Logback: the reliable, generic, fast and flexible logging framework.
Copyright (C) 1999-2015, QOS.ch. All rights reserved.
This program and the accompanying materials are dual-licensed under
either the terms of the Eclipse Public License v1.0 as published by
the Eclipse Foundation
  or (per the licensee's choosing)
under the terms of the GNU Lesser General Public License version 2.1
as published by the Free Software Foundation.
/**
 * Logback: the reliable, generic, fast and flexible logging framework.
 * Copyright (C) 1999-2015, QOS.ch. All rights reserved.
 *
 * This program and the accompanying materials are dual-licensed under
 * either the terms of the Eclipse Public License v1.0 as published by
 * the Eclipse Foundation
 *
 *   or (per the licensee's choosing)
 *
 * under the terms of the GNU Lesser General Public License version 2.1
 * as published by the Free Software Foundation.
 */
package ch.qos.logback.core.pattern;

A minimal converter which sets up the general interface for derived classes. 
It also implements the functionality to chain converters in a linked list.
Author:
ceki/**
 * A minimal converter which sets up the general interface for derived classes. 
 * It also implements the functionality to chain converters in a linked list.
 * 
 * @author ceki
 */
abstract public class Converter<E> {

    Converter<E> next;

    
The convert method is responsible for extracting data from the event and
storing it for later use by the write method.
Params:
event – /**
     * The convert method is responsible for extracting data from the event and
     * storing it for later use by the write method.
     * 
     * @param event
     */
    public abstract String convert(E event);

    
In its simplest incarnation, a convert simply appends the data extracted from
the event to the buffer passed as parameter.
Params:
buf – The input buffer where data is appended
event – The event from where data is extracted/**
     * In its simplest incarnation, a convert simply appends the data extracted from
     * the event to the buffer passed as parameter.
     * 
     * @param buf The input buffer where data is appended
     * @param event The event from where data is extracted
     */
    public void write(StringBuilder buf, E event) {
        buf.append(convert(event));
    }

    public final void setNext(Converter<E> next) {
        if (this.next != null) {
            throw new IllegalStateException("Next converter has been already set");
        }
        this.next = next;
    }

    public final Converter<E> getNext() {
        return next;
    }
}