Include ConsoleStdout for incremental output?

[amesgen]

I find ConsoleStdout from an existing test very useful to incrementally get log output while running WASI programs that use stdout/stderr:

browser_wasi_shim/test/adapters/browser/run-test.html

Lines 4 to 33 in b18b2da

	class ConsoleStdout extends Fd {
	constructor(write) {
	super();
	this.write = write;
	}
	fd_filestat_get() {
	const filestat = new wasi.Filestat(
	wasi.FILETYPE_CHARACTER_DEVICE,
	BigInt(0),
	);
	return { ret: 0, filestat };
	}
	fd_fdstat_get() {
	const fdstat = new wasi.Fdstat(wasi.FILETYPE_CHARACTER_DEVICE, 0);
	fdstat.fs_rights_base = BigInt(wasi.RIGHTS_FD_WRITE);
	return { ret: 0, fdstat };
	}
	fd_write(view8, iovs) {
	let nwritten = 0;
	for (let iovec of iovs) {
	let buffer = view8.slice(iovec.buf, iovec.buf + iovec.buf_len);
	this.write(buffer);
	nwritten += iovec.buf_len;
	}
	return { ret: 0, nwritten };
	}
	}

In particular, in conjunction with an additional static method

  static lineBuffered(write) {
    const dec = new TextDecoder("utf-8", { fatal: false });
    let line_buf = "";
    return new ConsoleStdout((buffer) => {
      line_buf += dec.decode(buffer, { stream: true });
      const lines = line_buf.split("\n");
      for (const [i, line] of lines.entries()) {
        if (i < lines.length - 1) {
          write(line);
        } else {
          line_buf = line;
        }
      }
    });
  }

which can eg be used like this

[
  new OpenFile(new File([])), // stdin
  ConsoleStdout.lineBuffered(msg => console.log(`[WASI stdout] ${msg}`)),
  ConsoleStdout.lineBuffered(msg => console.warn(`[WASI stderr] ${msg}`)),
]

---

Is it in scope to add this to the library such that it can be reused by other projects? If so, happy to create a PR.

[bjorn3]

Yeah, seems useful to have.