Initial revision

From-SVN: r102074

libjava/classpath/gnu/java/net/LineInputStream.java

@@ -0,0 +1,198 @@
+/* LineInputStream.java --
+   Copyright (C) 2002, 2003, 2004  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., 51 Franklin Street, Fifth Floor, Boston, MA
+02110-1301 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 gnu.java.net;
+
+import java.io.ByteArrayOutputStream;
+import java.io.FilterInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+
+/**
+ * An input stream that can read lines of input.
+ *
+ * @author Chris Burdess (dog@gnu.org)
+ */
+public class LineInputStream
+  extends FilterInputStream
+{
+  /*
+   * Line buffer.
+   */
+  private ByteArrayOutputStream buf;
+
+  /*
+   * Encoding to use when translating bytes to characters.
+   */
+  private String encoding;
+
+  /*
+   * End-of-stream flag.
+   */
+  private boolean eof;
+
+  /**
+   * Whether we can use block reads.
+   */
+  private final boolean blockReads;
+
+  /**
+   * Constructor using the US-ASCII character encoding.
+   * @param in the underlying input stream
+   */
+  public LineInputStream(InputStream in)
+  {
+    this(in, "US-ASCII");
+  }
+
+  /**
+   * Constructor.
+   * @param in the underlying input stream
+   * @param encoding the character encoding to use
+   */
+  public LineInputStream(InputStream in, String encoding)
+  {
+    super(in);
+    buf = new ByteArrayOutputStream();
+    this.encoding = encoding;
+    eof = false;
+    blockReads = in.markSupported();
+  }
+
+  /**
+   * Read a line of input.
+   */
+  public String readLine()
+    throws IOException
+  {
+    if (eof)
+      {
+        return null;
+      }
+    do
+      {
+        if (blockReads)
+          {
+            // Use mark and reset to read chunks of bytes
+            final int MIN_LENGTH = 1024;
+            int len, pos;
+            
+            len = in.available();
+            len = (len < MIN_LENGTH) ? MIN_LENGTH : len;
+            byte[] b = new byte[len];
+            in.mark(len);
+            // Read into buffer b
+            len = in.read(b, 0, len);
+            // Handle EOF
+            if (len == -1)
+              {
+                eof = true;
+                if (buf.size() == 0)
+                  {
+                    return null;
+                  }
+                else
+                  {
+                    // We don't care about resetting buf
+                    return buf.toString(encoding);
+                  }
+              }
+            // Get index of LF in b
+            pos = indexOf(b, len, (byte) 0x0a);
+            if (pos != -1)
+              {
+                // Write pos bytes to buf
+                buf.write(b, 0, pos);
+                // Reset stream, and read pos + 1 bytes
+                in.reset();
+                pos += 1;
+                while (pos > 0)
+                  {
+                    len = in.read(b, 0, pos);
+                    pos = (len == -1) ? -1 : pos - len;
+                  }
+                // Return line
+                String ret = buf.toString(encoding);
+                buf.reset();
+                return ret;
+              }
+            else
+              {
+                // Append everything to buf and fall through to re-read.
+                buf.write(b, 0, len);
+              }
+          }
+        else
+          {
+            // We must use character reads in order not to read too much
+            // from the underlying stream.
+            int c = in.read();
+            switch (c)
+              {
+              case -1:
+                eof = true;
+                if (buf.size() == 0)
+                  {
+                    return null;
+                  }
+                // Fall through and return contents of buffer.
+              case 0x0a:                // LF
+                String ret = buf.toString(encoding);
+                buf.reset();
+                return ret;
+              default:
+                buf.write(c);
+              }
+          }
+      }
+    while (true);
+  }
+
+  private int indexOf(byte[] b, int len, byte c)
+  {
+    for (int pos = 0; pos < len; pos++)
+      {
+        if (b[pos] == c)
+          {
+            return pos;
+          }
+      }
+    return -1;
+  }
+}
+