json/bundles/org.eclipse.json/src/org/eclipse/json/provisonnal/com/eclipsesource/json/WritingBuffer.java

/**
 *  Copyright (c) 2013-2015 Angelo ZERR.
 *  All rights reserved. This program and the accompanying materials
 *  are made available under the terms of the Eclipse Public License 2.0
 *  which accompanies this distribution, and is available at
 *  https://www.eclipse.org/legal/epl-2.0/
 *
 *  SPDX-License-Identifier: EPL-2.0
 *
 *  Contributors:
 *  Angelo Zerr <angelo.zerr@gmail.com> - initial API and implementation
 */
package org.eclipse.json.provisonnal.com.eclipsesource.json;

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


/**
 * A lightweight writing buffer to reduce the amount of write operations to be performed on the
 * underlying writer. This implementation is not thread-safe. It deliberately deviates from the
 * contract of Writer. In particular, it does not flush or close the wrapped writer nor does it
 * ensure that the wrapped writer is open.
 */
class WritingBuffer extends Writer {

  private final Writer writer;
  private final char[] buffer;
  private int fill = 0;

  WritingBuffer( Writer writer ) {
    this( writer, 16 );
  }

  WritingBuffer( Writer writer, int bufferSize ) {
    this.writer = writer;
    buffer = new char[bufferSize];
  }

  @Override
  public void write( int c ) throws IOException {
    if( fill > buffer.length - 1 ) {
      flush();
    }
    buffer[fill++] = (char)c;
  }

  @Override
  public void write( char[] cbuf, int off, int len ) throws IOException {
    if( fill > buffer.length - len ) {
      flush();
      if( len > buffer.length ) {
        writer.write( cbuf, off, len );
        return;
      }
    }
    System.arraycopy( cbuf, off, buffer, fill, len );
    fill += len;
  }

  @Override
  public void write( String str, int off, int len ) throws IOException {
    if( fill > buffer.length - len ) {
      flush();
      if( len > buffer.length ) {
        writer.write( str, off, len );
        return;
      }
    }
    str.getChars( off, off + len, buffer, fill );
    fill += len;
  }

  /**
   * Flushes the internal buffer but does not flush the wrapped writer.
   */
  @Override
  public void flush() throws IOException {
    writer.write( buffer, 0, fill );
    fill = 0;
  }

  /**
   * Does not close or flush the wrapped writer.
   */
  @Override
  public void close() throws IOException {
  }

}