MemoryStringWriter.java

/*!
* This program is free software; you can redistribute it and/or modify it under the
* terms of the GNU Lesser General Public License, version 2.1 as published by the Free Software
* Foundation.
*
* You should have received a copy of the GNU Lesser General Public License along with this
* program; if not, you can obtain a copy at http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html
* or from the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*
* This program 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 Lesser General Public License for more details.
*
* Copyright (c) 2002-2013 Pentaho Corporation..  All rights reserved.
*/

package org.pentaho.reporting.libraries.base.util;

import java.io.IOException;
import java.io.Writer;

public class MemoryStringWriter extends Writer {
  private int maximumBufferIncrement;
  private int cursor;
  private char[] buffer;

  /**
   * Create a new character-stream writer whose critical sections will synchronize on the writer itself.
   */
  public MemoryStringWriter() {
    this( 4096, 65536 );
  }

  /**
   * Create a new character-stream writer whose critical sections will synchronize on the writer itself.
   */
  public MemoryStringWriter( final int bufferSize ) {
    this( bufferSize, bufferSize * 4 );
  }

  /**
   * Create a new character-stream writer whose critical sections will synchronize on the writer itself.
   */
  public MemoryStringWriter( final int bufferSize, final int maximumBufferIncrement ) {
    this.maximumBufferIncrement = maximumBufferIncrement;
    this.buffer = new char[ bufferSize ];
  }

  /**
   * Writes a portion of an array of characters.
   *
   * @param cbuf Array of characters
   * @param off  Offset from which to start writing characters
   * @param len  Number of characters to write
   * @throws java.io.IOException If an I/O error occurs
   */
  public void write( final char[] cbuf, final int off, final int len ) throws IOException {
    if ( len < 0 ) {
      throw new IllegalArgumentException();
    }
    if ( off < 0 ) {
      throw new IndexOutOfBoundsException();
    }
    if ( cbuf == null ) {
      throw new NullPointerException();
    }
    if ( ( len + off ) > cbuf.length ) {
      throw new IndexOutOfBoundsException();
    }

    ensureSize( cursor + len );

    System.arraycopy( cbuf, off, this.buffer, cursor, len );
    cursor += len;
  }

  /**
   * Writes <code>b.length</code> bytes from the specified byte array to this output stream. The general contract for
   * <code>write(b)</code> is that it should have exactly the same effect as the call <code>write(b, 0,
   * b.length)</code>.
   *
   * @param cbuf the data.
   * @throws java.io.IOException if an I/O error occurs.
   * @see java.io.OutputStream#write(byte[], int, int)
   */
  public void write( final char[] cbuf ) throws IOException {
    write( cbuf, 0, cbuf.length );
  }

  private void ensureSize( final int size ) {
    if ( this.buffer.length >= size ) {
      return;
    }

    final int computedSize = (int) Math.min( ( this.buffer.length + 1 ) * 1.5,
      this.buffer.length + maximumBufferIncrement );
    final int newSize = Math.max( size, computedSize );
    final char[] newBuffer = new char[ newSize ];
    System.arraycopy( this.buffer, 0, newBuffer, 0, cursor );
    this.buffer = newBuffer;
  }

  /**
   * Flush the stream.  If the stream has saved any characters from the various write() methods in a buffer, write them
   * immediately to their intended destination.  Then, if that destination is another character or byte stream, flush
   * it.  Thus one flush() invocation will flush all the buffers in a chain of Writers and OutputStreams.
   * <p/>
   * If the intended destination of this stream is an abstraction provided by the underlying operating system, for
   * example a file, then flushing the stream guarantees only that bytes previously written to the stream are passed to
   * the operating system for writing; it does not guarantee that they are actually written to a physical device such as
   * a disk drive.
   *
   * @throws java.io.IOException If an I/O error occurs
   */
  public void flush() throws IOException {
  }

  /**
   * Close the stream, flushing it first.  Once a stream has been closed, further write() or flush() invocations will
   * cause an IOException to be thrown.  Closing a previously-closed stream, however, has no effect.
   *
   * @throws java.io.IOException If an I/O error occurs
   */
  public void close() throws IOException {

  }

  public char[] toByteArray() {
    final char[] retval = new char[ cursor ];
    System.arraycopy( buffer, 0, retval, 0, cursor );
    return retval;
  }

  public int getLength() {
    return cursor;
  }

  public char[] getRaw() {
    return buffer;
  }

  public MemoryStringReader createReader() {
    return new MemoryStringReader( buffer, 0, cursor );
  }

  public String toString() {
    return new String( buffer, 0, cursor );
  }
}