len > 2 {
+		return 2
+	}
+	return bytes.len
+}
+
+_write_none func(_ ?*mut anyopaque, _ io.WriteStream, _ []u8) usize ! io.WriteError {
+	return 0
+}
+
+_write_too_much func(_ ?*mut anyopaque, _ io.WriteStream, bytes []u8) usize ! io.WriteError {
+	return bytes.len + 1
+}
+
+_ok_vtable io.IoVTable :: io.IoVTable {
+	read = _read_ok,
+	write = _write_short,
+}
+
+_read_bad_vtable io.IoVTable :: io.IoVTable {
+	read = _read_too_much,
+	write = _write_short,
+}
+
+_eof_vtable io.IoVTable :: io.IoVTable {
+	read = _read_eof,
+	write = _write_short,
+}
+
+_write_none_vtable io.IoVTable :: io.IoVTable {
+	read = _read_ok,
+	write = _write_none,
+}
+
+_write_bad_vtable io.IoVTable :: io.IoVTable {
+	read = _read_ok,
+	write = _write_too_much,
+}
+
+reader_for func(vtable @io.IoVTable) io.Reader {
+	return io.Reader {
+		impl = io.Io {context = none, vtable = vtable},
+		stream = .stdin,
+	}
+}
+
+writer_for func(vtable @io.IoVTable) io.Writer {
+	return io.Writer {
+		impl = io.Io {context = none, vtable = vtable},
+		stream = .stdout,
+	}
+}
+
+rejects_bad_read func() bool {
+	buffer [1]mut u8 = [0]
+	_ = io.read(reader_for(&_read_bad_vtable), buffer[..]) catch |err| {
+		return err == .read_failed
+	}
+	return false
+}
+
+rejects_no_progress func() bool {
+	io.write_all(writer_for(&_write_none_vtable), "x") catch |err| {
+		return err == .no_progress
+	}
+	return false
+}
+
+rejects_bad_write func() bool {
+	_ = io.write(writer_for(&_write_bad_vtable), "x") catch |err| {
+		return err == .write_failed
+	}
+	return false
+}
+
+main func(system io.Io) i32 {
+	buffer [2]mut u8 = [0, 0]
+	count usize :: io.read(reader_for(&_ok_vtable), buffer[..]) catch 0
+	if count != 2 or buffer[0] != 'o' or buffer[1] != 'k' {
+		return 1
+	}
+	eof usize :: io.read(reader_for(&_eof_vtable), buffer[..]) catch 1
+	empty_read usize :: io.read(reader_for(&_read_bad_vtable), buffer[0..0]) catch 1
+	empty_write usize :: io.write(writer_for(&_write_bad_vtable), "") catch 1
+	if eof != 0 or empty_read != 0 or empty_write != 0 {
+		return 5
+	}
+	io.write_all(writer_for(&_ok_vtable), "partial") catch |_| {
+		return 2
+	}
+	if !rejects_bad_read() or !rejects_no_progress() or !rejects_bad_write() {
+		return 3
+	}
+	io.write_all(io.Writer {
+		impl = system,
+		stream = .stdout,
+	}, "io-ok\n") catch |_| {
+		return 4
+	}
+	return 0
+}