Hiding active binding for '.Random.seed'.

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

@@ -211,7 +211,7 @@ final class REngine implements Engine, Engine.Timings {
     private void initializeRNG() {
         assert REnvironment.globalEnv() != null;
         RFunction fun = context.lookupBuiltin(".fastr.set.seed");
-        ActiveBinding dotRandomSeed = new ActiveBinding(RType.Any, fun);
+        ActiveBinding dotRandomSeed = new ActiveBinding(RType.Any, fun, true);
         Frame frame = REnvironment.globalEnv().getFrame();
         FrameSlot slot = FrameSlotChangeMonitor.findOrAddFrameSlot(frame.getFrameDescriptor(), RRNG.RANDOM_SEED, FrameSlotKind.Object);
         FrameSlotChangeMonitor.setActiveBinding(frame, slot, dotRandomSeed, false, null);

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

@@ -69,14 +69,14 @@ public abstract class Exists extends RBuiltinNode.Arg4 {
             if (modeType != RType.Any && obj instanceof RPromise) {
                 obj = PromiseHelperNode.evaluateSlowPath((RPromise) obj);
             }
-            return RRuntime.asLogical(obj != null && obj != RMissing.instance && RRuntime.checkType(obj, modeType));
+            return RRuntime.asLogical(obj != null && RRuntime.checkType(obj, modeType));
         }
         for (REnvironment e = env; e != REnvironment.emptyEnv(); e = e.getParent()) {
             Object obj = e.get(name);
             if (modeType != RType.Any && obj instanceof RPromise) {
                 obj = PromiseHelperNode.evaluateSlowPath((RPromise) obj);
             }
-            if (obj != null && obj != RMissing.instance && RRuntime.checkType(obj, modeType)) {
+            if (obj != null && RRuntime.checkType(obj, modeType)) {
                 return RRuntime.LOGICAL_TRUE;
             }
         }

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

@@ -151,7 +151,9 @@ public class RNGFunctions {
                 int[] seedsArr = (int[]) seeds;
                 return RDataFactory.createIntVector(seedsArr, RDataFactory.INCOMPLETE_VECTOR);
             }
-            assert seeds != null;
+            if (seeds == null) {
+                return RNull.instance;
+            }
             return seeds;
         }
     }

com.oracle.truffle.r.runtime/src/com/oracle/truffle/r/runtime/env/frame/ActiveBinding.java

@@ -39,10 +39,17 @@ public class ActiveBinding implements RTruffleObject {
 
     private final RType expectedType;
     private final RFunction function;
+    private boolean initialized = false;
+    private boolean hidden = false;
 
-    public ActiveBinding(RType expectedType, RFunction fun) {
+    public ActiveBinding(RType expectedType, RFunction fun, boolean hidden) {
         this.expectedType = Objects.requireNonNull(expectedType);
         this.function = Objects.requireNonNull(fun);
+        this.hidden = hidden;
+    }
+
+    public ActiveBinding(RType expectedType, RFunction fun) {
+        this(expectedType, fun, false);
     }
 
     public RFunction getFunction() {
@@ -62,11 +69,29 @@ public class ActiveBinding implements RTruffleObject {
         return "active binding";
     }
 
+    public boolean isHidden() {
+        return hidden;
+    }
+
+    public boolean isInitialized() {
+        return initialized;
+    }
+
     public Object writeValue(Object value) {
-        return RContext.getEngine().evalFunction(function, REnvironment.baseEnv().getFrame(), RCaller.createInvalid(null), true, null, value);
+        Object result = RContext.getEngine().evalFunction(function, REnvironment.baseEnv().getFrame(), RCaller.createInvalid(null), true, null, value);
+        initialized = true;
+        return result;
     }
 
     public Object readValue() {
         return RContext.getEngine().evalFunction(function, REnvironment.baseEnv().getFrame(), RCaller.createInvalid(null), true, null);
     }
+
+    public static boolean isListed(Object value) {
+        if (isActiveBinding(value)) {
+            ActiveBinding binding = (ActiveBinding) value;
+            return !binding.hidden || binding.initialized;
+        }
+        return true;
+    }
 }

com.oracle.truffle.r.runtime/src/com/oracle/truffle/r/runtime/env/frame/REnvTruffleFrameAccess.java

@@ -39,6 +39,7 @@ import com.oracle.truffle.r.runtime.RError;
 import com.oracle.truffle.r.runtime.RError.Message;
 import com.oracle.truffle.r.runtime.RRuntime;
 import com.oracle.truffle.r.runtime.data.RDataFactory;
+import com.oracle.truffle.r.runtime.data.RMissing;
 import com.oracle.truffle.r.runtime.data.RStringVector;
 import com.oracle.truffle.r.runtime.env.REnvironment;
 import com.oracle.truffle.r.runtime.env.REnvironment.PutException;
@@ -75,7 +76,10 @@ public final class REnvTruffleFrameAccess extends REnvFrameAccess {
             Object value = FrameSlotChangeMonitor.getValue(slot, frame);
             // special treatment for active binding: call bound function
             if (ActiveBinding.isActiveBinding(value)) {
-                return ((ActiveBinding) value).readValue();
+                Object readValue = ((ActiveBinding) value).readValue();
+                // special case: if the active binding returns RMissing, then this should behave
+                // like the variable does not exist.
+                return readValue != RMissing.instance ? readValue : null;
             }
             return value;
         }
@@ -161,7 +165,8 @@ public final class REnvTruffleFrameAccess extends REnvFrameAccess {
         for (int i = 0; i < names.length; i++) {
             String name = names[i];
             FrameSlot frameSlot = fd.findFrameSlot(name);
-            if (FrameSlotChangeMonitor.getValue(frameSlot, frame) == null) {
+            Object value = FrameSlotChangeMonitor.getValue(frameSlot, frame);
+            if (value == null || !ActiveBinding.isListed(value)) {
                 continue;
             }
             if (REnvironment.includeName(name, allNames, pattern)) {