CustomMapTable.java

/*
 * Copyright (c) 2016. Starlis LLC / dba Empire Minecraft
 *
 * This source code is proprietary software and must not be redistributed without Starlis LLC's approval
 *
 */

package com.empireminecraft.util.java;

import com.google.common.base.Supplier;
import com.google.common.collect.HashBasedTable;
import com.google.common.collect.Table;
import it.unimi.dsi.fastutil.longs.Long2ObjectOpenHashMap;

import java.lang.reflect.Field;
import java.util.Map;

@SuppressWarnings({"Guava", "Convert2MethodRef"})
public final class CustomMapTable {
    private static Field BACKING_MAP;
    private static Field FACTORY;
    static {
        try {
            Class STANDARD_TABLE = Class.forName("com.google.common.collect.StandardTable");
            BACKING_MAP = STANDARD_TABLE.getDeclaredField("backingMap");
            FACTORY = STANDARD_TABLE.getDeclaredField("factory");
            BACKING_MAP.setAccessible(true);
            FACTORY.setAccessible(true);
        } catch (ClassNotFoundException | NoSuchFieldException e) {
            e.printStackTrace();
        }
    }

    private CustomMapTable() {
    }

    public static <R, C, V> Table<R, C, V> create(Supplier<Map<R, Map<C, V>>> rowMap, Supplier<? extends Map<C, V>> columnMap) {
        if (BACKING_MAP == null || FACTORY == null) {
            throw new IllegalStateException("Could not replace backing map or factory");
        }

        final HashBasedTable<R, C, V> backing = HashBasedTable.create();
        try {
            BACKING_MAP.set(backing, rowMap.get());
            FACTORY.set(backing, columnMap);
        } catch (IllegalAccessException e) {
            throw new IllegalStateException("Could not replace backing map or factory", e);
        }
        return backing;
    }

    // Don't know why but constructor references won't compile, must be lamda
    public static <V> Table<Long, Long, V> createLongLong() {
        return create(() -> new Long2ObjectOpenHashMap<>(), () -> new Long2ObjectOpenHashMap<>());
    }

    public static <C, V> Table<Long, C, V> createLong(Supplier<? extends Map<C, V>> columnMap) {
        return create(() -> new Long2ObjectOpenHashMap<>(), columnMap);
    }
}