org.apache.lucene.store.ByteArrayDataInput.java Source code

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Here is the source code for org.apache.lucene.store.ByteArrayDataInput.java

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/*
 * 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.lucene.store;

import org.apache.lucene.util.BytesRef;

/** 
 * DataInput backed by a byte array.
 * <b>WARNING:</b> This class omits all low-level checks.
 * @lucene.experimental 
 */
public final class ByteArrayDataInput extends DataInput {

    private byte[] bytes;

    private int pos;
    private int limit;

    public ByteArrayDataInput(byte[] bytes) {
        reset(bytes);
    }

    public ByteArrayDataInput(byte[] bytes, int offset, int len) {
        reset(bytes, offset, len);
    }

    public ByteArrayDataInput() {
        reset(BytesRef.EMPTY_BYTES);
    }

    public void reset(byte[] bytes) {
        reset(bytes, 0, bytes.length);
    }

    // NOTE: sets pos to 0, which is not right if you had
    // called reset w/ non-zero offset!!
    public void rewind() {
        pos = 0;
    }

    public int getPosition() {
        return pos;
    }

    public void setPosition(int pos) {
        this.pos = pos;
    }

    public void reset(byte[] bytes, int offset, int len) {
        this.bytes = bytes;
        pos = offset;
        limit = offset + len;
    }

    public int length() {
        return limit;
    }

    public boolean eof() {
        return pos == limit;
    }

    @Override
    public void skipBytes(long count) {
        pos += count;
    }

    @Override
    public short readShort() {
        return (short) (((bytes[pos++] & 0xFF) << 8) | (bytes[pos++] & 0xFF));
    }

    @Override
    public int readInt() {
        return ((bytes[pos++] & 0xFF) << 24) | ((bytes[pos++] & 0xFF) << 16) | ((bytes[pos++] & 0xFF) << 8)
                | (bytes[pos++] & 0xFF);
    }

    @Override
    public long readLong() {
        final int i1 = ((bytes[pos++] & 0xff) << 24) | ((bytes[pos++] & 0xff) << 16) | ((bytes[pos++] & 0xff) << 8)
                | (bytes[pos++] & 0xff);
        final int i2 = ((bytes[pos++] & 0xff) << 24) | ((bytes[pos++] & 0xff) << 16) | ((bytes[pos++] & 0xff) << 8)
                | (bytes[pos++] & 0xff);
        return (((long) i1) << 32) | (i2 & 0xFFFFFFFFL);
    }

    @Override
    public int readVInt() {
        byte b = bytes[pos++];
        if (b >= 0)
            return b;
        int i = b & 0x7F;
        b = bytes[pos++];
        i |= (b & 0x7F) << 7;
        if (b >= 0)
            return i;
        b = bytes[pos++];
        i |= (b & 0x7F) << 14;
        if (b >= 0)
            return i;
        b = bytes[pos++];
        i |= (b & 0x7F) << 21;
        if (b >= 0)
            return i;
        b = bytes[pos++];
        // Warning: the next ands use 0x0F / 0xF0 - beware copy/paste errors:
        i |= (b & 0x0F) << 28;
        if ((b & 0xF0) == 0)
            return i;
        throw new RuntimeException("Invalid vInt detected (too many bits)");
    }

    @Override
    public long readVLong() {
        byte b = bytes[pos++];
        if (b >= 0)
            return b;
        long i = b & 0x7FL;
        b = bytes[pos++];
        i |= (b & 0x7FL) << 7;
        if (b >= 0)
            return i;
        b = bytes[pos++];
        i |= (b & 0x7FL) << 14;
        if (b >= 0)
            return i;
        b = bytes[pos++];
        i |= (b & 0x7FL) << 21;
        if (b >= 0)
            return i;
        b = bytes[pos++];
        i |= (b & 0x7FL) << 28;
        if (b >= 0)
            return i;
        b = bytes[pos++];
        i |= (b & 0x7FL) << 35;
        if (b >= 0)
            return i;
        b = bytes[pos++];
        i |= (b & 0x7FL) << 42;
        if (b >= 0)
            return i;
        b = bytes[pos++];
        i |= (b & 0x7FL) << 49;
        if (b >= 0)
            return i;
        b = bytes[pos++];
        i |= (b & 0x7FL) << 56;
        if (b >= 0)
            return i;
        throw new RuntimeException("Invalid vLong detected (negative values disallowed)");
    }

    // NOTE: AIOOBE not EOF if you read too much
    @Override
    public byte readByte() {
        return bytes[pos++];
    }

    // NOTE: AIOOBE not EOF if you read too much
    @Override
    public void readBytes(byte[] b, int offset, int len) {
        System.arraycopy(bytes, pos, b, offset, len);
        pos += len;
    }
}