31   auto last = m_backrefs.size();
 
   32   m_backrefs.emplace_back(matcher);
 
   36 shared_ptr<RegexMatcher>
 
   39   auto backref = m_backrefs[i].lock();
 
   40   BOOST_ASSERT(backref != 
nullptr);
 
shared_ptr< RegexMatcher > getBackref(size_t i) const
 
size_t pushRef(const shared_ptr< RegexMatcher > &matcher)