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

// Copyright (C) 2010, 2011 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_nfa.h

 *  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 __regex

{

_GLIBCXX_BEGIN_NAMESPACE_VERSION

  // Base class for, um, automata.  Could be an NFA or a DFA.  Your choice.

  class _Automaton

  {

  public:

    typedef unsigned int _SizeT;

  public:

    virtual

    ~_Automaton() { }

    virtual _SizeT

    _M_sub_count() const = 0;

#ifdef _GLIBCXX_DEBUG

    virtual std::ostream&

    _M_dot(std::ostream& __ostr) const = 0;

#endif

  };

  // Generic shared pointer to an automaton.  

  typedef std::shared_ptr<_Automaton> _AutomatonPtr;

  // Operation codes that define the type of transitions within the base NFA

  // that represents the regular expression.

  enum _Opcode

  {

      _S_opcode_unknown       =   0,

      _S_opcode_alternative   =   1,

      _S_opcode_subexpr_begin =   4,

      _S_opcode_subexpr_end   =   5,

      _S_opcode_match         = 100,

      _S_opcode_accept        = 255

  };

  // Provides a generic facade for a templated match_results.

  struct _Results

  {

    virtual void _M_set_pos(int __i, int __j, const _PatternCursor& __p) = 0;

    virtual void _M_set_matched(int __i, bool __is_matched) = 0;

  };

  // Tags current state (for subexpr begin/end).

  typedef std::function<void (const _PatternCursor&, _Results&)> _Tagger;

  template<typename _FwdIterT, typename _TraitsT>

    struct _StartTagger

    {

      explicit

      _StartTagger(int __i)

      : _M_index(__i)

      { }

      void

      operator()(const _PatternCursor& __pc, _Results& __r)

      { __r._M_set_pos(_M_index, 0, __pc); }

      int       _M_index;

    };

  template<typename _FwdIterT, typename _TraitsT>

    struct _EndTagger

    {

      explicit

      _EndTagger(int __i)

      : _M_index(__i)

      { }

      void

      operator()(const _PatternCursor& __pc, _Results& __r)

      { __r._M_set_pos(_M_index, 1, __pc); }

      int       _M_index;

      _FwdIterT _M_pos;

    };

  // Indicates if current state matches cursor current.

  typedef std::function<bool (const _PatternCursor&)> _Matcher;

  // Matches any character

  inline bool

  _AnyMatcher(const _PatternCursor&)

  { return true; }

  // Matches a single character

  template<typename _InIterT, typename _TraitsT>

    struct _CharMatcher

    {

      typedef typename _TraitsT::char_type char_type;

      explicit

      _CharMatcher(char_type __c, const _TraitsT& __t = _TraitsT())

      : _M_traits(__t), _M_c(_M_traits.translate(__c))

      { }

      bool

      operator()(const _PatternCursor& __pc) const

      {

        typedef const _SpecializedCursor<_InIterT>& _CursorT;

        _CursorT __c = static_cast<_CursorT>(__pc);

        return _M_traits.translate(__c._M_current()) == _M_c;

      }

      const _TraitsT& _M_traits;

      char_type       _M_c;

    };

  // Matches a character range (bracket expression)

  template<typename _InIterT, typename _TraitsT>

    struct _RangeMatcher

    {

      typedef typename _TraitsT::char_type _CharT;

      typedef std::basic_string<_CharT>    _StringT;

      explicit

      _RangeMatcher(bool __is_non_matching, const _TraitsT& __t = _TraitsT())

      : _M_traits(__t), _M_is_non_matching(__is_non_matching)

      { }

      bool

      operator()(const _PatternCursor& __pc) const

      {

        typedef const _SpecializedCursor<_InIterT>& _CursorT;

        _CursorT __c = static_cast<_CursorT>(__pc);

        return true;

      }

      void

      _M_add_char(_CharT __c)

      { }

      void

      _M_add_collating_element(const _StringT& __s)

      { }

      void

      _M_add_equivalence_class(const _StringT& __s)

      { }

      void

      _M_add_character_class(const _StringT& __s)

      { }

      void

      _M_make_range()

      { }

      const _TraitsT& _M_traits;

      bool            _M_is_non_matching;

    };

  // Identifies a state in the NFA.

  typedef int _StateIdT;

  // The special case in which a state identifier is not an index.

  static const _StateIdT _S_invalid_state_id  = -1;

  // An individual state in an NFA

  //

  // In this case a "state" is an entry in the NFA definition coupled with its

  // outgoing transition(s).  All states have a single outgoing transition,

  // except for accepting states (which have no outgoing transitions) and alt

  // states, which have two outgoing transitions.

  //

  struct _State

  {

    typedef int  _OpcodeT;

    _OpcodeT     _M_opcode;    // type of outgoing transition

    _StateIdT    _M_next;      // outgoing transition

    _StateIdT    _M_alt;       // for _S_opcode_alternative

    unsigned int _M_subexpr;   // for _S_opcode_subexpr_*

    _Tagger      _M_tagger;    // for _S_opcode_subexpr_*

    _Matcher     _M_matches;   // for _S_opcode_match

    explicit _State(_OpcodeT __opcode)

    : _M_opcode(__opcode), _M_next(_S_invalid_state_id)

    { }

    _State(const _Matcher& __m)

    : _M_opcode(_S_opcode_match), _M_next(_S_invalid_state_id), _M_matches(__m)

    { }

    _State(_OpcodeT __opcode, unsigned int __s, const _Tagger& __t)

    : _M_opcode(__opcode), _M_next(_S_invalid_state_id), _M_subexpr(__s),

      _M_tagger(__t)

    { }

    _State(_StateIdT __next, _StateIdT __alt)

    : _M_opcode(_S_opcode_alternative), _M_next(__next), _M_alt(__alt)

    { }

#ifdef _GLIBCXX_DEBUG

    std::ostream&

    _M_print(std::ostream& ostr) const;

    // Prints graphviz dot commands for state.

    std::ostream&

    _M_dot(std::ostream& __ostr, _StateIdT __id) const;

#endif

  };

  // The Grep Matcher works on sets of states.  Here are sets of states.

  typedef std::set<_StateIdT> _StateSet;

 // A collection of all states making up an NFA

  //

  // An NFA is a 4-tuple M = (K, S, s, F), where

  //    K is a finite set of states,

  //    S is the alphabet of the NFA,

  //    s is the initial state,

  //    F is a set of final (accepting) states.

  //

  // This NFA class is templated on S, a type that will hold values of the

  // underlying alphabet (without regard to semantics of that alphabet).  The

  // other elements of the tuple are generated during construction of the NFA

  // and are available through accessor member functions.

  //

  class _Nfa

  : public _Automaton, public std::vector<_State>

  {

  public:

    typedef _State                              _StateT;

    typedef unsigned int                        _SizeT;

    typedef regex_constants::syntax_option_type _FlagT;

  public:

    _Nfa(_FlagT __f)

    : _M_flags(__f), _M_start_state(0), _M_subexpr_count(0)

    { }

    ~_Nfa()

    { }

    _FlagT

    _M_options() const

    { return _M_flags; }

    _StateIdT

    _M_start() const

    { return _M_start_state; }

    const _StateSet&

    _M_final_states() const

    { return _M_accepting_states; }

    _SizeT

    _M_sub_count() const

    { return _M_subexpr_count; }

    _StateIdT

    _M_insert_accept()

    {

      this->push_back(_StateT(_S_opcode_accept));

      _M_accepting_states.insert(this->size()-1);

      return this->size()-1;

    }

    _StateIdT

    _M_insert_alt(_StateIdT __next, _StateIdT __alt)

    {

      this->push_back(_StateT(__next, __alt));

      return this->size()-1;

    }

    _StateIdT

    _M_insert_matcher(_Matcher __m)

    {

      this->push_back(_StateT(__m));

      return this->size()-1;

    }

    _StateIdT

    _M_insert_subexpr_begin(const _Tagger& __t)

    {

      this->push_back(_StateT(_S_opcode_subexpr_begin, _M_subexpr_count++, __t));

      return this->size()-1;

    }

    _StateIdT

    _M_insert_subexpr_end(unsigned int __i, const _Tagger& __t)

    {

      this->push_back(_StateT(_S_opcode_subexpr_end, __i, __t));

      return this->size()-1;

    }

#ifdef _GLIBCXX_DEBUG

    std::ostream&

    _M_dot(std::ostream& __ostr) const;

#endif

  private:

    _FlagT     _M_flags;

    _StateIdT  _M_start_state;

    _StateSet  _M_accepting_states;

    _SizeT     _M_subexpr_count;

  };

  // Describes a sequence of one or more %_State, its current start and end(s).

  //

  // This structure contains fragments of an NFA during construction.

  class _StateSeq

  {

  public:

    // Constructs a single-node sequence

    _StateSeq(_Nfa& __ss, _StateIdT __s, _StateIdT __e = _S_invalid_state_id)

    : _M_nfa(__ss), _M_start(__s), _M_end1(__s), _M_end2(__e)

    { }

    // Constructs a split sequence from two other sequencces

    _StateSeq(const _StateSeq& __e1, const _StateSeq& __e2)

    : _M_nfa(__e1._M_nfa),

      _M_start(_M_nfa._M_insert_alt(__e1._M_start, __e2._M_start)),

      _M_end1(__e1._M_end1), _M_end2(__e2._M_end1)

    { }

    // Constructs a split sequence from a single sequence

    _StateSeq(const _StateSeq& __e, _StateIdT __id)

    : _M_nfa(__e._M_nfa),

      _M_start(_M_nfa._M_insert_alt(__id, __e._M_start)),

      _M_end1(__id), _M_end2(__e._M_end1)

    { }

    // Constructs a copy of a %_StateSeq

    _StateSeq(const _StateSeq& __rhs)

    : _M_nfa(__rhs._M_nfa), _M_start(__rhs._M_start),

      _M_end1(__rhs._M_end1), _M_end2(__rhs._M_end2)

    { }

    _StateSeq& operator=(const _StateSeq& __rhs);

    _StateIdT

    _M_front() const

    { return _M_start; }

    // Extends a sequence by one.

    void

    _M_push_back(_StateIdT __id);

    // Extends and maybe joins a sequence.

    void

    _M_append(_StateIdT __id);

    void

    _M_append(_StateSeq& __rhs);

    // Clones an entire sequence.

    _StateIdT

    _M_clone();

  private:

    _Nfa&     _M_nfa;

    _StateIdT _M_start;

    _StateIdT _M_end1;

    _StateIdT _M_end2;

  };

_GLIBCXX_END_NAMESPACE_VERSION

} // namespace __regex

} // namespace std

#include <bits/regex_nfa.tcc>