regex_compiler.tcc
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// class template regex -*- C++ -*-
// Copyright (C) 2013-2021 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 branches
// 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 nodes will be eliminated at the end of compilation.
*/
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
namespace __detail
{
template<typename _TraitsT>
_Compiler<_TraitsT>::
_Compiler(_IterT __b, _IterT __e,
const typename _TraitsT::locale_type& __loc, _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_scanner(__b, __e, _M_flags, __loc),
_M_nfa(make_shared<_RegexT>(__loc, _M_flags)),
_M_traits(_M_nfa->_M_traits),
_M_ctype(std::use_facet<_CtypeT>(__loc))
{
_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_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 _TraitsT>
void
_Compiler<_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);
// __alt2 is state._M_next, __alt1 is state._M_alt. The executor
// executes _M_alt before _M_next, as well as executing left
// alternative before right one.
_M_stack.push(_StateSeqT(*_M_nfa,
_M_nfa->_M_insert_alt(
__alt2._M_start, __alt1._M_start, false),
__end));
}
}
template<typename _TraitsT>
void
_Compiler<_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 _TraitsT>
bool
_Compiler<_TraitsT>::
_M_term()
{
if (this->_M_assertion())
return true;
if (this->_M_atom())
{
while (this->_M_quantifier());
return true;
}
return false;
}
template<typename _TraitsT>
bool
_Compiler<_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 negative, 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,
"Parenthesis is not closed.");
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 _TraitsT>
bool
_Compiler<_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,
"Nothing to repeat before a quantifier.");
__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_repeat(_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_repeat(_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_repeat(_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,
"Nothing to repeat before a quantifier.");
if (!_M_match_token(_ScannerT::_S_token_dup_count))
__throw_regex_error(regex_constants::error_badbrace,
"Unexpected token in brace expression.");
_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 = 0;
// {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;
}
if (!_M_match_token(_ScannerT::_S_token_interval_end))
__throw_regex_error(regex_constants::error_brace,
"Unexpected end of brace expression.");
__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_repeat(_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,
"Invalid range in brace expression.");
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 hack 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_repeat(__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();
std::swap(__tmp._M_next, __tmp._M_alt);
}
}
_M_stack.push(__e);
}
else
return false;
return true;
}
#define __INSERT_REGEX_MATCHER(__func, ...)\
do {\
if (!(_M_flags & regex_constants::icase))\
if (!(_M_flags & regex_constants::collate))\
__func<false, false>(__VA_ARGS__);\
else\
__func<false, true>(__VA_ARGS__);\
else\
if (!(_M_flags & regex_constants::collate))\
__func<true, false>(__VA_ARGS__);\
else\
__func<true, true>(__VA_ARGS__);\
} while (false)
template<typename _TraitsT>
bool
_Compiler<_TraitsT>::
_M_atom()
{
if (_M_match_token(_ScannerT::_S_token_anychar))
{
if (!(_M_flags & regex_constants::ECMAScript))
__INSERT_REGEX_MATCHER(_M_insert_any_matcher_posix);
else
__INSERT_REGEX_MATCHER(_M_insert_any_matcher_ecma);
}
else if (_M_try_char())
__INSERT_REGEX_MATCHER(_M_insert_char_matcher);
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))
__INSERT_REGEX_MATCHER(_M_insert_character_class_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,
"Parenthesis is not closed.");
__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,
"Parenthesis is not closed.");
__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 _TraitsT>
bool
_Compiler<_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;
__INSERT_REGEX_MATCHER(_M_insert_bracket_matcher, __neg);
return true;
}
#undef __INSERT_REGEX_MATCHER
template<typename _TraitsT>
template<bool __icase, bool __collate>
void
_Compiler<_TraitsT>::
_M_insert_any_matcher_ecma()
{
_M_stack.push(_StateSeqT(*_M_nfa,
_M_nfa->_M_insert_matcher
(_AnyMatcher<_TraitsT, true, __icase, __collate>
(_M_traits))));
}
template<typename _TraitsT>
template<bool __icase, bool __collate>
void
_Compiler<_TraitsT>::
_M_insert_any_matcher_posix()
{
_M_stack.push(_StateSeqT(*_M_nfa,
_M_nfa->_M_insert_matcher
(_AnyMatcher<_TraitsT, false, __icase, __collate>
(_M_traits))));
}
template<typename _TraitsT>
template<bool __icase, bool __collate>
void
_Compiler<_TraitsT>::
_M_insert_char_matcher()
{
_M_stack.push(_StateSeqT(*_M_nfa,
_M_nfa->_M_insert_matcher
(_CharMatcher<_TraitsT, __icase, __collate>
(_M_value[0], _M_traits))));
}
template<typename _TraitsT>
template<bool __icase, bool __collate>
void
_Compiler<_TraitsT>::
_M_insert_character_class_matcher()
{
__glibcxx_assert(_M_value.size() == 1);
_BracketMatcher<_TraitsT, __icase, __collate> __matcher
(_M_ctype.is(_CtypeT::upper, _M_value[0]), _M_traits);
__matcher._M_add_character_class(_M_value, false);
__matcher._M_ready();
_M_stack.push(_StateSeqT(*_M_nfa,
_M_nfa->_M_insert_matcher(std::move(__matcher))));
}
template<typename _TraitsT>
template<bool __icase, bool __collate>
void
_Compiler<_TraitsT>::
_M_insert_bracket_matcher(bool __neg)
{
_BracketMatcher<_TraitsT, __icase, __collate> __matcher(__neg, _M_traits);
pair<bool, _CharT> __last_char; // Optional<_CharT>
__last_char.first = false;
if (!(_M_flags & regex_constants::ECMAScript))
{
if (_M_try_char())
{
__last_char.first = true;
__last_char.second = _M_value[0];
}
else if (_M_match_token(_ScannerT::_S_token_bracket_dash))
{
__last_char.first = true;
__last_char.second = '-';
}
}
while (_M_expression_term(__last_char, __matcher));
if (__last_char.first)
__matcher._M_add_char(__last_char.second);
__matcher._M_ready();
_M_stack.push(_StateSeqT(
*_M_nfa,
_M_nfa->_M_insert_matcher(std::move(__matcher))));
}
template<typename _TraitsT>
template<bool __icase, bool __collate>
bool
_Compiler<_TraitsT>::
_M_expression_term(pair<bool, _CharT>& __last_char,
_BracketMatcher<_TraitsT, __icase, __collate>& __matcher)
{
if (_M_match_token(_ScannerT::_S_token_bracket_end))
return false;
const auto __push_char = [&](_CharT __ch)
{
if (__last_char.first)
__matcher._M_add_char(__last_char.second);
else
__last_char.first = true;
__last_char.second = __ch;
};
const auto __flush = [&]
{
if (__last_char.first)
{
__matcher._M_add_char(__last_char.second);
__last_char.first = false;
}
};
if (_M_match_token(_ScannerT::_S_token_collsymbol))
{
auto __symbol = __matcher._M_add_collate_element(_M_value);
if (__symbol.size() == 1)
__push_char(__symbol[0]);
else
__flush();
}
else if (_M_match_token(_ScannerT::_S_token_equiv_class_name))
{
__flush();
__matcher._M_add_equivalence_class(_M_value);
}
else if (_M_match_token(_ScannerT::_S_token_char_class_name))
{
__flush();
__matcher._M_add_character_class(_M_value, false);
}
else if (_M_try_char())
__push_char(_M_value[0]);
// POSIX doesn't allow '-' as a start-range char (say [a-z--0]),
// except when the '-' is the first or last character in the bracket
// expression ([--0]). ECMAScript treats all '-' after a range as a
// normal character. Also see above, where _M_expression_term gets called.
//
// As a result, POSIX rejects [-----], but ECMAScript doesn't.
// Boost (1.57.0) always uses POSIX style even in its ECMAScript syntax.
// Clang (3.5) always uses ECMAScript style even in its POSIX syntax.
//
// It turns out that no one reads BNFs ;)
else if (_M_match_token(_ScannerT::_S_token_bracket_dash))
{
if (!__last_char.first)
{
if (!(_M_flags & regex_constants::ECMAScript))
{
if (_M_match_token(_ScannerT::_S_token_bracket_end))
{
__push_char('-');
return false;
}
__throw_regex_error(
regex_constants::error_range,
"Unexpected dash in bracket expression. For POSIX syntax, "
"a dash is not treated literally only when it is at "
"beginning or end.");
}
__push_char('-');
}
else
{
if (_M_try_char())
{
__matcher._M_make_range(__last_char.second, _M_value[0]);
__last_char.first = false;
}
else if (_M_match_token(_ScannerT::_S_token_bracket_dash))
{
__matcher._M_make_range(__last_char.second, '-');
__last_char.first = false;
}
else
{
if (_M_scanner._M_get_token()
!= _ScannerT::_S_token_bracket_end)
__throw_regex_error(
regex_constants::error_range,
"Character is expected after a dash.");
__push_char('-');
}
}
}
else if (_M_match_token(_ScannerT::_S_token_quoted_class))
{
__flush();
__matcher._M_add_character_class(_M_value,
_M_ctype.is(_CtypeT::upper,
_M_value[0]));
}
else
__throw_regex_error(regex_constants::error_brack,
"Unexpected character in bracket expression.");
return true;
}
template<typename _TraitsT>
bool
_Compiler<_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 _TraitsT>
bool
_Compiler<_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 _TraitsT>
int
_Compiler<_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 __icase, bool __collate>
bool
_BracketMatcher<_TraitsT, __icase, __collate>::
_M_apply(_CharT __ch, false_type) const
{
return [this, __ch]
{
if (std::binary_search(_M_char_set.begin(), _M_char_set.end(),
_M_translator._M_translate(__ch)))
return true;
auto __s = _M_translator._M_transform(__ch);
for (auto& __it : _M_range_set)
if (_M_translator._M_match_range(__it.first, __it.second, __s))
return true;
if (_M_traits.isctype(__ch, _M_class_set))
return true;
if (std::find(_M_equiv_set.begin(), _M_equiv_set.end(),
_M_traits.transform_primary(&__ch, &__ch+1))
!= _M_equiv_set.end())
return true;
for (auto& __it : _M_neg_class_set)
if (!_M_traits.isctype(__ch, __it))
return true;
return false;
}() ^ _M_is_non_matching;
}
} // namespace __detail
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace
std::false_type
integral_constant< bool, false > false_type
The type used as a compile-time boolean with false value.
Definition: type_traits:86
std::move
constexpr std::remove_reference< _Tp >::type && move(_Tp &&__t) noexcept
Convert a value to an rvalue.
Definition: move.h:104
std::swap
void swap(any &__x, any &__y) noexcept
Exchange the states of two any objects.
Definition: any:428
std::use_facet
const _Facet & use_facet(const locale &__loc)
Return a facet.
Definition: locale_classes.tcc:132
std
ISO C++ entities toplevel namespace is std.
std::regex_constants::error_brace
constexpr error_type error_brace(_S_error_brace)
std::regex_constants::error_badbrace
constexpr error_type error_badbrace(_S_error_badbrace)
std::regex_constants::error_range
constexpr error_type error_range(_S_error_range)
std::regex_constants::ECMAScript
constexpr syntax_option_type ECMAScript
Definition: regex_constants.h:122
std::regex_constants::error_badrepeat
constexpr error_type error_badrepeat(_S_error_badrepeat)
std::regex_constants::egrep
constexpr syntax_option_type egrep
Definition: regex_constants.h:170
std::regex_constants::error_paren
constexpr error_type error_paren(_S_error_paren)
std::regex_constants::awk
constexpr syntax_option_type awk
Definition: regex_constants.h:152
std::regex_constants::extended
constexpr syntax_option_type extended
Definition: regex_constants.h:141
std::regex_constants::basic
constexpr syntax_option_type basic
Definition: regex_constants.h:132
std::regex_constants::error_brack
constexpr error_type error_brack(_S_error_brack)
std::regex_constants::grep
constexpr syntax_option_type grep
Definition: regex_constants.h:161
std::stack
A standard container giving FILO behavior.
Definition: stl_stack.h:100
std::stack::pop
void pop()
Removes first element.
Definition: stl_stack.h:272
std::stack::push
void push(const value_type &__x)
Add data to the top of the stack.
Definition: stl_stack.h:239
std::stack::empty
bool empty() const
Definition: stl_stack.h:199
std::stack::top
reference top()
Definition: stl_stack.h:212