Re: [Boost-users] Regex problem

12 Mar 2008

      Ah, you're right.  That was one of my attempts to fix it (which you  
can guess didn't work).

As for the inefficiency, this is my first stab at regex.  =)

Here's the complete function as it stands (or doesn't, since it still  
crashes):

void Page::removeScriptTags() {
	boost::regex tagRegex("(?:i)]*>.*?]*>");
	string source(*pageSource);
	string replaced = boost::regex_replace(source, tagRegex, " ",  
boost::match_default);
	delete pageSource;
	pageSource = new string(replaced);
}

PageSource, as I told earlier, is an allocated string that stores the  
contents of the webpage.  I thought that the problem might be that  
pageSource is on the heap, so I've been trying to move it to the stack  
to see if that makes a difference.  It doesn't seem like it does.  I  
still crash at this line:

	string replaced = boost::regex_replace(source, tagRegex, " ",  
boost::match_default);

Thanks,

Dave

On 12 Mar, 2008, at 6:39 AM, John Maddock wrote:
...
That shouldn't even compile - there are too many arguments to
regex_replace - it should just be,
*pageSource = boost::regex_replace(*pageSource, tagRegex, " ",
boost::match_default);
The expression is also needlessly inefficient, you could just make  
the whole
expression case insensitive by prefixing with "(?:i)", then "[\\w\ 
\W]" will
match *either* something that is a word character, *or* something  
that is
*not* a word character, which is probably not what you meant :-)   
Likewise
[.] will match a literal "." which again is probably not what you  
meant.  So
maybe try something like:
"(?:i)]*>.*?]*>"
...
...
and this code crashes when attempting to destruct "matches":
void Page::findTitleSummary() {
boost::cmatch matches;
boost::regex
bodyRegex("<[tT][iI][tT][lL][eE][\\w\\W]*?>([^<]*)");
if (boost::regex_search(pageSource->c_str(), matches, bodyRegex)) {
pageSummary = new string(matches[1]);
hasFoundSummary = true;
}
}
What am I missing?
Without seeing a compilable code sample to play with I don't know,  
but it
looks like you're accessing memory that's already gone out of scope
somewhere.
HTH, John.
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Re: [Boost-users] Regex problem

Dave DeLong