From: Petr Ovtchenkov <ptr@void-ptr.info>
To: libstdc++@gcc.gnu.org
Cc: gcc-patches@gcc.gnu.org
Subject: [PATCH 3/4] libstdc++: avoid character accumulation in istreambuf_iterator
Date: Wed, 15 Nov 2017 20:52:00 -0000 [thread overview]
Message-ID: <04e468027f8bad7858583db836073af1d7c524f1.1510778853.git.ptr@void-ptr.info> (raw)
In-Reply-To: <c04c340b983f7cd166683e50d8a872ea317be33d.1510778853.git.ptr@void-ptr.info>
Ask associated streambuf for character when needed instead of
accumulate it in istreambuf_iterator object.
Benefits from this:
- minus one class member in istreambuf_iterator
- trivial synchronization of states of istreambuf_iterator
and associated streambuf
---
libstdc++-v3/include/bits/streambuf_iterator.h | 34 ++++++++++++--------------
1 file changed, 15 insertions(+), 19 deletions(-)
diff --git a/libstdc++-v3/include/bits/streambuf_iterator.h b/libstdc++-v3/include/bits/streambuf_iterator.h
index 08fb13b..203da9d 100644
--- a/libstdc++-v3/include/bits/streambuf_iterator.h
+++ b/libstdc++-v3/include/bits/streambuf_iterator.h
@@ -95,19 +95,18 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
// NB: This implementation assumes the "end of stream" value
// is EOF, or -1.
mutable streambuf_type* _M_sbuf;
- mutable int_type _M_c;
public:
class proxy
{
friend class istreambuf_iterator;
private:
- proxy(int_type c, streambuf_type* sbuf_) :
+ proxy(int_type c, streambuf_type* sbuf_) :
_M_c(c),
_M_sbuf(sbuf_)
{ }
int_type _M_c;
- streambuf_type* _M_sbuf;
+ streambuf_type* _M_sbuf;
public:
char_type
@@ -118,7 +117,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
public:
/// Construct end of input stream iterator.
_GLIBCXX_CONSTEXPR istreambuf_iterator() _GLIBCXX_USE_NOEXCEPT
- : _M_sbuf(0), _M_c(traits_type::eof()) { }
+ : _M_sbuf(0) { }
#if __cplusplus >= 201103L
istreambuf_iterator(const istreambuf_iterator&) noexcept = default;
@@ -128,15 +127,15 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
/// Construct start of input stream iterator.
istreambuf_iterator(istream_type& __s) _GLIBCXX_USE_NOEXCEPT
- : _M_sbuf(__s.rdbuf()), _M_c(traits_type::eof()) { }
+ : _M_sbuf(__s.rdbuf()) { }
/// Construct start of streambuf iterator.
istreambuf_iterator(streambuf_type* __s) _GLIBCXX_USE_NOEXCEPT
- : _M_sbuf(__s), _M_c(traits_type::eof()) { }
+ : _M_sbuf(__s) { }
/// Construct start of istreambuf iterator.
istreambuf_iterator(const proxy& __p) _GLIBCXX_USE_NOEXCEPT
- : _M_sbuf(__p._M_sbuf), _M_c(traits_type::eof()) { }
+ : _M_sbuf(__p._M_sbuf) { }
/// Return the current character pointed to by iterator. This returns
/// streambuf.sgetc(). It cannot be assigned. NB: The result of
@@ -147,11 +146,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
#ifdef _GLIBCXX_DEBUG_PEDANTIC
// Dereferencing a past-the-end istreambuf_iterator is a
// libstdc++ extension
- __glibcxx_requires_cond(!_M_at_eof(),
+ int_type __tmp = _M_get();
+ __glibcxx_requires_cond(!traits_type::eq_int_type(__tmp,traits_type::eof()),
_M_message(__gnu_debug::__msg_deref_istreambuf)
._M_iterator(*this));
-#endif
+ return traits_type::to_char_type(__tmp);
+#else
return traits_type::to_char_type(_M_get());
+#endif
}
/// Advance the iterator. Calls streambuf.sbumpc().
@@ -172,7 +174,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
_M_message(__gnu_debug::__msg_inc_istreambuf)
._M_iterator(*this));
#endif
- _M_c = traits_type::eof();
}
return *this;
}
@@ -181,17 +182,15 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
proxy
operator++(int)
{
- _M_get();
- __glibcxx_requires_cond(_M_sbuf
- && !traits_type::eq_int_type(_M_c,traits_type::eof()),
+ int_type c = _M_get();
+ __glibcxx_requires_cond(!traits_type::eq_int_type(c,traits_type::eof()),
_M_message(__gnu_debug::__msg_inc_istreambuf)
._M_iterator(*this));
- proxy __old(_M_c, _M_sbuf);
+ proxy __old(c, _M_sbuf);
if (_M_sbuf)
{
_M_sbuf->sbumpc();
- _M_c = traits_type::eof();
}
return __old;
}
@@ -209,9 +208,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
_M_get() const
{
const int_type __eof = traits_type::eof();
- if (_M_sbuf && traits_type::eq_int_type(_M_c, __eof))
- _M_c = _M_sbuf->sgetc();
- return _M_c;
+ return _M_sbuf ? _M_sbuf->sgetc() : __eof;
}
bool
@@ -418,7 +415,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
else
__c = __sb->snextc();
}
- __first._M_c = __c;
}
return __first;
}
--
2.10.1
next prev parent reply other threads:[~2017-11-15 20:52 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-27 20:16 Make tests less istreambuf_iterator implementation dependent François Dumont
2017-09-28 12:12 ` Jonathan Wakely
2017-09-28 19:59 ` François Dumont
2017-09-28 21:56 ` Jonathan Wakely
2017-10-02 5:43 ` François Dumont
2017-10-03 14:20 ` Jonathan Wakely
2017-10-04 16:21 ` François Dumont
2017-10-04 23:23 ` Jonathan Wakely
2017-11-15 20:54 ` [PATCH 1/4] Revert "2017-10-04 Petr Ovtchenkov <ptr@void-ptr.info>" Petr Ovtchenkov
2017-11-15 20:58 ` [PATCH 2/4] libstdc++: istreambuf_iterator keep attached streambuf Petr Ovtchenkov
2017-11-15 20:52 ` Petr Ovtchenkov [this message]
2017-11-15 20:52 ` [PATCH 4/4] libstdc++: immutable _M_sbuf in istreambuf_iterator Petr Ovtchenkov
2017-11-15 22:30 ` [PATCH 3/4] libstdc++: avoid character accumulation " Paolo Carlini
2017-11-16 6:00 ` Petr Ovtchenkov
2017-11-16 9:51 ` Paolo Carlini
2017-11-16 11:34 ` Petr Ovtchenkov
2017-11-16 11:35 ` Paolo Carlini
2017-11-16 11:44 ` Petr Ovtchenkov
2017-11-16 11:57 ` Paolo Carlini
2017-11-16 11:03 ` [PATCH 1/4] Revert "2017-10-04 Petr Ovtchenkov <ptr@void-ptr.info>" Jonathan Wakely
2017-11-16 11:39 ` Petr Ovtchenkov
2017-11-16 11:41 ` Jonathan Wakely
2017-11-16 11:42 ` Jonathan Wakely
2017-11-16 12:03 ` Petr Ovtchenkov
-- strict thread matches above, loose matches on Subject: below --
2017-10-13 17:22 Make istreambuf_iterator::_M_sbuf immutable and add debug checks François Dumont
2017-10-23 19:24 ` François Dumont
2017-11-06 21:20 ` François Dumont
2017-11-16 6:07 ` Petr Ovtchenkov
2017-11-16 11:29 ` Jonathan Wakely
2017-11-16 11:57 ` Jonathan Wakely
2017-11-16 12:25 ` Petr Ovtchenkov
2017-11-16 17:48 ` François Dumont
2017-11-16 18:24 ` Petr Ovtchenkov
2017-11-16 23:00 ` François Dumont
2017-09-23 7:10 [PATCH] libstdc++: istreambuf_iterator keep attached streambuf Petr Ovtchenkov
2017-09-25 13:46 ` Jonathan Wakely
2017-09-28 10:34 ` Jonathan Wakely
2017-09-28 12:06 ` Petr Ovtchenkov
2017-09-28 12:38 ` Jonathan Wakely
2017-10-03 20:39 ` Petr Ovtchenkov
2017-10-04 5:04 ` [PATCH v2] " Petr Ovtchenkov
2017-10-06 16:01 ` [PATCH] libstdc++: istreambuf_iterator proxy (was: keep attached streambuf) François Dumont
2017-10-06 18:03 ` Petr Ovtchenkov
2017-10-08 15:45 ` [PATCH] libstdc++: istreambuf_iterator proxy François Dumont
2017-10-09 19:35 ` Petr Ovtchenkov
2017-10-10 5:52 ` Petr Ovtchenkov
2017-10-10 14:22 ` [PATCH] libstdc++: istreambuf_iterator proxy (was: keep attached streambuf) Jonathan Wakely
2017-08-24 11:58 [PATCH] streambuf_iterator: avoid debug-dependent behaviour Petr Ovtchenkov
2017-09-01 9:10 ` Jonathan Wakely
2017-09-07 21:02 ` François Dumont
2017-09-08 5:47 ` Petr Ovtchenkov
2017-09-09 20:17 ` François Dumont
2017-09-21 5:46 ` François Dumont
2017-09-28 10:50 ` Jonathan Wakely
2017-09-28 10:58 ` Jonathan Wakely
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