Examples

Additional examples are included in the OCL.js repository for both Node.js and webpack.

Company

This example models a company with employees and a manager, and enforces constraints on their ages and employment status.

Model

export class Company {
    name: string;
    employee: Person[];
    manager: Person;
}

export class Person {
    name: string;
    age: number;
    isUnemployed: boolean;
}

Constraints

import { OclEngine } from "@stekoe/ocl.js"
import { Company, Person } from "./company.js"

const oclEngine = OclEngine.create();

oclEngine.addOclExpression(`
    -- No one should work that long...
    context Company inv:
        self.employee->forAll(p : Person | p.age <= 65 )

    -- If a company has a manager,
    -- the company has at least one employee.
    context Company
        inv: self.manager.isUnemployed = false
        inv: self.employee->notEmpty()
`);

let company = new Company();
company.employee.push(new Person());

const oclResult = oclEngine.evaluate(company);

Person

This example demonstrates multiple invariants on a Person class covering marriage and children constraints.

import { OclEngine } from "@stekoe/ocl.js"

class Person {
    name: string;
    age: number;
    children: Person[];
    isMarried: boolean;
    husband: Person;
    wife: Person;
}

const oclResult = OclEngine.create()
  .addOclExpression(`
      -- Check that underage persons are not married
      context Person inv:
          age < 18 implies isMarried = false

      -- Check that each and every child is younger than 18 years old
      context Person inv:
          children->select(age >= 18)->isEmpty()

      -- If a person is married, wife or husband has to be at least 18 years old
      context Person inv:
          self.wife->notEmpty() implies self.wife.age >= 18 and
          self.husband->notEmpty() implies self.husband.age >= 18

      -- If there are children, one should be named Stephan ;)
      context Person inv:
          self.children->exists(child | child.name = 'Stephan')
  `)
  .evaluate(new Person());