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/*
* The MIT License
*
* Copyright (c) 2022, Mahmoud Ben Hassine ([email protected])
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package org.jeasy.rules.mvel;
import java.util.ArrayList;
import java.util.List;
import org.jeasy.rules.api.Action;
import org.jeasy.rules.api.Condition;
import org.jeasy.rules.api.Facts;
import org.jeasy.rules.api.Rule;
import org.jeasy.rules.core.BasicRule;
import org.mvel2.ParserContext;
/**
* A {@link org.jeasy.rules.api.Rule} implementation that uses MVEL to evaluate and execute the rule.
*
* @author Mahmoud Ben Hassine ([email protected])
*/
public class MVELRule extends BasicRule {
private Condition condition = Condition.FALSE;
private final List actions = new ArrayList<>();
private final ParserContext parserContext;
/** Create a new MVEL rule. */
public MVELRule() {
this(new ParserContext());
}
/**
* Create a new MVEL rule.
*
* @param parserContext used to parse condition/action expressions
*/
public MVELRule(ParserContext parserContext) {
super(Rule.DEFAULT_NAME, Rule.DEFAULT_DESCRIPTION, Rule.DEFAULT_PRIORITY);
this.parserContext = parserContext;
}
/**
* Set rule name.
*
* @param name of the rule
* @return this rule
*/
public MVELRule name(String name) {
this.name = name;
return this;
}
/**
* Set rule description.
*
* @param description of the rule
* @return this rule
*/
public MVELRule description(String description) {
this.description = description;
return this;
}
/**
* Set rule priority.
*
* @param priority of the rule
* @return this rule
*/
public MVELRule priority(int priority) {
this.priority = priority;
return this;
}
/**
* Specify the rule's condition as MVEL expression.
*
* @param condition of the rule
* @return this rule
*/
public MVELRule when(String condition) {
this.condition = new MVELCondition(condition, parserContext);
return this;
}
/**
* Add an action specified as an MVEL expression to the rule.
*
* @param action to add to the rule
* @return this rule
*/
public MVELRule then(String action) {
this.actions.add(new MVELAction(action, parserContext));
return this;
}
@Override
public boolean evaluate(Facts facts) {
return condition.evaluate(facts);
}
@Override
public void execute(Facts facts) throws Exception {
for (Action action : actions) {
action.execute(facts);
}
}
}