Re: New package emacs-parser-generator

[Yuan Fu]

>> 
>> Tree-sitter parses incrementally, I modified primitive insert/delete 
>> functions in insdel.c to incrementally parse changed content. There is no 
>> need for threads as incremental parsing is extremely fast. We don’t make 
>> copies of buffer string, instead, we pass tree-sitter library a function 
>> that reads directly from the buffer.
> 
> Ok where can I read about this function? How does treesitter handle 
> incremental parses which are state-dependent? For example PHPs lex-analyzer 
> works differently in different states of the grammar, like do you signal to 
> treesitter a point in the buffer so it can backtrack the parsers states in 
> order to correctly perform a incremental parse on the new content?

I assume you mean the read function? It can be found here:

https://github.com/casouri/emacs/blob/106d050ad5d02f673f8a089e1f10c1eacfedd124/src/tree-sitter.c#L372

Tree-sitter only requires to be informed of every change to the buffer, it will 
read the buffer for itself and update the AST. I have no idea if it backtracks 
behind the scenes. Presumably tree-sitter can figure out from where to 
backtrack from the change information we give it.

Yuan