Refactor static_buffer:

* Improve tests and coverage
* Add static_buffer_base::clear
* Use BOOST_BEAST_DECL

include/boost/beast/core/detail/buffers_pair.hpp

@@ -78,6 +78,7 @@ public:
     {
         b_[0] = *other.begin();
         b_[1] = *(other.begin() + 1);
+        return *this;
     }
 
     buffers_pair(value_type b0, value_type b1)

include/boost/beast/core/flat_static_buffer.hpp

@@ -76,7 +76,18 @@ public:
         reset(p, n);
     }
 
-    /// Change the number of readable and writable bytes to zero.
+    /** Clear the readable and writable bytes to zero.
+
+        This function causes the readable and writable bytes
+        to become empty. The capacity is not changed.
+
+        Buffer sequences previously obtained using @ref data or
+        @ref prepare become invalid.
+
+        @par Exception Safety
+
+        No-throw guarantee.
+    */
     BOOST_BEAST_DECL
     void
     clear() noexcept;

include/boost/beast/core/impl/static_buffer.hpp

@@ -29,6 +29,15 @@ static_buffer_base(
 {
 }
 
+void
+static_buffer_base::
+clear() noexcept
+{
+    in_off_ = 0;
+    in_size_ = 0;
+    out_size_ = 0;
+}
+
 auto
 static_buffer_base::
 data() const noexcept ->
@@ -73,7 +82,7 @@ prepare(std::size_t n) ->
     using net::mutable_buffer;
     if(n > capacity_ - in_size_)
         BOOST_THROW_EXCEPTION(std::length_error{
-            "buffer overflow"});
+            "static_buffer overflow"});
     out_size_ = n;
     auto const out_off =
         (in_off_ + in_size_) % capacity_;
@@ -117,17 +126,6 @@ consume(std::size_t n) noexcept
     }
 }
 
-void
-static_buffer_base::
-reset(void* p, std::size_t n) noexcept
-{
-    begin_ = static_cast<char*>(p);
-    capacity_ = n;
-    in_off_ = 0;
-    in_size_ = 0;
-    out_size_ = 0;
-}
-
 //------------------------------------------------------------------------------
 
 template<std::size_t N>

include/boost/beast/core/static_buffer.hpp

@@ -73,9 +73,25 @@ public:
 
         @param size The number of valid bytes pointed to by `p`.
     */
-    inline
+    BOOST_BEAST_DECL
     static_buffer_base(void* p, std::size_t size) noexcept;
 
+    /** Clear the readable and writable bytes to zero.
+
+        This function causes the readable and writable bytes
+        to become empty. The capacity is not changed.
+
+        Buffer sequences previously obtained using @ref data or
+        @ref prepare become invalid.
+
+        @par Exception Safety
+
+        No-throw guarantee.
+    */
+    BOOST_BEAST_DECL
+    void
+    clear() noexcept;
+
     //--------------------------------------------------------------------------
 
 #if BOOST_BEAST_DOXYGEN
@@ -115,7 +131,7 @@ public:
     }
 
     /// Returns a constant buffer sequence representing the readable bytes
-    inline
+    BOOST_BEAST_DECL
     const_buffers_type
     data() const noexcept;
     
@@ -127,7 +143,7 @@ public:
     }
 
     /// Returns a mutable buffer sequence representing the readable bytes
-    inline
+    BOOST_BEAST_DECL
     mutable_data_type
     data() noexcept;
 
@@ -149,7 +165,7 @@ public:
 
         Strong guarantee.
     */
-    inline
+    BOOST_BEAST_DECL
     mutable_buffers_type
     prepare(std::size_t n);
 
@@ -171,7 +187,7 @@ public:
 
         No-throw guarantee.
     */
-    inline
+    BOOST_BEAST_DECL
     void
     commit(std::size_t n) noexcept;
 
@@ -190,37 +206,9 @@ public:
 
         No-throw guarantee.
     */
-    inline
+    BOOST_BEAST_DECL
     void
     consume(std::size_t n) noexcept;
-
-protected:
-    /** Constructor
-
-        The buffer will be in an undefined state. It is necessary
-        for the derived class to call @ref reset in order to
-        initialize the object.
-    */
-    static_buffer_base() = default;
-
-    /** Reset the pointed-to buffer.
-
-        This function resets the internal state to the buffer provided.
-        All input and output sequences are invalidated. This function
-        allows the derived class to construct its members before
-        initializing the static buffer.
-
-        @param p A pointer to valid storage of at least `n` bytes.
-
-        @param size The number of valid bytes pointed to by `p`.
-
-        @par Exception Safety
-
-        No-throw guarantee.
-    */
-    inline
-    void
-    reset(void* p, std::size_t size) noexcept;
 };
 
 //------------------------------------------------------------------------------
@@ -261,15 +249,15 @@ class static_buffer : public static_buffer_base
     char buf_[N];
 
 public:
-    /// Constructor
-    static_buffer(static_buffer const&) noexcept;
-
     /// Constructor
     static_buffer() noexcept
         : static_buffer_base(buf_, N)
     {
     }
 
+    /// Constructor
+    static_buffer(static_buffer const&) noexcept;
+
     /// Assignment
     static_buffer& operator=(static_buffer const&) noexcept;