Jacques-Olivier Goussard wrote:
*Eric Niebler* wrote:
'll second the suggestion to look into xpressive. With xpressive, you can refer to one regex from another. And with the latest version (in the Boost Sandbox) you can put your list of cities into a symbol table and get very fast look-up -- much better than just a bunch of alternates.
Ok, I've taken a look and that doesn't seem to be what I need afteral. The regexp used must use the Perl semantic and are only known at runtime, so I would go for what you call dynamic expressions, however I'm not sure I see how I can use your symbol table neat trick with those, unless they are disconnected. I.e. I can easily translate "in (CITY) on westbrook" into sregex leftre = 'in'; sregex rightre = 'on westbrook'; sregex re = leftre >> (city_map) >> rightre;
but what to do with "in (CITY|heaven) on westbrook" ?
You're right, you can't /directly/ use symbol tables in dynamic regexes, but you can embed a static regex into a dynamic one. See the section on Dynamic Regex Grammars here: http://tinyurl.com/2nacj7. In particular, you can: sregex_compiler comp; // static regex, creates a symbol table from city_map: comp["CITY"] = (a1 = city_map); // dynamic regex calls static regex sregex re = comp.compile("in ((?$CITY)|heaven) on westbrook"); HTH, -- Eric Niebler Boost Consulting www.boost-consulting.com