rule_engine

Simple RuleEngine where each rule is abstracted using Strategy Design Pattern, keeping in mind that each algorithm can grow separately. A client can chain multiple rules and and execute. Strategy, builder, generics and open closed principles are used out of box to achieve the functionality.

Using Rule Engine

Create a new RuleStrategy class by implementing RuleStrategy. This is base interface having boolean validate(T rule) method.

Create a new Rule by extending Base Rule abstract class. Its constructor should pass the rule strategy.

Sample Client

RuleEngine ruleEngine = new RuleEngine.RuleExecutor()

            .addRule(new AgeRule
                    .Builder(new AgeRuleStrategy())
                    .dob(LocalDate.of(2018, 11, 11))
                    .onSuccess(Arrays.asList("success msg 1", "success msg 2"))
                    .onFail(Arrays.asList("Fail msg 1", "Fail msg 2"))
                    .build()
            )
            .addRule(new AgeRule
                    .Builder(new AgeRuleStrategy())
                    .dob(LocalDate.of(2016, 11, 11))
                    .onSuccess(Arrays.asList("success msg 1", "success msg 2"))
                    .onFail(Arrays.asList("Fail msg 1", "Fail msg 2"))
                    .build()
            )
            .execute();

    List<Result> results = ruleEngine.getResults();