WIP:preparser: adding 2 optional compiler directives delay_mode_path , delay_mode_distributed

[maor1993]

These 2 compiler directives are defined in Annex E of the 1800-2017

I ran into this while attempting to parse some stdcell libraries.
I unfortunately can't seem to add all of the annex directives as the nom crate seems to have an issue
digging deeper when attempting to use the alt function in sv-parser-parser/src/general/compiler_directives.rs:L9
the nom alt function supports only up to 21 elements, placing all of them breaks this.

regardless, without these two directives I can't parse said Verilog.

[dalance]

Thank you for your contribution!
I forgot the detailed usage of nom, could you use nested alt to avoid the element limit like below?

let ret = alt((
  alt((
    map(),
    map(),
  )),
  alt((
    map(),
    map(),
  ))
));

[maor1993]

I'll try this tomorrow :)

Thank you for your contribution! I forgot the detailed usage of nom, could you use nested alt to avoid the element limit like below?

let ret = alt((
  alt((
    map(),
    map(),
  )),
  alt((
    map(),
    map(),
  ))
));

[maor1993]

Yup, cascading alts worked 🥳
I added back delay_mode_unit and delay_mode_zero

I will mention this commit misses support for default_trireg_strength and default_decay_time as they might need a new literal? (default decay time valid values are either integerconst, realconst or the word infinite)

[maor1993]

I've done some more testing and It seems I've implemented something slightly wrong here, when I have a file with one of these directives defined and a module defined afterwards it seems to break the syntax tree.