libstdc++: Fix handling of invalid ranges in std::regex [PR102447]
std::regex currently allows invalid bracket ranges such as [\w-a] which are only allowed by ECMAScript when in web browser compatibility mode. It should be an error, because the start of the range is a character class, not a single character. The current implementation of _Compiler::_M_expression_term does not provide a way to reject this, because we only remember a previous character, not whether we just processed a character class (or collating symbol etc.) This patch replaces the pair<bool, CharT> used to emulate optional<CharT> with a custom class closer to pair<tribool,CharT>. That allows us to track three states, so that we can tell when we've just seen a character class. With this additional state the code in _M_expression_term for processing the _S_token_bracket_dash can be improved to correctly reject the [\w-a] case, without regressing for valid cases such as [\w-] and [----]. libstdc++-v3/ChangeLog: PR libstdc++/102447 * include/bits/regex_compiler.h (_Compiler::_BracketState): New class. (_Compiler::_BrackeyMatcher): New alias template. (_Compiler::_M_expression_term): Change pair<bool, CharT> parameter to _BracketState. Process first character for ECMAScript syntax as well as POSIX. * include/bits/regex_compiler.tcc (_Compiler::_M_insert_bracket_matcher): Pass _BracketState. (_Compiler::_M_expression_term): Use _BracketState to store state between calls. Improve handling of dashes in ranges. * testsuite/28_regex/algorithms/regex_match/cstring_bracket_01.cc: Add more tests for ranges containing dashes. Check invalid ranges with character class at the beginning.
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@ -121,13 +121,45 @@ namespace __detail
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void
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_M_insert_bracket_matcher(bool __neg);
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// Returns true if successfully matched one term and should continue.
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// Cache of the last atom seen in a bracketed range expression.
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struct _BracketState
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{
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enum class _Type : char { _None, _Char, _Class } _M_type = _Type::_None;
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_CharT _M_char;
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void
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set(_CharT __c) noexcept { _M_type = _Type::_Char; _M_char = __c; }
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_GLIBCXX_NODISCARD _CharT
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get() const noexcept { return _M_char; }
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void
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reset(_Type __t = _Type::_None) noexcept { _M_type = __t; }
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explicit operator bool() const noexcept
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{ return _M_type != _Type::_None; }
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// Previous token was a single character.
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_GLIBCXX_NODISCARD bool
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_M_is_char() const noexcept { return _M_type == _Type::_Char; }
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// Previous token was a character class, equivalent class,
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// collating symbol etc.
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_GLIBCXX_NODISCARD bool
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_M_is_class() const noexcept { return _M_type == _Type::_Class; }
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};
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template<bool __icase, bool __collate>
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using _BracketMatcher
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= std::__detail::_BracketMatcher<_TraitsT, __icase, __collate>;
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// Returns true if successfully parsed one term and should continue
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// compiling a bracket expression.
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// Returns false if the compiler should move on.
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template<bool __icase, bool __collate>
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bool
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_M_expression_term(pair<bool, _CharT>& __last_char,
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_BracketMatcher<_TraitsT, __icase, __collate>&
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__matcher);
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_M_expression_term(_BracketState& __last_char,
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_BracketMatcher<__icase, __collate>& __matcher);
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int
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_M_cur_int_value(int __radix);
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@ -403,7 +403,7 @@ namespace __detail
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_M_insert_character_class_matcher()
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{
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__glibcxx_assert(_M_value.size() == 1);
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_BracketMatcher<_TraitsT, __icase, __collate> __matcher
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_BracketMatcher<__icase, __collate> __matcher
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(_M_ctype.is(_CtypeT::upper, _M_value[0]), _M_traits);
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__matcher._M_add_character_class(_M_value, false);
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__matcher._M_ready();
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@ -417,26 +417,17 @@ namespace __detail
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_Compiler<_TraitsT>::
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_M_insert_bracket_matcher(bool __neg)
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{
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_BracketMatcher<_TraitsT, __icase, __collate> __matcher(__neg, _M_traits);
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pair<bool, _CharT> __last_char; // Optional<_CharT>
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__last_char.first = false;
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if (!(_M_flags & regex_constants::ECMAScript))
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{
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if (_M_try_char())
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{
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__last_char.first = true;
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__last_char.second = _M_value[0];
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}
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else if (_M_match_token(_ScannerT::_S_token_bracket_dash))
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{
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__last_char.first = true;
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__last_char.second = '-';
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}
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}
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_BracketMatcher<__icase, __collate> __matcher(__neg, _M_traits);
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_BracketState __last_char;
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if (_M_try_char())
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__last_char.set(_M_value[0]);
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else if (_M_match_token(_ScannerT::_S_token_bracket_dash))
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// Dash as first character is a normal character.
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__last_char.set('-');
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while (_M_expression_term(__last_char, __matcher))
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;
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if (__last_char.first)
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__matcher._M_add_char(__last_char.second);
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if (__last_char._M_is_char())
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__matcher._M_add_char(__last_char.get());
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__matcher._M_ready();
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_M_stack.push(_StateSeqT(
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*_M_nfa,
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@ -447,27 +438,27 @@ namespace __detail
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template<bool __icase, bool __collate>
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bool
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_Compiler<_TraitsT>::
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_M_expression_term(pair<bool, _CharT>& __last_char,
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_BracketMatcher<_TraitsT, __icase, __collate>& __matcher)
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_M_expression_term(_BracketState& __last_char,
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_BracketMatcher<__icase, __collate>& __matcher)
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{
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if (_M_match_token(_ScannerT::_S_token_bracket_end))
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return false;
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// Add any previously cached char into the matcher and update cache.
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const auto __push_char = [&](_CharT __ch)
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{
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if (__last_char.first)
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__matcher._M_add_char(__last_char.second);
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else
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__last_char.first = true;
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__last_char.second = __ch;
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if (__last_char._M_is_char())
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__matcher._M_add_char(__last_char.get());
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__last_char.set(__ch);
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};
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const auto __flush = [&]
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// Add any previously cached char into the matcher and update cache.
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const auto __push_class = [&]
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{
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if (__last_char.first)
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{
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__matcher._M_add_char(__last_char.second);
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__last_char.first = false;
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}
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if (__last_char._M_is_char())
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__matcher._M_add_char(__last_char.get());
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// We don't cache anything here, just record that the last thing
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// processed was a character class (or similar).
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__last_char.reset(_BracketState::_Type::_Class);
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};
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if (_M_match_token(_ScannerT::_S_token_collsymbol))
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@ -476,16 +467,16 @@ namespace __detail
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if (__symbol.size() == 1)
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__push_char(__symbol[0]);
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else
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__flush();
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__push_class();
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}
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else if (_M_match_token(_ScannerT::_S_token_equiv_class_name))
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{
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__flush();
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__push_class();
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__matcher._M_add_equivalence_class(_M_value);
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}
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else if (_M_match_token(_ScannerT::_S_token_char_class_name))
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{
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__flush();
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__push_class();
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__matcher._M_add_character_class(_M_value, false);
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}
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else if (_M_try_char())
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@ -502,49 +493,50 @@ namespace __detail
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// It turns out that no one reads BNFs ;)
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else if (_M_match_token(_ScannerT::_S_token_bracket_dash))
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{
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if (!__last_char.first)
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if (_M_match_token(_ScannerT::_S_token_bracket_end))
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{
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if (!(_M_flags & regex_constants::ECMAScript))
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{
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if (_M_match_token(_ScannerT::_S_token_bracket_end))
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{
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__push_char('-');
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return false;
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}
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__throw_regex_error(
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regex_constants::error_range,
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"Unexpected dash in bracket expression. For POSIX syntax, "
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"a dash is not treated literally only when it is at "
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"beginning or end.");
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}
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// For "-]" the dash is a literal character.
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__push_char('-');
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return false;
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}
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else
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else if (__last_char._M_is_class())
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{
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// "\\w-" is invalid, start of range must be a single char.
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__throw_regex_error(regex_constants::error_range,
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"Invalid start of range in bracket expression.");
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}
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else if (__last_char._M_is_char())
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{
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if (_M_try_char())
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{
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__matcher._M_make_range(__last_char.second, _M_value[0]);
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__last_char.first = false;
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// "x-y"
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__matcher._M_make_range(__last_char.get(), _M_value[0]);
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__last_char.reset();
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}
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else if (_M_match_token(_ScannerT::_S_token_bracket_dash))
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{
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__matcher._M_make_range(__last_char.second, '-');
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__last_char.first = false;
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// "x--"
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__matcher._M_make_range(__last_char.get(), '-');
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__last_char.reset();
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}
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else
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{
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if (_M_scanner._M_get_token()
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!= _ScannerT::_S_token_bracket_end)
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__throw_regex_error(
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regex_constants::error_range,
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"Character is expected after a dash.");
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__push_char('-');
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}
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__throw_regex_error(regex_constants::error_range,
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"Invalid end of range in bracket expression.");
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}
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else if (_M_flags & regex_constants::ECMAScript)
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{
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// A dash that is not part of an existing range. Might be the
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// start of a new range, or might just be a literal '-' char.
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// Only ECMAScript allows that in the middle of a bracket expr.
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__push_char('-');
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}
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else
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__throw_regex_error(regex_constants::error_range,
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"Invalid dash in bracket expression.");
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}
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else if (_M_match_token(_ScannerT::_S_token_quoted_class))
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{
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__flush();
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__push_class();
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__matcher._M_add_character_class(_M_value,
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_M_ctype.is(_CtypeT::upper,
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_M_value[0]));
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@ -69,6 +69,16 @@ test01()
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void
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test02()
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{
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VERIFY(regex_match("-", regex("[-]", regex_constants::ECMAScript)));
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VERIFY(regex_match("-", regex("[--]", regex_constants::ECMAScript)));
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VERIFY(regex_match("-", regex("[---]", regex_constants::ECMAScript)));
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VERIFY(regex_match("-", regex("[----]", regex_constants::ECMAScript)));
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VERIFY(regex_match("-", regex("[-----]", regex_constants::ECMAScript)));
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VERIFY(regex_match("-", regex("[-]", regex_constants::extended)));
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VERIFY(regex_match("-", regex("[--]", regex_constants::extended)));
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VERIFY(regex_match("-", regex("[---]", regex_constants::extended)));
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VERIFY(regex_match("-", regex("[----]", regex_constants::extended)));
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try
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{
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std::regex re("[-----]", std::regex::extended);
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{
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VERIFY(e.code() == std::regex_constants::error_range);
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}
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std::regex re("[-----]", std::regex::ECMAScript);
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VERIFY(!regex_match("b", regex("[-ac]", regex_constants::extended)));
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VERIFY(!regex_match("b", regex("[ac-]", regex_constants::extended)));
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}
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catch (const std::regex_error& e)
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{
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VERIFY(e.code() == std::regex_constants::error_range);
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}
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try
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{
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regex("[@--]", regex_constants::extended);
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VERIFY(false);
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}
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catch (const std::regex_error& e)
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{
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VERIFY(e.code() == std::regex_constants::error_range);
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}
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try
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{
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regex("[--%]", regex_constants::extended);
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VERIFY(false);
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}
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catch (const std::regex_error& e)
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{
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VERIFY(e.code() == std::regex_constants::error_range);
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}
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VERIFY(regex_match("].", regex("[][.hyphen.]-0]*", regex_constants::extended)));
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}
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VERIFY(regex_match("a-", debian_cron_namespace_ok));
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}
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// libstdc++/102447
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void
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test07()
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{
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VERIFY(regex_match("-", std::regex("[\\w-]", std::regex::ECMAScript)));
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VERIFY(regex_match("a", std::regex("[\\w-]", std::regex::ECMAScript)));
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VERIFY(regex_match("-", std::regex("[a-]", std::regex::ECMAScript)));
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VERIFY(regex_match("a", std::regex("[a-]", std::regex::ECMAScript)));
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try
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{
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std::regex re("[\\w-a]", std::regex::ECMAScript);
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VERIFY(false);
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}
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catch (const std::regex_error& e)
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{
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VERIFY(e.code() == std::regex_constants::error_range);
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}
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try
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{
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std::regex re("[\\w--]", std::regex::ECMAScript);
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VERIFY(false);
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}
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catch (const std::regex_error& e)
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{
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VERIFY(e.code() == std::regex_constants::error_range);
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}
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}
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int
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main()
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{
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test04();
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test05();
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test06();
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test07();
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return 0;
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}
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