Kotlin DSL Example

dslexample.kt

data class AddresBook(val contactGroups: List<ContactGroup>, val contacts: List<Contact>)
data class Contact(val name: String, val phones: List<String>)
data class ContactGroup(val name: String, val contacts: List<Contact>)

fun addressBook(lambda: AddressBookBuilder.()->Unit) = AddressBookBuilder().apply(lambda).build()

@DslMarker
annotation class AdressBookDslMarker

@AdressBookDslMarker
class AddressBookBuilder {
    private val contacts: MutableList<Contact> = mutableListOf()
    private val contactGroups: MutableList<ContactGroup> = mutableListOf()

    fun contact(lambda: ContactBuilder.()->Unit) = contacts.add(ContactBuilder().apply(lambda).build())
    fun contactGroup(lambda: ContactGroupBuilder.()->Unit) = contactGroups.add(ContactGroupBuilder().apply(lambda).build())
    fun build() = AddresBook(contactGroups, contacts)
}

@AdressBookDslMarker
class ContactGroupBuilder {
    var name: String = ""
    private val contacts: MutableList<Contact> = mutableListOf()

    fun contact(lambda: ContactBuilder.()->Unit) = contacts.add(ContactBuilder().apply(lambda).build())
    fun build() = ContactGroup(name, contacts)
}

@AdressBookDslMarker
class ContactBuilder {
    var name: String = ""
    private val phones: MutableList<String> = mutableListOf()

    fun phone(number: String) = phones.add(number)
    fun build() = Contact(name, phones)
}

val myAddressBook = addressBook {
    contact {
        name = "John Doe"
        phone("0712341234")
        phone("4-93489")
    }
    contactGroup {
        name = "friends"
        contact {
            name = "Jane"
            phone("0712341234")
        }
        contact {
            name = "Mr. T"
            phone("0712341234")
        }
    }
}

val otherAdressBook = AddresBook(
        listOf(
                ContactGroup(
                        "friends",
                        listOf(
                                Contact(
                                        "Jane",
                                        listOf("0712341234")
                                        ),
                                Contact(
                                        "Mr. T",
                                        listOf("0712341234")
                                )
                        )
                )
        ),
        listOf(
                Contact(
                        "John Doe",
                        listOf("4-93489", "0712341234")
                )
        )
)

fun main(args: Array<String>) {
    println(myAddressBook)
}