Re: How to parse keywords that can be used as identifiers?

Mark writes:
> I am working on a parser for a language that allows keywords to
> be used as identifiers. This causes all kinds of problems.
> I would like to know if somebody has already solved this problem,
> and, of course, how.
>
> Ps.
>
> I am using flex and bison to build the parser.


The Rexx language has this. It really is just a question of returning symbol
tokens and deciding in the parser (or extending the lexer with context). It
helps to know when a clause starts so as to force a keyword recognition ie to
force the rest of the line to be in error. Some sub-keywords are reserved in
context eg 'while' in 'do while' etc. There's a Rexx implementation at
ftp://flipper.pvv.unit.no/pub/rexx, called Regina, that uses Lex & Yacc. The
Rexx language home page is www.rexx.hursley.ibm.com, I think, off which is a
tutorial page(s).


Yours, Patrick
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Patrick Herring, Primrose Hill, London, UK
I tend to eat my UUCP feed once a day, so replies can take two days
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