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

// FIXME make comments doxygen format.

// This compiler refers to "Regular Expression Matching Can Be Simple And Fast"
// (http://swtch.com/~rsc/regexp/regexp1.html"),
// but doesn't strictly follow it.
//
// When compiling, states are *chained* instead of tree- or graph-constructed.
// It's more like structured programs: there's if statement and loop statement.
//
// For alternative structure(say "a|b"), aka "if statement", two branchs should
// be constructed. However, these two shall merge to an "end_tag" at the end of
// this operator:
//
//                branch1
//              /        \
// => begin_tag            end_tag =>
//              \        /
//                branch2
//
// This is the difference between this implementation and that in Russ's
// article.
//
// That's why we introduced dummy node here ------ "end_tag" is a dummy node.
// All dummy node will be eliminated at the end of compiling process.

namespace std _GLIBCXX_VISIBILITY(default)
{
namespace __detail
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION

  template<typename _FwdIter, typename _TraitsT>
    _Compiler<_FwdIter, _TraitsT>::
    _Compiler(_FwdIter __b, _FwdIter __e,
          const _TraitsT& __traits, _FlagT __flags)
    : _M_flags((__flags
        & (regex_constants::ECMAScript
           | regex_constants::basic
           | regex_constants::extended
           | regex_constants::grep
           | regex_constants::egrep
           | regex_constants::awk))
           ? __flags
           : __flags | regex_constants::ECMAScript),
    _M_traits(__traits),
    _M_ctype(std::use_facet<_CtypeT>(_M_traits.getloc())),
    _M_scanner(__b, __e, _M_flags, _M_traits.getloc()),
    _M_nfa(_M_flags)
    {
      _StateSeqT __r(_M_nfa, _M_nfa._M_start());
      __r._M_append(_M_nfa._M_insert_subexpr_begin());
      this->_M_disjunction();
      if (!_M_match_token(_ScannerT::_S_token_eof))
    __throw_regex_error(regex_constants::error_paren);
      __r._M_append(_M_pop());
      _GLIBCXX_DEBUG_ASSERT(_M_stack.empty());
      __r._M_append(_M_nfa._M_insert_subexpr_end());
      __r._M_append(_M_nfa._M_insert_accept());
      _M_nfa._M_eliminate_dummy();
    }

  template<typename _FwdIter, typename _TraitsT>
    void
    _Compiler<_FwdIter, _TraitsT>::
    _M_disjunction()
    {
      this->_M_alternative();
      while (_M_match_token(_ScannerT::_S_token_or))
    {
      _StateSeqT __alt1 = _M_pop();
      this->_M_alternative();
      _StateSeqT __alt2 = _M_pop();
      auto __end = _M_nfa._M_insert_dummy();
      __alt1._M_append(__end);
      __alt2._M_append(__end);
      _M_stack.push(_StateSeqT(_M_nfa,
                   _M_nfa._M_insert_alt(__alt1._M_start,
                            __alt2._M_start, false),
                   __end));
    }
    }

  template<typename _FwdIter, typename _TraitsT>
    void
    _Compiler<_FwdIter, _TraitsT>::
    _M_alternative()
    {
      if (this->_M_term())
    {
      _StateSeqT __re = _M_pop();
      this->_M_alternative();
      __re._M_append(_M_pop());
      _M_stack.push(__re);
    }
      else
    _M_stack.push(_StateSeqT(_M_nfa, _M_nfa._M_insert_dummy()));
    }

  template<typename _FwdIter, typename _TraitsT>
    bool
    _Compiler<_FwdIter, _TraitsT>::
    _M_term()
    {
      if (this->_M_assertion())
    return true;
      if (this->_M_atom())
    {
      this->_M_quantifier();
      return true;
    }
      return false;
    }

  template<typename _FwdIter, typename _TraitsT>
    bool
    _Compiler<_FwdIter, _TraitsT>::
    _M_assertion()
    {
      if (_M_match_token(_ScannerT::_S_token_line_begin))
    _M_stack.push(_StateSeqT(_M_nfa, _M_nfa._M_insert_line_begin()));
      else if (_M_match_token(_ScannerT::_S_token_line_end))
    _M_stack.push(_StateSeqT(_M_nfa, _M_nfa._M_insert_line_end()));
      else if (_M_match_token(_ScannerT::_S_token_word_bound))
    // _M_value[0] == 'n' means it's negtive, say "not word boundary".
    _M_stack.push(_StateSeqT(_M_nfa, _M_nfa.
          _M_insert_word_bound(_M_value[0] == 'n')));
      else if (_M_match_token(_ScannerT::_S_token_subexpr_lookahead_begin))
    {
      auto __neg = _M_value[0] == 'n';
      this->_M_disjunction();
      if (!_M_match_token(_ScannerT::_S_token_subexpr_end))
        __throw_regex_error(regex_constants::error_paren);
      auto __tmp = _M_pop();
      __tmp._M_append(_M_nfa._M_insert_accept());
      _M_stack.push(
          _StateSeqT(
        _M_nfa,
        _M_nfa._M_insert_lookahead(__tmp._M_start, __neg)));
    }
      else
    return false;
      return true;
    }

  template<typename _FwdIter, typename _TraitsT>
    void
    _Compiler<_FwdIter, _TraitsT>::
    _M_quantifier()
    {
      bool __neg = (_M_flags & regex_constants::ECMAScript);
      auto __init = [this, &__neg]()
    {
      if (_M_stack.empty())
        __throw_regex_error(regex_constants::error_badrepeat);
      __neg = __neg && _M_match_token(_ScannerT::_S_token_opt);
    };
      if (_M_match_token(_ScannerT::_S_token_closure0))
    {
      __init();
      auto __e = _M_pop();
      _StateSeqT __r(_M_nfa, _M_nfa._M_insert_alt(_S_invalid_state_id,
                              __e._M_start, __neg));
      __e._M_append(__r);
      _M_stack.push(__r);
    }
      else if (_M_match_token(_ScannerT::_S_token_closure1))
    {
      __init();
      auto __e = _M_pop();
      __e._M_append(_M_nfa._M_insert_alt(_S_invalid_state_id, __e._M_start,
                         __neg));
      _M_stack.push(__e);
    }
      else if (_M_match_token(_ScannerT::_S_token_opt))
    {
      __init();
      auto __e = _M_pop();
      auto __end = _M_nfa._M_insert_dummy();
      _StateSeqT __r(_M_nfa, _M_nfa._M_insert_alt(_S_invalid_state_id,
                              __e._M_start, __neg));
      __e._M_append(__end);
      __r._M_append(__end);
      _M_stack.push(__r);
    }
      else if (_M_match_token(_ScannerT::_S_token_interval_begin))
    {
      if (_M_stack.empty())
        __throw_regex_error(regex_constants::error_badrepeat);
      if (!_M_match_token(_ScannerT::_S_token_dup_count))
        __throw_regex_error(regex_constants::error_badbrace);
      _StateSeqT __r(_M_pop());
      _StateSeqT __e(_M_nfa, _M_nfa._M_insert_dummy());
      long __min_rep = _M_cur_int_value(10);
      bool __infi = false;
      long __n;

      // {3
      if (_M_match_token(_ScannerT::_S_token_comma))
        if (_M_match_token(_ScannerT::_S_token_dup_count)) // {3,7}
          __n = _M_cur_int_value(10) - __min_rep;
        else
          __infi = true;
      else
        __n = 0;
      if (!_M_match_token(_ScannerT::_S_token_interval_end))
        __throw_regex_error(regex_constants::error_brace);

      __neg = __neg && _M_match_token(_ScannerT::_S_token_opt);

      for (long __i = 0; __i < __min_rep; ++__i)
        __e._M_append(__r._M_clone());

      if (__infi)
        {
          auto __tmp = __r._M_clone();
          _StateSeqT __s(_M_nfa,
                 _M_nfa._M_insert_alt(_S_invalid_state_id,
                          __tmp._M_start, __neg));
          __tmp._M_append(__s);
          __e._M_append(__s);
        }
      else
        {
          if (__n < 0)
        __throw_regex_error(regex_constants::error_badbrace);
          auto __end = _M_nfa._M_insert_dummy();
          // _M_alt is the "match more" branch, and _M_next is the
          // "match less" one. Switch _M_alt and _M_next of all created
          // nodes. This is a hacking but IMO works well.
          std::stack<_StateIdT> __stack;
          for (long __i = 0; __i < __n; ++__i)
        {
          auto __tmp = __r._M_clone();
          auto __alt = _M_nfa._M_insert_alt(__tmp._M_start,
                            __end, __neg);
          __stack.push(__alt);
          __e._M_append(_StateSeqT(_M_nfa, __alt, __tmp._M_end));
        }
          __e._M_append(__end);
          while (!__stack.empty())
        {
          auto& __tmp = _M_nfa[__stack.top()];
          __stack.pop();
          swap(__tmp._M_next, __tmp._M_alt);
        }
        }
      _M_stack.push(__e);
    }
    }

  template<typename _FwdIter, typename _TraitsT>
    bool
    _Compiler<_FwdIter, _TraitsT>::
    _M_atom()
    {
      if (_M_match_token(_ScannerT::_S_token_anychar))
    _M_stack.push(_StateSeqT(_M_nfa,
                _M_nfa._M_insert_matcher
                (_AnyMatcher<_TraitsT>(_M_traits))));
      else if (_M_try_char())
    _M_stack.push(_StateSeqT(_M_nfa,
                 _M_nfa._M_insert_matcher
                 (_CharMatcher<_TraitsT>(_M_value[0],
                                 _M_traits,
                                 _M_flags))));
      else if (_M_match_token(_ScannerT::_S_token_backref))
    _M_stack.push(_StateSeqT(_M_nfa, _M_nfa.
                 _M_insert_backref(_M_cur_int_value(10))));
      else if (_M_match_token(_ScannerT::_S_token_quoted_class))
    {
      _GLIBCXX_DEBUG_ASSERT(_M_value.size() == 1);
      _BMatcherT __matcher(_M_ctype.is(_CtypeT::upper, _M_value[0]),
                   _M_traits, _M_flags);
      __matcher._M_add_character_class(_M_value);
      _M_stack.push(_StateSeqT(_M_nfa,
        _M_nfa._M_insert_matcher(std::move(__matcher))));
    }
      else if (_M_match_token(_ScannerT::_S_token_subexpr_no_group_begin))
    {
      _StateSeqT __r(_M_nfa, _M_nfa._M_insert_dummy());
      this->_M_disjunction();
      if (!_M_match_token(_ScannerT::_S_token_subexpr_end))
        __throw_regex_error(regex_constants::error_paren);
      __r._M_append(_M_pop());
      _M_stack.push(__r);
    }
      else if (_M_match_token(_ScannerT::_S_token_subexpr_begin))
    {
      _StateSeqT __r(_M_nfa, _M_nfa._M_insert_subexpr_begin());
      this->_M_disjunction();
      if (!_M_match_token(_ScannerT::_S_token_subexpr_end))
        __throw_regex_error(regex_constants::error_paren);
      __r._M_append(_M_pop());
      __r._M_append(_M_nfa._M_insert_subexpr_end());
      _M_stack.push(__r);
    }
      else if (!_M_bracket_expression())
    return false;
      return true;
    }

  template<typename _FwdIter, typename _TraitsT>
    bool
    _Compiler<_FwdIter, _TraitsT>::
    _M_bracket_expression()
    {
      bool __neg =
    _M_match_token(_ScannerT::_S_token_bracket_neg_begin);
      if (!(__neg || _M_match_token(_ScannerT::_S_token_bracket_begin)))
    return false;
      _BMatcherT __matcher(__neg, _M_traits, _M_flags);
      while (!_M_match_token(_ScannerT::_S_token_bracket_end))
    _M_expression_term(__matcher);
      _M_stack.push(_StateSeqT(_M_nfa,
                   _M_nfa._M_insert_matcher(std::move(__matcher))));
      return true;
    }

  template<typename _FwdIter, typename _TraitsT>
    void
    _Compiler<_FwdIter, _TraitsT>::
    _M_expression_term(_BMatcherT& __matcher)
    {
      if (_M_match_token(_ScannerT::_S_token_collsymbol))
    __matcher._M_add_collating_element(_M_value);
      else if (_M_match_token(_ScannerT::_S_token_equiv_class_name))
    __matcher._M_add_equivalence_class(_M_value);
      else if (_M_match_token(_ScannerT::_S_token_char_class_name))
    __matcher._M_add_character_class(_M_value);
      else if (_M_try_char()) // [a
    {
      auto __ch = _M_value[0];
      if (_M_try_char())
        {
          if (_M_value[0] == '-') // [a-
        {
          if (_M_try_char()) // [a-z]
            {
              __matcher._M_make_range(__ch, _M_value[0]);
              return;
            }
          // If the dash is the last character in the bracket
          // expression, it is not special.
          if (_M_scanner._M_get_token()
              != _ScannerT::_S_token_bracket_end)
            __throw_regex_error(regex_constants::error_range);
        }
          __matcher._M_add_char(_M_value[0]);
        }
      __matcher._M_add_char(__ch);
    }
      else
    __throw_regex_error(regex_constants::error_brack);
    }

  template<typename _FwdIter, typename _TraitsT>
    bool
    _Compiler<_FwdIter, _TraitsT>::
    _M_try_char()
    {
      bool __is_char = false;
      if (_M_match_token(_ScannerT::_S_token_oct_num))
    {
      __is_char = true;
      _M_value.assign(1, _M_cur_int_value(8));
    }
      else if (_M_match_token(_ScannerT::_S_token_hex_num))
    {
      __is_char = true;
      _M_value.assign(1, _M_cur_int_value(16));
    }
      else if (_M_match_token(_ScannerT::_S_token_ord_char))
    __is_char = true;
      return __is_char;
    }

  template<typename _FwdIter, typename _TraitsT>
    bool
    _Compiler<_FwdIter, _TraitsT>::
    _M_match_token(_TokenT token)
    {
      if (token == _M_scanner._M_get_token())
    {
      _M_value = _M_scanner._M_get_value();
      _M_scanner._M_advance();
      return true;
    }
      return false;
    }

  template<typename _FwdIter, typename _TraitsT>
    int
    _Compiler<_FwdIter, _TraitsT>::
    _M_cur_int_value(int __radix)
    {
      long __v = 0;
      for (typename _StringT::size_type __i = 0;
       __i < _M_value.length(); ++__i)
    __v =__v * __radix + _M_traits.value(_M_value[__i], __radix);
      return __v;
    }

  template<typename _TraitsT>
    bool
    _BracketMatcher<_TraitsT>::operator()(_CharT __ch) const
    {
      bool __ret = false;
      if (_M_traits.isctype(__ch, _M_class_set)
      || _M_char_set.count(_M_translate(__ch))
      || _M_equiv_set.count(_M_traits.transform_primary(&__ch, &__ch+1)))
    __ret = true;
      else
    {
      _StringT __s = _M_get_str(_M_flags & regex_constants::collate
                    ? _M_translate(__ch) : __ch);
      for (auto& __it : _M_range_set)
        if (__it.first <= __s && __s <= __it.second)
          {
        __ret = true;
        break;
          }
    }
      if (_M_is_non_matching)
    return !__ret;
      else
    return __ret;
    }

_GLIBCXX_END_NAMESPACE_VERSION
} // namespace __detail
} // namespace