Re: Command Languages Versus Programming Languages

On Thu, 21 Nov 2024 19:12:03 -0000 (UTC)
Kaz Kylheku <643-408-1753@kylheku.com> boring babbled:

On 2024-11-20, Janis Papanagnou <janis_papanagnou+ng@hotmail.com> wrote:

I'm curious what you mean by Regexps presented in a "procedural" form.
Can you give some examples?

>
Here is an example: using a regex match to capture a C comment /* ... */
in Lex compared to just recognizing the start sequence /* and handling
the discarding of the comment in the action.
>
Without non-greedy repetition matching, the regex for a C comment is
quite obtuse. The procedural handling is straightforward: read
characters until you see a * immediately followed by a /.

Its not that simple I'm afraid since comments can be commented out.

eg:

   // int i; /*
   int j;
   /*
   int k;
   */
  ++j;

A C99 and C++ compiler would see "int j" and compile it, a regex would
simply remove everything from the first /* to */.

Also the same probably applies to #ifdef's.