//==============================================================================
// tribble/io/DiagnosticOutputDfl.java
//------------------------------------------------------------------------------

package tribble.io;


// System imports

import java.io.OutputStream;
import java.io.PrintWriter;
import java.io.Writer;

import java.lang.String;
import java.lang.StringBuffer;
import java.lang.Throwable;


// Local imports

import tribble.io.DiagnosticOutputI;
import tribble.io.SuspendablePrintWriter;


/*******************************************************************************
* Diagnostic message (informational, warning, and error messages) output stream.
*
* <p>
* This is a default implementation of a diagnostic message output stream (see
* {@link tribble.io.DiagnosticOutputI}) that is capable of writing diagnostic
* messages as lines of text to an underlying output stream.  Such a stream is
* used to display informational, warning, and error diagnostic messages by such
* classes as lexical analyzers (lexers) and parsers.
* See the {@link #printMessage} method.
*
* @version	$Revision: 1.4 $ $Date: 2003/02/26 04:08:35 $
* @since	2001-05-18
* @author
*	David R. Tribble,
*	<a href="mailto:david@tribble.com">david@tribble.com</a>.
*	<br>
*	<a href="../Copyright.html">Copyright</a>
*	©2001-2003 by David R. Tribble all rights reserved.
*	<br>
*	Permission is granted to freely use and distribute this source code
*	provided that the original copyright and authorship notices remain
*	intact.
*
* @see	DiagnosticOutputI
*/

public class DiagnosticOutputDfl
    extends SuspendablePrintWriter
    implements DiagnosticOutputI
{
// Identification

    /** Revision information. */
    static final String		REV =
        "@(#)tribble/io/DiagnosticOutputDfl.java $Revision: 1.4 $ $Date: 2003/02/26 04:08:35 $\n";


// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
// Constants

    // (None)


// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
// Static methods

    // (None)


// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
// Protected variables

    /** Output message buffer. */
    protected StringBuffer	m_buf =		new StringBuffer(80);


// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
// Public constructors

    /***************************************************************************
    * Constructor.
    *
    * @param	out
    * An output stream to which diagnostic messages (warning and error messages)
    * are written.  This should not be null.
    *
    * @since	1.1, 2001-07-20
    */

    public DiagnosticOutputDfl(Writer out)
    {
        // Establish the output stream
        super(out);
    }


    /***************************************************************************
    * Constructor.
    *
    * @param	out
    * An output stream to which diagnostic messages (warning and error messages)
    * are written.  This should not be null.
    *
    * @since	1.1, 2001-07-20
    */

    public DiagnosticOutputDfl(OutputStream out)
    {
        // Establish the output stream
        super(new PrintWriter(out, true));
    }


// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
// Public methods

    /***************************************************************************
    * Writes a diagnostic message to the output stream.
    *
    * @param	fname
    * An optional source filename for the diagnostic message.
    * If it is not null and not empty, it and a colon (<tt>":"</tt>)
    * immediately following it are written.
    *
    * @param	line
    * An optional source line number for the diagnostic message.
    * If it is not zero, it and a colon (<tt>":"</tt>) immediately following it
    * are written.
    *
    * @param	msg
    * The message text.
    * This typically contains a prefix indicating the severity of the message,
    * such as <tt>"warning:"</tt> or <tt>"error:"</tt>.
    * Note that the message should not contain a terminating linefeed.
    *
    * @since	1.1, 2001-05-18
    */

    public synchronized void printMessage(String fname, int line, String msg)
        //implements DiagnosticOutputI
    {
        boolean		nonblank = false;

        // Check for an open output stream
        if (out == null)
            return;

        // Format and write the diagnostic message to the output stream
        m_buf.setLength(0);

        if (fname != null  &&  fname.length() > 0)
        {
            // Append the filename to the output message
            m_buf.append(fname);
            m_buf.append(":");
            nonblank = true;
        }

        if (line > 0)
        {
            // Append the line number to the output message
            m_buf.append(line);
            m_buf.append(":");
            nonblank = true;
        }

        if (msg != null)
        {
            // Append the client message to the output message
            if (nonblank)
                m_buf.append(" ");
            m_buf.append(msg);
        }

        if (m_buf.length() > 0)
        {
            synchronized (lock)
            {
                // Write the message to the output stream
                // Note: This is a nearly atomic operation
                super.println(m_buf);
                super.flush();
            }
        }

        if (m_buf.length() >= 1000)
            m_buf = new StringBuffer(200);
    }


// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
// Protected methods

    /***************************************************************************
    * Finalization.
    * Flushes the underlying output stream, if any, but does not close it.
    *
    * @since	1.1, 2001-05-18
    */

    protected synchronized void finalize()
        throws Throwable
    {
        // Flush and disassociate (but do not close) the output stream
        flush();
        out = null;
        m_buf = null;

        // Cascade
        super.finalize();
    }


// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
// Private constructors

    /***************************************************************************
    * Default constructor.
    * <b>Do not use this constructor.</b>
    *
    * @since	1.1, 2001-05-18
    */

    private DiagnosticOutputDfl()
    {
        // Do nothing
    }
}

// End DiagnosticOutputDfl.java