make RConnection RAttributable

com.oracle.truffle.r.runtime/src/com/oracle/truffle/r/runtime/conn/ConnectionSupport.java

@@ -249,11 +249,6 @@ public class ConnectionSupport implements RContext.StateFactory {
          */
         private OpenMode openMode;
 
-        /**
-         * The classes of the connection, which always includes "connection".
-         */
-        private final RStringVector classHr;
-
         /**
          * The actual connection, if delegated.
          */
@@ -295,7 +290,7 @@ public class ConnectionSupport implements RContext.StateFactory {
             String[] classes = new String[2];
             classes[0] = conClass.printName;
             classes[1] = "connection";
-            this.classHr = RDataFactory.createStringVector(classes, RDataFactory.COMPLETE_VECTOR);
+            getAttributes().put(RRuntime.CLASS_ATTR_KEY, RDataFactory.createStringVector(classes, RDataFactory.COMPLETE_VECTOR));
         }
 
         protected void openNonLazyConnection() throws IOException {
@@ -549,7 +544,7 @@ public class ConnectionSupport implements RContext.StateFactory {
         }
 
         public RStringVector getClassHr() {
-            return classHr;
+            return (RStringVector) getAttributes().get(RRuntime.CLASS_ATTR_KEY);
         }
 
         public boolean isClosed() {

com.oracle.truffle.r.runtime/src/com/oracle/truffle/r/runtime/conn/RConnection.java

@@ -36,10 +36,23 @@ import com.oracle.truffle.r.runtime.data.model.*;
  *
  * TODO Refactor the pushBack code into ConnectionsSupport
  */
-public abstract class RConnection implements RClassHierarchy, RTypedValue, AutoCloseable {
+public abstract class RConnection implements RClassHierarchy, RAttributable, RTypedValue, AutoCloseable {
 
     private LinkedList<String> pushBack;
 
+    /**
+     * Connections always have at least a class attribute.
+     */
+    private RAttributes attributes = RAttributes.create();
+
+    public RAttributes initAttributes() {
+        return attributes;
+    }
+
+    public RAttributes getAttributes() {
+        return attributes;
+    }
+
     public abstract String[] readLinesInternal(int n) throws IOException;
 
     public RType getRType() {

com.oracle.truffle.r.runtime/src/com/oracle/truffle/r/runtime/data/RAttributes.java

@@ -69,7 +69,7 @@ public final class RAttributes implements Iterable<RAttributes.RAttribute> {
 
     private static final ConditionProfile statsProfile = ConditionProfile.createBinaryProfile();
 
-    static RAttributes create() {
+    public static RAttributes create() {
         return new RAttributes();
     }