Construct buffer_prefix_view in-place

CHANGELOG.md

@@ -1,6 +1,7 @@
 Version 75:
 
 * Use file_body for valid requests, string_body otherwise.
+* Construct buffer_prefix_view in-place
 
 --------------------------------------------------------------------------------
 

include/beast/core/buffer_prefix.hpp

@@ -10,6 +10,7 @@
 
 #include <beast/config.hpp>
 #include <beast/core/type_traits.hpp>
+#include <beast/core/detail/in_place_init.hpp>
 #include <boost/asio/buffer.hpp>
 #include <cstdint>
 #include <type_traits>
@@ -78,12 +79,12 @@ public:
     /// Copy assignment.
     buffer_prefix_view& operator=(buffer_prefix_view const&);
 
-    /** Construct a shortened buffer sequence.
+    /** Construct a buffer sequence prefix.
 
-        @param n 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.
+        @param n 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.
 
         @param buffers The buffer sequence to adapt. A copy of
         the sequence will be made, but ownership of the underlying
@@ -91,6 +92,19 @@ public:
     */
     buffer_prefix_view(std::size_t n, BufferSequence const& buffers);
 
+    /** Construct a buffer sequence prefix in-place.
+
+        @param n 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.
+
+        @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);
+
     /// Get a bidirectional iterator to the first element.
     const_iterator
     begin() const;

include/beast/core/detail/in_place_init.hpp

@@ -9,6 +9,7 @@
 #define BEAST_DETAIL_IN_PLACE_INIT_HPP
 
 #include <boost/version.hpp>
+#include <boost/optional/optional.hpp>
 
 // Provide boost::in_place_init_t and boost::in_place_init
 // for Boost versions earlier than 1.63.0.

include/beast/core/impl/buffer_prefix.ipp

@@ -157,7 +157,8 @@ setup(std::size_t n)
 }
 
 template<class BufferSequence>
-buffer_prefix_view<BufferSequence>::const_iterator::
+buffer_prefix_view<BufferSequence>::
+const_iterator::
 const_iterator(const_iterator&& other)
     : b_(other.b_)
     , it_(std::move(other.it_))
@@ -165,7 +166,8 @@ const_iterator(const_iterator&& other)
 }
 
 template<class BufferSequence>
-buffer_prefix_view<BufferSequence>::const_iterator::
+buffer_prefix_view<BufferSequence>::
+const_iterator::
 const_iterator(const_iterator const& other)
     : b_(other.b_)
     , it_(other.it_)
@@ -174,7 +176,8 @@ const_iterator(const_iterator const& other)
 
 template<class BufferSequence>
 auto
-buffer_prefix_view<BufferSequence>::const_iterator::
+buffer_prefix_view<BufferSequence>::
+const_iterator::
 operator=(const_iterator&& other) ->
     const_iterator&
 {
@@ -185,7 +188,8 @@ operator=(const_iterator&& other) ->
 
 template<class BufferSequence>
 auto
-buffer_prefix_view<BufferSequence>::const_iterator::
+buffer_prefix_view<BufferSequence>::
+const_iterator::
 operator=(const_iterator const& other) ->
     const_iterator&
 {
@@ -256,6 +260,16 @@ buffer_prefix_view(std::size_t n, BufferSequence const& bs)
     setup(n);
 }
 
+template<class BufferSequence>
+template<class... Args>
+buffer_prefix_view<BufferSequence>::
+buffer_prefix_view(std::size_t n,
+        boost::in_place_init_t, Args&&... args)
+    : bs_(std::forward<Args>(args)...)
+{
+    setup(n);
+}
+
 template<class BufferSequence>
 inline
 auto