core/dev.fritz2.core/Lens

Lens

interface Lens<P, T>

Describes a focus point into a data structure, i.e. a property of a given complex entity for read and write access.

Properties

abstract val id: String

identifies the focus of this lens

Functions

open suspend fun apply(parent: P, mapper: suspend (T) -> T): P

manipulates the focus target's value inside the parent

fun <P> Lens<P, Boolean>.asString(): Lens<P, String>

fun <P> Lens<P, Boolean?>.asString(emptyValue: String = ""): Lens<P, String>

Creates a Lens from Boolean to String

fun <P> Lens<P, Byte>.asString(): Lens<P, String>

fun <P> Lens<P, Byte?>.asString(emptyValue: String = ""): Lens<P, String>

Creates a Lens from Byte to String

fun <P> Lens<P, Double>.asString(): Lens<P, String>

fun <P> Lens<P, Double?>.asString(emptyValue: String = ""): Lens<P, String>

Creates a Lens from Double to String

fun <P> Lens<P, Float>.asString(): Lens<P, String>

fun <P> Lens<P, Float?>.asString(emptyValue: String = ""): Lens<P, String>

Creates a Lens from Float to String

fun <P> Lens<P, Int>.asString(): Lens<P, String>

fun <P> Lens<P, Int?>.asString(emptyValue: String = ""): Lens<P, String>

Creates a Lens from Int to String

fun <P> Lens<P, Long>.asString(): Lens<P, String>

fun <P> Lens<P, Long?>.asString(emptyValue: String = ""): Lens<P, String>

Creates a Lens from Long to String

fun <P> Lens<P, Short>.asString(): Lens<P, String>

fun <P> Lens<P, Short?>.asString(emptyValue: String = ""): Lens<P, String>

Creates a Lens from Short to String

abstract fun get(parent: P): T

gets the value of the focus target

open operator fun <X> plus(other: Lens<T, X>): Lens<P, X>

appends to Lenses so that the resulting Lens points from the parent of the Lens this is called on to the target of other

abstract fun set(parent: P, value: T): P

sets the value of the focus target

open fun withNullParent(): Lens<P?, T>

For a lens on a non-nullable parent this method creates a lens that can be used on a nullable-parent Use this method only if you made sure, that it is never called on a null parent. Otherwise, a NullPointerException is thrown.