Re: Alternatives to Regexps

John Carter (ece@dwaf-hri.pwv.gov.za) wrote:


>I'm seeking pointers to alternatives to standard regular expression
>languages.


You can use context free grammars also at the lexical level. Sometimes
LR parsetables for grammars that actually represent regular languages
can be smaller than the DFA's generated from the regular expressions.
Furthermore, parsing actions gives you a natural way of obtaining the
attributes of lexical tokens, for example the values of number
constants.


For example, if you represent the set of floating point constants by a
regexp, you will basically have to parse the token once again to find
its value. If you use a parser as a lexer, you can naturally build the
value using parsing actions.


Torben Mogensen (torbenm@diku.dk)




--

Return to the comp.compilers page.
Search the comp.compilers archives again.