On 04/09/17 03:31 -0700, Tim Shen via libstdc++ wrote:
This fixes the follow-up comments in 71500.
Back-reference matching is different from other matching, as the
content the back-reference refers to is at "run-time", aka during
regex_match(), not regex() compilation.
For compilation we do have an abstraction layer to catch all
comparison customizations, namely _M_translator in regex_compiler.h.
Until this patch, we don't have an abstraction for "run-time"
matching. I believe that back-reference is the only place that needs
run-time matching, so I just build a _Backref_matcher in
regex_executot.tcc.
Tested on x86_64-linux-gnu.
Thanks!
--
Regards,
Tim Shen
commit a97b7fecd319e031ffc489a956b8cf3dc63eeb26
Author: Tim Shen <tims...@google.com>
Date: Mon Sep 4 03:19:35 2017 -0700
PR libstdc++/71500
* include/bits/regex_executor.tcc: Support icase in
regex_tratis<...> for back reference matches.
* testsuite/28_regex/regression.cc: Test case.
diff --git a/libstdc++-v3/include/bits/regex_executor.tcc
b/libstdc++-v3/include/bits/regex_executor.tcc
index 226e05856e1..f6149fecf9d 100644
--- a/libstdc++-v3/include/bits/regex_executor.tcc
+++ b/libstdc++-v3/include/bits/regex_executor.tcc
@@ -335,6 +335,54 @@ namespace __detail
_M_states._M_queue(__state._M_next, _M_cur_results);
}
+ template<typename _BiIter, typename _TraitsT>
+ struct _Backref_matcher
+ {
+ _Backref_matcher(bool __icase, const _TraitsT& __traits)
+ : _M_traits(__traits) { }
+
+ bool
+ _M_apply(_BiIter __expected_begin,
+ _BiIter __expected_end, _BiIter __actual_begin,
+ _BiIter __actual_end)
+ {
+ return _M_traits.transform(__expected_begin, __expected_end)
+ == _M_traits.transform(__actual_begin, __actual_end);
+ }
+
+ const _TraitsT& _M_traits;
+ };
+
+ template<typename _BiIter, typename _CharT>
+ struct _Backref_matcher<_BiIter, std::regex_traits<_CharT>>
+ {
+ using _TraitsT = std::regex_traits<_CharT>;
+ _Backref_matcher(bool __icase, const _TraitsT& __traits)
+ : _M_icase(__icase), _M_traits(__traits) { }
+
+ bool
+ _M_apply(_BiIter __expected_begin,
+ _BiIter __expected_end, _BiIter __actual_begin,
+ _BiIter __actual_end)
+ {
+ if (!_M_icase)
+ return std::equal(__expected_begin, __expected_end,
+ __actual_begin, __actual_end);
This is only valid in C++14 and higher, because the 4-argument version
of std::equal isn't present in C++11.
+ typedef std::ctype<_CharT> __ctype_type;
+ const auto& __fctyp = use_facet<__ctype_type>(_M_traits.getloc());
+ return std::equal(__expected_begin, __expected_end,
+ __actual_begin, __actual_end,
Same here.
+ [this, &__fctyp](_CharT __lhs, _CharT __rhs)
+ {
+ return __fctyp.tolower(__lhs)
+ == __fctyp.tolower(__rhs);
+ });
We need to rewrite this to check the lengths are equal first, and then
call the 3-argument version of std::equal.
Alternatively, we could move the implementation of the C++14
std::equal overloads to __equal and make that available for C++11.
I'll try that.
