[Bug libstdc++/64239] New: regex_iterator::operator= should copy match_results::position

[Bug libstdc++/64239] New: regex_iterator::operator= should copy match_results::position

[kariya_mitsuru at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64239

            Bug ID: 64239
           Summary: regex_iterator::operator= should copy
                    match_results::position
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: kariya_mitsuru at hotmail dot com

Created attachment 34231
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=34231&action=edit
g++ -v

Please see the following sample.

========================================== sample code
==========================================
#include <iostream>
#include <regex>
#include <string>

int main()
{
    std::regex re("\\w+");
    std::string s("-a-b-c-");

    for (auto it1 = std::sregex_iterator(s.begin(), s.end(), re), end =
std::sregex_iterator(); it1 != end; ++it1) {
        auto it2 = it1;
        std::cout << "position() = " << it1->position() << ", length() = " <<
it1->length() << ", str() = '" << it1->str() << "'\n"
                     "position() = " << it2->position() << ", length() = " <<
it2->length() << ", str() = '" << it2->str() << "'\n\n";
    }
}
=================================================================================================

============================= output =============================
position() = 1, length() = 1, str() = 'a'
position() = 1, length() = 1, str() = 'a'

position() = 3, length() = 1, str() = 'b'
position() = 1, length() = 1, str() = 'b'

position() = 5, length() = 1, str() = 'c'
position() = 1, length() = 1, str() = 'c'

==================================================================

cf. http://melpon.org/wandbox/permlink/IiULKqL2GwCwwvHc

Though the C++11 standard says nothing about regex_iterator::operator=, I think
that it2->position() should be equal to it1->position().

So, the output should be 

============================= output =============================
position() = 1, length() = 1, str() = 'a'
position() = 1, length() = 1, str() = 'a'

position() = 3, length() = 1, str() = 'b'
position() = 3, length() = 1, str() = 'b'

position() = 5, length() = 1, str() = 'c'
position() = 5, length() = 1, str() = 'c'

==================================================================

[Bug libstdc++/64239] regex_iterator::operator= should copy match_results::position

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64239

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2014-12-10
                 CC|                            |timshen at gcc dot gnu.org
     Ever confirmed|0                           |1

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
The problem is that match_results::_M_in_iterator is always false after
copy/moving a match_results object. I don't even understand what that member is
for or what's name means. Tim?

[Bug libstdc++/64239] regex_iterator::operator= should copy match_results::position

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64239

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
match_results::swap() fails to handle _M_in_iterator as well.

[Bug libstdc++/64239] regex_iterator::operator= should copy match_results::position

[kariya_mitsuru at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64239

--- Comment #3 from Mitsuru Kariya <kariya_mitsuru at hotmail dot com> ---
Sorry, I confused the copy ctor with the copy assignment operator.
But it seems that both are same results.

operator= version : http://melpon.org/wandbox/permlink/ZHzYukOyuluuzpwu

I didn't notice, but both the copy ctor and the copy assignment operator of
match_results are also same results as Mr. Wakely pointed out above.

copy ctor version : http://melpon.org/wandbox/permlink/Z4Z0kr5yTcB0iyEk
operator= version : http://melpon.org/wandbox/permlink/tHBSWP3hJpinggzw

[Bug libstdc++/64239] regex_iterator::operator= should copy match_results::position

[timshen at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64239

--- Comment #4 from Tim Shen <timshen at gcc dot gnu.org> ---
Sorry, I was once thinking that we should always use
match_results::prefix().first as the "start position of a match". It's true for
regex_match and regex_search, but not true for regex_iterator. That's why
match_results::_M_begin exists.

_M_in_iterator was just a dumb mistake that I can't even understand now,
probably for my misunderstanding on the "start position of a match". Sorry :(

Also, obviously I forgot to update ctor/assign/swap after adding
match_results::_M_match.

I'm testing the patch that fixes this. Later I'll post it in the mailing list.
It removes _M_in_iterator. To backport it to 4.9 branch, _M_in_iterator needs
to remain.

Thanks for reporting and investigating!

[Bug libstdc++/64239] regex_iterator::operator= should copy match_results::position

[timshen at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64239

--- Comment #5 from Tim Shen <timshen at gcc dot gnu.org> ---
Author: timshen
Date: Sat Dec 13 22:19:18 2014
New Revision: 218710

URL: https://gcc.gnu.org/viewcvs?rev=218710&root=gcc&view=rev
Log:
    PR libstdc++/64239
    * include/bits/regex.h (match_results<>::match_results,
    match_results<>::operator=, match_results<>::position,
    match_results<>::swap): Remove match_results::_M_in_iterator.
    Fix ctor/assign/swap.
    * include/bits/regex.tcc: (__regex_algo_impl<>,
    regex_iterator<>::operator++): Set match_results::_M_begin as
    "start position".
    * testsuite/28_regex/iterators/regex_iterator/char/
    string_position_01.cc: Test cases.


Modified:
    trunk/libstdc++-v3/ChangeLog
    trunk/libstdc++-v3/include/bits/regex.h
    trunk/libstdc++-v3/include/bits/regex.tcc
   
trunk/libstdc++-v3/testsuite/28_regex/iterators/regex_iterator/char/string_position_01.cc

[Bug libstdc++/64239] regex_iterator::operator= should copy match_results::position

[timshen at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64239

--- Comment #6 from Tim Shen <timshen at gcc dot gnu.org> ---
Author: timshen
Date: Sat Dec 13 23:10:39 2014
New Revision: 218711

URL: https://gcc.gnu.org/viewcvs?rev=218711&root=gcc&view=rev
Log:
    PR libstdc++/64239
    * include/bits/regex.h (match_results<>::match_results,
    match_results<>::operator=, match_results<>::position,
    match_results<>::swap): Fix ctor/assign/swap.
    * include/bits/regex.tcc: (__regex_algo_impl<>,
    regex_iterator<>::operator++): Set match_results::_M_begin as
    "start position".
    * testsuite/28_regex/iterators/regex_iterator/char/
    string_position_01.cc: Test cases.

Modified:
    branches/gcc-4_9-branch/libstdc++-v3/ChangeLog
    branches/gcc-4_9-branch/libstdc++-v3/include/bits/regex.h
    branches/gcc-4_9-branch/libstdc++-v3/include/bits/regex.tcc
   
branches/gcc-4_9-branch/libstdc++-v3/testsuite/28_regex/iterators/regex_iterator/char/string_position_01.cc

[Bug libstdc++/64239] regex_iterator::operator= should copy match_results::position

[kariya_mitsuru at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64239

--- Comment #7 from Mitsuru Kariya <kariya_mitsuru at hotmail dot com> ---
When I used the match_results::swap on r218710, I got a compilation error.

========================================== sample code
==========================================
#include <regex>

int main()
{
  std::cmatch mm1, mm2;

  mm1.swap(mm2);
}
=================================================================================================

========================================== g++ output
===========================================
In file included from /usr/local/gcc-218710/include/c++/5.0.0/regex:59:0,
                 from swap.cpp:1:
/usr/local/gcc-218710/include/c++/5.0.0/bits/regex.h: In instantiation of 'void
std::match_results< <template-parameter-1-1>, <template-parameter-1-2>
>::swap(std::match_results< <template-parameter-1-1>, <template-parameter-1-2>
>&) [with _Bi_iter = const char*; _Alloc = std::allocator<std::sub_match<const
char*> >]':
swap.cpp:7:15:   required from here
/usr/local/gcc-218710/include/c++/5.0.0/bits/regex.h:1864:6: error: no matching
function for call to 'std::match_results<const char*>::swap(const char*&, const
char*&)'
  swap(_M_begin, __that._M_begin);
      ^
/usr/local/gcc-218710/include/c++/5.0.0/bits/regex.h:1861:7: note: candidate:
void std::match_results< <template-parameter-1-1>, <template-parameter-1-2>
>::swap(std::match_results< <template-parameter-1-1>, <template-parameter-1-2>
>&) [with _Bi_iter = const char*; _Alloc = std::allocator<std::sub_match<const
char*> >]
       swap(match_results& __that)
       ^
/usr/local/gcc-218710/include/c++/5.0.0/bits/regex.h:1861:7: note:   candidate
expects 1 argument, 2 provided
=================================================================================================

============================================ g++ -v
=============================================
Using built-in specs.
COLLECT_GCC=/usr/local/gcc-218710/bin/g++
COLLECT_LTO_WRAPPER=/usr/local/gcc-218710/libexec/gcc/x86_64-unknown-linux-gnu/5.0.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: ../gcc.218710/configure --prefix=/usr/local/gcc-218710
--enable-checking=yes --disable-nls --enable-languages=c,c++,lto
Thread model: posix
gcc version 5.0.0 20141213 (experimental) (GCC)
=================================================================================================

Note that the sample code above was compiled successfully on r218555.

I think that the match_results::swap needs "use std::swap;" for swapping
_M_begin.

[Bug libstdc++/64239] regex_iterator::operator= should copy match_results::position

[timshen at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64239

--- Comment #8 from Tim Shen <timshen at gcc dot gnu.org> ---
Author: timshen
Date: Fri Jan  9 03:58:59 2015
New Revision: 219373

URL: https://gcc.gnu.org/viewcvs?rev=219373&root=gcc&view=rev
Log:
    PR libstdc++/64239
    * include/bits/regex.h (match_results<>::swap): Use std::swap
    instead of swap.
    * include/bits/regex_compiler.tcc (_Compiler<>::_M_quantifier):
    Likewise.
    * testsuite/28_regex/match_results/swap.cc: New testcase.

Added:
    trunk/libstdc++-v3/testsuite/28_regex/match_results/swap.cc
Modified:
    trunk/libstdc++-v3/ChangeLog
    trunk/libstdc++-v3/include/bits/regex.h
    trunk/libstdc++-v3/include/bits/regex_compiler.tcc

[Bug libstdc++/64239] regex_iterator::operator= should copy match_results::position

[timshen at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64239

--- Comment #9 from Tim Shen <timshen at gcc dot gnu.org> ---
Author: timshen
Date: Fri Jan  9 05:52:18 2015
New Revision: 219374

URL: https://gcc.gnu.org/viewcvs?rev=219374&root=gcc&view=rev
Log:
    PR libstdc++/64239
    Backported form mainline
    2015-01-09  Tim Shen  <timshen@google.com>

    * include/bits/regex.h (match_results<>::swap): Use std::swap
    instead of swap.
    * include/bits/regex_compiler.tcc (_Compiler<>::_M_quantifier):
    Likewise.
    * testsuite/28_regex/match_results/swap.cc: New testcase.

Added:
   
branches/gcc-4_9-branch/libstdc++-v3/testsuite/28_regex/match_results/swap.cc
Modified:
    branches/gcc-4_9-branch/libstdc++-v3/ChangeLog
    branches/gcc-4_9-branch/libstdc++-v3/include/bits/regex.h
    branches/gcc-4_9-branch/libstdc++-v3/include/bits/regex_compiler.tcc

[Bug libstdc++/64239] regex_iterator::operator= should copy match_results::position

[timshen at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64239

Tim Shen <timshen at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED

--- Comment #10 from Tim Shen <timshen at gcc dot gnu.org> ---
Resolved.

[Bug libstdc++/64239] regex_iterator::operator= should copy match_results::position

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64239

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |4.9.3