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regex_automaton.h (_NFA<>::_M_insert_repeat): Add _S_opcode_repeat support to distingush a loop from _S_opcode_alternative. 

2014-04-27  Tim Shen  <timshen91@gmail.com>

	* include/bits/regex_automaton.h (_NFA<>::_M_insert_repeat):
	Add _S_opcode_repeat support to distingush a loop from
	_S_opcode_alternative.
	* include/bits/regex_automaton.tcc (_State_base::_M_print,
	_State_base::_M_dot, _NFA<>::_M_eliminate_dummy,
	_StateSeq<>::_M_clone): Likewise.
	* include/bits/regex_compiler.tcc (_Compiler<>::_M_quantifier):
	Likewise.
	* include/bits/regex_executor.tcc (_Executor<>::_M_dfs): Likewise.
	* include/bits/regex_scanner.tcc (_Scanner<>::_M_eat_escape_ecma):
	Uglify local variable __i.
	* include/bits/regex_compiler.h (_BracketMatcher<>::_M_make_cache):
	Use size_t instead of int to compare with vector::size().

2014-04-27  Tim Shen  <timshen91@gmail.com>

	* include/bits/regex_executor.h: Add _M_rep_count to track how
	many times this repeat node are visited.
	* include/bits/regex_executor.tcc (_Executor<>::_M_rep_once_more,
	_Executor<>::_M_dfs): Use _M_rep_count to prevent entering
	infinite loop.

2014-04-27  Tim Shen  <timshen91@gmail.com>

	* include/bits/regex.tcc (__regex_algo_impl<>): Remove
	_GLIBCXX_REGEX_DFS_QUANTIFIERS_LIMIT and use
	_GLIBCXX_REGEX_USE_THOMPSON_NFA instead.
	* include/bits/regex_automaton.h: Remove quantifier counting variable.
	* include/bits/regex_automaton.tcc (_State_base::_M_dot):
	Adjust debug NFA dump.

From-SVN: r209844
This commit is contained in:
Tim Shen 2014-04-27 23:48:47 +00:00 committed by Tim Shen
parent f956adb961
commit a670a9bb54
10 changed files with 175 additions and 101 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

33
libstdc++-v3/ChangeLog
View File

@ -1,3 +1,36 @@
2014-04-27 Tim Shen <timshen91@gmail.com>
* include/bits/regex_automaton.h (_NFA<>::_M_insert_repeat):
Add _S_opcode_repeat support to distingush a loop from
_S_opcode_alternative.
* include/bits/regex_automaton.tcc (_State_base::_M_print,
_State_base::_M_dot, _NFA<>::_M_eliminate_dummy,
_StateSeq<>::_M_clone): Likewise.
* include/bits/regex_compiler.tcc (_Compiler<>::_M_quantifier):
Likewise.
* include/bits/regex_executor.tcc (_Executor<>::_M_dfs): Likewise.
* include/bits/regex_scanner.tcc (_Scanner<>::_M_eat_escape_ecma):
Uglify local variable __i.
* include/bits/regex_compiler.h (_BracketMatcher<>::_M_make_cache):
Use size_t instead of int to compare with vector::size().
2014-04-27 Tim Shen <timshen91@gmail.com>
* include/bits/regex_executor.h: Add _M_rep_count to track how
many times this repeat node are visited.
* include/bits/regex_executor.tcc (_Executor<>::_M_rep_once_more,
_Executor<>::_M_dfs): Use _M_rep_count to prevent entering
infinite loop.
2014-04-27 Tim Shen <timshen91@gmail.com>
* include/bits/regex.tcc (__regex_algo_impl<>): Remove
_GLIBCXX_REGEX_DFS_QUANTIFIERS_LIMIT and use
_GLIBCXX_REGEX_USE_THOMPSON_NFA instead.
* include/bits/regex_automaton.h: Remove quantifier counting variable.
* include/bits/regex_automaton.tcc (_State_base::_M_dot):
Adjust debug NFA dump.
2014-04-25 Lars Gullik Bjønnes <larsbj@gullik.org>
PR libstdc++/60710

35
libstdc++-v3/include/bits/regex.tcc
View File

@ -28,12 +28,12 @@
* Do not attempt to use it directly. @headername{regex}
*/
// See below __regex_algo_impl to get what this is talking about. The default
// value 1 indicated a conservative optimization without giving up worst case
// performance.
#ifndef _GLIBCXX_REGEX_DFS_QUANTIFIERS_LIMIT
#define _GLIBCXX_REGEX_DFS_QUANTIFIERS_LIMIT 1
#endif
// A non-standard switch to let the user pick the matching algorithm.
// If _GLIBCXX_REGEX_USE_THOMPSON_NFA is defined, the thompson NFA
// algorithm will be used. This algorithm is not enabled by default,
// and cannot be used if the regex contains back-references, but has better
// (polynomial instead of exponential) worst case performace.
// See __regex_algo_impl below.
namespace std _GLIBCXX_VISIBILITY(default)
{
@ -66,24 +66,15 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
for (auto& __it : __res)
__it.matched = false;
// This function decide which executor to use under given circumstances.
// The _S_auto policy now is the following: if a NFA has no
// back-references and has more than _GLIBCXX_REGEX_DFS_QUANTIFIERS_LIMIT
// quantifiers (*, +, ?), the BFS executor will be used, other wise
// DFS executor. This is because DFS executor has a exponential upper
// bound, but better best-case performace. Meanwhile, BFS executor can
// effectively prevent from exponential-long time matching (which must
// contains many quantifiers), but it's slower in average.
//
// For simple regex, BFS executor could be 2 or more times slower than
// DFS executor.
//
// Of course, BFS executor cannot handle back-references.
// __policy is used by testsuites so that they can use Thompson NFA
// without defining a macro. Users should define
// _GLIBCXX_REGEX_USE_THOMPSON_NFA if they need to use this approach.
bool __ret;
if (!__re._M_automaton->_M_has_backref
&& (__policy == _RegexExecutorPolicy::_S_alternate
|| __re._M_automaton->_M_quant_count
> _GLIBCXX_REGEX_DFS_QUANTIFIERS_LIMIT))
#ifndef _GLIBCXX_REGEX_USE_THOMPSON_NFA
&& __policy == _RegexExecutorPolicy::_S_alternate
#endif
)
{
_Executor<_BiIter, _Alloc, _TraitsT, false>
__executor(__s, __e, __m, __re, __flags);

21
libstdc++-v3/include/bits/regex_automaton.h
View File

@ -52,6 +52,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{
_S_opcode_unknown,
_S_opcode_alternative,
_S_opcode_repeat,
_S_opcode_backref,
_S_opcode_line_begin_assertion,
_S_opcode_line_end_assertion,
@ -74,9 +75,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
size_t _M_backref_index; // for _S_opcode_backref
struct
{
// for _S_opcode_alternative.
_StateIdT _M_quant_index;
// for _S_opcode_alternative or _S_opcode_subexpr_lookahead
// for _S_opcode_alternative, _S_opcode_repeat and
// _S_opcode_subexpr_lookahead
_StateIdT _M_alt;
// for _S_opcode_word_boundary or _S_opcode_subexpr_lookahead or
// quantifiers (ungreedy if set true)
@ -120,7 +120,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
explicit
_NFA_base(_FlagT __f)
: _M_flags(__f), _M_start_state(0), _M_subexpr_count(0),
_M_quant_count(0), _M_has_backref(false)
_M_has_backref(false)
{ }
_NFA_base(_NFA_base&&) = default;
@ -145,7 +145,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
_FlagT _M_flags;
_StateIdT _M_start_state;
_SizeT _M_subexpr_count;
_SizeT _M_quant_count;
bool _M_has_backref;
};
@ -175,7 +174,17 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
_StateT __tmp(_S_opcode_alternative);
// It labels every quantifier to make greedy comparison easier in BFS
// approach.
__tmp._M_quant_index = this->_M_quant_count++;
__tmp._M_next = __next;
__tmp._M_alt = __alt;
return _M_insert_state(std::move(__tmp));
}
_StateIdT
_M_insert_repeat(_StateIdT __next, _StateIdT __alt, bool __neg)
{
_StateT __tmp(_S_opcode_repeat);
// It labels every quantifier to make greedy comparison easier in BFS
// approach.
__tmp._M_next = __next;
__tmp._M_alt = __alt;
__tmp._M_neg = __neg;

9
libstdc++-v3/include/bits/regex_automaton.tcc
View File

@ -41,6 +41,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
switch (_M_opcode)
{
case _S_opcode_alternative:
case _S_opcode_repeat:
ostr << "alt next=" << _M_next << " alt=" << _M_alt;
break;
case _S_opcode_subexpr_begin:
@ -72,11 +73,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
switch (_M_opcode)
{
case _S_opcode_alternative:
case _S_opcode_repeat:
__ostr << __id << " [label=\"" << __id << "\\nALT\"];\n"
<< __id << " -> " << _M_next
<< " [label=\"epsilon\", tailport=\"s\"];\n"
<< " [label=\"next\", tailport=\"s\"];\n"
<< __id << " -> " << _M_alt
<< " [label=\"epsilon\", tailport=\"n\"];\n";
<< " [label=\"alt\", tailport=\"n\"];\n";
break;
case _S_opcode_backref:
__ostr << __id << " [label=\"" << __id << "\\nBACKREF "
@ -174,6 +176,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
== _S_opcode_dummy)
__it._M_next = (*this)[__it._M_next]._M_next;
if (__it._M_opcode == _S_opcode_alternative
|| __it._M_opcode == _S_opcode_repeat
|| __it._M_opcode == _S_opcode_subexpr_lookahead)
while (__it._M_alt >= 0 && (*this)[__it._M_alt]._M_opcode
== _S_opcode_dummy)
@ -198,6 +201,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
auto __id = _M_nfa._M_insert_state(__dup);
__m[__u] = __id;
if (__dup._M_opcode == _S_opcode_alternative
|| __dup._M_opcode == _S_opcode_repeat
|| __dup._M_opcode == _S_opcode_subexpr_lookahead)
if (__dup._M_alt != _S_invalid_state_id && __m[__dup._M_alt] == -1)
__stack.push(__dup._M_alt);
@ -217,6 +221,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
__ref._M_next = __m[__ref._M_next];
}
if (__ref._M_opcode == _S_opcode_alternative
|| __ref._M_opcode == _S_opcode_repeat
|| __ref._M_opcode == _S_opcode_subexpr_lookahead)
if (__ref._M_alt != _S_invalid_state_id)
{

2
libstdc++-v3/include/bits/regex_compiler.h
View File

@ -421,7 +421,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
void
_M_make_cache(true_type)
{
for (int __i = 0; __i < _M_cache.size(); __i++)
for (size_t __i = 0; __i < _M_cache.size(); __i++)
_M_cache[static_cast<_UnsignedCharT>(__i)] =
_M_apply(__i, false_type());
}

20
libstdc++-v3/include/bits/regex_compiler.tcc
View File

@ -188,8 +188,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{
__init();
auto __e = _M_pop();
_StateSeqT __r(_M_nfa, _M_nfa._M_insert_alt(_S_invalid_state_id,
__e._M_start, __neg));
_StateSeqT __r(_M_nfa, _M_nfa._M_insert_repeat(_S_invalid_state_id,
__e._M_start, __neg));
__e._M_append(__r);
_M_stack.push(__r);
}
@ -197,8 +197,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{
__init();
auto __e = _M_pop();
__e._M_append(_M_nfa._M_insert_alt(_S_invalid_state_id, __e._M_start,
__neg));
__e._M_append(_M_nfa._M_insert_repeat(_S_invalid_state_id,
__e._M_start, __neg));
_M_stack.push(__e);
}
else if (_M_match_token(_ScannerT::_S_token_opt))
@ -206,8 +206,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
__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));
_StateSeqT __r(_M_nfa, _M_nfa._M_insert_repeat(_S_invalid_state_id,
__e._M_start, __neg));
__e._M_append(__end);
__r._M_append(__end);
_M_stack.push(__r);
@ -244,8 +244,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{
auto __tmp = __r._M_clone();
_StateSeqT __s(_M_nfa,
_M_nfa._M_insert_alt(_S_invalid_state_id,
__tmp._M_start, __neg));
_M_nfa._M_insert_repeat(_S_invalid_state_id,
__tmp._M_start, __neg));
__tmp._M_append(__s);
__e._M_append(__s);
}
@ -261,8 +261,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
for (long __i = 0; __i < __n; ++__i)
{
auto __tmp = __r._M_clone();
auto __alt = _M_nfa._M_insert_alt(__tmp._M_start,
__end, __neg);
auto __alt = _M_nfa._M_insert_repeat(__tmp._M_start,
__end, __neg);
__stack.push(__alt);
__e._M_append(_StateSeqT(_M_nfa, __alt, __tmp._M_end));
}

10
libstdc++-v3/include/bits/regex_executor.h
View File

@ -73,6 +73,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
_M_results(__results),
_M_match_queue(__dfs_mode ? nullptr
: new vector<pair<_StateIdT, _ResultsVec>>()),
_M_rep_count(_M_nfa.size()),
_M_visited(__dfs_mode ? nullptr : new vector<bool>(_M_nfa.size())),
_M_flags((__flags & regex_constants::match_prev_avail)
? (__flags
@ -102,6 +103,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
_M_search();
private:
template<bool __match_mode>
void
_M_rep_once_more(_StateIdT);
template<bool __match_mode>
void
_M_dfs(_StateIdT __start);
@ -149,9 +154,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
_ResultsVec& _M_results;
// Used in BFS, saving states that need to be considered for the next
// character.
std::unique_ptr<vector<pair<_StateIdT, _ResultsVec>>> _M_match_queue;
unique_ptr<vector<pair<_StateIdT, _ResultsVec>>> _M_match_queue;
// Used in BFS, indicating that which state is already visited.
std::unique_ptr<vector<bool>> _M_visited;
vector<pair<_BiIter, int>> _M_rep_count;
unique_ptr<vector<bool>> _M_visited;
_FlagT _M_flags;
// To record current solution.
_StateIdT _M_start_state;

143
libstdc++-v3/include/bits/regex_executor.tcc
View File

@ -161,7 +161,39 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
return false;
}
// TODO: Use a function vector to dispatch, instead of using switch-case.
// __rep_count records how many times (__rep_count.second)
// this node is visited under certain input iterator
// (__rep_count.first). This prevent the executor from entering
// infinite loop by refusing to continue when it's already been
// visited more than twice. It's `twice` instead of `once` because
// we need to spare one more time for potential group capture.
template<typename _BiIter, typename _Alloc, typename _TraitsT,
bool __dfs_mode>
template<bool __match_mode>
void _Executor<_BiIter, _Alloc, _TraitsT, __dfs_mode>::
_M_rep_once_more(_StateIdT __i)
{
const auto& __state = _M_nfa[__i];
auto& __rep_count = _M_rep_count[__i];
if (__rep_count.second == 0 || __rep_count.first != _M_current)
{
auto __back = __rep_count;
__rep_count.first = _M_current;
__rep_count.second = 1;
_M_dfs<__match_mode>(__state._M_alt);
__rep_count = __back;
}
else
{
if (__rep_count.second < 2)
{
__rep_count.second++;
_M_dfs<__match_mode>(__state._M_alt);
__rep_count.second--;
}
}
};
template<typename _BiIter, typename _Alloc, typename _TraitsT,
bool __dfs_mode>
template<bool __match_mode>
@ -184,69 +216,61 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
// of this quantifier". Executing _M_next first or _M_alt first don't
// mean the same thing, and we need to choose the correct order under
// given greedy mode.
case _S_opcode_alternative:
// Greedy.
if (!__state._M_neg)
{
// "Once more" is preferred in greedy mode.
_M_dfs<__match_mode>(__state._M_alt);
// If it's DFS executor and already accepted, we're done.
if (!__dfs_mode || !_M_has_sol)
_M_dfs<__match_mode>(__state._M_next);
}
else // Non-greedy mode
{
if (__dfs_mode)
{
// vice-versa.
case _S_opcode_repeat:
{
// Greedy.
if (!__state._M_neg)
{
_M_rep_once_more<__match_mode>(__i);
// If it's DFS executor and already accepted, we're done.
if (!__dfs_mode || !_M_has_sol)
_M_dfs<__match_mode>(__state._M_next);
if (!_M_has_sol)
_M_dfs<__match_mode>(__state._M_alt);
}
else
{
// DON'T attempt anything, because there's already another
// state with higher priority accepted. This state cannot be
// better by attempting its next node.
if (!_M_has_sol)
{
_M_dfs<__match_mode>(__state._M_next);
// DON'T attempt anything if it's already accepted. An
// accepted state *must* be better than a solution that
// matches a non-greedy quantifier one more time.
if (!_M_has_sol)
_M_dfs<__match_mode>(__state._M_alt);
}
}
}
else // Non-greedy mode
{
if (__dfs_mode)
{
// vice-versa.
_M_dfs<__match_mode>(__state._M_next);
if (!_M_has_sol)
_M_rep_once_more<__match_mode>(__i);
}
else
{
// DON'T attempt anything, because there's already another
// state with higher priority accepted. This state cannot be
// better by attempting its next node.
if (!_M_has_sol)
{
_M_dfs<__match_mode>(__state._M_next);
// DON'T attempt anything if it's already accepted. An
// accepted state *must* be better than a solution that
// matches a non-greedy quantifier one more time.
if (!_M_has_sol)
_M_rep_once_more<__match_mode>(__i);
}
}
}
}
break;
case _S_opcode_subexpr_begin:
// If there's nothing changed since last visit, do NOT continue.
// This prevents the executor from get into infinite loop when using
// "()*" to match "".
if (!_M_cur_results[__state._M_subexpr].matched
|| _M_cur_results[__state._M_subexpr].first != _M_current)
{
auto& __res = _M_cur_results[__state._M_subexpr];
auto __back = __res.first;
__res.first = _M_current;
_M_dfs<__match_mode>(__state._M_next);
__res.first = __back;
}
{
auto& __res = _M_cur_results[__state._M_subexpr];
auto __back = __res.first;
__res.first = _M_current;
_M_dfs<__match_mode>(__state._M_next);
__res.first = __back;
}
break;
case _S_opcode_subexpr_end:
if (_M_cur_results[__state._M_subexpr].second != _M_current
|| _M_cur_results[__state._M_subexpr].matched != true)
{
auto& __res = _M_cur_results[__state._M_subexpr];
auto __back = __res;
__res.second = _M_current;
__res.matched = true;
_M_dfs<__match_mode>(__state._M_next);
__res = __back;
}
else
{
auto& __res = _M_cur_results[__state._M_subexpr];
auto __back = __res;
__res.second = _M_current;
__res.matched = true;
_M_dfs<__match_mode>(__state._M_next);
__res = __back;
}
break;
case _S_opcode_line_begin_assertion:
if (_M_at_begin())
@ -339,6 +363,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
}
}
break;
case _S_opcode_alternative:
_M_dfs<__match_mode>(__state._M_alt);
if (!__dfs_mode || !_M_has_sol)
_M_dfs<__match_mode>(__state._M_next);
break;
default:
_GLIBCXX_DEBUG_ASSERT(false);
}

2
libstdc++-v3/include/bits/regex_scanner.tcc
View File

@ -335,7 +335,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
else if (__c == 'x' || __c == 'u')
{
_M_value.erase();
for (int i = 0; i < (__c == 'x' ? 2 : 4); i++)
for (int __i = 0; __i < (__c == 'x' ? 2 : 4); __i++)
{
if (_M_current == _M_end
|| !_M_ctype.is(_CtypeT::xdigit, *_M_current))

1
libstdc++-v3/testsuite/28_regex/algorithms/regex_match/ecma/char/emptygroup.cc
View File

@ -50,6 +50,7 @@ test01()
const char s[] = "";
VERIFY( regex_match_debug(s, m, re) );
}
VERIFY(regex_match_debug("", regex("(?:)*")));
}
int