prefix operators supported

src/org/jetbrains/jet/j2k/ast/PrefixOperator.java

@@ -0,0 +1,22 @@
+package org.jetbrains.jet.j2k.ast;
+
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * @author ignatov
+ */
+public class PrefixOperator extends Expression {
+  private final String myOp;
+  private final Expression myExpression;
+
+  public PrefixOperator(String op, Expression expression) {
+    myOp = op;
+    myExpression = expression;
+  }
+
+  @NotNull
+  @Override
+  public String toKotlin() {
+    return "(" + myOp + myExpression.toKotlin() + ")";
+  }
+}

src/org/jetbrains/jet/j2k/visitors/ExpressionVisitor.java

@@ -205,15 +205,18 @@ public class ExpressionVisitor extends StatementVisitor implements Visitor {
     if (expression.getOperationSign().getTokenType() == JavaTokenType.PLUSPLUS) op = "++";
     if (expression.getOperationSign().getTokenType() == JavaTokenType.MINUSMINUS) op = "--";
 
-    myResult = new PostfixOperator(
-      op,
-      expressionToExpression(expression.getOperand())
-    );
+    myResult = new PostfixOperator(op, expressionToExpression(expression.getOperand()));
   }
 
   @Override
   public void visitPrefixExpression(PsiPrefixExpression expression) {
     super.visitPrefixExpression(expression);
+
+    String op = "";
+    if (expression.getOperationSign().getTokenType() == JavaTokenType.PLUSPLUS) op = "++";
+    if (expression.getOperationSign().getTokenType() == JavaTokenType.MINUSMINUS) op = "--";
+
+    myResult = new PrefixOperator(op, expressionToExpression(expression.getOperand()));
   }
 
   @Override

test/org/jetbrains/jet/j2k/ast/PrefixOperatorTest.java

@@ -0,0 +1,17 @@
+package org.jetbrains.jet.j2k.ast;
+
+import junit.framework.Assert;
+import org.jetbrains.jet.j2k.JetTestCaseBase;
+
+/**
+ * @author ignatov
+ */
+public class PrefixOperatorTest extends JetTestCaseBase {
+  public void testIncrement() throws Exception {
+    Assert.assertEquals(statementToKotlin("++i;"), "(++i)");
+  }
+
+  public void testDecrement() throws Exception {
+    Assert.assertEquals(statementToKotlin("--i;"), "(--i)");
+  }
+}