Initial revision

From-SVN: r26263

libjava/java/io/PushbackInputStream.java

@@ -0,0 +1,124 @@
+/* Copyright (C) 1998, 1999  Cygnus Solutions
+
+   This file is part of libgcj.
+
+This software is copyrighted work licensed under the terms of the
+Libgcj License.  Please consult the file "LIBGCJ_LICENSE" for
+details.  */
+ 
+package java.io;
+
+/**
+ * @author Warren Levy <warrenl@cygnus.com>
+ * @date October 15, 1998.  
+ */
+/* 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.
+ */
+ 
+public class PushbackInputStream extends FilterInputStream
+{
+  /* Internal buffer array for data. */
+  protected byte[] buf;
+
+  /* The current position in the buffer. */
+  protected int pos;
+
+  public PushbackInputStream(InputStream in)
+  {
+    this(in, 1);
+  }
+
+  public PushbackInputStream(InputStream in, int size)
+  {
+    super(in);
+    if (size < 0)
+      throw new IllegalArgumentException();
+    buf = new byte[size];
+    pos = buf.length;
+  }
+
+  public int available() throws IOException
+  {
+    return pos + super.available();
+  }
+
+  public void close() throws IOException
+  {
+    buf = null;
+    super.close();
+  }
+
+  public boolean markSupported()
+  {
+    return false;
+  }
+
+  public int read() throws IOException
+  {
+    if (pos < buf.length)
+      return ((int) buf[pos++]) & 0xFF;
+
+    return super.read();
+  }
+
+  public int read(byte[] b, int off, int len) throws IOException
+  {
+    if (off < 0 || len < 0 || off + len > b.length)
+      throw new ArrayIndexOutOfBoundsException();
+
+    int numBytes = Math.min(buf.length - pos, len);
+    for (int i = 0; i < numBytes; i++)
+      b[off++] = buf[pos++];
+
+    // `off' was just incremented to include `numBytes', so we can
+    // just pass ithere.
+    return numBytes + super.read(b, off, len - numBytes);
+  }
+
+  public void unread(int b) throws IOException
+  {
+    if (pos <= 0)
+      throw new IOException();
+
+    buf[--pos] = (byte) b;
+  }
+
+  public void unread(byte[] b) throws IOException
+  {
+    unread(b, 0, b.length);
+  }
+
+  public void unread(byte[] b, int off, int len) throws IOException
+  {
+    if (pos < len)
+      throw new IOException();
+
+    // Note the order that these bytes are being added is the opposite
+    // of what would be done if they were added to the buffer one at a time.
+    // See the Java Class Libraries book p. 1390.
+    System.arraycopy(b, off, buf, pos - len, len);
+
+    // Don't put this into the arraycopy above, an exception might be thrown
+    // and in that case we don't want to modify pos.
+    pos -= len;
+  }
+
+  // JDK1.2
+  public long skip(long n) throws IOException
+  {
+    final long origN = n;
+
+    if (n > 0L)
+      {
+	int numread = (int) Math.min((long) (buf.length - pos), n);
+	pos += numread;
+	n -= numread;
+	n -= super.skip(n);
+      }
+
+    return origN - n;
+  }
+}