elvis for primitive types; unboxing support

idea/src/org/jetbrains/jet/codegen/ExpressionCodegen.java

@@ -62,6 +62,10 @@ public class ExpressionCodegen extends JetVisitor {
         }
     }
 
+    private void genToStack(JetExpression expr) {
+        gen(expr, expressionType(expr));
+    }
+
     @Override
     public void visitExpression(JetExpression expression) {
         throw new UnsupportedOperationException("Codegen for " + expression + " is not yet implemented");
@@ -621,11 +625,13 @@ public class ExpressionCodegen extends JetVisitor {
 
     private void generateElvis(JetBinaryExpression expression) {
         final Type exprType = expressionType(expression);
-        gen(expression.getLeft(), exprType);
+        final Type leftType = expressionType(expression.getLeft());
+        gen(expression.getLeft(), leftType);
         v.dup();
         Label end = new Label();
         Label ifNull = new Label();
         v.ifnull(ifNull);
+        StackValue.onStack(leftType).put(exprType, v);
         v.goTo(end);
         v.mark(ifNull);
         v.pop();

idea/src/org/jetbrains/jet/codegen/StackValue.java

@@ -69,10 +69,40 @@ public abstract class StackValue {
         }
     }
 
+    private static void unbox(final Type type, InstructionAdapter v) {
+        if (type == Type.INT_TYPE) {
+            v.invokevirtual("java/lang/Number", "intValue", "()I");
+        }
+        else if (type == Type.BOOLEAN_TYPE) {
+            v.invokevirtual("java/lang/Boolean", "booleanValue", "()Z");
+        }
+        else if (type == Type.CHAR_TYPE) {
+            v.invokevirtual("java/lang/Character", "charValue", "()C");
+        }
+        else if (type == Type.SHORT_TYPE) {
+            v.invokevirtual("java/lang/Number", "shortValue", "()S");
+        }
+        else if (type == Type.LONG_TYPE) {
+            v.invokevirtual("java/lang/Number", "longValue", "()J");
+        }
+        else if (type == Type.BYTE_TYPE) {
+            v.invokevirtual("java/lang/Number", "byteValue", "()B");
+        }
+        else if (type == Type.FLOAT_TYPE) {
+            v.invokevirtual("java/lang/Number", "floatValue", "()F");
+        }
+        else if (type == Type.DOUBLE_TYPE) {
+            v.invokevirtual("java/lang/Number", "doubleValue", "()D");
+        }
+    }
+
     protected void coerce(Type type, InstructionAdapter v) {
         if (type.getSort() == Type.OBJECT) {
             box(this.type, v);
         }
+        else if (this.type.getSort() == Type.OBJECT && type.getSort() <= Type.DOUBLE) {
+            unbox(type, v);
+        }
         else if (type != this.type) {
             v.cast(this.type, type);
         }

idea/tests/org/jetbrains/jet/codegen/NamespaceGenTest.java

@@ -275,6 +275,13 @@ public class NamespaceGenTest extends CodegenTestCase {
         assertEquals("null", main.invoke(null, new Object[] { null }));
     }
 
+    public void testElvisInt() throws Exception {
+        loadText("fun foo(a: Int?): Int = a ?: 239");
+        final Method main = generateFunction();
+        assertEquals(610, main.invoke(null, 610));
+        assertEquals(239, main.invoke(null, new Object[]{null}));
+    }
+
     public void _testVarargs() throws Exception {
         loadText("fun foo() = java.util.Arrays.asList(\"IntelliJ\", \"IDEA\")");
         final Method main = generateFunction();