1.3. Preprocessor

1.3.1. Why a preprocessor?

Yes, I can hear you, but yes, you need a preprocessor for some equations. For a better documentation, you can inline a nice ASCII art equation, and for some formula manipulation, you can directly process it within your source code.

1.3.2. Example

$ cat ../tests/preprocess/formattest.c

#include <stdio.h>

    int
main(int argc, char **argv)
{
    int y;
    /* Eq:format integrate( a, b,       */
    /* fromage * sin( camembert ) / 2, fromage )   */
    return 0;
}

The important point here is the special comment. Let’s see the result before explaining it.

$ eq preprocess -o temp.c -f ../tests/preprocess/formattest.c

$ cat temp.c

#include <stdio.h>

    int
main(int argc, char **argv)
{
    int y;
    /* Eq:format integrate( a, b,       */
    /* fromage * sin( camembert ) / 2, fromage )   */
    /*<@<*/
    /*   b                                    */
    /*   _                                    */
    /*  /   fromage.sin(camembert)            */
    /*  |  ------------------------ dfromage  */
    /* _/             2                       */
    /*  a                                     */
    /*                                        */
    /*                                        */
    /*>@>*/
    return 0;
}

1.3.3. Source code markup

The little embedded markup format is really simple. To use it, you must write it in <strong>mono line</strong> comment. Let’s digg a bit in the definition which trigger the processing :

Eq:	Tell Eq that he can process something
format	The eq command to call, you are limited here, you don’t have all the command at disposition.
<@<	Begin marker of output
>@>	End marker of output

The <@< and >@> are ugly, but they permit the preprocessor to re-analyze the file and update the previous render, if someone got a better idea, please send me a mail about it.

1.3.4. Supported languages

$ eq show --languages
Supported languages for preprocessing :
=======================================
	.c    - C like
	.C    - C++ like
	.cc   - C++ like
	.cpp  - C++ like
	.h    - C like
	.hpp  - C++ like
	.java - C++ like
	.cs   - C++ like
	.hs   - Haskell
	.lhs  - Haskell
	.ml   - OCaml
	.mli  - OCaml
	.py   - Shell like
	.rb   - Shell like
	.sh   - Shell like
	.ps1  - Shell like

As you can see, many languages are already supported for formatting. Some language name are common due to the similarity of their mono line comment format. If you want your favorite language to be included here, please drop me a mail.

For the moment Eq use the file extension to guess the language. It might change in the future.