Re: Simple configurable expression parser (in pure Lua)

[Lorenzo Donati <lorenzodonatibz@...>]

On 15/06/2022 20:07, Flyer31 Test wrote:
> Though from MS, the free available Visual Studio Code together with
> Sumneco Lua extension is really VERY VERY perfect (do not mixup with
> VS Studio, which is NOT free available, and has NOT as good editor as
> VS Code strangely...).
>
> You get autohelp and autocompletion for all Lua functions (except if
> you use the : operator for meta references, this does not work ... so
> e.g. instead of "str:sub(1,5 )" you should better code "string.sub(
> str, 1, 5)" if you want autocomplete/autohelp support ... but this
> really is the only negative thing I could find there.
>
> You can also quite easily add own help files, if you have own
> libraries, and such help files are simple ascii/unicode text files
> supporting markup language (for e. g. italic / bold font of title
> lines...). And these help files are Lua files and really nice to edit
> ... . After this you will see autocomplete/autohelp for your own
> library functions - really quite amazing.
>
> (I have tried also SciTE and Notepad++ before I then chose VS Studio Code...).
>
> On Wed, Jun 15, 2022 at 6:55 AM Lorenzo Donati
> <lorenzodonatibz@tiscali.it> wrote:
> > Unfortunately that can't be useful for me. I'm on Windows and use
> > another editor: SciTE, which  (BTW) embeds Lua.
Sorry, but You seem to have misunderstood my needs. I don't need an 
editor plugin for parsing expression and getting help.

I need a Lua library (or piece of code) that can parse expressions in 
different languages (at least C, C++, Lua, LaTex)  because I need the 
result of the parsing (some kind of easily modifiable representation, 
e.g. an AST) to rebuild the expressions using a different syntax and/or 
after altering them in some ways.

Use case:

I have this expression from a C code snippet:

"(a + b) & (1u << 5)"

*Using Lua code° I need to transform it in an equivalent Lua form to 
calculate its value (in this case it is sufficient to remove the "u" 
from 1u), AND I need to transform it to a LaTeX math mode expression
to typeset it in a document.

The net result is that I can create a PDF using PDFlatex from a LaTeX 
source generated using a Lua program. And this PDF will show a replica 
of the C expression but will also show its value (calculated using its 
Lua equivalent expression).

All this without entering 3 different expressions and avoiding
having to keep them in sync (Multiply that use case for 10 or 20 for 
each document I need to produce, and it would be a nightmare to keep in 
sync manually).

I already have lots of ad-hoc solutions, hence I needed a more general 
approach (applicable to other languages as-well, hence the 
configurability of the parser).

I also have some different but similar use cases, but I hope this 
clarifies the problem.


Cheers!

-- Lorenzo