Minify HTML with Boost regex in C++ - c++

Question

Question
How to minify HTML using C++?
Resources
An external library could be the answer, but I'm more looking for improvements of my current code. Although I'm all ears for other possibilities.
Current code
This is my interpretation in c++ of the following answer.
The only part I had to change from the original post is this part on top: "(?ix)"
...and a few escape signs
#include <boost/regex.hpp>
void minifyhtml(string* s) {
boost::regex nowhitespace(
"(?ix)"
"(?>" // Match all whitespans other than single space.
"[^\\S ]\\s*" // Either one [\t\r\n\f\v] and zero or more ws,
"| \\s{2,}" // or two or more consecutive-any-whitespace.
")" // Note: The remaining regex consumes no text at all...
"(?=" // Ensure we are not in a blacklist tag.
"[^<]*+" // Either zero or more non-"<" {normal*}
"(?:" // Begin {(special normal*)*} construct
"<" // or a < starting a non-blacklist tag.
"(?!/?(?:textarea|pre|script)\\b)"
"[^<]*+" // more non-"<" {normal*}
")*+" // Finish "unrolling-the-loop"
"(?:" // Begin alternation group.
"<" // Either a blacklist start tag.
"(?>textarea|pre|script)\\b"
"| \\z" // or end of file.
")" // End alternation group.
")" // If we made it here, we are not in a blacklist tag.
);
// #todo Don't remove conditional html comments
boost::regex nocomments("<!--(.*)-->");
*s = boost::regex_replace(*s, nowhitespace, " ");
*s = boost::regex_replace(*s, nocomments, "");
}
Only the first regex is from the original post, the other one is something I'm working on and should be considered far from complete. It should hopefully give a good idea of what I try to accomplish though.

Answer 1

Regexps are a powerful tool, but I think that using them in this case will be a bad idea. For example, regexp you provided is maintenance nightmare. By looking at this regexp you can't quickly understand what the heck it is supposed to match.
You need a html parser that would tokenize input file, or allow you to access tokens either as a stream or as an object tree. Basically read tokens, discards those tokens and attributes you don't need, then write what remains into output. Using something like this would allow you to develop solution faster than if you tried to tackle it using regexps.
I think you might be able to use xml parser or you could search for xml parser with html support.
In C++, libxml (which might have HTML support module), Qt 4, tinyxml, plus libstrophe uses some kind of xml parser that could work.
Please note that C++ (especially C++03) might not be the best language for this kind of program. Although I strongly dislike python, python has "Beautiful Soup" module that would work very well for this kind of problem.
Qt 4 might work because it provides decent unicode string type (and you'll need it if you're going to parse html).