Add support for PRUNE and SKIP (no MARK's though).

include/boost/regex/v4/basic_regex_parser.hpp

@@ -2760,7 +2760,57 @@ bool basic_regex_parser<charT, traits>::parse_perl_verb()
             return false;
          }
          ++m_position;
-         this->append_state(syntax_element_commit);
+         static_cast<re_commit*>(this->append_state(syntax_element_commit, sizeof(re_commit)))->action = commit_commit;
+         this->m_pdata->m_disable_match_any = true;
+         return true;
+      }
+      break;
+   case 'P':
+      if(++m_position == m_end)
+      {
+         // Rewind to start of (* sequence:
+         --m_position;
+         while(this->m_traits.syntax_type(*m_position) != regex_constants::syntax_open_mark) --m_position;
+         fail(regex_constants::error_perl_extension, m_position - m_base);
+         return false;
+      }
+      if(match_verb("RUNE"))
+      {
+         if((m_position == m_end) || (this->m_traits.syntax_type(*m_position) != regex_constants::syntax_close_mark))
+         {
+            // Rewind to start of (* sequence:
+            --m_position;
+            while(this->m_traits.syntax_type(*m_position) != regex_constants::syntax_open_mark) --m_position;
+            fail(regex_constants::error_perl_extension, m_position - m_base);
+            return false;
+         }
+         ++m_position;
+         static_cast<re_commit*>(this->append_state(syntax_element_commit, sizeof(re_commit)))->action = commit_prune;
+         this->m_pdata->m_disable_match_any = true;
+         return true;
+      }
+      break;
+   case 'S':
+      if(++m_position == m_end)
+      {
+         // Rewind to start of (* sequence:
+         --m_position;
+         while(this->m_traits.syntax_type(*m_position) != regex_constants::syntax_open_mark) --m_position;
+         fail(regex_constants::error_perl_extension, m_position - m_base);
+         return false;
+      }
+      if(match_verb("KIP"))
+      {
+         if((m_position == m_end) || (this->m_traits.syntax_type(*m_position) != regex_constants::syntax_close_mark))
+         {
+            // Rewind to start of (* sequence:
+            --m_position;
+            while(this->m_traits.syntax_type(*m_position) != regex_constants::syntax_open_mark) --m_position;
+            fail(regex_constants::error_perl_extension, m_position - m_base);
+            return false;
+         }
+         ++m_position;
+         static_cast<re_commit*>(this->append_state(syntax_element_commit, sizeof(re_commit)))->action = commit_skip;
          this->m_pdata->m_disable_match_any = true;
          return true;
       }

include/boost/regex/v4/perl_matcher.hpp

@@ -554,6 +554,8 @@ private:
    bool m_recursive_result;
    // how many memory blocks have we used up?:
    unsigned used_block_count;
+   // We have unwound to a lookahead/lookbehind, used by COMMIT/PRUNE/SKIP:
+   bool m_unwound_lookahead;
 #endif
 
    // these operations aren't allowed, so are declared private,

include/boost/regex/v4/perl_matcher_common.hpp

@@ -354,6 +354,9 @@ bool perl_matcher<BidiIterator, Allocator, traits>::match_prefix()
 #endif
    if(!m_has_found_match)
       position = restart; // reset search postion
+#ifdef BOOST_REGEX_RECURSIVE
+   m_can_backtrack = true; // reset for further searches
+#endif
    return m_has_found_match;
 }
 

include/boost/regex/v4/perl_matcher_non_recursive.hpp

@@ -1014,6 +1014,27 @@ bool perl_matcher<BidiIterator, Allocator, traits>::match_commit()
    // however we might not unwind correctly in that case, so for now,
    // just mark that we don't backtrack into whatever is left (or rather
    // we'll unwind it unconditionally without pausing to try other matches).
+
+   switch(static_cast<const re_commit*>(pstate)->action)
+   {
+   case commit_commit:
+      if(base != last)
+      {
+         restart = last;
+         --restart;
+      }
+      break;
+   case commit_skip:
+      if(position != base)
+      {
+         restart = position;
+         --restart;
+      }
+      break;
+   case commit_prune:
+      break;
+   }
+
    saved_state* pmp = m_backup_state;
    --pmp;
    if(pmp < m_stack_base)
@@ -1025,8 +1046,6 @@ bool perl_matcher<BidiIterator, Allocator, traits>::match_commit()
    (void) new (pmp)saved_state(16);
    m_backup_state = pmp;
    pstate = pstate->next.p;
-   // If we don't find a match we don't want to search further either:
-   restart = last;
    return true;
 }
 
@@ -1102,6 +1121,7 @@ bool perl_matcher<BidiIterator, Allocator, traits>::unwind(bool have_match)
    };
 
    m_recursive_result = have_match;
+   m_unwound_lookahead = false;
    unwind_proc_type unwinder;
    bool cont;
    //
@@ -1166,6 +1186,7 @@ bool perl_matcher<BidiIterator, Allocator, traits>::unwind_assertion(bool r)
    m_recursive_result = pmp->positive ? r : !r;
    boost::BOOST_REGEX_DETAIL_NS::inplace_destroy(pmp++);
    m_backup_state = pmp;
+   m_unwound_lookahead = true;
    return !result; // return false if the assertion was matched to stop search.
 }
 
@@ -1653,7 +1674,24 @@ template <class BidiIterator, class Allocator, class traits>
 bool perl_matcher<BidiIterator, Allocator, traits>::unwind_commit(bool b)
 {
    boost::BOOST_REGEX_DETAIL_NS::inplace_destroy(m_backup_state++);
-   while(unwind(b)) {}
+   while(unwind(b) && !m_unwound_lookahead){}
+   if(m_unwound_lookahead && pstate)
+   {
+      //
+      // If we stop because we just unwound an assertion, put the
+      // commit state back on the stack again:
+      //
+      saved_state* pmp = m_backup_state;
+      --pmp;
+      if(pmp < m_stack_base)
+      {
+         extend_stack();
+         pmp = m_backup_state;
+         --pmp;
+      }
+      (void) new (pmp)saved_state(16);
+      m_backup_state = pmp;
+   }
    return false;
 }
 

include/boost/regex/v4/perl_matcher_recursive.hpp

@@ -1001,7 +1001,16 @@ template <class BidiIterator, class Allocator, class traits>
 bool perl_matcher<BidiIterator, Allocator, traits>::match_commit()
 {
    m_can_backtrack = false;
-   restart = last;
+   int action = static_cast<const re_commit*>(pstate)->action;
+   switch(action)
+   {
+   case commit_commit:
+      restart = last;
+      break;
+   case commit_skip:
+      restart = position;
+      break;
+   }
    pstate = pstate->next.p;
    return true;
 }

include/boost/regex/v4/states.hpp

@@ -260,6 +260,21 @@ struct re_recurse : public re_jump
    int state_id;             // identifier of first nested repeat within the recursion.
 };
 
+/*** struct re_commit *************************************************
+Used for the PRUNE, SKIP and COMMIT verbs which basically differ only in what happens
+if no match is found and we start searching forward.
+**********************************************************************/
+enum commit_type
+{
+   commit_prune,
+   commit_skip,
+   commit_commit,
+};
+struct re_commit : public re_syntax_base
+{
+   commit_type action;
+};
+
 /*** enum re_jump_size_type *******************************************
 Provides compiled size of re_jump structure (allowing for trailing alignment).
 We provide this so we know how manybytes to insert when constructing the machine