Dear Tim
You are a great people and full of passion. In my home town (Hong Kong),
people just "use" open source, not contributing it.
Thanks
>From Peter
________________________________
From: Tim Boudreau <niftin...@gmail.com>
Sent: Wednesday, October 9, 2019 1:42 PM
To: dev@netbeans.apache.org <dev@netbeans.apache.org>
Subject: Re: Can anyone give me a help about developing antlr formatter
Okay. If you'd like to try some stuff, I could hook you up with some
modules. Antlr support - syntax highlighting, navigator panels, syntax
tree views, has been working for a while; formatting is pretty solid now.
I've spent the last week stabilizing the "live preview" functionality,
which actually generates NetBeans language support with syntax highlighting
for *the grammar you are currently editing* - so you can have a syntax
highlighted preview, and associate a file extension with that grammar and
open those files and interact with them with full IDE support that is
updated whenever you edit the grammar.
Basically the PITA with developing Antlr grammars is when you break some
rule that worked, change a whole bunch of other stuff before you know you
broke it, and then have to figure out which thing you did caused the
problem. So being able to visually, and instantly, see if something is
broken seems like a basic thing that's needed to make grammar development
much less painful.
Here's a screen shot:
https://timboudreau.com/files/screen/10-09-2019_01-39-44.png
All that gets a bit complex:
- User edits the grammar file
- Listener on the grammar file notices and tells highlighters of documents
in the language of that grammar to request a reparse
- They ask for a new parse from a parser which
- Is actually going to run code in an isolated classloader that loads
from an in-memory filesystem where the grammar and generated analyzer code
was compiled
- Notices that the grammar file - whose document is mapped into that
in-memory filesystem - has changed
- Initiates a new run of Antlr generating parser and lexer
- Compiles them into that memory filesystem
- Generates the source for a thing that will call that parser with
document contents, and retrieve the tokens, parse tree, etc. copied into
proxy objects so the classloader does not leak types
- Creates a new isolated classloader over the class output for all that
- Replaces that classloader in the proxy parser
- Passes the document text into that parser, extracts the proxied parse
tree and wraps that in a NetBeans Parser.Result
The good news is all that can happen in < 100ms. It works, but I've been
chasing bugs in the choreography of that process to ensure the new parse
runs against the right version of the grammar - each layer of that will use
the previous result if nothing has changed but the input text, and it works
out to being a big chain of lists of weakly referenced susbscribers to
things that subscribe to other things (i.e. the parser subscribes to
replacement of the classloader environment; the highlighters subscribe to
changes on the parser).
It requires a few hacks that will probably get turned into patches -
there's no way via API to get the cache for Source objects for the
in-language document to invalidate its cached parser results because *some
other document* changed, so that has to be done via reflection; and
similarly, there is no direct way to force a Language instance to be
discarded by its LanguageHierarchy, but if you don't, it will keep a cache
of token ids that will be completely wrong (particularly if the grammar is
unparseable and you get a lexer with a dummy set of token ids with one
token, flip back to a valid language, and back again, which is the normal
state of life in an IDE).
But for basic doing-stuff-with-Antlr it's in decent shape, and it's all
factored into many separate modules, so perhaps I could get some out there.
-Tim
On Wed, Oct 2, 2019 at 2:08 AM Peter Cheung <mcheun...@hotmail.com> wrote:
> Dear Tim
> Sorry i am doing my own antlr plugin
> https://gitlab.com/mcheung63/netbeans-antlr to support my compiler
> development which using antlr. If you plugin can well format antlr, then i
> can focus my compiler rather than antlr in netbeans.
> thanks
> Peter
>
>
--
http://timboudreau.com
