* 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, 93 insertions, 0 deletions

diff --git a/cpp/src/qpid/framing/MethodHolder.cpp b/cpp/src/qpid/framing/MethodHolder.cpp
new file mode 100644
index 0000000000..27046af43c
--- /dev/null
+++ b/cpp/src/qpid/framing/MethodHolder.cpp
@@ -0,0 +1,93 @@
+/*
+ *
+ * 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 "MethodHolder.h"
+#include "amqp_types.h"
+#include "qpid/framing/Buffer.h"
+#include "qpid/framing/variant.h"
+
+using namespace boost;
+
+namespace qpid {
+namespace framing {
+
+struct SetVariantVisitor : public NoBlankVisitor<> {
+    QPID_USING_NOBLANK();
+    MethodId id;
+    SetVariantVisitor(MethodId m) : id(m) {}
+    template <class T> void operator()(T& t) const { setVariant(t, id); }
+};
+
+inline void setVariant(MethodVariant& var, ClassId c, MethodId m) {
+    setVariant(var,c);
+    boost::apply_visitor(SetVariantVisitor(m), var);
+}
+
+void MethodHolder::setMethod(ClassId c, MethodId m) {
+    setVariant(method, c, m);
+}
+
+MethodHolder::MethodHolder(ClassId c, MethodId m) {
+    setMethod(c,m);
+}
+
+struct GetClassId : public NoBlankVisitor<ClassId> {
+    QPID_USING_NOBLANK(ClassId);
+    template <class T> ClassId operator()(const T&) const {
+        return T::CLASS_ID;
+    }
+};
+
+struct GetMethodId : public NoBlankVisitor<MethodId> {
+    QPID_USING_NOBLANK(ClassId);
+    template <class T> MethodId operator()(const T&) const {
+        return T::METHOD_ID;
+    }
+};
+
+void MethodHolder::encode(Buffer& b) const {
+    const AMQMethodBody* body = getMethod();
+    b.putShort(body->amqpClassId());
+    b.putShort(body->amqpMethodId());
+    body->encodeContent(b);
+}
+
+void MethodHolder::decode(Buffer& b) {
+    ClassId classId = b.getShort();
+    ClassId methodId = b.getShort();
+    setVariant(method, classId, methodId);
+    getMethod()->decodeContent(b);
+}
+
+uint32_t  MethodHolder::size() const {
+    return sizeof(ClassId)+sizeof(MethodId)+getMethod()->size();
+}
+
+
+AMQMethodBody* MethodHolder::getMethod() {
+    return applyApplyVisitor(AddressVisitor<AMQMethodBody*>(), method);
+}
+
+const AMQMethodBody* MethodHolder::getMethod() const {
+    return const_cast<MethodHolder*>(this)->getMethod();
+}
+
+}} // namespace qpid::framing