| /* BufferedReader.java |
| Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005 |
| Free Software Foundation, Inc. |
| |
| This file is part of GNU Classpath. |
| |
| GNU Classpath is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 2, or (at your option) |
| any later version. |
| |
| GNU Classpath is distributed in the hope that it will be useful, but |
| WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with GNU Classpath; see the file COPYING. If not, write to the |
| Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA |
| 02111-1307 USA. |
| |
| Linking this library statically or dynamically with other modules is |
| making a combined work based on this library. Thus, the terms and |
| conditions of the GNU General Public License cover the whole |
| combination. |
| |
| As a special exception, the copyright holders of this library give you |
| permission to link this library with independent modules to produce an |
| executable, regardless of the license terms of these independent |
| modules, and to copy and distribute the resulting executable under |
| terms of your choice, provided that you also meet, for each linked |
| independent module, the terms and conditions of the license of that |
| module. An independent module is a module which is not derived from |
| or based on this library. If you modify this library, you may extend |
| this exception to your version of the library, but you are not |
| obligated to do so. If you do not wish to do so, delete this |
| exception statement from your version. */ |
| |
| |
| package java.io; |
| |
| /* Written using "Java Class Libraries", 2nd edition, plus online |
| * API docs for JDK 1.2 beta from http://www.javasoft.com. |
| * Status: Believed complete and correct. |
| */ |
| |
| /** |
| * This subclass of <code>FilterReader</code> buffers input from an |
| * underlying implementation to provide a possibly more efficient read |
| * mechanism. It maintains the buffer and buffer state in instance |
| * variables that are available to subclasses. The default buffer size |
| * of 8192 chars can be overridden by the creator of the stream. |
| * <p> |
| * This class also implements mark/reset functionality. It is capable |
| * of remembering any number of input chars, to the limits of |
| * system memory or the size of <code>Integer.MAX_VALUE</code> |
| * |
| * @author Per Bothner (bothner@cygnus.com) |
| * @author Aaron M. Renn (arenn@urbanophile.com) |
| */ |
| public class BufferedReader extends Reader |
| { |
| Reader in; |
| char[] buffer; |
| /* Index of current read position. Must be >= 0 and <= limit. */ |
| /* There is a special case where pos may be equal to limit+1; this |
| * is used as an indicator that a readLine was done with a '\r' was |
| * the very last char in the buffer. Since we don't want to read-ahead |
| * and potentially block, we set pos this way to indicate the situation |
| * and deal with it later. Doing it this way rather than having a |
| * separate boolean field to indicate the condition has the advantage |
| * that it is self-clearing on things like mark/reset. |
| */ |
| int pos; |
| /* Limit of valid data in buffer. Must be >= pos and <= buffer.length. */ |
| /* This can be < pos in the one special case described above. */ |
| int limit; |
| |
| /* The value -1 means there is no mark, or the mark has been invalidated. |
| Otherwise, markPos is the index in the buffer of the marked position. |
| Must be >= 0 and <= pos. |
| Note we do not explicitly store the read-limit. |
| The implicit read-limit is (buffer.length - markPos), which is |
| guaranteed to be >= the read-limit requested in the call to mark. */ |
| int markPos = -1; |
| |
| // The JCL book specifies the default buffer size as 8K characters. |
| // This is package-private because it is used by LineNumberReader. |
| static final int DEFAULT_BUFFER_SIZE = 8192; |
| |
| /** |
| * The line buffer for <code>readLine</code>. |
| */ |
| private StringBuffer sbuf = null; |
| |
| /** |
| * Create a new <code>BufferedReader</code> that will read from the |
| * specified subordinate stream with a default buffer size of 8192 chars. |
| * |
| * @param in The subordinate stream to read from |
| */ |
| public BufferedReader(Reader in) |
| { |
| this(in, DEFAULT_BUFFER_SIZE); |
| } |
| |
| /** |
| * Create a new <code>BufferedReader</code> that will read from the |
| * specified subordinate stream with a buffer size that is specified by the |
| * caller. |
| * |
| * @param in The subordinate stream to read from |
| * @param size The buffer size to use |
| * |
| * @exception IllegalArgumentException if size <= 0 |
| */ |
| public BufferedReader(Reader in, int size) |
| { |
| super(in.lock); |
| if (size <= 0) |
| throw new IllegalArgumentException("Illegal buffer size: " + size); |
| this.in = in; |
| buffer = new char[size]; |
| } |
| |
| /** |
| * This method closes the underlying stream and frees any associated |
| * resources. |
| * |
| * @exception IOException If an error occurs |
| */ |
| public void close() throws IOException |
| { |
| synchronized (lock) |
| { |
| if (in != null) |
| in.close(); |
| in = null; |
| buffer = null; |
| } |
| } |
| |
| /** |
| * Returns <code>true</code> to indicate that this class supports mark/reset |
| * functionality. |
| * |
| * @return <code>true</code> |
| */ |
| public boolean markSupported() |
| { |
| return true; |
| } |
| |
| /** |
| * Mark a position in the input to which the stream can be |
| * "reset" by calling the <code>reset()</code> method. The parameter |
| * <code>readLimit</code> is the number of chars that can be read from the |
| * stream after setting the mark before the mark becomes invalid. For |
| * example, if <code>mark()</code> is called with a read limit of 10, then |
| * when 11 chars of data are read from the stream before the |
| * <code>reset()</code> method is called, then the mark is invalid and the |
| * stream object instance is not required to remember the mark. |
| * <p> |
| * Note that the number of chars that can be remembered by this method |
| * can be greater than the size of the internal read buffer. It is also |
| * not dependent on the subordinate stream supporting mark/reset |
| * functionality. |
| * |
| * @param readLimit The number of chars that can be read before the mark |
| * becomes invalid |
| * |
| * @exception IOException If an error occurs |
| * @exception IllegalArgumentException if readLimit is negative. |
| */ |
| public void mark(int readLimit) throws IOException |
| { |
| if (readLimit < 0) |
| throw new IllegalArgumentException("Read-ahead limit is negative"); |
| |
| synchronized (lock) |
| { |
| checkStatus(); |
| // In this method we need to be aware of the special case where |
| // pos + 1 == limit. This indicates that a '\r' was the last char |
| // in the buffer during a readLine. We'll want to maintain that |
| // condition after we shift things around and if a larger buffer is |
| // needed to track readLimit, we'll have to make it one element |
| // larger to ensure we don't invalidate the mark too early, if the |
| // char following the '\r' is NOT a '\n'. This is ok because, per |
| // the spec, we are not required to invalidate when passing readLimit. |
| // |
| // Note that if 'pos > limit', then doing 'limit -= pos' will cause |
| // limit to be negative. This is the only way limit will be < 0. |
| |
| if (pos + readLimit > limit) |
| { |
| char[] old_buffer = buffer; |
| int extraBuffSpace = 0; |
| if (pos > limit) |
| extraBuffSpace = 1; |
| if (readLimit + extraBuffSpace > limit) |
| buffer = new char[readLimit + extraBuffSpace]; |
| limit -= pos; |
| if (limit >= 0) |
| { |
| System.arraycopy(old_buffer, pos, buffer, 0, limit); |
| pos = 0; |
| } |
| } |
| |
| if (limit < 0) |
| { |
| // Maintain the relationship of 'pos > limit'. |
| pos = 1; |
| limit = markPos = 0; |
| } |
| else |
| markPos = pos; |
| // Now pos + readLimit <= buffer.length. thus if we need to read |
| // beyond buffer.length, then we are allowed to invalidate markPos. |
| } |
| } |
| |
| /** |
| * Reset the stream to the point where the <code>mark()</code> method |
| * was called. Any chars that were read after the mark point was set will |
| * be re-read during subsequent reads. |
| * <p> |
| * This method will throw an IOException if the number of chars read from |
| * the stream since the call to <code>mark()</code> exceeds the mark limit |
| * passed when establishing the mark. |
| * |
| * @exception IOException If an error occurs; |
| */ |
| public void reset() throws IOException |
| { |
| synchronized (lock) |
| { |
| checkStatus(); |
| if (markPos < 0) |
| throw new IOException("mark never set or invalidated"); |
| |
| // Need to handle the extremely unlikely case where a readLine was |
| // done with a '\r' as the last char in the buffer; which was then |
| // immediately followed by a mark and a reset with NO intervening |
| // read of any sort. In that case, setting pos to markPos would |
| // lose that info and a subsequent read would thus not skip a '\n' |
| // (if one exists). The value of limit in this rare case is zero. |
| // We can assume that if limit is zero for other reasons, then |
| // pos is already set to zero and doesn't need to be readjusted. |
| if (limit > 0) |
| pos = markPos; |
| } |
| } |
| |
| /** |
| * This method determines whether or not a stream is ready to be read. If |
| * this method returns <code>false</code> then this stream could (but is |
| * not guaranteed to) block on the next read attempt. |
| * |
| * @return <code>true</code> if this stream is ready to be read, |
| * <code>false</code> otherwise |
| * |
| * @exception IOException If an error occurs |
| */ |
| public boolean ready() throws IOException |
| { |
| synchronized (lock) |
| { |
| checkStatus(); |
| return pos < limit || in.ready(); |
| } |
| } |
| |
| /** |
| * This method read chars from a stream and stores them into a caller |
| * supplied buffer. It starts storing the data at index |
| * <code>offset</code> into |
| * the buffer and attempts to read <code>len</code> chars. This method can |
| * return before reading the number of chars requested. The actual number |
| * of chars read is returned as an int. A -1 is returned to indicate the |
| * end of the stream. |
| * <p> |
| * This method will block until some data can be read. |
| * |
| * @param buf The array into which the chars read should be stored |
| * @param offset The offset into the array to start storing chars |
| * @param count The requested number of chars to read |
| * |
| * @return The actual number of chars read, or -1 if end of stream. |
| * |
| * @exception IOException If an error occurs. |
| * @exception IndexOutOfBoundsException If offset and count are not |
| * valid regarding buf. |
| */ |
| public int read(char[] buf, int offset, int count) throws IOException |
| { |
| if (offset < 0 || offset + count > buf.length || count < 0) |
| throw new IndexOutOfBoundsException(); |
| |
| synchronized (lock) |
| { |
| checkStatus(); |
| // Once again, we need to handle the special case of a readLine |
| // that has a '\r' at the end of the buffer. In this case, we'll |
| // need to skip a '\n' if it is the next char to be read. |
| // This special case is indicated by 'pos > limit'. |
| boolean retAtEndOfBuffer = false; |
| |
| int avail = limit - pos; |
| if (count > avail) |
| { |
| if (avail > 0) |
| count = avail; |
| else // pos >= limit |
| { |
| if (limit == buffer.length) |
| markPos = -1; // read too far - invalidate the mark. |
| if (pos > limit) |
| { |
| // Set a boolean and make pos == limit to simplify things. |
| retAtEndOfBuffer = true; |
| --pos; |
| } |
| if (markPos < 0) |
| { |
| // Optimization: can read directly into buf. |
| if (count >= buffer.length && !retAtEndOfBuffer) |
| return in.read(buf, offset, count); |
| pos = limit = 0; |
| } |
| avail = in.read(buffer, limit, buffer.length - limit); |
| if (retAtEndOfBuffer && avail > 0 && buffer[limit] == '\n') |
| { |
| --avail; |
| limit++; |
| } |
| if (avail < count) |
| { |
| if (avail <= 0) |
| return avail; |
| count = avail; |
| } |
| limit += avail; |
| } |
| } |
| System.arraycopy(buffer, pos, buf, offset, count); |
| pos += count; |
| return count; |
| } |
| } |
| |
| /* Read more data into the buffer. Update pos and limit appropriately. |
| Assumes pos==limit initially. May invalidate the mark if read too much. |
| Return number of chars read (never 0), or -1 on eof. */ |
| private int fill() throws IOException |
| { |
| checkStatus(); |
| // Handle the special case of a readLine that has a '\r' at the end of |
| // the buffer. In this case, we'll need to skip a '\n' if it is the |
| // next char to be read. This special case is indicated by 'pos > limit'. |
| boolean retAtEndOfBuffer = false; |
| if (pos > limit) |
| { |
| retAtEndOfBuffer = true; |
| --pos; |
| } |
| |
| if (markPos >= 0 && limit == buffer.length) |
| markPos = -1; |
| if (markPos < 0) |
| pos = limit = 0; |
| int count = in.read(buffer, limit, buffer.length - limit); |
| if (count > 0) |
| limit += count; |
| |
| if (retAtEndOfBuffer && buffer[pos] == '\n') |
| { |
| --count; |
| // If the mark was set to the location of the \n, then we |
| // must change it to fully pretend that the \n does not |
| // exist. |
| if (markPos == pos) |
| ++markPos; |
| ++pos; |
| } |
| |
| return count; |
| } |
| |
| public int read() throws IOException |
| { |
| synchronized (lock) |
| { |
| checkStatus(); |
| if (pos >= limit && fill () <= 0) |
| return -1; |
| return buffer[pos++]; |
| } |
| } |
| |
| /* Return the end of the line starting at this.pos and ending at limit. |
| * The index returns is *before* any line terminators, or limit |
| * if no line terminators were found. |
| */ |
| private int lineEnd(int limit) |
| { |
| int i = pos; |
| for (; i < limit; i++) |
| { |
| char ch = buffer[i]; |
| if (ch == '\n' || ch == '\r') |
| break; |
| } |
| return i; |
| } |
| |
| /** |
| * This method reads a single line of text from the input stream, returning |
| * it as a <code>String</code>. A line is terminated by "\n", a "\r", or |
| * an "\r\n" sequence. The system dependent line separator is not used. |
| * The line termination characters are not returned in the resulting |
| * <code>String</code>. |
| * |
| * @return The line of text read, or <code>null</code> if end of stream. |
| * |
| * @exception IOException If an error occurs |
| */ |
| public String readLine() throws IOException |
| { |
| checkStatus(); |
| // Handle the special case where a previous readLine (with no intervening |
| // reads/skips) had a '\r' at the end of the buffer. |
| // In this case, we'll need to skip a '\n' if it's the next char to be read. |
| // This special case is indicated by 'pos > limit'. |
| if (pos > limit) |
| { |
| int ch = read(); |
| if (ch < 0) |
| return null; |
| if (ch != '\n') |
| --pos; |
| } |
| int i = lineEnd(limit); |
| if (i < limit) |
| { |
| String str = String.valueOf(buffer, pos, i - pos); |
| pos = i + 1; |
| // If the last char in the buffer is a '\r', we must remember |
| // to check if the next char to be read after the buffer is refilled |
| // is a '\n'. If so, skip it. To indicate this condition, we set pos |
| // to be limit + 1, which normally is never possible. |
| if (buffer[i] == '\r') |
| if (pos == limit || buffer[pos] == '\n') |
| pos++; |
| return str; |
| } |
| if (sbuf == null) |
| sbuf = new StringBuffer(200); |
| else |
| sbuf.setLength(0); |
| sbuf.append(buffer, pos, i - pos); |
| pos = i; |
| // We only want to return null when no characters were read before |
| // EOF. So we must keep track of this separately. Otherwise we |
| // would treat an empty `sbuf' as an EOF condition, which is wrong |
| // when there is just a newline. |
| boolean eof = false; |
| for (;;) |
| { |
| // readLine should block. So we must not return until a -1 is reached. |
| if (pos >= limit) |
| { |
| // here count == 0 isn't sufficient to give a failure. |
| int count = fill(); |
| if (count < 0) |
| { |
| eof = true; |
| break; |
| } |
| continue; |
| } |
| int ch = buffer[pos++]; |
| if (ch == '\n' || ch == '\r') |
| { |
| // Check here if a '\r' was the last char in the buffer; if so, |
| // mark it as in the comment above to indicate future reads |
| // should skip a newline that is the next char read after |
| // refilling the buffer. |
| if (ch == '\r') |
| if (pos == limit || buffer[pos] == '\n') |
| pos++; |
| break; |
| } |
| i = lineEnd(limit); |
| sbuf.append(buffer, pos - 1, i - (pos - 1)); |
| pos = i; |
| } |
| return (sbuf.length() == 0 && eof) ? null : sbuf.toString(); |
| } |
| |
| /** |
| * This method skips the specified number of chars in the stream. It |
| * returns the actual number of chars skipped, which may be less than the |
| * requested amount. |
| * <p> |
| * This method first discards chars in the buffer, then calls the |
| * <code>skip</code> method on the underlying stream to skip the |
| * remaining chars. |
| * |
| * @param count The requested number of chars to skip |
| * |
| * @return The actual number of chars skipped. |
| * |
| * @exception IOException If an error occurs. |
| * @exception IllegalArgumentException If count is negative. |
| */ |
| public long skip(long count) throws IOException |
| { |
| synchronized (lock) |
| { |
| checkStatus(); |
| if (count < 0) |
| throw new IllegalArgumentException("skip value is negative"); |
| if (count == 0) |
| return 0; |
| // Yet again, we need to handle the special case of a readLine |
| // that has a '\r' at the end of the buffer. In this case, we need |
| // to ignore a '\n' if it is the next char to be read. |
| // This special case is indicated by 'pos > limit' (i.e. avail < 0). |
| // To simplify things, if we're dealing with the special case for |
| // readLine, just read the next char (since the fill method will |
| // skip the '\n' for us). By doing this, we'll have to back up pos. |
| // That's easier than trying to keep track of whether we've skipped |
| // one element or not. |
| if (pos > limit) |
| { |
| if (read() < 0) |
| return 0; |
| else |
| --pos; |
| } |
| |
| int avail = limit - pos; |
| |
| if (count < avail) |
| { |
| pos += count; |
| return count; |
| } |
| |
| pos = limit; |
| long todo = count - avail; |
| if (todo > buffer.length) |
| { |
| markPos = -1; |
| todo -= in.skip(todo); |
| } |
| else |
| { |
| while (todo > 0) |
| { |
| avail = fill(); |
| if (avail <= 0) |
| break; |
| if (avail > todo) |
| avail = (int) todo; |
| pos += avail; |
| todo -= avail; |
| } |
| } |
| return count - todo; |
| } |
| } |
| |
| private void checkStatus() throws IOException |
| { |
| if (in == null) |
| throw new IOException("Stream closed"); |
| } |
| } |