New Tools note

[Helene.Kirchner@loria.fr]

A new Tools note--submitted in April, but never installed--
is now available:


        * Note [[T-7]]. Axel Schairer:
          Using standard tools to create lexers and parsers for CASL.
          April 1999.

http://www.brics.dk/Projects/CoFI/Notes/T-7/


Abstract

The CASL language as described in [CoF98] defines a concrete syntax
for comments and announces a concrete syntax for annotations, which is
proposed in [RM99] and was discussed at the CoFI WG meeting, March
1999, in Amsterdam. The discussion also addressed the question how
comments and annotations should be handled by approved CASL tools. 

The approach discussed requires CASL parsers to handle all comments
and annotations by representing them in the abstract syntax tree which
they construct from a CASL input. This gives rise to pragmatic
problems when parser generator tools using a technique similar to
flex/bison are used to implement the lexing and context free parsing
components of CASL parsers.

This note proposes a solution that allows specialized CASL frontends
to handle only the comments and annotations that are relevant for the
tool the frontend is a part of, allowing the construction of
specialized CASL parsers using a wide range of existing parser
generator tools.

This note only considers annotations present in the source text, not
annotations that are created while parsing or further processing.