import groovy.transform.*

@ToString
class Vehicle {
  String brand
  String model
  Integer wheels
}
class Car extends Vehicle {}
class Bike extends Vehicle {}

// FactoryBuilderSupport
class VehicleBuilder extends BuilderSupport {

    @Override protected Object createNode(Object name, Map attributes = [:]) {
        return createNode(name, attributes, null)
    }

    @Override protected Object createNode(Object name, Map attributes = [:], Object value) {
       switch(name) {
           case 'car': return new Car()
           case 'bike': return new Bike()

           case 'wheels':
           assert value instanceof Integer
           return ['wheels', value]

           case 'brand':
           assert value instanceof String
           return ['brand', value]

           case 'model':
           assert value instanceof String
           return ['model', value]

           default:
           throw new IllegalStateException("What type of vehicle are you trying to build ? $name ?")
       }
    }

    @Override protected void setParent(Object parent, Object child) {
        assert child instanceof List
        assert child.size() == 2

        switch(child.first()) {
            case 'wheels':
                parent.wheels = child.last()
                break
            case 'brand':
                parent.brand = child.last()
                break
            case 'model':
                parent.model = child.last()
                break
        }
    }

    static main(def args) {
      println VehicleBuilder.newInstance().car {
           wheels 4
           brand 'ferrari'
           model 'F450'
       }
    }
}

VehicleBuilder.main(null)

import groovy.transform.*

@ToString
class Vehicle {
  String brand
  String model
  Integer wheels
}
class Car extends Vehicle {}
class Bike extends Vehicle {}

// FactoryBuilderSupport
class VehicleBuilder extends BuilderSupport {

    @Override protected Object createNode(Object name, Map attributes = [:]) {
        return createNode(name, attributes, null)
    }

    @Override protected Object createNode(Object name, Map attributes = [:], Object value) {
       switch(name) {
           case 'car': return new Car()
           case 'bike': return new Bike()

           case 'wheels':
           assert value instanceof Integer
           return ['wheels', value]

           case 'brand':
           assert value instanceof String
           return ['brand', value]

           case 'model':
           assert value instanceof String
           return ['model', value]

           default:
           throw new IllegalStateException("What type of vehicle are you trying to build ? $name ?")
       }
    }

    @Override protected void setParent(Object parent, Object child) {
        assert child instanceof List
        assert child.size() == 2

        switch(child.first()) {
            case 'wheels':
                parent.wheels = child.last()
                break
            case 'brand':
                parent.brand = child.last()
                break
            case 'model':
                parent.model = child.last()
                break
        }
    }

    static main(def args) {
      println VehicleBuilder.newInstance().car {
           wheels 4
           brand 'ferrari'
           model 'F450'
       }
    }
}

VehicleBuilder.main(null)