001/* StringBufferInputStream.java -- Read an String as a stream
002   Copyright (C) 1998, 1999, 2001, 2005  Free Software Foundation, Inc.
003
004This file is part of GNU Classpath.
005
006GNU Classpath is free software; you can redistribute it and/or modify
007it under the terms of the GNU General Public License as published by
008the Free Software Foundation; either version 2, or (at your option)
009any later version.
010 
011GNU Classpath is distributed in the hope that it will be useful, but
012WITHOUT ANY WARRANTY; without even the implied warranty of
013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014General Public License for more details.
015
016You should have received a copy of the GNU General Public License
017along with GNU Classpath; see the file COPYING.  If not, write to the
018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
01902110-1301 USA.
020
021Linking this library statically or dynamically with other modules is
022making a combined work based on this library.  Thus, the terms and
023conditions of the GNU General Public License cover the whole
024combination.
025
026As a special exception, the copyright holders of this library give you
027permission to link this library with independent modules to produce an
028executable, regardless of the license terms of these independent
029modules, and to copy and distribute the resulting executable under
030terms of your choice, provided that you also meet, for each linked
031independent module, the terms and conditions of the license of that
032module.  An independent module is a module which is not derived from
033or based on this library.  If you modify this library, you may extend
034this exception to your version of the library, but you are not
035obligated to do so.  If you do not wish to do so, delete this
036exception statement from your version. */
037
038
039package java.io;
040
041/* Written using "Java Class Libraries", 2nd edition, ISBN 0-201-31002-3
042 * "The Java Language Specification", ISBN 0-201-63451-1
043 * plus online API docs for JDK 1.2 beta from http://www.javasoft.com.
044 * Status:  Believed complete and correct.  Deprecated in JDK 1.1.
045 */
046 
047/**
048  * This class permits a <code>String</code> to be read as an input stream.
049  * The low eight bits of each character in the <code>String</code> are the
050  * bytes that are returned. The high eight bits of each character are
051  * discarded.
052  * <p>
053  * The mark/reset functionality in this class behaves differently than
054  * normal.  The <code>mark()</code> method is always ignored and the 
055  * <code>reset()</code> method always resets in stream to start reading from 
056  * position 0 in the String.  Note that since this method does not override 
057  * <code>markSupported()</code> in <code>InputStream</code>, calling that 
058  * method will return <code>false</code>.
059  * <p>
060  * Note that this class is deprecated because it does not properly handle
061  * 16-bit Java characters.  It is provided for backwards compatibility only
062  * and should not be used for new development.  The <code>StringReader</code>
063  * class should be used instead.
064  *
065  * @deprecated
066  *
067  * @author Aaron M. Renn (arenn@urbanophile.com)
068  * @author Warren Levy (warrenl@cygnus.com)
069  */
070public class StringBufferInputStream extends InputStream
071{
072  /** The String which is the input to this stream. */
073  protected String buffer;
074
075  /** Position of the next byte in buffer to be read. */
076  protected int pos = 0;
077
078  /** The length of the String buffer. */
079  protected int count;
080
081 /**
082  * Create a new <code>StringBufferInputStream</code> that will read bytes
083  * from the passed in <code>String</code>.  This stream will read from the
084  * beginning to the end of the <code>String</code>.
085  *
086  * @param s The <code>String</code> this stream will read from.
087  */
088  public StringBufferInputStream(String s)
089  {
090    buffer = s;
091    count = s.length();
092  }
093
094 /**
095  * This method returns the number of bytes available to be read from this
096  * stream.  The value returned will be equal to <code>count - pos</code>.
097  *
098  * @return The number of bytes that can be read from this stream before
099  * blocking, which is all of them
100  */
101  public int available()
102  {
103    return count - pos;
104  }
105
106 /**
107  * This method reads one byte from the stream.  The <code>pos</code> counter 
108  * is advanced to the next byte to be read.  The byte read is returned as
109  * an int in the range of 0-255.  If the stream position is already at the
110  * end of the buffer, no byte is read and a -1 is returned in order to
111  * indicate the end of the stream.
112  *
113  * @return The byte read, or -1 if end of stream
114  */
115  public int read()
116  {
117    if (pos >= count)
118      return -1;        // EOF
119
120    return ((int) buffer.charAt(pos++)) & 0xFF;
121  }
122
123/**
124  * This method reads bytes from the stream and stores them into a caller
125  * supplied buffer.  It starts storing the data at index <code>offset</code> 
126  * into the buffer and attempts to read <code>len</code> bytes.  This method
127  * can return before reading the number of bytes requested if the end of the
128  * stream is encountered first.  The actual number of bytes read is 
129  * returned.  If no bytes can be read because the stream is already at 
130  * the end of stream position, a -1 is returned.
131  * <p>
132  * This method does not block.
133  *
134  * @param b The array into which the bytes read should be stored.
135  * @param off The offset into the array to start storing bytes
136  * @param len The requested number of bytes to read
137  *
138  * @return The actual number of bytes read, or -1 if end of stream.
139  */
140  public int read(byte[] b, int off, int len)
141  {
142    if (off < 0 || len < 0 || off + len > b.length)
143      throw new ArrayIndexOutOfBoundsException();
144
145    if (pos >= count)
146      return -1;        // EOF
147
148    int numRead = Math.min(len, count - pos);
149    if (numRead < 0)
150      return 0;
151
152    buffer.getBytes(pos, pos + numRead, b, off);
153    pos += numRead;
154    return numRead;
155  }
156
157 /**
158  * This method sets the read position in the stream to the beginning
159  * setting the <code>pos</code> variable equal to 0.  Note that this differs
160  * from the common implementation of the <code>reset()</code> method.
161  */
162  public void reset()
163  {
164    pos = 0;
165  }
166
167 /**
168  * This method attempts to skip the requested number of bytes in the
169  * input stream.  It does this by advancing the <code>pos</code> value by the
170  * specified number of bytes.  It this would exceed the length of the
171  * buffer, then only enough bytes are skipped to position the stream at
172  * the end of the buffer.  The actual number of bytes skipped is returned.
173  *
174  * @param n The requested number of bytes to skip
175  *
176  * @return The actual number of bytes skipped.
177  */
178  public long skip(long n)
179  {
180    if (n < 0)
181      return 0L;
182
183    long actualSkip = Math.min(n, count - pos);
184    pos += actualSkip;
185    return actualSkip;
186  }
187}