/*
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 * 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
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 */
package com.oracle.truffle.api.test;

import org.junit.*;

import com.oracle.truffle.api.*;
import com.oracle.truffle.api.frame.*;
import com.oracle.truffle.api.nodes.*;

/**
 * <h3>Creating a Root Node</h3>
 *
 * <p>
 * A Truffle root node is the entry point into a Truffle tree that represents a guest language
 * method. It contains a {@link RootNode#execute(VirtualFrame)} method that can return a
 * {@link java.lang.Object} value as the result of the guest language method invocation. This method
 * must however never be called directly. Instead, the Truffle runtime must be used to create a
 * {@link CallTarget} object from a root node using the
 * {@link TruffleRuntime#createCallTarget(RootNode)} method. This call target object can then be
 * executed using the {@link CallTarget#call(Object...)} method or one of its overloads.
 * </p>
 *
 * <p>
 * The next part of the Truffle API introduction is at
 * {@link com.oracle.truffle.api.test.ChildNodeTest}.
 * </p>
 */
public class RootNodeTest {

    @Test
    public void test() {
        TruffleRuntime runtime = Truffle.getRuntime();
        TestRootNode rootNode = new TestRootNode();
        CallTarget target = runtime.createCallTarget(rootNode);
        Object result = target.call();
        Assert.assertEquals(42, result);
    }

    class TestRootNode extends RootNode {

        public TestRootNode() {
            super(null);
        }

        @Override
        public Object execute(VirtualFrame frame) {
            return 42;
        }
    }
}