/*
* Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package com.oracle.truffle.api.test;
import org.junit.Assert;
import org.junit.Test;
import com.oracle.truffle.api.CallTarget;
import com.oracle.truffle.api.Truffle;
import com.oracle.truffle.api.TruffleRuntime;
import com.oracle.truffle.api.frame.VirtualFrame;
import com.oracle.truffle.api.nodes.Node;
import com.oracle.truffle.api.nodes.RootNode;
/**
* <h3>Using Final Fields in Node Classes</h3>
*
* <p>
* The usage of final fields in node classes is highly encouraged. It is beneficial for performance
* to declare every field that is not pointing to a child node as final. This gives the Truffle
* runtime an increased opportunity to optimize this node.
* </p>
*
* <p>
* If a node has a value which may change at run time, but will rarely do so, it is recommended to
* speculate on the field being final. This involves starting executing with a node where this field
* is final and only if this turns out to be no longer the case, the node is replaced with an
* alternative implementation of the operation (see {@link ReplaceTest}).
* </p>
*
* <p>
* The next part of the Truffle API introduction is at
* {@link com.oracle.truffle.api.test.ReplaceTest}.
* </p>
*/
public class FinalFieldTest {
@Test
public void test() {
TruffleRuntime runtime = Truffle.getRuntime();
TestRootNode rootNode = new TestRootNode(new TestChildNode[]{new TestChildNode(20), new TestChildNode(22)});
CallTarget target = runtime.createCallTarget(rootNode);
Object result = target.call();
Assert.assertEquals(42, result);
}
private static class TestRootNode extends RootNode {
@Children private final TestChildNode[] children;
TestRootNode(TestChildNode[] children) {
super(null);
this.children = children;
}
@Override
public Object execute(VirtualFrame frame) {
int sum = 0;
for (int i = 0; i < children.length; ++i) {
sum += children[i].execute();
}
return sum;
}
}
private static class TestChildNode extends Node {
private final int value;
TestChildNode(int value) {
this.value = value;
}
public int execute() {
return value;
}
}
}