src/main/org/apache/tools/ant/filters/TailFilter.java - ant - Git at Google

 /*
  * The Apache Software License, Version 1.1
  *
  * Copyright (c) 2002 The Apache Software Foundation.  All rights
  * reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  *
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in
  *    the documentation and/or other materials provided with the
  *    distribution.
  *
  * 3. The end-user documentation included with the redistribution, if
  *    any, must include the following acknowlegement:
  *       "This product includes software developed by the
  *        Apache Software Foundation (http://www.apache.org/)."
  *    Alternately, this acknowlegement may appear in the software itself,
  *    if and wherever such third-party acknowlegements normally appear.
  *
  * 4. The names "The Jakarta Project", "Ant", and "Apache Software
  *    Foundation" must not be used to endorse or promote products derived
  *    from this software without prior written permission. For written
  *    permission, please contact apache@apache.org.
  *
  * 5. Products derived from this software may not be called "Apache"
  *    nor may "Apache" appear in their names without prior written
  *    permission of the Apache Group.
  *
  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  * ====================================================================
  *
  * This software consists of voluntary contributions made by many
  * individuals on behalf of the Apache Software Foundation.  For more
  * information on the Apache Software Foundation, please see
  * <http://www.apache.org/>.
  */
 package org.apache.tools.ant.filters;

 import java.io.IOException;
 import java.io.Reader;

 import org.apache.tools.ant.types.Parameter;

 /**
  * Reads the last <code>n</code> lines of a stream. (Default is last10 lines.)
  *
  * Example:
  *
  * <pre>&lt;tailfilter lines=&quot;3&quot;/&gt;</pre>
  *
  * Or:
  *
  * <pre>&lt;filterreader classname=&quot;org.apache.tools.ant.filters.TailFilter&quot;&gt;
  *   &lt;param name=&quot;lines&quot; value=&quot;3&quot;/&gt;
  * &lt;/filterreader&gt;</pre>
  *
  * @author <a href="mailto:umagesh@apache.org">Magesh Umasankar</a>
  */
 public final class TailFilter
     extends BaseParamFilterReader
     implements ChainableReader {
     /** Parameter name for the number of lines to be returned. */
     private static final String LINES_KEY = "lines";

     /** Number of lines currently read in. */
     private long linesRead = 0;

     /** Number of lines to be returned in the filtered stream. */
     private long lines = 10;

     /** Buffer to hold in characters read ahead. */
     private char[] buffer = new char[4096];

     /** The character position that has been returned from the buffer. */
     private int returnedCharPos = -1;

     /** Whether or not read-ahead been completed. */
     private boolean completedReadAhead = false;

     /** Current index position on the buffer. */
     private int bufferPos = 0;

     /**
      * Constructor for "dummy" instances.
      *
      * @see BaseFilterReader#BaseFilterReader()
      */
     public TailFilter() {
         super();
     }

     /**
      * Creates a new filtered reader.
      *
      * @param in A Reader object providing the underlying stream.
      *           Must not be <code>null</code>.
      */
     public TailFilter(final Reader in) {
         super(in);
     }

     /**
      * Returns the next character in the filtered stream. If the read-ahead
      * has been completed, the next character in the buffer is returned.
      * Otherwise, the stream is read to the end and buffered (with the buffer
      * growing as necessary), then the appropriate position in the buffer is
      * set to read from.
      *
      * @return the next character in the resulting stream, or -1
      * if the end of the resulting stream has been reached
      *
      * @exception IOException if the underlying stream throws an IOException
      * during reading
      */
     public final int read() throws IOException {
         if (!getInitialized()) {
             initialize();
             setInitialized(true);
         }

         if (!completedReadAhead) {
             int ch = -1;
             while ((ch = in.read()) != -1) {
                 if (buffer.length == bufferPos) {
                     if (returnedCharPos != -1) {
                         final char[] tmpBuffer = new char[buffer.length];
                         System.arraycopy(buffer, returnedCharPos + 1, tmpBuffer,
                                          0, buffer.length - (returnedCharPos + 1));
                         buffer = tmpBuffer;
                         bufferPos = bufferPos - (returnedCharPos + 1);
                         returnedCharPos = -1;
                     } else {
                         final char[] tmpBuffer = new char[buffer.length * 2];
                         System.arraycopy(buffer, 0, tmpBuffer, 0, bufferPos);
                         buffer = tmpBuffer;
                     }
                 }

                 if (ch == '\n' || ch == -1) {
                     ++linesRead;

                     if (linesRead == lines) {
                         int i = 0;
                         for (i = returnedCharPos + 1;
                             buffer[i] != 0 && buffer[i] != '\n'; i++) {
                         }
                         returnedCharPos = i;
                         --linesRead;
                     }
                 }
                 if (ch == -1) {
                     break;
                 }

                 buffer[bufferPos] = (char) ch;
                 bufferPos++;
             }
             completedReadAhead = true;
         }

         ++returnedCharPos;
         if (returnedCharPos >= bufferPos) {
             return -1;
         } else {
             return buffer[returnedCharPos];
         }
     }

     /**
      * Sets the number of lines to be returned in the filtered stream.
      *
      * @param lines the number of lines to be returned in the filtered stream
      */
     public final void setLines(final long lines) {
         this.lines = lines;
     }

     /**
      * Returns the number of lines to be returned in the filtered stream.
      *
      * @return the number of lines to be returned in the filtered stream
      */
     private final long getLines() {
         return lines;
     }

     /**
      * Creates a new TailFilter using the passed in
      * Reader for instantiation.
      *
      * @param rdr A Reader object providing the underlying stream.
      *            Must not be <code>null</code>.
      *
      * @return a new filter based on this configuration, but filtering
      *         the specified reader
      */
     public final Reader chain(final Reader rdr) {
         TailFilter newFilter = new TailFilter(rdr);
         newFilter.setLines(getLines());
         newFilter.setInitialized(true);
         return newFilter;
     }

     /**
      * Scans the parameters list for the "lines" parameter and uses
      * it to set the number of lines to be returned in the filtered stream.
      */
     private final void initialize() {
         Parameter[] params = getParameters();
         if (params != null) {
             for (int i = 0; i < params.length; i++) {
                 if (LINES_KEY.equals(params[i].getName())) {
                     setLines(new Long(params[i].getValue()).longValue());
                     break;
                 }
             }
         }
     }
 }
	/*
	* The Apache Software License, Version 1.1
	*
	* Copyright (c) 2002 The Apache Software Foundation. All rights
	* reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	*
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	*
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in
	* the documentation and/or other materials provided with the
	* distribution.
	*
	* 3. The end-user documentation included with the redistribution, if
	* any, must include the following acknowlegement:
	* "This product includes software developed by the
	* Apache Software Foundation (http://www.apache.org/)."
	* Alternately, this acknowlegement may appear in the software itself,
	* if and wherever such third-party acknowlegements normally appear.
	*
	* 4. The names "The Jakarta Project", "Ant", and "Apache Software
	* Foundation" must not be used to endorse or promote products derived
	* from this software without prior written permission. For written
	* permission, please contact apache@apache.org.
	*
	* 5. Products derived from this software may not be called "Apache"
	* nor may "Apache" appear in their names without prior written
	* permission of the Apache Group.
	*
	* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
	* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
	* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
	* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
	* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
	* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
	* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
	* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
	* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	* SUCH DAMAGE.
	* ====================================================================
	*
	* This software consists of voluntary contributions made by many
	* individuals on behalf of the Apache Software Foundation. For more
	* information on the Apache Software Foundation, please see
	* <http://www.apache.org/>.
	*/
	package org.apache.tools.ant.filters;

	import java.io.IOException;
	import java.io.Reader;

	import org.apache.tools.ant.types.Parameter;

	/**
	* Reads the last <code>n</code> lines of a stream. (Default is last10 lines.)
	*
	* Example:
	*
	* <pre><tailfilter lines="3"/></pre>
	*
	* Or:
	*
	* <pre><filterreader classname="org.apache.tools.ant.filters.TailFilter">
	* <param name="lines" value="3"/>
	* </filterreader></pre>
	*
	* @author <a href="mailto:umagesh@apache.org">Magesh Umasankar</a>
	*/
	public final class TailFilter
	extends BaseParamFilterReader
	implements ChainableReader {
	/** Parameter name for the number of lines to be returned. */
	private static final String LINES_KEY = "lines";

	/** Number of lines currently read in. */
	private long linesRead = 0;

	/** Number of lines to be returned in the filtered stream. */
	private long lines = 10;

	/** Buffer to hold in characters read ahead. */
	private char[] buffer = new char[4096];

	/** The character position that has been returned from the buffer. */
	private int returnedCharPos = -1;

	/** Whether or not read-ahead been completed. */
	private boolean completedReadAhead = false;

	/** Current index position on the buffer. */
	private int bufferPos = 0;

	/**
	* Constructor for "dummy" instances.
	*
	* @see BaseFilterReader#BaseFilterReader()
	*/
	public TailFilter() {
	super();
	}

	/**
	* Creates a new filtered reader.
	*
	* @param in A Reader object providing the underlying stream.
	* Must not be <code>null</code>.
	*/
	public TailFilter(final Reader in) {
	super(in);
	}

	/**
	* Returns the next character in the filtered stream. If the read-ahead
	* has been completed, the next character in the buffer is returned.
	* Otherwise, the stream is read to the end and buffered (with the buffer
	* growing as necessary), then the appropriate position in the buffer is
	* set to read from.
	*
	* @return the next character in the resulting stream, or -1
	* if the end of the resulting stream has been reached
	*
	* @exception IOException if the underlying stream throws an IOException
	* during reading
	*/
	public final int read() throws IOException {
	if (!getInitialized()) {
	initialize();
	setInitialized(true);
	}

	if (!completedReadAhead) {
	int ch = -1;
	while ((ch = in.read()) != -1) {
	if (buffer.length == bufferPos) {
	if (returnedCharPos != -1) {
	final char[] tmpBuffer = new char[buffer.length];
	System.arraycopy(buffer, returnedCharPos + 1, tmpBuffer,
	0, buffer.length - (returnedCharPos + 1));
	buffer = tmpBuffer;
	bufferPos = bufferPos - (returnedCharPos + 1);
	returnedCharPos = -1;
	} else {
	final char[] tmpBuffer = new char[buffer.length * 2];
	System.arraycopy(buffer, 0, tmpBuffer, 0, bufferPos);
	buffer = tmpBuffer;
	}
	}

	if (ch == '\n' \|\| ch == -1) {
	++linesRead;

	if (linesRead == lines) {
	int i = 0;
	for (i = returnedCharPos + 1;
	buffer[i] != 0 && buffer[i] != '\n'; i++) {
	}
	returnedCharPos = i;
	--linesRead;
	}
	}
	if (ch == -1) {
	break;
	}

	buffer[bufferPos] = (char) ch;
	bufferPos++;
	}
	completedReadAhead = true;
	}

	++returnedCharPos;
	if (returnedCharPos >= bufferPos) {
	return -1;
	} else {
	return buffer[returnedCharPos];
	}
	}

	/**
	* Sets the number of lines to be returned in the filtered stream.
	*
	* @param lines the number of lines to be returned in the filtered stream
	*/
	public final void setLines(final long lines) {
	this.lines = lines;
	}

	/**
	* Returns the number of lines to be returned in the filtered stream.
	*
	* @return the number of lines to be returned in the filtered stream
	*/
	private final long getLines() {
	return lines;
	}

	/**
	* Creates a new TailFilter using the passed in
	* Reader for instantiation.
	*
	* @param rdr A Reader object providing the underlying stream.
	* Must not be <code>null</code>.
	*
	* @return a new filter based on this configuration, but filtering
	* the specified reader
	*/
	public final Reader chain(final Reader rdr) {
	TailFilter newFilter = new TailFilter(rdr);
	newFilter.setLines(getLines());
	newFilter.setInitialized(true);
	return newFilter;
	}

	/**
	* Scans the parameters list for the "lines" parameter and uses
	* it to set the number of lines to be returned in the filtered stream.
	*/
	private final void initialize() {
	Parameter[] params = getParameters();
	if (params != null) {
	for (int i = 0; i < params.length; i++) {
	if (LINES_KEY.equals(params[i].getName())) {
	setLines(new Long(params[i].getValue()).longValue());
	break;
	}
	}
	}
	}
	}