regex_grep_matcher.h
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// class template regex -*- C++ -*-
// Copyright (C) 2010-2013 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_grep_matcher.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)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _BiIter>
class sub_match;
template<typename _Bi_iter, typename _Allocator>
class match_results;
_GLIBCXX_END_NAMESPACE_VERSION
namespace __detail
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
/**
* @defgroup regex-detail Base and Implementation Classes
* @ingroup regex
* @{
*/
/// A _Results facade specialized for wrapping a templated match_results.
template<typename _FwdIterT, typename _Alloc>
class _SpecializedResults
: public _Results
{
public:
_SpecializedResults(const _Automaton::_SizeT __size,
const _SpecializedCursor<_FwdIterT>& __cursor,
match_results<_FwdIterT, _Alloc>& __m);
~_SpecializedResults()
{
if (_M_managed)
delete &_M_results;
}
private:
_SpecializedResults(const _SpecializedResults& __rhs)
: _M_results(*new match_results<_FwdIterT, _Alloc>(__rhs._M_results)),
_M_managed(true)
{ }
public:
void
_M_set_pos(int __i, int __j, const _PatternCursor& __pc);
void
_M_set_range(int __i, const _PatternCursor& __pc)
{
typedef const _SpecializedCursor<_FwdIterT>& _CursorT;
_CursorT __c = static_cast<_CursorT>(__pc);
_M_results.at(__i).first = __c._M_begin();
_M_results.at(__i).second = __c._M_end();
}
void
_M_set_matched(int __i, bool __is_matched)
{ _M_results.at(__i).matched = __is_matched; }
std::unique_ptr<_Results>
_M_clone() const
{ return unique_ptr<_Results>(new _SpecializedResults(*this)); }
void
_M_assign(const _Results& __rhs)
{
auto __r = static_cast<const _SpecializedResults*>(&__rhs);
_M_results = __r->_M_results;
}
private:
match_results<_FwdIterT, _Alloc>& _M_results;
bool _M_managed;
};
template<typename _FwdIterT, typename _Alloc>
_SpecializedResults<_FwdIterT, _Alloc>::
_SpecializedResults(const _Automaton::_SizeT __size,
const _SpecializedCursor<_FwdIterT>& __cursor,
match_results<_FwdIterT, _Alloc>& __m)
: _M_results(__m), _M_managed(false)
{
_M_results.clear();
_M_results.reserve(__size + 2);
_M_results.resize(__size);
typename match_results<_FwdIterT, _Alloc>::value_type __sm;
__sm.first = __sm.second = __cursor._M_begin();
_M_results.push_back(__sm);
__sm.first = __sm.second = __cursor._M_end();
_M_results.push_back(__sm);
}
template<typename _FwdIterT, typename _Alloc>
void
_SpecializedResults<_FwdIterT, _Alloc>::
_M_set_pos(int __i, int __j, const _PatternCursor& __pc)
{
typedef const _SpecializedCursor<_FwdIterT>& _CursorT;
_CursorT __c = static_cast<_CursorT>(__pc);
if (__j == 0)
_M_results.at(__i).first = __c._M_pos();
else
_M_results.at(__i).second = __c._M_pos();
}
/// Executes a regular expression NFA/DFA over a range using a
/// variant of the parallel execution algorithm featured in the grep
/// utility, modified to use Laurikari tags.
class _Grep_matcher
{
public:
_Grep_matcher(_PatternCursor& __p,
_Results& __r,
const _AutomatonPtr& __automaton,
regex_constants::match_flag_type __flags)
: _M_nfa(static_pointer_cast<_Nfa>(__automaton)),
_M_str_cur(__p), _M_results(__r)
{ }
virtual
~_Grep_matcher()
{ }
// Set matched when string exactly match the pattern.
virtual bool
_M_match() = 0;
// Set matched when some prefix of the string matches the pattern.
virtual bool
_M_search_from_first() = 0;
protected:
const std::shared_ptr<_Nfa> _M_nfa;
_PatternCursor& _M_str_cur;
_Results& _M_results;
};
// Time complexity: exponential
// Space complexity: O(_M_str_cur.size())
// _M_dfs() take a state, along with current string cursor(_M_str_cur),
// trying to match current state with current character.
// Only _S_opcode_match will consume a character.
class _DFSMatcher
: public _Grep_matcher
{
public:
_DFSMatcher(_PatternCursor& __p,
_Results& __r,
const _AutomatonPtr& __automaton,
regex_constants::match_flag_type __flags)
: _Grep_matcher(__p, __r, __automaton, __flags)
{ }
bool
_M_match()
{ return _M_dfs<true>(_M_nfa->_M_start()); }
bool
_M_search_from_first()
{ return _M_dfs<false>(_M_nfa->_M_start()); }
private:
template<bool __match_mode>
bool
_M_dfs(_StateIdT __i);
};
// It's essentially a variant of Single-Source-Shortest-Path problem, where,
// the matching results is the final distance and should be minimized.
// Instead of using Dijkstra Algorithm, I pick up the queue-optimizaed
// (BFS-like) Bellman-Ford algorithm,
// SPFA(http://en.wikipedia.org/wiki/Shortest_Path_Faster_Algorithm).
//
// Every entry of _M_current saves the solution(grouping status) for every
// matching head. When states transfer, solutions will be compared and
// deduplicated(based on which greedy mode we have).
//
// Time complexity: O(_M_str_cur.size() * _M_nfa.size())
// Space complexity: O(_M_nfa.size() * _M_nfa.mark_count())
class _BFSMatcher
: public _Grep_matcher
{
public:
_BFSMatcher(_PatternCursor& __p,
_Results& __r,
const _AutomatonPtr& __automaton,
regex_constants::match_flag_type __flags)
: _Grep_matcher(__p, __r, __automaton, __flags)
{
if (_M_nfa->_M_start() != _S_invalid_state_id)
_M_current[_M_nfa->_M_start()] = _M_results._M_clone();
_M_e_closure();
}
bool
_M_match()
{ return _M_main_loop<true>(); }
bool
_M_search_from_first()
{ return _M_main_loop<false>(); }
private:
template<bool __match_mode>
bool
_M_main_loop();
void
_M_e_closure();
void
_M_move();
bool
_M_match_less_than(_StateIdT __u, _StateIdT __v) const;
bool
_M_includes_some() const;
std::map<_StateIdT, std::unique_ptr<_Results>> _M_current;
};
//@} regex-detail
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace __detail
} // namespace std
#include <bits/regex_grep_matcher.tcc>