this is gold, thank you!!!
do you know if MemoryInputStream is the only one usable? is there any list
of available GJS streams one can use? I think memory is just fine though,
thanks again a lot!
On Tue, Nov 7, 2017 at 6:46 PM, Sam Jansen <sam.jan...@starleaf.com> wrote:
> Hi Andrea,
>
> I've come up with something that... almost does what you're looking at
> here. Perhaps it's useful as a guide of what one can do with the Gio
> interface.
>
> I think you may hit some awkward problems with modelling Node-style
> streams with GLib ones. But perhaps it is possible and this helps. I don't
> really know the Node stream semantics so I have assumed various things in
> my Readable implementation as you'll see... Note that MemoryInputStream
> really is just a byte stream; so there is no guarantee you'll receive the
> exact block of bytes that was written -- for example, when I run this I get
> a first chunk of "12", followed by "3", "4", etc.
>
>
> let Gio = imports.gi.Gio;
> let byteArray = imports.byteArray;
> let mainloop = imports.mainloop;
>
> class Readable {
> constructor() {
> this._mio = Gio.MemoryInputStream.new();
> this._callbacks = {};
> this._startNext();
> }
>
> _startNext() {
> // Enqueue an async read; and re-enqueue when it finishes, so we're
> // always waiting for data...
> this._mio.read_bytes_async(4096, 1, null, (source, res) => {
> this._onData(this._mio.read_bytes_finish(res));
> this._startNext();
> });
> }
>
> _onData(bytes) {
> if (this._callbacks['data']) {
> let ba = byteArray.fromGBytes(bytes);
> this._callbacks['data'](ba);
> this._read();
> }
> }
>
> push(bytes) {
> if (bytes == null) {
> mainloop.quit('main');
> return;
> }
> this._mio.add_bytes(bytes);
> }
>
> on(name, callback) {
> this._callbacks[name] = callback;
> if (name === 'data') {
> this._read();
> }
> }
> }
>
> class Counter extends Readable {
> constructor(opt) {
> super(opt);
> this._max = 1000;
> this._index = 1;
> }
>
> _read() {
> const i = this._index++;
> if (i > this._max)
> this.push(null);
> else {
> const str = '' + i;
> const buf = byteArray.fromString(str); // Buffer.from(str, 'ascii');
> this.push(buf);
> }
> }
> }
>
> (new Counter).on('data', (str) => {
> print("data", str.toString());
> });
>
> mainloop.run('main');
>
>
> On 7 November 2017 at 10:08, Andrea Giammarchi <
> andrea.giammar...@gmail.com> wrote:
>
>> I am trying to implement a stream module and apparently I have everything
>> I need but practically I'm unable to use streams.
>>
>> If I instantiate a `new Gio.InputStream` I have the following error:
>> cannot create instance of abstract (non-instantiatable) type
>> 'GInputStream'
>>
>> I cannot even extend it ... so I've though "ok, maybe it's like an
>> interface, I implement it and that's it"
>>
>> But then a JS class wouldn't work as base_stream for a
>> Gio.BufferedInputStream, and if I extend the JS class to be a
>> GObject.Object then:
>> Gjs-WARNING **: JS ERROR: TypeError: Object is of type GObject.Object -
>> cannot convert to GInputStream
>>
>> where GInputStream is the one I cannot use in the first place.
>>
>> I've reached full circle then so ... I wonder if anyone has any idea how
>> to use/create/extend streams in GJS (not talking about file streams but
>> streams in general) or if it's even possible.
>>
>> In node, as example, I could do this and it will work:
>>
>> ```js
>>
>> const { Readable } = require('stream');
>>
>> class Counter extends Readable {
>> constructor(opt) {
>> super(opt);
>> this._max = 1000;
>> this._index = 1;
>> }
>>
>> _read() {
>> const i = this._index++;
>> if (i > this._max)
>> this.push(null);
>> else {
>> const str = '' + i;
>> const buf = Buffer.from(str, 'ascii');
>> this.push(buf);
>> }
>> }
>> }
>>
>> (new Counter).on('data', console.log);
>>
>> ```
>>
>> _______________________________________________
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>> javascript-list@gnome.org
>> https://mail.gnome.org/mailman/listinfo/javascript-list
>>
>>
>
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