[boost::xpressive] Multipass swap?

Question

recursion

Plz tell me who is in the know, otherwise the whole Google has already broken.
There is a line in which boost::xpressive replaces one with the other, but the result is the same string, which must also be replaced (oh, how I said!).
Example:

sregex tmp = sregex::compile( &quot;([0-9]+)\\-([0-9]+)&quot;);<br/>
string t = regex_replace(string(&quot;8-8-8-8&quot;), tmp, string(&quot;$1&quot;), regex_constants::format_perl);<br/>

The result is “8-8”, but I want 8.
Maybe there is some key / parameter?
Of course, you can “recursively / in a loop”, but how then to determine that there was no replacement? It would not be desirable to compare lines before and after.

Answer 1

>> Не хочется же строки до и после сравнивать.
It's strange, but I had exactly such an idea (compare before and after), while reading the question (until I read this last line).
If you do not want to compare the strings themselves, you can compare the hashes of these strings, for example md5 or sha1.