Add null_resource

test/doc_allocators.cpp

@@ -0,0 +1,85 @@
+//
+// Copyright (c) 2019 Vinnie Falco (vinnie.falco@gmail.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)
+//
+// Official repository: https://github.com/cppalliance/json
+//
+
+#include <boost/json.hpp>
+
+#include "test_suite.hpp"
+
+BOOST_JSON_NS_BEGIN
+
+//[doc_allocators_1
+void do_rpc( string_view s )
+{
+    // The parser will use this storage for its temporary needs
+    unsigned char temp[ 4000 ];
+
+    // The null resource guarantees we will never dynamically allocate
+    null_resource mr1;
+
+    // Construct a strict parser using the temp buffer and no dynamic memory
+    parser p( &mr1, parse_options(), temp );
+
+    // Now we need a buffer to hold the actual JSON values
+    unsigned char buf[ 6000 ];
+
+    // The static resource is monotonic, using only a caller-provided buffer
+    static_resource mr2( buf );
+
+    // We need to catch any exceptions thrown by the two memory resources
+    try
+    {
+        // This error code indicates errors not related to memory exhaustion
+        error_code ec;
+
+        // Parse the entire string we received from the network client
+        p.write( s, ec );
+
+        // Inform the parser that the complete input has been provided
+        if(! ec )
+            p.finish( ec );
+
+        if(! ec )
+        {
+            // Retrieve the value. It will use `buf` for storage.
+            value jv = p.release();
+
+            // At this point we can inspect jv and perform the requested RPC.
+        }
+        else
+        {
+            // An error occurred. A real program would report the error
+            // message back to the network client, indicating that the
+            // received JSON was invalid.
+        }
+
+    }
+    catch(std::bad_alloc const&)
+    {
+        // The memory needed to parse this JSON exceeded our statically
+        // define upper limits. A real program would send an error message
+        // back to the network client informing that their JSON is too large.
+    }
+}
+//]
+
+//----------------------------------------------------------
+
+class doc_allocators_test
+{
+public:
+    void
+    run()
+    {
+        BOOST_TEST_PASS();
+    }
+};
+
+TEST_SUITE(doc_allocators_test, "boost.json.doc_allocators");
+
+BOOST_JSON_NS_END