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10.3.2 Why not having used yacc and such

There are several reasons why we decided not to use grammars to parse the files. Firstly it would have made the design of the style sheets much more tricky, and today a2ps would know only 4 or 5 languages.

Secondly, it limits the number of persons who could build a style sheet.

Thirdly, we did not feel the need for such a powerful tool: handling the keywords and the sequences is just what the users expect.

Fourthly, any extension of a2ps would have required to recompile.

And last but not least, using a parser requires that the sources are syntactic bug free, which is too strong a requirement.

Nevertheless, PreScript gives the possibility to have on the one hand a syntactic parser which would produce PreScript code, and on the other hand, a2ps, which would make it PostScript. This schema seems to us a good compromise. If it is still not enough for you, you can use the library.