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Shrink buffer_prefix_view

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Vinnie Falco
2017-07-12 09:02:55 -07:00
parent 9ffb8e0f0f
commit 9bfb5374f1
4 changed files with 87 additions and 130 deletions
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1
CHANGELOG.md
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@ -2,6 +2,7 @@ Version 80:
* Javadoc tidying
* Add basic_dynamic_body.hpp
* Shrink buffer_prefix_view
--------------------------------------------------------------------------------

61
include/beast/core/buffer_prefix.hpp
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@ -31,25 +31,24 @@ class buffer_prefix_view
using buffers_type = typename
std::decay<BufferSequence>::type;
using iter_type = typename buffers_type::const_iterator;
using iter_type =
typename buffers_type::const_iterator;
BufferSequence bs_;
iter_type back_;
iter_type end_;
std::size_t size_;
iter_type end_;
template<class Deduced>
buffer_prefix_view(Deduced&& other,
std::size_t nback, std::size_t nend)
buffer_prefix_view(
Deduced&& other, std::size_t dist)
: bs_(std::forward<Deduced>(other).bs_)
, back_(std::next(bs_.begin(), nback))
, end_(std::next(bs_.begin(), nend))
, size_(other.size_)
, end_(std::next(bs_.begin(), dist))
{
}
void
setup(std::size_t n);
setup(std::size_t size);
public:
/// The type for each element in the list of buffers.
@ -92,11 +91,13 @@ public:
the sequence will be made, but ownership of the underlying
memory is not transferred.
*/
buffer_prefix_view(std::size_t n, BufferSequence const& buffers);
buffer_prefix_view(
std::size_t size,
BufferSequence const& buffers);
/** Construct a buffer sequence prefix in-place.
@param n The maximum number of bytes in the prefix.
@param size The maximum number of bytes in the prefix.
If this is larger than the size of passed, buffers,
the resulting sequence will represent the entire
input sequence.
@ -104,8 +105,10 @@ public:
@param args Arguments forwarded to the contained buffers constructor.
*/
template<class... Args>
buffer_prefix_view(std::size_t n,
boost::in_place_init_t, Args&&... args);
buffer_prefix_view(
std::size_t size,
boost::in_place_init_t,
Args&&... args);
/// Get a bidirectional iterator to the first element.
const_iterator
@ -122,23 +125,23 @@ public:
passed buffer, but with a size that is equal to or less
than the size of the original buffer.
@param n The size of the returned buffer.
@param size The size of the returned buffer.
@param buffer The buffer to shorten. The underlying
memory is not modified.
@return A new buffer that points to the first `n` bytes
of the original buffer.
@return A new buffer that points to the first `size`
bytes of the original buffer.
*/
inline
boost::asio::const_buffer
buffer_prefix(std::size_t n,
buffer_prefix(std::size_t size,
boost::asio::const_buffer buffer)
{
using boost::asio::buffer_cast;
using boost::asio::buffer_size;
return { buffer_cast<void const*>(buffer),
(std::min)(n, buffer_size(buffer)) };
(std::min)(size, buffer_size(buffer)) };
}
/** Returns a prefix of a mutable buffer.
@ -147,23 +150,23 @@ buffer_prefix(std::size_t n,
passed buffer, but with a size that is equal to or less
than the size of the original buffer.
@param n The size of the returned buffer.
@param size The size of the returned buffer.
@param buffer The buffer to shorten. The underlying
memory is not modified.
@return A new buffer that points to the first `n` bytes
@return A new buffer that points to the first `size` bytes
of the original buffer.
*/
inline
boost::asio::mutable_buffer
buffer_prefix(std::size_t n,
buffer_prefix(std::size_t size,
boost::asio::mutable_buffer buffer)
{
using boost::asio::buffer_cast;
using boost::asio::buffer_size;
return { buffer_cast<void*>(buffer),
(std::min)(n, buffer_size(buffer)) };
return {buffer_cast<void*>(buffer),
(std::min)(size, buffer_size(buffer))};
}
/** Returns a prefix of a buffer sequence.
@ -172,7 +175,7 @@ buffer_prefix(std::size_t n,
presents a shorter subset of the original list of buffers starting
with the first byte of the original sequence.
@param n The maximum number of bytes in the wrapped
@param size The maximum number of bytes in the wrapped
sequence. If this is larger than the size of passed,
buffers, the resulting sequence will represent the
entire input sequence.
@ -188,17 +191,19 @@ buffer_prefix_view<BufferSequence>
#else
inline
typename std::enable_if<
! std::is_same<BufferSequence, boost::asio::const_buffer>::value &&
! std::is_same<BufferSequence, boost::asio::mutable_buffer>::value,
buffer_prefix_view<BufferSequence>>::type
! std::is_same<BufferSequence,
boost::asio::const_buffer>::value &&
! std::is_same<BufferSequence,
boost::asio::mutable_buffer>::value,
buffer_prefix_view<BufferSequence>>::type
#endif
buffer_prefix(std::size_t n, BufferSequence const& buffers)
buffer_prefix(std::size_t size, BufferSequence const& buffers)
{
static_assert(
is_const_buffer_sequence<BufferSequence>::value ||
is_mutable_buffer_sequence<BufferSequence>::value,
"BufferSequence requirements not met");
return buffer_prefix_view<BufferSequence>(n, buffers);
return buffer_prefix_view<BufferSequence>(size, buffers);
}
} // beast

146
include/beast/core/impl/buffer_prefix.ipp
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@ -21,24 +21,24 @@ namespace detail {
inline
boost::asio::const_buffer
buffer_prefix(std::size_t n,
buffer_prefix(std::size_t size,
boost::asio::const_buffer buffer)
{
using boost::asio::buffer_cast;
using boost::asio::buffer_size;
return { buffer_cast<void const*>(buffer),
(std::min)(n, buffer_size(buffer)) };
return {buffer_cast<void const*>(buffer),
(std::min)(size, buffer_size(buffer))};
}
inline
boost::asio::mutable_buffer
buffer_prefix(std::size_t n,
buffer_prefix(std::size_t size,
boost::asio::mutable_buffer buffer)
{
using boost::asio::buffer_cast;
using boost::asio::buffer_size;
return { buffer_cast<void*>(buffer),
(std::min)(n, buffer_size(buffer)) };
return {buffer_cast<void*>(buffer),
(std::min)(size, buffer_size(buffer))};
}
} // detail
@ -49,6 +49,7 @@ class buffer_prefix_view<BufferSequence>::const_iterator
friend class buffer_prefix_view<BufferSequence>;
buffer_prefix_view const* b_ = nullptr;
std::size_t remain_;
iter_type it_;
public:
@ -65,10 +66,10 @@ public:
std::bidirectional_iterator_tag;
const_iterator() = default;
const_iterator(const_iterator&& other);
const_iterator(const_iterator const& other);
const_iterator& operator=(const_iterator&& other);
const_iterator& operator=(const_iterator const& other);
const_iterator(const_iterator&& other) = default;
const_iterator(const_iterator const& other) = default;
const_iterator& operator=(const_iterator&& other) = default;
const_iterator& operator=(const_iterator const& other) = default;
bool
operator==(const_iterator const& other) const
@ -85,9 +86,7 @@ public:
reference
operator*() const
{
if(it_ == b_->back_)
return detail::buffer_prefix(b_->size_, *it_);
return *it_;
return detail::buffer_prefix(remain_, *it_);
}
pointer
@ -96,7 +95,7 @@ public:
const_iterator&
operator++()
{
++it_;
remain_ -= boost::asio::buffer_size(*it_++);
return *this;
}
@ -104,14 +103,14 @@ public:
operator++(int)
{
auto temp = *this;
++(*this);
remain_ -= boost::asio::buffer_size(*it_++);
return temp;
}
const_iterator&
operator--()
{
--it_;
remain_ += boost::asio::buffer_size(*--it_);
return *this;
}
@ -119,15 +118,24 @@ public:
operator--(int)
{
auto temp = *this;
--(*this);
remain_ += boost::asio::buffer_size(*--it_);
return temp;
}
private:
const_iterator(buffer_prefix_view const& b,
bool at_end)
std::true_type)
: b_(&b)
, it_(at_end ? b.end_ : b.bs_.begin())
, remain_(0)
, it_(b_->end_)
{
}
const_iterator(buffer_prefix_view const& b,
std::false_type)
: b_(&b)
, remain_(b_->size_)
, it_(b_->bs_.begin())
{
}
};
@ -135,74 +143,31 @@ private:
template<class BufferSequence>
void
buffer_prefix_view<BufferSequence>::
setup(std::size_t n)
setup(std::size_t size)
{
for(end_ = bs_.begin(); end_ != bs_.end(); ++end_)
size_ = 0;
end_ = bs_.begin();
auto const last = bs_.end();
while(end_ != last)
{
auto const len =
boost::asio::buffer_size(*end_);
if(n <= len)
boost::asio::buffer_size(*end_++);
if(len >= size)
{
size_ = n;
back_ = end_++;
return;
size_ += size;
break;
}
n -= len;
size -= len;
size_ += len;
}
size_ = 0;
back_ = end_;
}
template<class BufferSequence>
buffer_prefix_view<BufferSequence>::
const_iterator::
const_iterator(const_iterator&& other)
: b_(other.b_)
, it_(std::move(other.it_))
{
}
template<class BufferSequence>
buffer_prefix_view<BufferSequence>::
const_iterator::
const_iterator(const_iterator const& other)
: b_(other.b_)
, it_(other.it_)
{
}
template<class BufferSequence>
auto
buffer_prefix_view<BufferSequence>::
const_iterator::
operator=(const_iterator&& other) ->
const_iterator&
{
b_ = other.b_;
it_ = std::move(other.it_);
return *this;
}
template<class BufferSequence>
auto
buffer_prefix_view<BufferSequence>::
const_iterator::
operator=(const_iterator const& other) ->
const_iterator&
{
if(&other == this)
return *this;
b_ = other.b_;
it_ = other.it_;
return *this;
}
template<class BufferSequence>
buffer_prefix_view<BufferSequence>::
buffer_prefix_view(buffer_prefix_view&& other)
: buffer_prefix_view(std::move(other),
std::distance<iter_type>(other.bs_.begin(), other.back_),
std::distance<iter_type>(other.bs_.begin(), other.end_))
std::distance<iter_type>(
other.bs_.begin(), other.end_))
{
}
@ -210,8 +175,8 @@ template<class BufferSequence>
buffer_prefix_view<BufferSequence>::
buffer_prefix_view(buffer_prefix_view const& other)
: buffer_prefix_view(other,
std::distance<iter_type>(other.bs_.begin(), other.back_),
std::distance<iter_type>(other.bs_.begin(), other.end_))
std::distance<iter_type>(
other.bs_.begin(), other.end_))
{
}
@ -221,14 +186,11 @@ buffer_prefix_view<BufferSequence>::
operator=(buffer_prefix_view&& other) ->
buffer_prefix_view&
{
auto const nback = std::distance<iter_type>(
other.bs_.begin(), other.back_);
auto const nend = std::distance<iter_type>(
auto const dist = std::distance<iter_type>(
other.bs_.begin(), other.end_);
bs_ = std::move(other.bs_);
back_ = std::next(bs_.begin(), nback);
end_ = std::next(bs_.begin(), nend);
size_ = other.size_;
end_ = std::next(bs_.begin(), dist);
return *this;
}
@ -238,33 +200,31 @@ buffer_prefix_view<BufferSequence>::
operator=(buffer_prefix_view const& other) ->
buffer_prefix_view&
{
auto const nback = std::distance<iter_type>(
other.bs_.begin(), other.back_);
auto const nend = std::distance<iter_type>(
auto const dist = std::distance<iter_type>(
other.bs_.begin(), other.end_);
bs_ = other.bs_;
back_ = std::next(bs_.begin(), nback);
end_ = std::next(bs_.begin(), nend);
size_ = other.size_;
end_ = std::next(bs_.begin(), dist);
return *this;
}
template<class BufferSequence>
buffer_prefix_view<BufferSequence>::
buffer_prefix_view(std::size_t n, BufferSequence const& bs)
buffer_prefix_view(std::size_t size,
BufferSequence const& bs)
: bs_(bs)
{
setup(n);
setup(size);
}
template<class BufferSequence>
template<class... Args>
buffer_prefix_view<BufferSequence>::
buffer_prefix_view(std::size_t n,
buffer_prefix_view(std::size_t size,
boost::in_place_init_t, Args&&... args)
: bs_(std::forward<Args>(args)...)
{
setup(n);
setup(size);
}
template<class BufferSequence>
@ -273,7 +233,7 @@ auto
buffer_prefix_view<BufferSequence>::begin() const ->
const_iterator
{
return const_iterator{*this, false};
return const_iterator{*this, std::false_type{}};
}
template<class BufferSequence>
@ -282,7 +242,7 @@ auto
buffer_prefix_view<BufferSequence>::end() const ->
const_iterator
{
return const_iterator{*this, true};
return const_iterator{*this, std::true_type{}};
}
} // beast

9
test/core/buffer_prefix.cpp
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@ -172,15 +172,6 @@ public:
BEAST_EXPECT(bsize2(pb) == 2);
BEAST_EXPECT(bsize3(pb) == 2);
BEAST_EXPECT(bsize4(pb) == 2);
std::size_t n = 0;
for(auto it = pb.end(); it != pb.begin(); --it)
{
decltype(pb)::const_iterator it2(std::move(it));
BEAST_EXPECT(buffer_size(*it2) == 1);
it = std::move(it2);
++n;
}
BEAST_EXPECT(n == 2);
}
void run() override