com.prealpha.minelib.nbt.ListTag.java Source code

Introduction

Here is the source code for com.prealpha.minelib.nbt.ListTag.java

Source

/*
 * Minelib, a Minecraft library
 * Copyright (C) 2011 Meyer Kizner
 * 
 * This file is part of Minelib.
 * 
 * Minelib 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.
 * 
 * Minelib 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
 * Minelib. If not, see <http://www.gnu.org/licenses/>.
 */

package com.prealpha.minelib.nbt;

import static com.google.common.base.Preconditions.*;

import java.nio.ByteBuffer;
import java.util.Collection;
import java.util.List;

import com.google.common.collect.Constraint;
import com.google.common.collect.Constraints;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Lists;

public final class ListTag extends Tag {
    private final List<Tag> value;

    private final Type elementType;

    public ListTag(Type elementType) {
        checkNotNull(elementType);
        this.elementType = elementType;
        List<Tag> baseList = Lists.newArrayList();
        Constraint<Tag> constraint = new TypeConstraint();
        value = Constraints.constrainedList(baseList, constraint);
    }

    public ListTag(Collection<? extends Tag> collection) {
        checkArgument(!collection.isEmpty());
        List<Tag> baseList = Lists.newArrayList(collection);
        elementType = baseList.get(0).getTagType();
        Constraint<Tag> constraint = new TypeConstraint();
        for (Tag tag : baseList) {
            constraint.checkElement(tag);
        }
        value = Constraints.constrainedList(baseList, constraint);
    }

    @Override
    public Type getTagType() {
        return Type.LIST;
    }

    @Override
    public List<Tag> getValue() {
        return value;
    }

    public Type getElementType() {
        return elementType;
    }

    @Override
    public ByteBuffer toBytes() {
        // make a copy to avoid encoding twice
        List<ByteBuffer> payloadBytes = ImmutableList.copyOf(Lists.transform(value, Tag.ENCODER));

        int length = 5; // for the element type (1) and count (4)
        for (ByteBuffer buffer : payloadBytes) {
            length += buffer.capacity();
        }

        ByteBuffer payload = ByteBuffer.allocate(length);
        payload.put(elementType.getBinaryType());
        payload.putInt(value.size());
        for (ByteBuffer buffer : payloadBytes) {
            payload.put(buffer);
        }
        payload.position(0);
        return payload;
    }

    private final class TypeConstraint implements Constraint<Tag> {
        @Override
        public Tag checkElement(Tag element) {
            checkArgument(element.getTagType() == elementType);
            return element;
        }
    }
}