* Summary: new Frame type to replace AMQFrame. Instead of holding

	  a shared_ptr to a heap-allocated AMQBody subclass, it holds the
	  body in-line in a boost::variant of all the concrete AMQBody
	  subclasses. Actually there are nested variants, the compiler
	  does not cope well with a single variant of 130-some types.

	  Creating, encoding and decoding a local Frame doess 0 heap
	  allocation apart from that done by the concrete
	  AMQBody::encode/decode - e.g. method bodies with std::string
	  fields.  for method bodies

	  All variants contain type boost::blank. This guarantees 0 heap
	  alloocation by the variant and represents the "uninitialized"
	  state. variant.h provides NoBlankVisitor to help write visitors
	  for variants containing blank. 
	
	* src/qpid/framing/MethodHolder.h, .cpp: Holds a variant
	  containing a method body. 

	* src/qpid/framing/Frame.h, .cpp: New Frame holds body in a
	  variant rather than via heap allocation.

	* src/qpid/framing/variant.h: Utilities for using boost::variant.

	* src/qpid/framing/amqp_types.h: Added FrameType typedef.

	* src/qpid/framing/AMQMethodBody.h: Friends with MethodHolder.

	* src/Makefile.am:
	 - Improved ruby generation rule.
	 - Run method_variants template.
	 - Added new source files
	 - Pre-compiled header rule for method_variants.h

	* rubygen/templates/method_variants.rb: Generate variants
	  to hold methods of each class, and MethodVariant to hold all
	  the class variants.

	* rubygen/cppgen.rb: variant, tuple methods.

	* MethodBodyClass.h.tmpl: Added default constructor to method bodies.

	* amqpgen.rb (AmqpRoot::merge): fix bug in merge.


git-svn-id: https://svn.apache.org/repos/asf/incubator/qpid/trunk/qpid@563683 13f79535-47bb-0310-9956-ffa450edef68

1 files changed, 80 insertions, 0 deletions

diff --git a/cpp/src/qpid/framing/MethodHolder.h b/cpp/src/qpid/framing/MethodHolder.h
new file mode 100644
index 0000000000..b93c6b83b1
--- /dev/null
+++ b/cpp/src/qpid/framing/MethodHolder.h
@@ -0,0 +1,80 @@
+#ifndef QPID_FRAMING_METHODBODYHOLDER_H
+#define QPID_FRAMING_METHODBODYHOLDER_H
+
+/*
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ * 
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ *
+ */
+
+#include "qpid/framing/method_variants.h"
+
+#include <boost/type_traits/has_nothrow_copy.hpp>
+
+namespace qpid {
+namespace framing {
+
+class AMQMethodBody;
+
+/**
+ * Holder for arbitrary method body.
+ */
+class MethodHolder
+{
+  public:
+    MethodHolder() {}
+    MethodHolder(const MethodVariant& mv) : method(mv) {}
+
+    /** Construct from a concrete method body type.
+     * ClassVariant<T>::value is the containing class variant.
+     */
+    template <class T>
+    MethodHolder(const T& t)
+        : method(typename ClassVariant<T>::value(t)) {}
+
+    /** Construct from class/method ID, set the method accordingly. */
+    MethodHolder(ClassId, MethodId);
+
+    /** Set the method to the type corresponding to ClassId, MethodId */
+    void setMethod(ClassId, MethodId);
+    
+    AMQMethodBody* getMethod();
+    const AMQMethodBody* getMethod() const;
+    
+    MethodVariant method;
+
+    void encode(Buffer&) const;
+    void decode(Buffer&);
+    uint32_t size() const;
+};
+
+inline std::ostream& operator<<(std::ostream& out, const MethodHolder& h) {
+    return out << h.method;
+}
+
+
+}} // namespace qpid::framing
+
+namespace boost {
+template<> struct has_nothrow_copy<qpid::framing::MethodHolder> 
+    : public boost::true_type {};
+}
+
+
+
+#endif  /*!QPID_FRAMING_METHODBODYHOLDER_H*/