perl_matcher_recursive.hpp

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/*
 *
 * Copyright (c) 2002
 * John Maddock
 *
 * Use, modification and distribution are subject to the 
 * Boost Software License, Version 1.0. (See accompanying file 
 * LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 *
 */

 /*
  *   LOCATION:    see http://www.boost.org for most recent version.
  *   FILE         perl_matcher_common.cpp
  *   VERSION      see <boost/version.hpp>
  *   DESCRIPTION: Definitions of perl_matcher member functions that are 
  *                specific to the recursive implementation.
  */

#ifndef BOOST_REGEX_V4_PERL_MATCHER_RECURSIVE_HPP
#define BOOST_REGEX_V4_PERL_MATCHER_RECURSIVE_HPP

#ifdef BOOST_MSVC
#pragma warning(push)
#pragma warning(disable: 4103)
#endif
#ifdef BOOST_HAS_ABI_HEADERS
#  include BOOST_ABI_PREFIX
#endif
#ifdef BOOST_MSVC
#pragma warning(pop)
#endif

#ifdef BOOST_MSVC
#pragma warning(push)
#pragma warning(disable: 4800)
#endif

namespace boost{
namespace re_detail{

template <class BidiIterator>
class backup_subex
{
   int index;
   sub_match<BidiIterator> sub;
public:
   template <class A>
   backup_subex(const match_results<BidiIterator, A>& w, int i)
      : index(i), sub(w[i], false) {}
   template <class A>
   void restore(match_results<BidiIterator, A>& w)
   {
      w.set_first(sub.first, index);
      w.set_second(sub.second, index, sub.matched);
   }
   const sub_match<BidiIterator>& get() { return sub; }
};

template <class BidiIterator, class Allocator, class traits>
bool perl_matcher<BidiIterator, Allocator, traits>::match_all_states()
{
   static matcher_proc_type const s_match_vtable[29] = 
   {
      (&perl_matcher<BidiIterator, Allocator, traits>::match_startmark),
      &perl_matcher<BidiIterator, Allocator, traits>::match_endmark,
      &perl_matcher<BidiIterator, Allocator, traits>::match_literal,
      &perl_matcher<BidiIterator, Allocator, traits>::match_start_line,
      &perl_matcher<BidiIterator, Allocator, traits>::match_end_line,
      &perl_matcher<BidiIterator, Allocator, traits>::match_wild,
      &perl_matcher<BidiIterator, Allocator, traits>::match_match,
      &perl_matcher<BidiIterator, Allocator, traits>::match_word_boundary,
      &perl_matcher<BidiIterator, Allocator, traits>::match_within_word,
      &perl_matcher<BidiIterator, Allocator, traits>::match_word_start,
      &perl_matcher<BidiIterator, Allocator, traits>::match_word_end,
      &perl_matcher<BidiIterator, Allocator, traits>::match_buffer_start,
      &perl_matcher<BidiIterator, Allocator, traits>::match_buffer_end,
      &perl_matcher<BidiIterator, Allocator, traits>::match_backref,
      &perl_matcher<BidiIterator, Allocator, traits>::match_long_set,
      &perl_matcher<BidiIterator, Allocator, traits>::match_set,
      &perl_matcher<BidiIterator, Allocator, traits>::match_jump,
      &perl_matcher<BidiIterator, Allocator, traits>::match_alt,
      &perl_matcher<BidiIterator, Allocator, traits>::match_rep,
      &perl_matcher<BidiIterator, Allocator, traits>::match_combining,
      &perl_matcher<BidiIterator, Allocator, traits>::match_soft_buffer_end,
      &perl_matcher<BidiIterator, Allocator, traits>::match_restart_continue,
      (::boost::is_random_access_iterator<BidiIterator>::value ? &perl_matcher<BidiIterator, Allocator, traits>::match_dot_repeat_fast : &perl_matcher<BidiIterator, Allocator, traits>::match_dot_repeat_slow),
      &perl_matcher<BidiIterator, Allocator, traits>::match_char_repeat,
      &perl_matcher<BidiIterator, Allocator, traits>::match_set_repeat,
      &perl_matcher<BidiIterator, Allocator, traits>::match_long_set_repeat,
      &perl_matcher<BidiIterator, Allocator, traits>::match_backstep,
      &perl_matcher<BidiIterator, Allocator, traits>::match_assert_backref,
      &perl_matcher<BidiIterator, Allocator, traits>::match_toggle_case,
   };

   if(state_count > max_state_count)
      raise_error(traits_inst, regex_constants::error_space);
   while(pstate)
   {
      matcher_proc_type proc = s_match_vtable[pstate->type];
      ++state_count;
      if(!(this->*proc)())
      {
         if((m_match_flags & match_partial) && (position == last) && (position != search_base))
            m_has_partial_match = true;
         return 0;
      }
   }
   return true;
}

template <class BidiIterator, class Allocator, class traits>
bool perl_matcher<BidiIterator, Allocator, traits>::match_startmark()
{
   int index = static_cast<const re_brace*>(pstate)->index;
   bool r = true;
   switch(index)
   {
   case 0:
      pstate = pstate->next.p;
      break;
   case -1:
   case -2:
      {
         // forward lookahead assert:
         BidiIterator old_position(position);
         const re_syntax_base* next_pstate = static_cast<const re_jump*>(pstate->next.p)->alt.p->next.p;
         pstate = pstate->next.p->next.p;
         r = match_all_states();
         pstate = next_pstate;
         position = old_position;
         if((r && (index != -1)) || (!r && (index != -2)))
            r = false;
         else
            r = true;
         break;
      }
   case -3:
      {
         // independent sub-expression:
         bool old_independent = m_independent;
         m_independent = true;
         const re_syntax_base* next_pstate = static_cast<const re_jump*>(pstate->next.p)->alt.p->next.p;
         pstate = pstate->next.p->next.p;
         r = match_all_states();
         pstate = next_pstate;
         m_independent = old_independent;
#ifdef BOOST_REGEX_MATCH_EXTRA
         if(r && (m_match_flags & match_extra))
         {
            //
            // our captures have been stored in *m_presult
            // we need to unpack them, and insert them
            // back in the right order when we unwind the stack:
            //
            unsigned i;
            match_results<BidiIterator, Allocator> tm(*m_presult);
            for(i = 0; i < tm.size(); ++i)
               (*m_presult)[i].get_captures().clear();
            // match everything else:
            r = match_all_states();
            // now place the stored captures back:
            for(i = 0; i < tm.size(); ++i)
            {
               typedef typename sub_match<BidiIterator>::capture_sequence_type seq;
               seq& s1 = (*m_presult)[i].get_captures();
               const seq& s2 = tm[i].captures();
               s1.insert(
                  s1.end(), 
                  s2.begin(), 
                  s2.end());
            }
         }
#endif
         break;
      }
   case -4:
      {
      // conditional expression:
      const re_alt* alt = static_cast<const re_alt*>(pstate->next.p);
      BOOST_ASSERT(alt->type == syntax_element_alt);
      pstate = alt->next.p;
      if(pstate->type == syntax_element_assert_backref)
      {
         if(!match_assert_backref())
            pstate = alt->alt.p;
         break;
      }
      else
      {
         // zero width assertion, have to match this recursively:
         BOOST_ASSERT(pstate->type == syntax_element_startmark);
         bool negated = static_cast<const re_brace*>(pstate)->index == -2;
         BidiIterator saved_position = position;
         const re_syntax_base* next_pstate = static_cast<const re_jump*>(pstate->next.p)->alt.p->next.p;
         pstate = pstate->next.p->next.p;
         bool r = match_all_states();
         position = saved_position;
         if(negated)
            r = !r;
         if(r)
            pstate = next_pstate;
         else
            pstate = alt->alt.p;
         break;
      }
      }
   default:
   {
      BOOST_ASSERT(index > 0);
      if((m_match_flags & match_nosubs) == 0)
      {
         backup_subex<BidiIterator> sub(*m_presult, index);
         m_presult->set_first(position, index);
         pstate = pstate->next.p;
         r = match_all_states();
         if(r == false)
            sub.restore(*m_presult);
#ifdef BOOST_REGEX_MATCH_EXTRA
         //
         // we have a match, push the capture information onto the stack:
         //
         else if(sub.get().matched && (match_extra & m_match_flags))
            ((*m_presult)[index]).get_captures().push_back(sub.get());
#endif
      }
      else
      {
         pstate = pstate->next.p;
      }
      break;
   }
   }
   return r;
}

template <class BidiIterator, class Allocator, class traits>
bool perl_matcher<BidiIterator, Allocator, traits>::match_alt()
{
   bool take_first, take_second;
   const re_alt* jmp = static_cast<const re_alt*>(pstate);

   // find out which of these two alternatives we need to take:
   if(position == last)
   {
      take_first = jmp->can_be_null & mask_take;
      take_second = jmp->can_be_null & mask_skip;
   }
   else
   {
      take_first = can_start(*position, jmp->_map, (unsigned char)mask_take);
      take_second = can_start(*position, jmp->_map, (unsigned char)mask_skip);
  }

   if(take_first)
   {
      // we can take the first alternative,
      // see if we need to push next alternative:
      if(take_second)
      {
         BidiIterator oldposition(position);
         const re_syntax_base* old_pstate = jmp->alt.p;
         pstate = pstate->next.p;
         if(!match_all_states())
         {
            pstate = old_pstate;
            position = oldposition;
         }
         return true;
      }
      pstate = pstate->next.p;
      return true;
   }
   if(take_second)
   {
      pstate = jmp->alt.p;
      return true;
   }
   return false;  // neither option is possible
}

template <class BidiIterator, class Allocator, class traits>
bool perl_matcher<BidiIterator, Allocator, traits>::match_rep()
{
#ifdef BOOST_MSVC
#pragma warning(push)
#pragma warning(disable:4127 4244)
#endif
   const re_repeat* rep = static_cast<const re_repeat*>(pstate);
   //
   // Always copy the repeat count, so that the state is restored
   // when we exit this scope:
   //
   repeater_count<BidiIterator> r(rep->state_id, &next_count, position);
   //
   // If we've had at least one repeat already, and the last one 
   // matched the NULL string then set the repeat count to
   // maximum:
   //
   next_count->check_null_repeat(position, rep->max);

   // find out which of these two alternatives we need to take:
   bool take_first, take_second;
   if(position == last)
   {
      take_first = rep->can_be_null & mask_take;
      take_second = rep->can_be_null & mask_skip;
   }
   else
   {
      take_first = can_start(*position, rep->_map, (unsigned char)mask_take);
      take_second = can_start(*position, rep->_map, (unsigned char)mask_skip);
   }

   if(next_count->get_count() < rep->min)
   {
      // we must take the repeat:
      if(take_first)
      {
         // increase the counter:
         ++(*next_count);
         pstate = rep->next.p;
         return match_all_states();
      }
      return false;
   }
   bool greedy = (rep->greedy) && (!(m_match_flags & regex_constants::match_any) || m_independent);   
   if(greedy)
   {
      // try and take the repeat if we can:
      if((next_count->get_count() < rep->max) && take_first)
      {
         // store position in case we fail:
         BidiIterator pos = position;
         // increase the counter:
         ++(*next_count);
         pstate = rep->next.p;
         if(match_all_states())
            return true;
         // failed repeat, reset posistion and fall through for alternative:
         position = pos;
      }
      if(take_second)
      {
         pstate = rep->alt.p;
         return true;
      }
      return false; // can't take anything, fail...
   }
   else // non-greedy
   {
      // try and skip the repeat if we can:
      if(take_second)
      {
         // store position in case we fail:
         BidiIterator pos = position;
         pstate = rep->alt.p;
         if(match_all_states())
            return true;
         // failed alternative, reset posistion and fall through for repeat:
         position = pos;
      }
      if((next_count->get_count() < rep->max) && take_first)
      {
         // increase the counter:
         ++(*next_count);
         pstate = rep->next.p;
         return match_all_states();
      }
   }
   return false;
#ifdef BOOST_MSVC
#pragma warning(pop)
#endif
}

template <class BidiIterator, class Allocator, class traits>
bool perl_matcher<BidiIterator, Allocator, traits>::match_dot_repeat_slow()
{
#ifdef BOOST_MSVC
#pragma warning(push)
#pragma warning(disable:4127)
#endif
   unsigned count = 0;
   const re_repeat* rep = static_cast<const re_repeat*>(pstate);
   re_syntax_base* psingle = rep->next.p;
   // match compulsary repeats first:
   while(count < rep->min)
   {
      pstate = psingle;
      if(!match_wild())
         return false;
      ++count;
   }
   bool greedy = (rep->greedy) && (!(m_match_flags & regex_constants::match_any) || m_independent);   
   if(greedy)
   {
      // normal repeat:
      while(count < rep->max)
      {
         pstate = psingle;
         if(!match_wild())
            break;
         ++count;
      }
      if((rep->leading) && (count < rep->max))
         restart = position;
      pstate = rep;
      return backtrack_till_match(count - rep->min);
   }
   else
   {
      // non-greedy, keep trying till we get a match:
      BidiIterator save_pos;
      do
      {
         if((rep->leading) && (rep->max == UINT_MAX))
            restart = position;
         pstate = rep->alt.p;
         save_pos = position;
         ++state_count;
         if(match_all_states())
            return true;
         if(count >= rep->max)
            return false;
         ++count;
         pstate = psingle;
         position = save_pos;