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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.RootNode;

Calling Another Tree
 A guest language implementation can create multiple call targets using the TruffleRuntime.createCallTarget(RootNode) method. Those call targets can be passed around as normal Java objects and used for calling guest language methods. 
 The next part of the Truffle API introduction is at ArgumentsTest. 
/**
 * <h3>Calling Another Tree</h3>
 *
 * <p>
 * A guest language implementation can create multiple call targets using the
 * {@link TruffleRuntime#createCallTarget(RootNode)} method. Those call targets can be passed around
 * as normal Java objects and used for calling guest language methods.
 * </p>
 *
 * <p>
 * The next part of the Truffle API introduction is at
 * {@link com.oracle.truffle.api.test.ArgumentsTest}.
 * </p>
 */
public class CallTest {

    @Test
    public void test() {
        TruffleRuntime runtime = Truffle.getRuntime();
        CallTarget foo = runtime.createCallTarget(new ConstantRootNode(20));
        CallTarget bar = runtime.createCallTarget(new ConstantRootNode(22));
        CallTarget main = runtime.createCallTarget(new DualCallNode(foo, bar));
        Object result = main.call();
        Assert.assertEquals(42, result);
    }

    class DualCallNode extends RootNode {

        private final CallTarget firstTarget;
        private final CallTarget secondTarget;

        DualCallNode(CallTarget firstTarget, CallTarget secondTarget) {
            super(null);
            this.firstTarget = firstTarget;
            this.secondTarget = secondTarget;
        }

        @Override
        public Object execute(VirtualFrame frame) {
            return ((Integer) firstTarget.call()) + ((Integer) secondTarget.call());
        }
    }

    class ConstantRootNode extends RootNode {

        private final int value;

        ConstantRootNode(int value) {
            super(null);
            this.value = value;
        }

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