Return std::size_t from Body::writer::put (API Change)

`put` returns the number of bytes actually transferred
from the input buffers.

Actions Required:

* Return the number of bytes actually transferred from the
  input buffers in user defined `Body::writer::put` functions.

test/benchmarks/parser.cpp

@@ -199,11 +199,11 @@ public:
             ec.assign(0, ec.category());
         }
 
-        void
-        on_data(string_view,
-            error_code& ec)
+        std::size_t
+        on_data(string_view s, error_code& ec)
         {
             ec.assign(0, ec.category());
+            return s.size();
         }
 
         void

test/core/CMakeLists.txt

@@ -1,6 +1,6 @@
 # Part of Beast
 
-GroupSources(examples examples)
+GroupSources(example example)
 GroupSources(extras/beast extras)
 GroupSources(include/beast beast)
 

test/exemplars.cpp

@@ -125,9 +125,11 @@ struct BodyWriter
         @param buffers The constant buffer sequence to store.
 
         @param ec Set to the error, if any occurred.
+
+        @return The number of bytes transferred from the input buffers.
     */
     template<class ConstBufferSequence>
-    void
+    std::size_t
     put(ConstBufferSequence const& buffers, error_code& ec)
     {
         // The specification requires this to indicate "no error"

test/http/doc_examples.cpp

@@ -49,13 +49,13 @@ BOOST_STATIC_ASSERT(::detail::is_mutable_container<string_view>::value == false)
 BOOST_STATIC_ASSERT(::detail::is_mutable_container<std::vector<char>>::value == true);
 BOOST_STATIC_ASSERT(::detail::is_mutable_container<std::list<char>>::value == false);
 
-class doc_http_samples_test
+class doc_examples_test
     : public beast::unit_test::suite
     , public beast::test::enable_yield_to
 {
 public:
     // two threads, for some examples using a pipe
-    doc_http_samples_test()
+    doc_examples_test()
         : enable_yield_to(2)
     {
     }
@@ -386,6 +386,27 @@ public:
 
     //--------------------------------------------------------------------------
 
+    void
+    doIncrementalRead()
+    {
+        test::pipe c{ios_};
+        std::string s(2048, '*');
+        ostream(c.server.buffer) <<
+            "HTTP/1.1 200 OK\r\n"
+            "Content-Length: 2048\r\n"
+            "Server: test\r\n"
+            "\r\n" <<
+            s;
+        error_code ec;
+        flat_buffer b;
+        std::stringstream ss;
+        read_and_print_body<false>(ss, c.server, b, ec);
+        if(BEAST_EXPECTS(! ec, ec.message()))
+            BEAST_EXPECT(ss.str() == s);
+    }
+
+    //--------------------------------------------------------------------------
+
     void
     run()
     {
@@ -399,10 +420,11 @@ public:
         doDeferredBody();
         doFileBody();
         doConstAndMutableBody();
+        doIncrementalRead();
     }
 };
 
-BEAST_DEFINE_TESTSUITE(doc_http_samples,http,beast);
+BEAST_DEFINE_TESTSUITE(doc_examples,http,beast);
 
 } // http
 } // beast

test/http/test_parser.hpp

@@ -118,7 +118,7 @@ public:
             ec.assign(0, ec.category());
     }
 
-    void
+    std::size_t
     on_data(string_view s,
         error_code& ec)
     {
@@ -127,6 +127,7 @@ public:
             fc_->fail(ec);
         else
             ec.assign(0, ec.category());
+        return s.size();
     }
 
     void