Make buffer_prefix_view public

fix #408

include/beast/core/impl/buffer_prefix.ipp

@@ -0,0 +1,279 @@
+//
+// Copyright (c) 2013-2017 Vinnie Falco (vinnie dot falco at gmail dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef BEAST_IMPL_BUFFER_PREFIX_IPP
+#define BEAST_IMPL_BUFFER_PREFIX_IPP
+
+#include <algorithm>
+#include <cstdint>
+#include <iterator>
+#include <stdexcept>
+#include <type_traits>
+#include <utility>
+
+namespace beast {
+
+namespace detail {
+
+inline
+boost::asio::const_buffer
+buffer_prefix(std::size_t n,
+    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)) };
+}
+
+inline
+boost::asio::mutable_buffer
+buffer_prefix(std::size_t n,
+    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)) };
+}
+
+} // detail
+
+template<class BufferSequence>
+class buffer_prefix_view<BufferSequence>::const_iterator
+{
+    friend class buffer_prefix_view<BufferSequence>;
+
+    using iter_type =
+        typename BufferSequence::const_iterator;
+
+    buffer_prefix_view const* b_ = nullptr;
+    typename BufferSequence::const_iterator it_;
+
+public:
+    using value_type = typename std::conditional<
+        std::is_convertible<typename
+            std::iterator_traits<iter_type>::value_type,
+                boost::asio::mutable_buffer>::value,
+                    boost::asio::mutable_buffer,
+                        boost::asio::const_buffer>::type;
+    using pointer = value_type const*;
+    using reference = value_type;
+    using difference_type = std::ptrdiff_t;
+    using iterator_category =
+        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);
+
+    bool
+    operator==(const_iterator const& other) const
+    {
+        return b_ == other.b_ && it_ == other.it_;
+    }
+
+    bool
+    operator!=(const_iterator const& other) const
+    {
+        return !(*this == other);
+    }
+
+    reference
+    operator*() const
+    {
+        if(it_ == b_->back_)
+            return detail::buffer_prefix(b_->size_, *it_);
+        return *it_;
+    }
+
+    pointer
+    operator->() const = delete;
+
+    const_iterator&
+    operator++()
+    {
+        ++it_;
+        return *this;
+    }
+
+    const_iterator
+    operator++(int)
+    {
+        auto temp = *this;
+        ++(*this);
+        return temp;
+    }
+
+    const_iterator&
+    operator--()
+    {
+        --it_;
+        return *this;
+    }
+
+    const_iterator
+    operator--(int)
+    {
+        auto temp = *this;
+        --(*this);
+        return temp;
+    }
+
+private:
+    const_iterator(buffer_prefix_view const& b,
+            bool at_end)
+        : b_(&b)
+        , it_(at_end ? b.end_ : b.bs_.begin())
+    {
+    }
+};
+
+template<class BufferSequence>
+void
+buffer_prefix_view<BufferSequence>::
+setup(std::size_t n)
+{
+    for(end_ = bs_.begin(); end_ != bs_.end(); ++end_)
+    {
+        auto const len =
+            boost::asio::buffer_size(*end_);
+        if(n <= len)
+        {
+            size_ = n;
+            back_ = end_++;
+            return;
+        }
+        n -= 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_))
+{
+}
+
+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_))
+{
+}
+
+template<class BufferSequence>
+auto
+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>(
+        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_;
+    return *this;
+}
+
+template<class BufferSequence>
+auto
+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>(
+        other.bs_.begin(), other.end_);
+    bs_ = other.bs_;
+    back_ = std::next(bs_.begin(), nback);
+    end_ = std::next(bs_.begin(), nend);
+    size_ = other.size_;
+    return *this;
+}
+
+template<class BufferSequence>
+buffer_prefix_view<BufferSequence>::
+buffer_prefix_view(std::size_t n, BufferSequence const& bs)
+    : bs_(bs)
+{
+    setup(n);
+}
+
+template<class BufferSequence>
+inline
+auto
+buffer_prefix_view<BufferSequence>::begin() const ->
+    const_iterator
+{
+    return const_iterator{*this, false};
+}
+
+template<class BufferSequence>
+inline
+auto
+buffer_prefix_view<BufferSequence>::end() const ->
+    const_iterator
+{
+    return const_iterator{*this, true};
+}
+
+} // beast
+
+#endif