/*
* Copyright 2014 Igor Maznitsa (http://www.igormaznitsa.com).
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.igormaznitsa.prol.trace;
import com.igormaznitsa.prol.logic.Goal;
/**
* Interface describes a trace listener which can get events during a goal
* processing
*
* @author Igor Maznitsa (igor.maznitsa@igormaznitsa.com)
*/
public interface TraceListener {
/**
* It will be called when the goal is called the first time
*
* @param goal the goal to be called
* @return true if the goal can be processed, if it is false, the goal will
* not be processed and it will return fail
*/
public boolean onProlGoalCall(Goal goal);
/**
* It will be called when the goal is recalled
*
* @param goal the goal to be recalled
* @return true if the goal can be processed, if it is false, the goal will
* not be processed and it will return fail
*/
public boolean onProlGoalRedo(Goal goal);
/**
* It will be called when a goal is failed
*
* @param goal the goal which one is failed
*/
public void onProlGoalFail(Goal goal);
/**
* It will be called when a goal is completed
*
* @param goal the source goal
*/
public void onProlGoalExit(Goal goal);
}