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package com.oracle.truffle.api.library.test.examples;

import static org.junit.Assert.assertEquals;

import org.junit.Test;

import com.oracle.truffle.api.CallTarget;
import com.oracle.truffle.api.Truffle;
import com.oracle.truffle.api.dsl.Cached;
import com.oracle.truffle.api.dsl.NodeChild;
import com.oracle.truffle.api.dsl.Specialization;
import com.oracle.truffle.api.library.test.examples.ArrayStrategy1.ArgumentNode;
import com.oracle.truffle.api.library.test.examples.ArrayStrategy1.ExpressionNode;
import com.oracle.truffle.api.library.test.examples.ArrayStrategy1.ExampleRootNode;
import com.oracle.truffle.api.library.test.examples.ArrayStrategy2Factory.ArrayReadNodeGen;

Runnable source code for array strategy2 from the
motivation
article.
/**
 * Runnable source code for array strategy2 from the
 * <a href="https://github.com/oracle/graal/blob/master/truffle/docs/TruffleLibaries.md">motivation
 * article</a>.
 */
@SuppressWarnings("unused")
public class ArrayStrategy2 {

    interface Array {
        int read(int index);
    }

    static final class BufferArray implements Array {

        private int length;
        private int[] buffer;

        BufferArray(int length) {
            this.length = length;
            this.buffer = new int[length];
        }

        /* ... */
        @Override
        public int read(int index) {
            return buffer[index];
        }
    }

    static final class SequenceArray implements Array {
        private final int start;
        private final int stride;
        private final int length;

        SequenceArray(int start, int stride, int length) {
            this.start = start;
            this.stride = stride;
            this.length = length;
        }

        @Override
        public int read(int index) {
            return start + (stride * index);
        }
    }

    @NodeChild
    @NodeChild
    abstract static class ArrayReadNode extends ExpressionNode {
        @Specialization(guards = "array.getClass() == arrayClass", limit = "2")
        int doCached(Array array, int index,
                        @Cached("array.getClass()") Class<? extends Array> arrayClass) {
            return arrayClass.cast(array).read(index);
        }

        @Specialization(replaces = "doCached")
        int doDefault(Array array, int index) {
            return array.read(index);
        }
    }

    @Test
    public void runExample() {
        ArrayReadNode read = ArrayReadNodeGen.create(new ArgumentNode(0), new ArgumentNode(1));
        CallTarget target = Truffle.getRuntime().createCallTarget(new ExampleRootNode(read));

        assertEquals(3, target.call(new SequenceArray(1, 2, 3), 1));
        assertEquals(0, target.call(new BufferArray(2), 1));
    }

}