/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.jena.sparql.service.enhancer.slice.api;

import java.io.IOException;

public class ReadableChannelOverSliceAccessor<A>
    extends ReadableChannelBase<A>
{
    protected SliceAccessor<A> accessor;
    protected long posInSlice;

    public ReadableChannelOverSliceAccessor(SliceAccessor<A> accessor, long posInSlice) {
        super();
        this.accessor = accessor;
        this.posInSlice = posInSlice;
    }

    @Override
    public ArrayOps<A> getArrayOps() {
        return accessor.getSlice().getArrayOps();
    }

    @Override
    public void closeActual() throws IOException {
        accessor.close();
    }

    @Override
    public int read(A array, int position, int length) throws IOException {
        accessor.claimByOffsetRange(posInSlice, posInSlice + length);
        int result = accessor.unsafeRead(array, position, posInSlice, length);
        if (result > 0) {
            posInSlice += result;
        }
        return result;
    }
}
