Paper/src/main/java/net/minecraft/server/LongHashtable.java

package net.minecraft.server;

import java.util.ArrayList;
import java.util.Arrays;

public class LongHashtable<V> extends LongHash
{
    Object values[][][] = new Object[256][][];
    Entry cache = null;

    public void put(int msw, int lsw, V value) {
        put(toLong(msw, lsw), value);
    }

    public V get(int msw, int lsw) {
        return get(toLong(msw, lsw));
    }

    public void put(long key, V value) {
        int mainIdx = (int) (key & 255);
        int outerIdx = (int) ((key >> 32) & 255);
        Object outer[][] = this.values[mainIdx], inner[];
        if (outer == null)
            this.values[mainIdx] = outer = new Object[256][];
        inner = outer[outerIdx];
        if (inner == null) {
            outer[outerIdx] = inner = new Object[5];
            inner[0] = cache = new Entry(key, value);
        } else {
            int i;
            for (i = 0; i < inner.length; i++) {
                if (inner[i] == null || ((Entry) inner[i]).key == key) {
                    inner[i] = cache = new Entry(key, value);
                    return;
                }
            }
            outer[outerIdx] = inner = Arrays.copyOf(inner, i + i);
            inner[i] = new Entry(key, value);
        }
    }

    public V get(long key) {
        return containsKey(key) ? (V) cache.value : null;
    }

    public boolean containsKey(long key) {
        if (cache != null && cache.key == key)
            return true;
        int mainIdx = (int) (key & 255);
        int outerIdx = (int) ((key >> 32) & 255);
        Object outer[][] = this.values[mainIdx], inner[];
        if (outer == null)
            return false;
        inner = outer[outerIdx];
        if (inner == null)
            return false;
        else {
            for (int i = 0; i < inner.length; i++) {
                Entry e = (Entry) inner[i];
                if (e == null)
                    return false;
                else if (e.key == key) {
                    cache = e;
                    return true;
                }
            }
            return false;
        }
    }

    public void remove(long key) {
        Object[][] outer = this.values[(int) (key & 255)];
        if (outer == null) return;

        Object[] inner = outer[(int) ((key >> 32) & 255)];
        if (inner == null) return;

        for (int i = 0; i < inner.length; i++) {
            // No more data! bail
            if (inner[i] == null) continue;

            // Found our key -- purge it
            if (((Entry) inner[i]).key == key) {

                // Move all the elements down
                for (i++; i < inner.length; i++) {
                    if (inner[i] == null) break;
                    inner[i-1] = inner[i];
                }
                inner[i-1] = null;
                cache = null;
                return;
            }
        }        
    }
    
    public ArrayList<V> values() {
        ArrayList<V> ret = new ArrayList<V>();
        for (Object[][] outer : this.values) {
            if (outer == null)
                continue;
            for (Object[] inner : outer) {
                if (inner == null)
                    continue;
                for (Object entry : inner) {
                    if (entry == null)
                        break;
                    ret.add((V) ((Entry) entry).value);
                }
            }
        }
        return ret;
    }

    private class Entry
    {
        long key;
        Object value;

        Entry(long k, Object v) {
            key = k;
            value = v;
        }
    }
}