org.apache.solr.internal.csv.ExtendedBufferedReader Maven / Gradle / Ivy
/*
* 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.solr.internal.csv;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.Reader;
/**
* ExtendedBufferedReader
*
* A special reader decorater which supports more
* sophisticated access to the underlying reader object.
*
* In particular the reader supports a look-ahead option,
* which allows you to see the next char returned by
* next().
* Furthermore the skip-method supports skipping until
* (but excluding) a given char. Similar functionality
* is supported by the reader as well.
*
*/
class ExtendedBufferedReader extends BufferedReader {
/** the end of stream symbol */
public static final int END_OF_STREAM = -1;
/** undefined state for the lookahead char */
public static final int UNDEFINED = -2;
/** the lookahead chars */
private int lookaheadChar = UNDEFINED;
/** the last char returned */
private int lastChar = UNDEFINED;
/** the line counter */
private int lineCounter = 0;
private CharBuffer line = new CharBuffer();
/**
* Created extended buffered reader using default buffer-size
*
*/
public ExtendedBufferedReader(Reader r) {
super(r);
/* note uh: do not fetch the first char here,
* because this might block the method!
*/
}
/**
* Create extended buffered reader using the given buffer-size
*/
public ExtendedBufferedReader(Reader r, int bufSize) {
super(r, bufSize);
/* note uh: do not fetch the first char here,
* because this might block the method!
*/
}
/**
* Reads the next char from the input stream.
* @return the next char or END_OF_STREAM if end of stream has been reached.
*/
@Override
public int read() throws IOException {
// initialize the lookahead
if (lookaheadChar == UNDEFINED) {
lookaheadChar = super.read();
}
lastChar = lookaheadChar;
if (super.ready()) {
lookaheadChar = super.read();
} else {
lookaheadChar = UNDEFINED;
}
if (lastChar == '\n') {
lineCounter++;
}
return lastChar;
}
/**
* Returns the last read character again.
*
* @return the last read char or UNDEFINED
*/
public int readAgain() {
return lastChar;
}
/**
* Non-blocking reading of len chars into buffer buf starting
* at bufferposition off.
*
* performs an iterative read on the underlying stream
* as long as the following conditions hold:
* - less than len chars have been read
* - end of stream has not been reached
* - next read is not blocking
*
* @return nof chars actually read or END_OF_STREAM
*/
@Override
public int read(char[] buf, int off, int len) throws IOException {
// do not claim if len == 0
if (len == 0) {
return 0;
}
// init lookahead, but do not block !!
if (lookaheadChar == UNDEFINED) {
if (ready()) {
lookaheadChar = super.read();
} else {
return -1;
}
}
// 'first read of underlying stream'
if (lookaheadChar == -1) {
return -1;
}
// continue until the lookaheadChar would block
int cOff = off;
while (len > 0 && ready()) {
if (lookaheadChar == -1) {
// eof stream reached, do not continue
return cOff - off;
} else {
buf[cOff++] = (char) lookaheadChar;
if (lookaheadChar == '\n') {
lineCounter++;
}
lastChar = lookaheadChar;
lookaheadChar = super.read();
len--;
}
}
return cOff - off;
}
/**
* Reads all characters up to (but not including) the given character.
*
* @param c the character to read up to
* @return the string up to the character c
* @throws IOException If there is a low-level I/O error.
*/
public String readUntil(char c) throws IOException {
if (lookaheadChar == UNDEFINED) {
lookaheadChar = super.read();
}
line.clear(); // reuse
while (lookaheadChar != c && lookaheadChar != END_OF_STREAM) {
line.append((char) lookaheadChar);
if (lookaheadChar == '\n') {
lineCounter++;
}
lastChar = lookaheadChar;
lookaheadChar = super.read();
}
return line.toString();
}
/**
* @return A String containing the contents of the line, not
* including any line-termination characters, or null
* if the end of the stream has been reached
*/
@Override
public String readLine() throws IOException {
if (lookaheadChar == UNDEFINED) {
lookaheadChar = super.read();
}
line.clear(); //reuse
// return null if end of stream has been reached
if (lookaheadChar == END_OF_STREAM) {
return null;
}
// do we have a line termination already
char laChar = (char) lookaheadChar;
if (laChar == '\n' || laChar == '\r') {
lastChar = lookaheadChar;
lookaheadChar = super.read();
// ignore '\r\n' as well
if ((char) lookaheadChar == '\n') {
lastChar = lookaheadChar;
lookaheadChar = super.read();
}
lineCounter++;
return line.toString();
}
// create the rest-of-line return and update the lookahead
line.append(laChar);
String restOfLine = super.readLine(); // TODO involves copying
lastChar = lookaheadChar;
lookaheadChar = super.read();
if (restOfLine != null) {
line.append(restOfLine);
}
lineCounter++;
return line.toString();
}
/**
* Skips char in the stream
*
* ATTENTION: invalidates the line-counter !!!!!
*
* @return nof skiped chars
*/
@Override
public long skip(long n) throws IllegalArgumentException, IOException {
if (lookaheadChar == UNDEFINED) {
lookaheadChar = super.read();
}
// illegal argument
if (n < 0) {
throw new IllegalArgumentException("negative argument not supported");
}
// no skipping
if (n == 0 || lookaheadChar == END_OF_STREAM) {
return 0;
}
// skip and reread the lookahead-char
long skiped = 0;
if (n > 1) {
skiped = super.skip(n - 1);
}
lookaheadChar = super.read();
// fixme uh: we should check the skiped sequence for line-terminations...
lineCounter = Integer.MIN_VALUE;
return skiped + 1;
}
/**
* Skips all chars in the input until (but excluding) the given char
*
* @return counter
* @throws IOException If there is a low-level I/O error.
*/
public long skipUntil(char c) throws IllegalArgumentException, IOException {
if (lookaheadChar == UNDEFINED) {
lookaheadChar = super.read();
}
long counter = 0;
while (lookaheadChar != c && lookaheadChar != END_OF_STREAM) {
if (lookaheadChar == '\n') {
lineCounter++;
}
lookaheadChar = super.read();
counter++;
}
return counter;
}
/**
* Returns the next char in the stream without consuming it.
*
* Remember the next char read by read(..) will always be
* identical to lookAhead().
*
* @return the next char (without consuming it) or END_OF_STREAM
*/
public int lookAhead() throws IOException {
if (lookaheadChar == UNDEFINED) {
lookaheadChar = super.read();
}
return lookaheadChar;
}
/**
* Returns the nof line read
* ATTENTION: the skip-method does invalidate the line-number counter
*
* @return the current-line-number (or -1)
*/
public int getLineNumber() {
if (lineCounter > -1) {
return lineCounter;
} else {
return -1;
}
}
@Override
public boolean markSupported() {
/* note uh: marking is not supported, cause we cannot
* see into the future...
*/
return false;
}
}