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Java Rule Engine for the masses
/**
* This software is licensed under the Apache 2 license, quoted below.
*
* Copyright (c) 1999-2019, Live Software & Consultants Inc ([email protected])
*
* 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 org.algorithmx.rules.model;
import org.algorithmx.rules.annotation.Description;
import org.algorithmx.rules.annotation.Otherwise;
import org.algorithmx.rules.annotation.Then;
import org.algorithmx.rules.spring.util.Assert;
import org.algorithmx.rules.util.LambdaUtils;
import java.lang.annotation.Annotation;
import java.lang.invoke.SerializedLambda;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
/**
* Indicates the annotated (@Action) method is an Action and is eligible to be execute based on the result
* of the associated Rule. An Action is always associated to a Rule and does not exist ow its own.
*
* The only requirement for an Action method is the @Action annotation.The method can take arbitrary number of
* arguments but must return nothing (aka : void).
*
* @author Max Arulananthan
* @since 1.0
*/
public final class ActionDefinition implements Comparable {
// Action class
private final Class actionClass;
// Description of the Action
private final String description;
// then method
private final MethodDefinition action;
private ActionDefinition(Class actionClass, String description, MethodDefinition action) {
super();
Assert.notNull(actionClass, "action class cannot be null");
Assert.notNull(action, "action cannot be null");
this.actionClass = actionClass;
this.description = description;
this.action = action;
}
/**
* Loads all the ActionConsumer actions in the given class. A method is considered an Action if takes arbitrary number
* of arguments and returns nothing (ie: void) and the method is annotated with @ActionConsumer.
*
* @param c desired class
* @return all the associated actions
*/
public static ActionDefinition[] loadThenActions(Class c) {
return load(c, Then.class);
}
/**
* Loads all the ActionConsumer actions in the given class. A method is considered an Action if takes arbitrary number
* of arguments and returns nothing (ie: void) and the method is annotated with @Otherwise.
*
* @param c desired class
* @return all the associated actions
*/
public static ActionDefinition[] loadElseActions(Class c) {
return load(c, Otherwise.class);
}
/**
* Loads all the actions in the given class. A method is considered an Action if takes arbitrary number
* of arguments and returns nothing (ie: void) and the method is annotated with given annotation.
*
* @param c desired class
* @param annotationClass desired Annotation Class.
* @param Annotation Type.
* @return all the associated actions
*/
private static ActionDefinition[] load(Class c, Class annotationClass) {
MethodDefinition[] actions = MethodDefinition.load(c, (Method method) ->
void.class.equals(method.getReturnType()) && Modifier.isPublic(method.getModifiers())
&& method.getAnnotation(annotationClass) != null);
if (actions == null || actions.length == 0) return null;
ActionDefinition[] result = new ActionDefinition[actions.length];
for (int i = 0; i < result.length; i++) {
Description descriptionAnnotation = actions[i].getMethod().getAnnotation(Description.class);
result[i] = new ActionDefinition(c, descriptionAnnotation != null ? descriptionAnnotation.value() : null,
actions[i]);
}
return result;
}
/**
* Loads the action in the given Lambda. A method is considered an Action if takes arbitrary number
* of arguments and returns nothing (ie: void).
*
* @param lambda supplied lambda.
* @param description action description.
* @return ActionDefinition.
*/
public static ActionDefinition load(SerializedLambda lambda, String description) {
Class implementationClass = LambdaUtils.getImplementationClass(lambda);
Assert.notNull(implementationClass, "implementationClass cannot be null");
Method implementationMethod = LambdaUtils.getImplementationMethod(lambda, implementationClass);
Assert.notNull(implementationMethod, "implementationMethod cannot be null");
Assert.isTrue(void.class.equals(implementationMethod.getReturnType()),
"Action Lambda not defined correctly. Please define method public void then(...)");
MethodDefinition[] actions = MethodDefinition.load(implementationClass, implementationMethod);
return new ActionDefinition(implementationClass, description, actions[0]);
}
@Override
public int compareTo(ActionDefinition other) {
Integer parameterCount = action.getMethod().getParameterCount();
return parameterCount.compareTo(other.action.getMethod().getParameterCount());
}
public Class getActionClass() {
return actionClass;
}
public String getDescription() {
return description;
}
public MethodDefinition getAction() {
return action;
}
/**
* Determines if the action is a statically implemented method call (such as a lambda).
*
* @return true if statically implemented; false otherwise.
*/
public boolean isStatic() {
return action.isStatic();
}
@Override
public String toString() {
return "ActionDefinition{" +
"actionClass=" + actionClass +
", description='" + description + '\'' +
", action=" + action +
'}';
}
}