* 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, 72 insertions, 0 deletions

diff --git a/cpp/rubygen/templates/method_variants.rb b/cpp/rubygen/templates/method_variants.rb
new file mode 100755
index 0000000000..0787657089
--- /dev/null
+++ b/cpp/rubygen/templates/method_variants.rb
@@ -0,0 +1,72 @@
+#!/usr/bin/env ruby
+$: << ".."                      # Include .. in load path
+require 'cppgen'
+
+# Generate the full AMQP class/method model as C++ types.
+class AmqpCppModelGen < CppGen
+  
+  def initialize(outdir, amqp)
+    super(outdir, amqp)
+  end
+
+  def gen_set_variant(varname, idtype, pairs, errmsg)
+    pairs.sort!
+    scope("inline void setVariant(#{varname}& var, #{idtype} id) {") {
+      scope("switch (id) {") {
+        pairs.each { |i,t| 
+          genl "case #{i}: var=#{t}(); break;";
+        }
+        genl "default: THROW_QPID_ERROR(FRAMING_ERROR, (boost::format(\"#{errmsg}\")%id).str());"
+      }
+    }
+    genl
+  end
+
+  def gen_class(c)
+    varname="#{c.name.caps}Variant"
+    mtypes=c.methods.map { |m| m.body_name }
+    typedef(blank_variant(mtypes), varname)
+    genl
+    pairs=c.methods.map { |m| [m.index.to_i,m.body_name] }
+    gen_set_variant(varname, "MethodId", pairs,
+                    "%d is not a valid method index in class #{c.name}")
+    mtypes.each { |t|
+      genl "template<> struct ClassVariant<#{t}> { typedef #{varname} value; };"
+    }
+    genl
+  end
+
+  def gen_all()
+    varname="MethodVariant"
+    types=@amqp.classes.map { |c| "#{c.name.caps}Variant" }
+    pairs=@amqp.classes.map { |c| [c.index.to_i,"#{c.name.caps}Variant"] }
+    typedef(blank_variant(types), varname) 
+    genl
+    gen_set_variant(varname, "ClassId", pairs,
+                    "%d is not a valid class index.")
+  end
+
+  def generate()
+    h_file("qpid/framing/method_variants.h") {
+      @amqp.methods.each { |m| include "qpid/framing/#{m.body_name}.h"}
+      include "qpid/framing/amqp_types.h"
+      include "qpid/QpidError.h"
+      include "qpid/framing/variant.h"
+      include "<boost/format.hpp>"
+      genl
+      namespace("qpid::framing") {
+        genl "// Metafunction returns class variant containing method T."
+        genl "template <class T> struct ClassVariant {};"
+        genl
+        @amqp.classes.each { |c| gen_class c }
+      }
+      namespace("qpid::framing") {
+        gen_all
+        genl
+      }
+    }
+  end
+end
+
+AmqpCppModelGen.new(Outdir, Amqp).generate();
+