TruffleRLanguage#toString: do not print scalar NA as vector

Author: steve-s

com.oracle.truffle.r.engine/src/com/oracle/truffle/r/engine/TruffleRLanguageImpl.java

@@ -150,6 +150,12 @@ protected String toString(RContext context, Object value) {
             return value.toString();
         }
 
+        // special class designated to exchange NA values with the outside world
+        // this value is a scalar, the only way to get it is via getArrayMember on an R vector
+        if (value instanceof RInteropNA) {
+            return "NA";
+        }
+
         // the debugger also passes result of TruffleRLanguage.findMetaObject() to this method
         Object unwrapped = value;
         // print promises by other means than the "print" function to avoid evaluating them
@@ -165,10 +171,6 @@ protected String toString(RContext context, Object value) {
         if (RMissingHelper.isMissing(unwrapped)) {
             return "missing";
         }
-        // special class designated to exchange NA values with the outside world
-        if (unwrapped instanceof RInteropNA) {
-            unwrapped = ((RInteropNA) unwrapped).getValue();
-        }
 
         // the value unwrapped from an RPromise can be primitive Java type, but now we know that we
         // are dealing with primitive that is supposed to be treated as R vector

com.oracle.truffle.r.test/src/com/oracle/truffle/r/test/tck/JavaEmbeddingTest.java

@@ -60,6 +60,8 @@ public void testToString() {
         assertEquals("[1] 1", context.eval("R", "1").toString());
         assertEquals("[1] TRUE", context.eval("R", "TRUE").toString());
         assertEquals("[1] NA", context.eval("R", "NA").toString());
+        // NA scalar value:
+        assertEquals("NA", context.eval("R", "NA").getArrayElement(0).toString());
         // @formatter:off
         String dataFrameExpected =
                 "  x y\n" +

com.oracle.truffle.r.test/src/com/oracle/truffle/r/test/tck/ToStringTesterInstrument.java

@@ -45,7 +45,8 @@ protected void onEnter(VirtualFrame frame) {
                 testData.byteAsString = env.toString(rLanguage, (byte) 42);
                 testData.doubleAsString = env.toString(rLanguage, 42.5);
                 testData.stringAsString = env.toString(rLanguage, "Hello");
-                testData.booleanAsString = env.toString(rLanguage, true);
+                testData.trueAsString = env.toString(rLanguage, true);
+                testData.falseAsString = env.toString(rLanguage, false);
             }
         });
     }
@@ -55,6 +56,7 @@ public static final class TestData {
         public String byteAsString;
         public String doubleAsString;
         public String stringAsString;
-        public String booleanAsString;
+        public String trueAsString;
+        public String falseAsString;
     }
 }

com.oracle.truffle.r.test/src/com/oracle/truffle/r/test/tck/TruffleRLanguageTest.java

@@ -54,7 +54,8 @@ public void testToString() {
         assertEquals("42", testData.byteAsString);
         assertEquals("42.5", testData.doubleAsString);
         assertEquals("Hello", testData.stringAsString);
-        assertEquals("true", testData.booleanAsString);
+        assertEquals("TRUE", testData.trueAsString);
+        assertEquals("FALSE", testData.falseAsString);
     }
 
 }