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/
Widget.scala
136 lines (116 loc) · 4.79 KB
/
Widget.scala
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package io.taig.schelm
import cats.Monoid
import cats.implicits._
import scala.annotation.tailrec
sealed abstract class Widget[+Event, Context, Payload]
extends Product
with Serializable {
def component(
context: Context
): Component[Widget[Event, Context, Payload], Event] = this match {
case Widget.Pure(component, _) => component
case Widget.Render(apply) => apply(context).component(context)
case Widget.Local(f, widget) => widget.component(f(context))
}
def component(
implicit ev: Unit =:= Context
): Component[Widget[Event, Context, Payload], Event] = component(unit)
def payload(context: Context): Payload = this match {
case Widget.Pure(_, payload) => payload
case Widget.Render(apply) => apply(context).payload(context)
case Widget.Local(f, widget) => widget.payload(f(context))
}
def payload(implicit ev: Unit =:= Context): Payload = payload(unit)
def render(context: Context): Widget[Event, Unit, Payload] =
Widget.render(context, this)
def merge(implicit F: Monoid[Payload], ev: Unit =:= Context): Payload = {
val payloads = component match {
case component: Component.Element[Widget[_, Context, Payload], _] =>
component.children.values.map(_.merge).combineAll
case component: Component.Fragment[Widget[_, Context, Payload]] =>
component.children.values.map(_.merge).combineAll
case component: Component.Lazy[Widget[_, Context, Payload]] =>
component.eval.value.merge
case _: Component.Text => F.empty
}
payload(unit) |+| payloads
}
}
object Widget {
final case class Pure[+Event, Context, Payload](
component: Component[Widget[Event, Context, Payload], Event],
payload: Payload
) extends Widget[Event, Context, Payload]
final case class Render[+Event, Context, Payload](
apply: Context => Widget[Event, Context, Payload]
) extends Widget[Event, Context, Payload]
final case class Local[+Event, Context, Payload](
f: Context => Context,
widget: Widget[Event, Context, Payload]
) extends Widget[Event, Context, Payload]
def apply[Event, Context, Payload](
apply: Context => Widget[Event, Context, Payload]
): Widget[Event, Context, Payload] =
Render(apply)
def pure[Event, Context, Payload](
component: Component[Widget[Event, Context, Payload], Event],
payload: Payload
): Widget[Event, Context, Payload] = Pure(component, payload)
def empty[Event, Context, Payload: Monoid](
component: Component[Widget[Event, Context, Payload], Event]
): Widget[Event, Context, Payload] =
Pure(component, Monoid[Payload].empty)
def local[Event, Context, Payload](
f: Context => Context
)(widget: Widget[Event, Context, Payload]): Widget[Event, Context, Payload] =
Local(f, widget)
@tailrec
def render[Event, Context, Payload](
context: Context,
widget: Widget[Event, Context, Payload]
): Widget[Event, Unit, Payload] =
widget match {
case Pure(component, payload) => Pure(render(context, component), payload)
case Render(apply) => render(context, apply(context))
case Local(f, widget) => render(f(context), widget)
}
def render[Event, Context, Payload](
context: Context,
component: Component[Widget[Event, Context, Payload], Event]
): Component[Widget[Event, Unit, Payload], Event] =
component match {
case component: Component.Element[Widget[Event, Context, Payload], Event] =>
val children = component.children.map { (_, child) =>
render(context, child)
}
component.copy(children = children)
case Component.Fragment(children) =>
Component.Fragment(children.map((_, child) => render(context, child)))
case Component.Lazy(eval, hash) =>
Component.Lazy(eval.map(render(context, _)), hash)
case component: Component.Text => component
}
def payload[Event, Context, Payload](
widget: Widget[Event, Context, Payload]
)(transform: Payload => Payload): Widget[Event, Context, Payload] =
widget match {
case Pure(component, payload) => Pure(component, transform(payload))
case Render(apply) =>
Render(context => payload(apply(context))(transform))
case Local(f, widget) => Local(f, payload(widget)(transform))
}
def component[Event, Context, Payload](
widget: Widget[Event, Context, Payload]
)(
transform: Component[Widget[Event, Context, Payload], Event] => Component[
Widget[Event, Context, Payload],
Event
]
): Widget[Event, Context, Payload] =
widget match {
case Pure(component, payload) => Pure(transform(component), payload)
case Render(apply) =>
Render(context => component(apply(context))(transform))
case Local(f, widget) => Local(f, component(widget)(transform))
}
}