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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
 * data (collectively the "Software"), free of charge and under any and all
 * copyright rights in the Software, and any and all patent rights owned or
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 * unmodified Software as contributed to or provided by such licensor, or (ii)
 * the Larger Works (as defined below), to deal in both
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 * (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
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package com.oracle.truffle.js.nodes.access;

import java.util.ArrayList;
import java.util.List;
import java.util.Set;

import com.oracle.truffle.api.CompilerDirectives;
import com.oracle.truffle.api.frame.Frame;
import com.oracle.truffle.api.frame.FrameDescriptor;
import com.oracle.truffle.api.frame.FrameSlot;
import com.oracle.truffle.api.frame.FrameUtil;
import com.oracle.truffle.api.frame.VirtualFrame;
import com.oracle.truffle.api.instrumentation.Tag;
import com.oracle.truffle.api.nodes.NodeCost;
import com.oracle.truffle.api.nodes.NodeInfo;
import com.oracle.truffle.js.nodes.JavaScriptNode;
import com.oracle.truffle.js.nodes.ReadNode;
import com.oracle.truffle.js.runtime.JSArguments;
import com.oracle.truffle.js.runtime.JSFrameUtil;

public abstract class LazyReadFrameSlotNode extends JavaScriptNode implements ReadNode {
    protected final Object identifier;

    public LazyReadFrameSlotNode(Object identifier) {
        this.identifier = identifier;
    }

    public Object getIdentifier() {
        return identifier;
    }

    public static LazyReadFrameSlotNode create(Object identifier) {
        return new LazyReadFrameSlotUninitNode(identifier);
    }

    @Override
    protected JavaScriptNode copyUninitialized(Set<Class<? extends Tag>> materializedTags) {
        return copy();
    }

    @NodeInfo(cost = NodeCost.UNINITIALIZED)
    private static final class LazyReadFrameSlotUninitNode extends LazyReadFrameSlotNode {
        LazyReadFrameSlotUninitNode(Object identifier) {
            super(identifier);
        }

        @Override
        public Object execute(VirtualFrame frame) {
            CompilerDirectives.transferToInterpreterAndInvalidate();

            Frame outerFrame = frame;
            for (int frameLevel = 0;; frameLevel++) {
                Frame outerScope = outerFrame;
                List<FrameSlot> parentSlotList = new ArrayList<>();
                for (int scopeLevel = 0;; scopeLevel++) {
                    FrameDescriptor outerFrameDescriptor = outerScope.getFrameDescriptor();
                    FrameSlot slot = outerFrameDescriptor.findFrameSlot(identifier);
                    if (slot != null) {
                        FrameSlot[] parentSlots = parentSlotList.toArray(ScopeFrameNode.EMPTY_FRAME_SLOT_ARRAY);
                        ScopeFrameNode scopeFrameNode = ScopeFrameNode.create(frameLevel, scopeLevel, parentSlots);
                        JSReadFrameSlotNode resolved = JSReadFrameSlotNode.create(slot, scopeFrameNode, JSFrameUtil.hasTemporalDeadZone(slot));
                        return this.replace(resolved).execute(frame);
                    }

                    FrameSlot parentSlot = outerFrameDescriptor.findFrameSlot(ScopeFrameNode.PARENT_SCOPE_IDENTIFIER);
                    if (parentSlot == null) {
                        break;
                    }
                    outerScope = (Frame) FrameUtil.getObjectSafe(outerScope, parentSlot);
                    parentSlotList.add(parentSlot);
                }

                outerFrame = JSArguments.getEnclosingFrame(outerFrame.getArguments());
                if (outerFrame == JSFrameUtil.NULL_MATERIALIZED_FRAME) {
                    break;
                }
            }

            throw new RuntimeException("frame slot not found");
        }
    }
}