Interface Rule

easy-rules-core/src/main/java/org/jeasy/rules/api/Rule.java:34–89

Abstraction for a rule that can be fired by a rules engine. Rules are registered in a namespace of rule of type Rules in which they must have a unique name. @author Mahmoud Ben Hassine (mahmoud.benhassine@icloud.com)

 * @author Mahmoud Ben Hassine (mahmoud.benhassine@icloud.com)
 */
public interface Rule extends Comparable<Rule> {

    /**
     * Default rule name.
     */
    String DEFAULT_NAME = "rule";

    /**
     * Default rule description.
     */
    String DEFAULT_DESCRIPTION = "description";

    /**
     * Default rule priority.
     */
    int DEFAULT_PRIORITY = Integer.MAX_VALUE - 1;

    /**
     * Getter for rule name.
     * @return the rule name
     */
    default String getName() {
        return DEFAULT_NAME;
    }

    /**
     * Getter for rule description.
     * @return rule description
     */
    default String getDescription() {
        return DEFAULT_DESCRIPTION;
    }

    /**
     * Getter for rule priority.
     * @return rule priority
     */
    default int getPriority() {
        return DEFAULT_PRIORITY;
    }

    /**
     * This method implements the rule's condition(s).
     * <strong>Implementations should handle any runtime exception and return true/false accordingly</strong>
     *
     * @return true if the rule should be applied given the provided facts, false otherwise
     */
    boolean evaluate(Facts facts);

    /**
     * This method implements the rule's action(s).
     * @throws Exception thrown if an exception occurs when performing action(s)
     */
    void execute(Facts facts) throws Exception;

}