regex_automaton.tcc

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// class template regex -*- C++ -*-

// Copyright (C) 2013-2014 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.

// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.

// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
// <http://www.gnu.org/licenses/>.

/**
 *  @file bits/regex_automaton.tcc
 *  This is an internal header file, included by other library headers.
 *  Do not attempt to use it directly. @headername{regex}
 */

namespace std _GLIBCXX_VISIBILITY(default)
{
namespace __detail
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION

#ifdef _GLIBCXX_DEBUG
  std::ostream&
  _State_base::_M_print(std::ostream& ostr) const
  {
    switch (_M_opcode)
    {
      case _S_opcode_alternative:
    ostr << "alt next=" << _M_next << " alt=" << _M_alt;
    break;
      case _S_opcode_subexpr_begin:
    ostr << "subexpr begin next=" << _M_next << " index=" << _M_subexpr;
    break;
      case _S_opcode_subexpr_end:
    ostr << "subexpr end next=" << _M_next << " index=" << _M_subexpr;
    break;
      case _S_opcode_backref:
    ostr << "backref next=" << _M_next << " index=" << _M_backref_index;
    break;
      case _S_opcode_match:
    ostr << "match next=" << _M_next;
    break;
      case _S_opcode_accept:
    ostr << "accept next=" << _M_next;
    break;
      default:
    ostr << "unknown next=" << _M_next;
    break;
    }
    return ostr;
  }

  // Prints graphviz dot commands for state.
  std::ostream&
  _State_base::_M_dot(std::ostream& __ostr, _StateIdT __id) const
  {
    switch (_M_opcode)
    {
      case _S_opcode_alternative:
    __ostr << __id << " [label=\"" << __id << "\\nALT\"];\n"
           << __id << " -> " << _M_next
           << " [label=\"epsilon\", tailport=\"s\"];\n"
           << __id << " -> " << _M_alt
           << " [label=\"epsilon\", tailport=\"n\"];\n";
    break;
      case _S_opcode_backref:
    __ostr << __id << " [label=\"" << __id << "\\nBACKREF "
           << _M_subexpr << "\"];\n"
           << __id << " -> " << _M_next << " [label=\"<match>\"];\n";
    break;
      case _S_opcode_line_begin_assertion:
    __ostr << __id << " [label=\"" << __id << "\\nLINE_BEGIN \"];\n"
           << __id << " -> " << _M_next << " [label=\"epsilon\"];\n";
    break;
      case _S_opcode_line_end_assertion:
    __ostr << __id << " [label=\"" << __id << "\\nLINE_END \"];\n"
           << __id << " -> " << _M_next << " [label=\"epsilon\"];\n";
    break;
      case _S_opcode_word_boundary:
    __ostr << __id << " [label=\"" << __id << "\\nWORD_BOUNDRY "
           << _M_neg << "\"];\n"
           << __id << " -> " << _M_next << " [label=\"epsilon\"];\n";
    break;
      case _S_opcode_subexpr_lookahead:
    __ostr << __id << " [label=\"" << __id << "\\nLOOK_AHEAD\"];\n"
           << __id << " -> " << _M_next
           << " [label=\"epsilon\", tailport=\"s\"];\n"
           << __id << " -> " << _M_alt
           << " [label=\"<assert>\", tailport=\"n\"];\n";
    break;
      case _S_opcode_subexpr_begin:
    __ostr << __id << " [label=\"" << __id << "\\nSBEGIN "
           << _M_subexpr << "\"];\n"
           << __id << " -> " << _M_next << " [label=\"epsilon\"];\n";
    break;
      case _S_opcode_subexpr_end:
    __ostr << __id << " [label=\"" << __id << "\\nSEND "
           << _M_subexpr << "\"];\n"
           << __id << " -> " << _M_next << " [label=\"epsilon\"];\n";
    break;
      case _S_opcode_dummy:
    break;
      case _S_opcode_match:
    __ostr << __id << " [label=\"" << __id << "\\nMATCH\"];\n"
           << __id << " -> " << _M_next << " [label=\"<match>\"];\n";
    break;
      case _S_opcode_accept:
    __ostr << __id << " [label=\"" << __id << "\\nACC\"];\n" ;
    break;
      default:
    _GLIBCXX_DEBUG_ASSERT(false);
    break;
    }
    return __ostr;
  }

  template<typename _TraitsT>
    std::ostream&
    _NFA<_TraitsT>::_M_dot(std::ostream& __ostr) const
    {
      __ostr << "digraph _Nfa {\n"
            "  rankdir=LR;\n";
      for (size_t __i = 0; __i < this->size(); ++__i)
        (*this)[__i]._M_dot(__ostr, __i);
      __ostr << "}\n";
      return __ostr;
    }
#endif

  template<typename _TraitsT>
    _StateIdT
    _NFA<_TraitsT>::_M_insert_backref(size_t __index)
    {
      // To figure out whether a backref is valid, a stack is used to store
      // unfinished sub-expressions. For example, when parsing
      // "(a(b)(c\\1(d)))" at '\\1', _M_subexpr_count is 3, indicating that 3
      // sub expressions are parsed or partially parsed(in the stack), aka,
      // "(a..", "(b)" and "(c..").
      // _M_paren_stack is {1, 3}, for incomplete "(a.." and "(c..". At this
      // time, "\\2" is valid, but "\\1" and "\\3" are not.
      if (__index >= _M_subexpr_count)
    __throw_regex_error(regex_constants::error_backref);
      for (auto __it : this->_M_paren_stack)
    if (__index == __it)
      __throw_regex_error(regex_constants::error_backref);
      this->_M_has_backref = true;
      _StateT __tmp(_S_opcode_backref);
      __tmp._M_backref_index = __index;
      return _M_insert_state(std::move(__tmp));
    }

  template<typename _TraitsT>
    void
    _NFA<_TraitsT>::_M_eliminate_dummy()
    {
      for (auto& __it : *this)
    {
      while (__it._M_next >= 0 && (*this)[__it._M_next]._M_opcode
         == _S_opcode_dummy)
        __it._M_next = (*this)[__it._M_next]._M_next;
      if (__it._M_opcode == _S_opcode_alternative
          || __it._M_opcode == _S_opcode_subexpr_lookahead)
        while (__it._M_alt >= 0 && (*this)[__it._M_alt]._M_opcode
           == _S_opcode_dummy)
          __it._M_alt = (*this)[__it._M_alt]._M_next;
    }
    }

  // Just apply DFS on the sequence and re-link their links.
  template<typename _TraitsT>
    _StateSeq<_TraitsT>
    _StateSeq<_TraitsT>::_M_clone()
    {
      std::map<_StateIdT, _StateIdT> __m;
      std::stack<_StateIdT> __stack;
      __stack.push(_M_start);
      while (!__stack.empty())
    {
      auto __u = __stack.top();
      __stack.pop();
      auto __dup = _M_nfa[__u];
      auto __id = _M_nfa._M_insert_state(__dup);
      __m[__u] = __id;
      if (__u == _M_end)
        continue;
      if (__m.count(__dup._M_next) == 0)
        __stack.push(__dup._M_next);
      if (__dup._M_opcode == _S_opcode_alternative
          || __dup._M_opcode == _S_opcode_subexpr_lookahead)
        if (__m.count(__dup._M_alt) == 0)
          __stack.push(__dup._M_alt);
    }
      for (auto __it : __m)
    {
      auto& __ref = _M_nfa[__it.second];
      if (__ref._M_next != -1)
        {
          _GLIBCXX_DEBUG_ASSERT(__m.count(__ref._M_next));
          __ref._M_next = __m[__ref._M_next];
        }
      if (__ref._M_opcode == _S_opcode_alternative
          || __ref._M_opcode == _S_opcode_subexpr_lookahead)
        if (__ref._M_alt != -1)
          {
        _GLIBCXX_DEBUG_ASSERT(__m.count(__ref._M_alt));
        __ref._M_alt = __m[__ref._M_alt];
          }
    }
      return _StateSeq(_M_nfa, __m[_M_start], __m[_M_end]);
    }

_GLIBCXX_END_NAMESPACE_VERSION
} // namespace __detail
} // namespace