add isException/throwException messages

Author: timfel

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/exception/PBaseException.java

@@ -40,12 +40,14 @@
  */
 package com.oracle.graal.python.builtins.objects.exception;
 
+import com.oracle.graal.python.builtins.objects.PNone;
 import com.oracle.graal.python.builtins.objects.frame.PFrame;
 import com.oracle.graal.python.builtins.objects.object.PythonObject;
 import com.oracle.graal.python.builtins.objects.traceback.PTraceback;
 import com.oracle.graal.python.builtins.objects.tuple.PTuple;
 import com.oracle.graal.python.builtins.objects.type.LazyPythonClass;
 import com.oracle.graal.python.builtins.objects.type.TypeNodes.GetNameNode;
+import com.oracle.graal.python.nodes.PRaiseNode;
 import com.oracle.graal.python.nodes.object.GetLazyClassNode;
 import com.oracle.graal.python.nodes.statement.ExceptNode;
 import com.oracle.graal.python.runtime.exception.PException;
@@ -54,9 +56,12 @@
 import com.oracle.graal.python.runtime.sequence.storage.BasicSequenceStorage;
 import com.oracle.graal.python.runtime.sequence.storage.SequenceStorage;
 import com.oracle.truffle.api.CompilerAsserts;
+import com.oracle.truffle.api.dsl.Cached;
+import com.oracle.truffle.api.library.ExportMessage;
+import com.oracle.truffle.api.profiles.ConditionProfile;
 
 public final class PBaseException extends PythonObject {
-
+    private static final Object[] EMPTY_ARGS = new Object[0];
     private static final ErrorMessageFormatter FORMATTER = new ErrorMessageFormatter();
 
     private PTuple args; // can be null for lazily generated message
@@ -225,4 +230,30 @@ public void reifyException(PFrame.Reference curFrameInfo) {
         // TODO: frames: provide legacy stack walk method via Python option
         // TruffleStackTrace.fillIn(exception);
     }
+
+    @ExportMessage
+    @SuppressWarnings("static-method")
+    boolean isException() {
+        return true;
+    }
+
+    @ExportMessage
+    RuntimeException throwException(@Cached("createBinaryProfile()") ConditionProfile hasExc,
+                    @Cached GetLazyClassNode getClass,
+                    @Cached PRaiseNode raiseNode) {
+        PException exc = getException();
+        if (hasExc.profile(exc != null)) {
+            throw exc;
+        } else {
+            Object[] newArgs = messageArgs;
+            if (newArgs == null) {
+                newArgs = EMPTY_ARGS;
+            }
+            Object format = messageFormat;
+            if (format == null) {
+                format = PNone.NO_VALUE;
+            }
+            throw raiseNode.execute(getClass.execute(this), this, format, newArgs);
+        }
+    }
 }