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/*
 * Copyright (c) 2008-2019, Hazelcast, Inc. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.hazelcast.map.impl.iterator;

import com.hazelcast.map.impl.MapDataSerializerHook;
import com.hazelcast.nio.ObjectDataInput;
import com.hazelcast.nio.ObjectDataOutput;
import com.hazelcast.nio.serialization.IdentifiedDataSerializable;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

/**
 * Base class for a cursor class holding a collection of items and the next position from which to resume fetching.
 *
 * @param  the type of item being iterated
 */
public abstract class AbstractCursor implements IdentifiedDataSerializable {
    private List objects;
    private int nextTableIndexToReadFrom;

    public AbstractCursor() {
    }

    public AbstractCursor(List entries, int nextTableIndexToReadFrom) {
        this.objects = entries;
        this.nextTableIndexToReadFrom = nextTableIndexToReadFrom;
    }

    public List getBatch() {
        return objects;
    }

    public int getNextTableIndexToReadFrom() {
        return nextTableIndexToReadFrom;
    }

    @Override
    public int getFactoryId() {
        return MapDataSerializerHook.F_ID;
    }

    abstract void writeElement(ObjectDataOutput out, T element) throws IOException;

    abstract T readElement(ObjectDataInput in) throws IOException;

    @Override
    public void writeData(ObjectDataOutput out) throws IOException {
        out.writeInt(nextTableIndexToReadFrom);
        int size = objects.size();
        out.writeInt(size);
        for (T entry : objects) {
            writeElement(out, entry);
        }
    }

    @Override
    public void readData(ObjectDataInput in) throws IOException {
        nextTableIndexToReadFrom = in.readInt();
        int size = in.readInt();
        objects = new ArrayList(size);
        for (int i = 0; i < size; i++) {
            objects.add(readElement(in));
        }
    }
}