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;
import java.util.Map;
import java.util.HashMap;
/** 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 implements Cloneable,Closeable {
private boolean preUTF8Strings; // true if we are reading old (modified UTF8) string format
/** Reads and returns a single byte.
* @see IndexOutput#writeByte(byte)
*/
public abstract byte readByte() throws IOException;
/** Reads a specified number of bytes into an array at the specified offset.
* @param b the array to read bytes into
* @param offset the offset in the array to start storing bytes
* @param len the number of bytes to read
* @see IndexOutput#writeBytes(byte[],int)
*/
public abstract void readBytes(byte[] b, int offset, int len)
throws IOException;
/** Reads a specified number of bytes into an array at the
* specified offset with control over whether the read
* should be buffered (callers who have their own buffer
* should pass in "false" for useBuffer). Currently only
* {@link BufferedIndexInput} respects this parameter.
* @param b the array to read bytes into
* @param offset the offset in the array to start storing bytes
* @param len the number of bytes to read
* @param useBuffer set to false if the caller will handle
* buffering.
* @see IndexOutput#writeBytes(byte[],int)
*/
public void readBytes(byte[] b, int offset, int len, boolean useBuffer)
throws IOException
{
// Default to ignoring useBuffer entirely
readBytes(b, offset, len);
}
/** Reads four bytes and returns an int.
* @see IndexOutput#writeInt(int)
*/
public int readInt() throws IOException {
return ((readByte() & 0xFF) << 24) | ((readByte() & 0xFF) << 16)
| ((readByte() & 0xFF) << 8) | (readByte() & 0xFF);
}
/** Reads an int stored in variable-length format. Reads between one and
* five bytes. Smaller values take fewer bytes. Negative numbers are not
* supported.
* @see IndexOutput#writeVInt(int)
*/
public int readVInt() throws IOException {
byte b = readByte();
int i = b & 0x7F;
for (int shift = 7; (b & 0x80) != 0; shift += 7) {
b = readByte();
i |= (b & 0x7F) << shift;
}
return i;
}
/** Reads eight bytes and returns a long.
* @see IndexOutput#writeLong(long)
*/
public long readLong() throws IOException {
return (((long)readInt()) << 32) | (readInt() & 0xFFFFFFFFL);
}
/** Reads a long stored in variable-length format. Reads between one and
* nine bytes. Smaller values take fewer bytes. Negative numbers are not
* supported. */
public long readVLong() throws IOException {
byte b = readByte();
long i = b & 0x7F;
for (int shift = 7; (b & 0x80) != 0; shift += 7) {
b = readByte();
i |= (b & 0x7FL) << shift;
}
return i;
}
/** Call this if readString should read characters stored
* in the old modified UTF8 format (length in java chars
* and java's modified UTF8 encoding). This is used for
* indices written pre-2.4 See LUCENE-510 for details. */
public void setModifiedUTF8StringsMode() {
preUTF8Strings = true;
}
/** Reads a string.
* @see IndexOutput#writeString(String)
*/
public String readString() throws IOException {
if (preUTF8Strings)
return readModifiedUTF8String();
int length = readVInt();
final byte[] bytes = new byte[length];
readBytes(bytes, 0, length);
return new String(bytes, 0, length, "UTF-8");
}
private String readModifiedUTF8String() throws IOException {
int length = readVInt();
final char[] chars = new char[length];
readChars(chars, 0, length);
return new String(chars, 0, length);
}
/** Reads Lucene's old "modified UTF-8" encoded
* characters into an array.
* @param buffer the array to read characters into
* @param start the offset in the array to start storing characters
* @param length the number of characters to read
* @see IndexOutput#writeChars(String,int,int)
* @deprecated -- please use readString or readBytes
* instead, and construct the string
* from those utf8 bytes
*/
public void readChars(char[] buffer, int start, int length)
throws IOException {
final int end = start + length;
for (int i = start; i < end; i++) {
byte b = readByte();
if ((b & 0x80) == 0)
buffer[i] = (char)(b & 0x7F);
else if ((b & 0xE0) != 0xE0) {
buffer[i] = (char)(((b & 0x1F) << 6)
| (readByte() & 0x3F));
} else
buffer[i] = (char)(((b & 0x0F) << 12)
| ((readByte() & 0x3F) << 6)
| (readByte() & 0x3F));
}
}
/**
* 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
*/
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();
}
}
}
/** 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();
/** Returns a clone of this stream.
*
* <p>Clones of a stream access the same data, and are positioned at the same
* point as the stream they were cloned from.
*
* <p>Expert: Subclasses must ensure that clones may be positioned at
* different points in the input from each other and from the stream they
* were cloned from.
*/
@Override
public Object clone() {
IndexInput clone = null;
try {
clone = (IndexInput)super.clone();
} catch (CloneNotSupportedException e) {}
return clone;
}
public Map<String,String> readStringStringMap() throws IOException {
final Map<String,String> map = new HashMap<String,String>();
final int count = readInt();
for(int i=0;i<count;i++) {
final String key = readString();
final String val = readString();
map.put(key, val);
}
return map;
}
}