package org.apache.lucene.store;
/**
* 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.
*/
import java.io.IOException;
import java.io.Closeable;
/** Abstract base class for input from a file in a {@link Directory}. A
* random-access input stream. Used for all Lucene index input operations.
* @see Directory
*/
public abstract class IndexInput extends DataInput implements Cloneable,Closeable {
/**
* Expert
*
* Similar to {@link #readChars(char[], int, int)} but does not do any conversion operations on the bytes it is reading in. It still
* has to invoke {@link #readByte()} just as {@link #readChars(char[], int, int)} does, but it does not need a buffer to store anything
* and it does not have to do any of the bitwise operations, since we don't actually care what is in the byte except to determine
* how many more bytes to read
* @param length The number of chars to read
* @deprecated this method operates on old "modified utf8" encoded
* strings
*/
@Deprecated
public void skipChars(int length) throws IOException{
for (int i = 0; i < length; i++) {
byte b = readByte();
if ((b & 0x80) == 0){
//do nothing, we only need one byte
} else if ((b & 0xE0) != 0xE0) {
readByte();//read an additional byte
} else {
//read two additional bytes.
readByte();
readByte();
}
}
}
private final String resourceDescription;
/** @deprecated please pass resourceDescription */
@Deprecated
protected IndexInput() {
this("anonymous IndexInput");
}
/** resourceDescription should be a non-null, opaque string
* describing this resource; it's returned from
* {@link #toString}. */
protected IndexInput(String resourceDescription) {
if (resourceDescription == null) {
throw new IllegalArgumentException("resourceDescription must not be null");
}
this.resourceDescription = resourceDescription;
}
/** Closes the stream to further operations. */
public abstract void close() throws IOException;
/** Returns the current position in this file, where the next read will
* occur.
* @see #seek(long)
*/
public abstract long getFilePointer();
/** Sets current position in this file, where the next read will occur.
* @see #getFilePointer()
*/
public abstract void seek(long pos) throws IOException;
/** The number of bytes in the file. */
public abstract long length();
/**
* Copies <code>numBytes</code> bytes to the given {@link IndexOutput}.
* <p>
* <b>NOTE:</b> this method uses an intermediate buffer to copy the bytes.
* Consider overriding it in your implementation, if you can make a better,
* optimized copy.
* <p>
* <b>NOTE</b> ensure that there are enough bytes in the input to copy to
* output. Otherwise, different exceptions may be thrown, depending on the
* implementation.
*/
public void copyBytes(IndexOutput out, long numBytes) throws IOException {
assert numBytes >= 0: "numBytes=" + numBytes;
byte copyBuf[] = new byte[BufferedIndexInput.BUFFER_SIZE];
while (numBytes > 0) {
final int toCopy = (int) (numBytes > copyBuf.length ? copyBuf.length : numBytes);
readBytes(copyBuf, 0, toCopy);
out.writeBytes(copyBuf, 0, toCopy);
numBytes -= toCopy;
}
}
@Override
public String toString() {
return resourceDescription;
}
}