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 * The Universal Permissive License (UPL), Version 1.0
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 * person obtaining a copy of this software, associated documentation and/or
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 * the Larger Works (as defined below), to deal in both
 *
 * (a) the Software, and
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 * (b) any piece of software and/or hardware listed in the lrgrwrks.txt file if
 * one is included with the Software each a "Larger Work" to which the Software
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 * Software and the Larger Work(s), and to sublicense the foregoing rights on
 * either these or other terms.
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 * This license is subject to the following condition:
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 * minimum a reference to the UPL must be included in all copies or substantial
 * portions of the Software.
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package com.oracle.truffle.sl.nodes.access;

import com.oracle.truffle.api.CompilerDirectives.TruffleBoundary;
import com.oracle.truffle.api.dsl.Cached;
import com.oracle.truffle.api.dsl.Specialization;
import com.oracle.truffle.api.nodes.Node;
import com.oracle.truffle.api.nodes.UnexpectedResultException;
import com.oracle.truffle.api.object.DynamicObject;
import com.oracle.truffle.api.object.LongLocation;
import com.oracle.truffle.api.object.Property;
import com.oracle.truffle.api.object.Shape;
import com.oracle.truffle.sl.runtime.SLNull;

public abstract class SLReadPropertyCacheNode extends Node {

    protected static final int CACHE_LIMIT = 3;

    protected final String propertyName;

    public SLReadPropertyCacheNode(String propertyName) {
        this.propertyName = propertyName;
    }

    public static SLReadPropertyCacheNode create(String propertyName) {
        return SLReadPropertyCacheNodeGen.create(propertyName);
    }

    public abstract Object executeObject(DynamicObject receiver);

    public abstract long executeLong(DynamicObject receiver) throws UnexpectedResultException;

    /*
     * We use a separate long specialization to avoid boxing for long.
     */
    @Specialization(limit = "CACHE_LIMIT", guards = {"longLocation != null", "shape.check(receiver)"}, assumptions = "shape.getValidAssumption()")
    @SuppressWarnings("unused")
    protected long doCachedLong(DynamicObject receiver,   //
                    @Cached("receiver.getShape()") Shape shape,   //
                    @Cached("getLongLocation(shape)") LongLocation longLocation) {
        return longLocation.getLong(receiver, true);
    }

    protected LongLocation getLongLocation(Shape shape) {
        Property property = shape.getProperty(propertyName);
        if (property != null && property.getLocation() instanceof LongLocation) {
            return (LongLocation) property.getLocation();
        }
        return null;
    }

    /*
     * As soon as we have seen an object read, we cannot avoid boxing long anymore therefore we can
     * contain all long cache entries.
     */
    @Specialization(limit = "CACHE_LIMIT", contains = "doCachedLong", guards = "shape.check(receiver)", assumptions = "shape.getValidAssumption()")
    protected static Object doCachedObject(DynamicObject receiver,   //
                    @Cached("receiver.getShape()") Shape shape,   //
                    @Cached("shape.getProperty(propertyName)") Property property) {
        if (property == null) {
            return SLNull.SINGLETON;
        } else {
            return property.get(receiver, shape);
        }
    }

    /*
     * The generic case is used if the number of shapes accessed overflows the limit.
     */
    @Specialization(contains = "doCachedObject")
    @TruffleBoundary
    protected Object doGeneric(DynamicObject receiver, @Cached("new()") LRUPropertyLookup lruCache) {
        if (!lruCache.shape.check(receiver)) {
            Shape receiverShape = receiver.getShape();
            lruCache.shape = receiverShape;
            lruCache.property = receiverShape.getProperty(propertyName);
        }
        if (lruCache.property != null) {
            return lruCache.property.get(receiver, true);
        } else {
            return SLNull.SINGLETON;
        }
    }

    protected static class LRUPropertyLookup {

        private Shape shape;
        private Property property;

        public LRUPropertyLookup() {
        }

    }

}