com.crowsofwar.avatar.common.data.CachedEntity.java Source code

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Here is the source code for com.crowsofwar.avatar.common.data.CachedEntity.java

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/* 
  This file is part of AvatarMod.
    
  AvatarMod is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.
      
  AvatarMod is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.
      
  You should have received a copy of the GNU General Public License
  along with AvatarMod. If not, see <http://www.gnu.org/licenses/>.
*/

package com.crowsofwar.avatar.common.data;

import javax.annotation.Nullable;

import com.crowsofwar.avatar.common.entity.AvatarEntity;

import io.netty.buffer.ByteBuf;
import net.minecraft.nbt.NBTTagCompound;
import net.minecraft.world.World;

/**
 * Represents an AvatarEntity which is stored by ID but also cached for
 * performance.
 * <p>
 * Note: is not synced; designed to be manipulated by someone with a
 * synchronized ID.
 * 
 * @author CrowsOfWar
 */
public class CachedEntity<T extends AvatarEntity> {

    private T cachedEntity;
    private int entityId;

    public CachedEntity(int id) {
        this.entityId = id;
    }

    /**
     * Reads this cached entity from NBT. Warning: Will use values directly from
     * this compound, so make sure that a sub-compound is used specifically for
     * this cached entity.
     */
    public void readFromNBT(NBTTagCompound nbt) {
        entityId = nbt.getInteger("EntityId");
    }

    public void writeToNBT(NBTTagCompound nbt) {
        nbt.setInteger("EntityId", entityId);
    }

    public void fromBytes(ByteBuf buf) {
        entityId = buf.readInt();
    }

    public void toBytes(ByteBuf buf) {
        buf.writeInt(entityId);
    }

    public int getEntityId() {
        return entityId;
    }

    public void setEntityId(int entityId) {
        this.entityId = entityId;
    }

    /**
     * Gets the entity, searching for it if necessary. Then returns the entity.
     * <p>
     * Null if entity cannot be found.
     */
    public @Nullable T getEntity(World world) {
        if (checkCacheValidity() && entityId > -1) {
            cachedEntity = AvatarEntity.lookupEntity(world, entityId);
        }
        return cachedEntity;
    }

    /**
     * Sets the entity Id and cache. Can be set to null.
     */
    public void setEntity(@Nullable T entity) {
        cachedEntity = entity;
        entityId = entity == null ? -1 : entity.getAvId();
    }

    /**
     * Checks whether the cached entity is invalid (null or dead). If so, sets
     * to null and returns true. Else returns false.
     * 
     * @return whether cache is invalid; if true the cached entity is null
     */
    private boolean checkCacheValidity() {
        if (entityId < 0 || cachedEntity == null || cachedEntity.isDead || cachedEntity.getAvId() != entityId) {
            cachedEntity = null;
            return true;
        }

        return false;
    }

}