attribute printing for matrices

com.oracle.truffle.r.nodes/src/com/oracle/truffle/r/nodes/builtin/base/PrettyPrinterNode.java

@@ -103,7 +103,13 @@ public abstract class PrettyPrinterNode extends RNode {
             CompilerDirectives.transferToInterpreterAndInvalidate();
             multiDimPrinter = adoptChild(PrintVectorMultiDimNodeFactory.create(null, null));
         }
-        return (String) multiDimPrinter.executeString(frame, vector, RRuntime.asLogical(isListOrStringVector));
+        StringBuilder sb = new StringBuilder();
+        sb.append((String) multiDimPrinter.executeString(frame, vector, RRuntime.asLogical(isListOrStringVector)));
+        Map<String, Object> attributes = vector.getAttributes();
+        if (attributes != null) {
+            sb.append(printAttributes(frame, vector, attributes));
+        }
+        return builderToString(sb);
     }
 
     @Specialization
@@ -179,8 +185,8 @@ public abstract class PrettyPrinterNode extends RNode {
                 // names attribute already printed
                 continue;
             }
-            if (attr.getKey().equals(RRuntime.DIM_ATTR_KEY)) {
-                // dim attribute never gets printed
+            if (attr.getKey().equals(RRuntime.DIM_ATTR_KEY) || attr.getKey().equals(RRuntime.DIMNAMES_ATTR_KEY)) {
+                // dim and dimnames attributes never gets printed
                 continue;
             }
             builder.append("\n");
@@ -887,7 +893,7 @@ public abstract class PrettyPrinterNode extends RNode {
             } else {
                 int dimSize = dimensions[numDimensions - 1];
                 if (dimSize == 0) {
-                    return null;
+                    return "";
                 }
                 StringBuilder sb = new StringBuilder();
                 if (numDimensions == 3) {
@@ -911,7 +917,7 @@ public abstract class PrettyPrinterNode extends RNode {
                         String dimId = getDimId(vector, numDimensions, dimInd);
                         String innerDims = printDim(frame, vector, isListOrStringVector, numDimensions - 1, arrayBase, accDimensions, dimId);
                         if (innerDims == null) {
-                            return null;
+                            return "";
                         } else {
                             sb.append(innerDims);
                         }

com.oracle.truffle.r.nodes/src/com/oracle/truffle/r/nodes/builtin/base/Print.java

@@ -50,7 +50,7 @@ public abstract class Print extends RBuiltinNode {
     @Specialization
     public Object print(VirtualFrame frame, Object o) {
         String s = (String) prettyPrinter.executeString(frame, o, null);
-        if (s != null) {
+        if (s != null && !s.isEmpty()) {
             printHelper(s);
         }
         return new RInvisible(o); // TODO should we actually call "invisible(o)"?