Implement setting invocation spec.

It's not actually used yet, however.

lib/QAST/JASTCompiler.nqp

@@ -1396,6 +1396,7 @@ QAST::OperationsJAST.map_classlib_core_op('setmethcache', $TYPE_OPS, 'setmethcac
 QAST::OperationsJAST.map_classlib_core_op('setmethcacheauth', $TYPE_OPS, 'setmethcacheauth', [$RT_OBJ, $RT_INT], $RT_OBJ, :tc);
 QAST::OperationsJAST.map_classlib_core_op('settypecache', $TYPE_OPS, 'settypecache', [$RT_OBJ, $RT_OBJ], $RT_OBJ, :tc);
 QAST::OperationsJAST.map_classlib_core_op('isinvokable', $TYPE_OPS, 'isinvokable', [$RT_OBJ], $RT_INT, :tc);
+QAST::OperationsJAST.map_classlib_core_op('setinvokespec', $TYPE_OPS, 'setinvokespec', [$RT_OBJ, $RT_OBJ, $RT_STR, $RT_OBJ], $RT_OBJ, :tc);
 
 # defined - overridden by HLL, but by default same as .DEFINITE.
 QAST::OperationsJAST.map_classlib_core_op('defined', $TYPE_OPS, 'isconcrete', [$RT_OBJ], $RT_INT, :tc);

src/org/perl6/nqp/runtime/Ops.java

@@ -1081,9 +1081,18 @@ public static SixModelObject settypecache(SixModelObject obj, SixModelObject typ
     	obj.st.TypeCheckCache = cache;
     	return obj;
     }
+    public static SixModelObject setinvokespec(SixModelObject obj, SixModelObject ch,
+    		String name, SixModelObject invocationHandler, ThreadContext tc) {
+    	InvocationSpec is = new InvocationSpec();
+    	is.ClassHandle = ch;
+    	is.AttrName = name;
+    	is.Hint = STable.NO_HINT;
+    	is.InvocationHandler = invocationHandler;
+    	obj.st.InvocationSpec = is;
+    	return obj;
+    }
     public static long isinvokable(SixModelObject obj, ThreadContext tc) {
-    	// TODO: Update when invocation protocol done.
-    	return obj instanceof CodeRef ? 1 : 0;
+    	return obj instanceof CodeRef || obj.st.InvocationSpec != null ? 1 : 0;
     }
 
     /* Box/unbox operations. */

src/org/perl6/nqp/sixmodel/InvocationSpec.java

@@ -0,0 +1,25 @@
+package org.perl6.nqp.sixmodel;
+
+/* How do we invoke this thing? Specifies either an attribute to look at for
+ * an invokable thing, or alternatively a method to call. */
+public class InvocationSpec {
+    /**
+     * Class handle where we find the attribute to invoke.
+     */
+    public SixModelObject ClassHandle;
+
+    /**
+     * Attribute name where we find the attribute to invoke.
+     */
+    public String AttrName;
+
+    /**
+     * Attribute lookup hint used in gradual typing.
+     */
+    public long Hint;
+
+    /**
+     * Thing that handles invocation.
+     */
+    public SixModelObject InvocationHandler;
+}

src/org/perl6/nqp/sixmodel/STable.java

@@ -95,6 +95,12 @@ public STable(REPR REPR, SixModelObject HOW) {
      */
     public ContainerSpec ContainerSpec;
 
+    /**
+     * If this is invokable, then this contains information needed to
+     * figure out how to invoke it. If not, it'll be null.
+     */
+    public InvocationSpec InvocationSpec;
+
     /**
      * Information - if any - about how we can turn something of this type
      * into a boolean.