Implement nqp::isrwcont on JVM backend.

Author: jnthn

src/vm/jvm/QAST/Compiler.nqp

@@ -2531,6 +2531,7 @@ QAST::OperationsJAST.map_classlib_core_op('iscont', $TYPE_OPS, 'iscont', [$RT_OB
 QAST::OperationsJAST.map_classlib_core_op('iscont_i', $TYPE_OPS, 'iscont_i', [$RT_OBJ], $RT_INT);
 QAST::OperationsJAST.map_classlib_core_op('iscont_n', $TYPE_OPS, 'iscont_n', [$RT_OBJ], $RT_INT);
 QAST::OperationsJAST.map_classlib_core_op('iscont_s', $TYPE_OPS, 'iscont_s', [$RT_OBJ], $RT_INT);
+QAST::OperationsJAST.map_classlib_core_op('isrwcont', $TYPE_OPS, 'isrwcont', [$RT_OBJ], $RT_INT, :tc);
 QAST::OperationsJAST.map_classlib_core_op('decont', $TYPE_OPS, 'decont', [$RT_OBJ], $RT_OBJ, :tc);
 QAST::OperationsJAST.map_classlib_core_op('decont_i', $TYPE_OPS, 'decont_i', [$RT_OBJ], $RT_INT, :tc);
 QAST::OperationsJAST.map_classlib_core_op('decont_n', $TYPE_OPS, 'decont_n', [$RT_OBJ], $RT_NUM, :tc);

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

@@ -3277,6 +3277,14 @@ public static SixModelObject setcontspec(SixModelObject obj, String confname, Si
     public static long iscont(SixModelObject obj) {
         return obj == null || obj.st.ContainerSpec == null ? 0 : 1;
     }
+    public static long isrwcont(SixModelObject obj, ThreadContext tc) {
+        if (obj != null) {
+            ContainerSpec cs = obj.st.ContainerSpec;
+            if (cs != null && cs.canStore(tc, obj))
+                return 1;
+        }
+        return 0;
+    }
     private static short getContainerPrimitive(SixModelObject obj) {
         if (obj != null && !(obj instanceof TypeObject)) {
             ContainerSpec cs = obj.st.ContainerSpec;

src/vm/jvm/runtime/org/perl6/nqp/sixmodel/ContainerSpec.java

@@ -35,4 +35,9 @@ public abstract class ContainerSpec {
 
     /* Deserializes the container data, if any. */
     public abstract void deserialize(ThreadContext tc, STable st, SerializationReader reader);
+
+    /* Can the container store values. Usually yes, so default to true. */
+    public boolean canStore(ThreadContext tc, SixModelObject cont) {
+        return true;
+    }
 }