| /* StringReader.java -- permits a String to be read as a character input stream |
| Copyright (C) 1998, 1999, 2000 Free Software Foundation |
| |
| 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. |
| |
| As a special exception, if you link this library with other files to |
| produce an executable, this library does not by itself cause the |
| resulting executable to be covered by the GNU General Public License. |
| This exception does not however invalidate any other reasons why the |
| executable file might be covered by the GNU General Public License. */ |
| |
| package java.io; |
| |
| /* Written using "Java Class Libraries", 2nd edition, ISBN 0-201-31002-3 |
| * "The Java Language Specification", ISBN 0-201-63451-1 |
| * plus online API docs for JDK 1.2 beta from http://www.javasoft.com. |
| * Status: Believed complete and correct |
| */ |
| |
| /** |
| * This class permits a <code>String</code> to be read as a character |
| * input stream. |
| * <p> |
| * The mark/reset functionality in this class behaves differently than |
| * normal. If no mark has been set, then calling the <code>reset()</code> |
| * method rewinds the read pointer to the beginning of the <code>String</code>. |
| * |
| * @version 0.0 |
| * |
| * @author Aaron M. Renn (arenn@urbanophile.com) |
| * @author Warren Levy <warrenl@cygnus.com> |
| * @date October 19, 1998. |
| */ |
| public class StringReader extends Reader |
| { |
| /* A String provided by the creator of the stream. */ |
| private String buf; |
| |
| /* Position of the next char in buf to be read. */ |
| private int pos; |
| |
| /* The currently marked position in the stream. */ |
| private int markedPos; |
| |
| /* The index in buf one greater than the last valid character. */ |
| private int count; |
| |
| /** |
| * Create a new <code>StringReader</code> that will read chars from the |
| * passed in <code>String</code>. This stream will read from the beginning to the |
| * end of the <code>String</code>. |
| * |
| * @param s The <code>String</code> this stream will read from. |
| */ |
| public StringReader(String buffer) |
| { |
| super(); |
| buf = buffer; |
| |
| count = buffer.length(); |
| markedPos = pos = 0; |
| } |
| |
| public void close() |
| { |
| synchronized (lock) |
| { |
| buf = null; |
| } |
| } |
| |
| public void mark(int readAheadLimit) throws IOException |
| { |
| synchronized (lock) |
| { |
| if (buf == null) |
| throw new IOException("Stream closed"); |
| |
| // readAheadLimit is ignored per Java Class Lib. book, p. 1692. |
| markedPos = pos; |
| } |
| } |
| |
| public boolean markSupported() |
| { |
| return true; |
| } |
| |
| public int read() throws IOException |
| { |
| synchronized (lock) |
| { |
| if (buf == null) |
| throw new IOException("Stream closed"); |
| |
| if (pos < count) |
| return ((int) buf.charAt(pos++)) & 0xFFFF; |
| return -1; |
| } |
| } |
| |
| public int read(char[] b, int off, int len) throws IOException |
| { |
| synchronized (lock) |
| { |
| if (buf == null) |
| throw new IOException("Stream closed"); |
| |
| /* Don't need to check pos value, arraycopy will check it. */ |
| if (off < 0 || len < 0 || off + len > b.length) |
| throw new ArrayIndexOutOfBoundsException(); |
| |
| if (pos >= count) |
| return -1; |
| |
| int lastChar = Math.min(count, pos + len); |
| buf.getChars(pos, lastChar, b, off); |
| int numChars = lastChar - pos; |
| pos = lastChar; |
| return numChars; |
| } |
| } |
| |
| /** |
| * This method determines if the stream is ready to be read. This class |
| * is always ready to read and so always returns <code>true</code>, unless |
| * close() has previously been called in which case an IOException is |
| * thrown. |
| * |
| * @return <code>true</code> to indicate that this object is ready to be read. |
| * @exception IOException If the stream is closed. |
| */ |
| public boolean ready() throws IOException |
| { |
| if (buf == null) |
| throw new IOException("Stream closed"); |
| |
| return true; |
| } |
| |
| /** |
| * Sets the read position in the stream to the previously |
| * marked position or to 0 (i.e., the beginning of the stream) if the mark |
| * has not already been set. |
| */ |
| public void reset() throws IOException |
| { |
| synchronized (lock) |
| { |
| if (buf == null) |
| throw new IOException("Stream closed"); |
| |
| pos = markedPos; |
| } |
| } |
| |
| /** |
| * This method attempts to skip the requested number of chars in the |
| * input stream. It does this by advancing the <code>pos</code> value by |
| * the specified number of chars. It this would exceed the length of the |
| * buffer, then only enough chars are skipped to position the stream at |
| * the end of the buffer. The actual number of chars skipped is returned. |
| * |
| * @param num_chars The requested number of chars to skip |
| * |
| * @return The actual number of chars skipped. |
| */ |
| public long skip(long n) throws IOException |
| { |
| synchronized (lock) |
| { |
| if (buf == null) |
| throw new IOException("Stream closed"); |
| |
| // Even though the var numChars is a long, in reality it can never |
| // be larger than an int since the result of subtracting 2 positive |
| // ints will always fit in an int. Since we have to return a long |
| // anyway, numChars might as well just be a long. |
| long numChars = Math.min((long) (count - pos), n < 0 ? 0L : n); |
| pos += numChars; |
| return numChars; |
| } |
| } |
| } |