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Re: Extend usage of C++11 direct init in __debug::vector
- From: Jonathan Wakely <jwakely at redhat dot com>
- To: François Dumont <frs dot dumont at gmail dot com>
- Cc: "libstdc++ at gcc dot gnu dot org" <libstdc++ at gcc dot gnu dot org>, gcc-patches <gcc-patches at gcc dot gnu dot org>
- Date: Mon, 15 Oct 2018 11:10:54 +0100
- Subject: Re: Extend usage of C++11 direct init in __debug::vector
- References: <b493e7b9-5755-7d3d-52da-ca47ae5fbfec@gmail.com>
On 15/10/18 07:23 +0200, François Dumont wrote:
This patch extend usage of C++11 direct initialization in
__debug::vector and makes some calls to operator - more consistent.
Note that I also rewrote following expression in erase method:
- return begin() + (__first.base() - cbegin().base());
+ return { _Base::begin() + (__first.base() - _Base::cbegin()), this };
The latter version was building 2 safe iterators and incrementing 1
with the additional debug check inherent to such an operation whereas
the new version just build 1 safe iterator with directly the expected
offset.
Makes sense.
2018-10-15 François Dumont <fdumont@gcc.gnu.org>
* include/debug/vector (vector<>::cbegin()): Use C++11 direct
initialization.
(vector<>::cend()): Likewise.
(vector<>::emplace(const_iterator, _Args&&...)): Likewise and use
consistent iterator comparison.
(vector<>::insert(const_iterator, size_type, const _Tp&)): Likewise.
(vector<>::insert(const_iterator, _InputIterator, _InputIterator)):
Likewise.
(vector<>::erase(const_iterator)): Likewise.
(vector<>::erase(const_iterator, const_iterator)): Likewise.
Tested under Linux x86_64 Debug mode and committed.
François
@@ -542,7 +542,8 @@ namespace __debug
{
__glibcxx_check_insert(__position);
bool __realloc = this->_M_requires_reallocation(this->size() + 1);
- difference_type __offset = __position.base() - _Base::begin();
+ difference_type __offset
+ = __position.base() - __position._M_get_sequence()->_M_base().begin();
What's the reason for this change?
Doesn't __glibcxx_check_insert(__position) already ensure that
__position is attached to *this, and so _Base::begin() returns the
same thing as __position._M_get_sequence()->_M_base().begin() ?
If they're equivalent, the original code seems more readable.