org.elasticsearch.common.io.FastCharArrayReader Maven / Gradle / Ivy
/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch 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.elasticsearch.common.io;
import java.io.IOException;
import java.io.Reader;
/**
*
*/
public class FastCharArrayReader extends Reader {
/**
* The character buffer.
*/
protected char buf[];
/**
* The current buffer position.
*/
protected int pos;
/**
* The position of mark in buffer.
*/
protected int markedPos = 0;
/**
* The index of the end of this buffer. There is not valid
* data at or beyond this index.
*/
protected int count;
/**
* Creates a CharArrayReader from the specified array of chars.
*
* @param buf Input buffer (not copied)
*/
public FastCharArrayReader(char buf[]) {
this.buf = buf;
this.pos = 0;
this.count = buf.length;
}
/**
* Creates a CharArrayReader from the specified array of chars.
*
* The resulting reader will start reading at the given
* offset. The total number of char values that can be
* read from this reader will be either length or
* buf.length-offset, whichever is smaller.
*
* @param buf Input buffer (not copied)
* @param offset Offset of the first char to read
* @param length Number of chars to read
* @throws IllegalArgumentException If offset is negative or greater than
* buf.length, or if length is negative, or if
* the sum of these two values is negative.
*/
public FastCharArrayReader(char buf[], int offset, int length) {
if ((offset < 0) || (offset > buf.length) || (length < 0) ||
((offset + length) < 0)) {
throw new IllegalArgumentException();
}
this.buf = buf;
this.pos = offset;
this.count = Math.min(offset + length, buf.length);
this.markedPos = offset;
}
/**
* Checks to make sure that the stream has not been closed
*/
private void ensureOpen() throws IOException {
if (buf == null)
throw new IOException("Stream closed");
}
/**
* Reads a single character.
*
* @throws IOException If an I/O error occurs
*/
@Override
public int read() throws IOException {
ensureOpen();
if (pos >= count)
return -1;
else
return buf[pos++];
}
/**
* Reads characters into a portion of an array.
*
* @param b Destination buffer
* @param off Offset at which to start storing characters
* @param len Maximum number of characters to read
* @return The actual number of characters read, or -1 if
* the end of the stream has been reached
* @throws IOException If an I/O error occurs
*/
@Override
public int read(char b[], int off, int len) throws IOException {
ensureOpen();
if ((off < 0) || (off > b.length) || (len < 0) ||
((off + len) > b.length) || ((off + len) < 0)) {
throw new IndexOutOfBoundsException();
} else if (len == 0) {
return 0;
}
if (pos >= count) {
return -1;
}
if (pos + len > count) {
len = count - pos;
}
if (len <= 0) {
return 0;
}
System.arraycopy(buf, pos, b, off, len);
pos += len;
return len;
}
/**
* Skips characters. Returns the number of characters that were skipped.
*
* The n parameter may be negative, even though the
* skip method of the {@link Reader} superclass throws
* an exception in this case. If n is negative, then
* this method does nothing and returns 0.
*
* @param n The number of characters to skip
* @return The number of characters actually skipped
* @throws IOException If the stream is closed, or an I/O error occurs
*/
@Override
public long skip(long n) throws IOException {
ensureOpen();
if (pos + n > count) {
n = count - pos;
}
if (n < 0) {
return 0;
}
pos += n;
return n;
}
/**
* Tells whether this stream is ready to be read. Character-array readers
* are always ready to be read.
*
* @throws IOException If an I/O error occurs
*/
@Override
public boolean ready() throws IOException {
ensureOpen();
return (count - pos) > 0;
}
/**
* Tells whether this stream supports the mark() operation, which it does.
*/
@Override
public boolean markSupported() {
return true;
}
/**
* Marks the present position in the stream. Subsequent calls to reset()
* will reposition the stream to this point.
*
* @param readAheadLimit Limit on the number of characters that may be
* read while still preserving the mark. Because
* the stream's input comes from a character array,
* there is no actual limit; hence this argument is
* ignored.
* @throws IOException If an I/O error occurs
*/
@Override
public void mark(int readAheadLimit) throws IOException {
ensureOpen();
markedPos = pos;
}
/**
* Resets the stream to the most recent mark, or to the beginning if it has
* never been marked.
*
* @throws IOException If an I/O error occurs
*/
@Override
public void reset() throws IOException {
ensureOpen();
pos = markedPos;
}
/**
* Closes the stream and releases any system resources associated with
* it. Once the stream has been closed, further read(), ready(),
* mark(), reset(), or skip() invocations will throw an IOException.
* Closing a previously closed stream has no effect.
*/
@Override
public void close() {
buf = null;
}
}