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crystal.viewF.scala Maven / Gradle / Ivy
// Copyright (c) 2016-2023 Association of Universities for Research in Astronomy, Inc. (AURA)
// For license information see LICENSE or https://opensource.org/licenses/BSD-3-Clause
package crystal
import cats.Id
import cats.Monad
import cats.Monoid
import cats.effect.*
import cats.syntax.all.*
import monocle.Iso
import monocle.Lens
import monocle.Optional
import monocle.Prism
import monocle.Traversal
import scala.annotation.targetName
sealed abstract class ViewOps[F[_]: Monad, G[_], A] {
val get: G[A]
val setCB: (A, (G[A], G[A]) => F[Unit]) => F[Unit] = (a, cb) => modCB(_ => a, cb)
def setCB(v: A, cb: G[A] => F[Unit]): F[Unit] = setCB(v, (_, a) => cb(a))
val set: A => F[Unit] = a => mod(_ => a)
val modCB: (A => A, (G[A], G[A]) => F[Unit]) => F[Unit]
def modCB(f: A => A, cb: G[A] => F[Unit]): F[Unit] = modCB(f, (_, a) => cb(a))
val mod: (A => A) => F[Unit] = f => modCB(f, (_, _) => Monad[F].unit)
def modAndGet(f: A => A)(using Async[F]): F[G[A]]
}
// The difference between a View and a StateSnapshot is that the modifier doesn't act on the current value,
// but passes the modifier function to an external source of truth. Since we are defining no getter
// from such source of truth, a View is defined in terms of a modifier function instead of a setter.
// Also, Views remember their previous values.
class ViewF[F[_]: Monad, A](val get: A, val modCB: (A => A, (A, A) => F[Unit]) => F[Unit])
extends ViewOps[F, Id, A] { self =>
def modAndExtract[B](f: (A => (A, B)))(using F: Async[F]): F[B] =
F.async { cb =>
mod { (a: A) =>
val (fa, b) = f(a)
cb(b.asRight)
fa
// No need to run cb on errors, it will fail the async installation effect.
}.as(F.unit.some)
}
// In a ViewF, we can derive modAndGet. In ViewOptF and ViewListF we have to pass it, since their
// mod functions have no idea of the enclosing structure.
def modAndGet(f: A => A)(using Async[F]): F[A] =
modAndExtract(f.andThen(a => (a, a)))
def zoom[B](getB: A => B)(modB: (B => B) => A => A): ViewF[F, B] =
new ViewF(
getB(get),
(f: B => B, cb: (B, B) => F[Unit]) =>
modCB(modB(f), (previous, current) => cb(getB(previous), getB(current)))
)
def zoomOpt[B](
getB: A => Option[B]
)(modB: (B => B) => A => A): ViewOptF[F, B] =
new ViewOptF(
getB(get),
(f: B => B, cb: (Option[B], Option[B]) => F[Unit]) =>
modCB(modB(f), (previous, current) => cb(getB(previous), getB(current)))
) {
def modAndGet(f: B => B)(using Async[F]): F[Option[B]] =
self.modAndGet(modB(f)).map(getB)
}
def zoomList[B](
getB: A => List[B]
)(modB: (B => B) => A => A): ViewListF[F, B] =
new ViewListF(
getB(get),
(f: B => B, cb: (List[B], List[B]) => F[Unit]) =>
modCB(modB(f), (previous, current) => cb(getB(previous), getB(current)))
) {
def modAndGet(f: B => B)(using Async[F]): F[List[B]] =
self.modAndGet(modB(f)).map(getB)
}
def as[B](iso: Iso[A, B]): ViewF[F, B] = zoom(iso.asLens)
def asViewOpt: ViewOptF[F, A] = zoom(Iso.id[A].asOptional)
def asViewList: ViewListF[F, A] = zoom(Iso.id[A].asTraversal)
def zoom[B](lens: Lens[A, B]): ViewF[F, B] =
zoom(lens.get)(lens.modify)
def zoom[B](optional: Optional[A, B]): ViewOptF[F, B] =
zoomOpt(optional.getOption)(optional.modify)
def zoom[B](prism: Prism[A, B]): ViewOptF[F, B] =
zoomOpt(prism.getOption)(prism.modify)
def zoom[B](traversal: Traversal[A, B]): ViewListF[F, B] =
zoomList(traversal.getAll)(traversal.modify)
def withOnMod(f: (A, A) => F[Unit]): ViewF[F, A] =
new ViewF[F, A](
get,
(modF, cb) =>
modCB(modF, (previous, current) => f(previous, current) >> cb(previous, current))
)
def withOnMod(f: A => F[Unit]): ViewF[F, A] =
withOnMod((_, current) => f(current))
def widen[B >: A]: ViewF[F, B] = self.asInstanceOf[ViewF[F, B]]
def unsafeNarrow[B <: A]: ViewF[F, B] =
zoom(_.asInstanceOf[B])(modB => a => modB(a.asInstanceOf[B]))
def to[F1[_]: Monad](toF1: F[Unit] => F1[Unit], fromF1: F1[Unit] => F[Unit]): ViewF[F1, A] =
ViewF(get, (mod, cb) => toF1(modCB(mod, (previous, current) => fromF1(cb(previous, current)))))
def mapValue[B, C](f: ViewF[F, B] => C)(using ev: A =:= Option[B]): Option[C] =
// _.get is safe here since it's only being called when the value is defined.
// The zoom getter function is stored to use in callbacks, so we have to pass _.get
// instead of capturing the value here. Otherwise, callbacks see a stale value.
get.map(_ => f(zoom(_.get)(f => a1 => ev.flip(a1.map(f)))))
def toOptionView[B](using ev: A =:= Option[B]): Option[ViewF[F, B]] =
mapValue[B, ViewF[F, B]](identity)
@targetName("mapValuePot")
def mapValue[B, C](f: ViewF[F, B] => C)(using ev: A =:= Pot[B]): Pot[C] =
// _.get is safe here since it's only being called when the value is defined.
// The zoom getter function is stored to use in callbacks, so we have to pass _.get
// instead of capturing the value here. Otherwise, callbacks see a stale value.
get.map(_ => f(zoom(_.toOption.get)(f => a1 => ev.flip(a1.map(f)))))
def toPotView[B](using ev: A =:= Pot[B]): Pot[ViewF[F, B]] =
mapValue[B, ViewF[F, B]](identity)
@targetName("mapValuePotOption")
def mapValue[B, C](f: ViewF[F, B] => C)(using ev: A =:= PotOption[B]): PotOption[C] =
// _.get is safe here since it's only being called when the value is defined.
// The zoom getter function is stored to use in callbacks, so we have to pass _.get
// instead of capturing the value here. Otherwise, callbacks see a stale value.
get.map(_ => f(zoom(_.toOption.get)(f => a1 => ev.flip(a1.map(f)))))
def toPotOptionView[B](using ev: A =:= PotOption[B]): PotOption[ViewF[F, B]] =
mapValue[B, ViewF[F, B]](identity)
def when(cond: A => Boolean): Boolean = cond(get)
def unless(cond: A => Boolean): Boolean = !when(cond)
override def toString(): String = s"ViewF($get, )"
}
object ViewF {
def apply[F[_]: Monad, A](
value: A,
modCB: (A => A, (A, A) => F[Unit]) => F[Unit]
): ViewF[F, A] =
new ViewF(value, modCB)
}
abstract class ViewOptF[F[_]: Monad, A](
val get: Option[A],
val modCB: (A => A, (Option[A], Option[A]) => F[Unit]) => F[Unit]
) extends ViewOps[F, Option, A] { self =>
def as[B](iso: Iso[A, B]): ViewOptF[F, B] = zoom(iso.asLens)
def exists(cond: A => Boolean): Boolean = get.exists(cond)
def forall(cond: A => Boolean): Boolean = get.forall(cond)
def contains(cond: A): Boolean = get.contains(cond)
def asViewList: ViewListF[F, A] = zoom(Iso.id[A].asTraversal)
def asView(using Monoid[F[Unit]]): Option[ViewF[F, A]] = mapValue(identity)
def zoom[B](getB: A => B)(modB: (B => B) => A => A): ViewOptF[F, B] =
new ViewOptF(
get.map(getB),
(f: B => B, cb: (Option[B], Option[B]) => F[Unit]) =>
modCB(modB(f), (previous, current) => cb(previous.map(getB), current.map(getB)))
) {
def modAndGet(f: B => B)(using Async[F]): F[Option[B]] =
self.modAndGet(modB(f)).map(_.map(getB))
}
def zoomOpt[B](
getB: A => Option[B]
)(modB: (B => B) => A => A): ViewOptF[F, B] =
new ViewOptF(
get.flatMap(getB),
(f: B => B, cb: (Option[B], Option[B]) => F[Unit]) =>
modCB(
modB(f),
(previous, current) => cb(previous.flatMap(getB), current.flatMap(getB))
)
) {
def modAndGet(f: B => B)(using Async[F]): F[Option[B]] =
self.modAndGet(modB(f)).map(_.flatMap(getB))
}
def zoomList[B](
getB: A => List[B]
)(modB: (B => B) => A => A): ViewListF[F, B] =
new ViewListF(
get.map(getB).orEmpty,
(f: B => B, cb: (List[B], List[B]) => F[Unit]) =>
modCB(
modB(f),
(previous, current) => cb(previous.toList.flatMap(getB), current.toList.flatMap(getB))
)
) {
def modAndGet(f: B => B)(using Async[F]): F[List[B]] =
self.modAndGet(modB(f)).map(_.map(getB).orEmpty)
}
def zoom[B](lens: Lens[A, B]): ViewOptF[F, B] =
zoom(lens.get)(lens.modify)
def zoom[B](optional: Optional[A, B]): ViewOptF[F, B] =
zoomOpt(optional.getOption)(optional.modify)
def zoom[B](prism: Prism[A, B]): ViewOptF[F, B] =
zoomOpt(prism.getOption)(prism.modify)
def zoom[B](
traversal: Traversal[A, B]
): ViewListF[F, B] =
zoomList(traversal.getAll)(traversal.modify)
def withOnMod(f: (Option[A], Option[A]) => F[Unit]): ViewOptF[F, A] =
new ViewOptF[F, A](
get,
(modF, cb) =>
modCB(modF, (previous, current) => f(previous, current) >> cb(previous, current))
) {
def modAndGet(f: A => A)(using Async[F]): F[Option[A]] =
self.modAndGet(f)
}
def withOnMod(f: Option[A] => F[Unit]): ViewOptF[F, A] =
withOnMod((_, current) => f(current))
def widen[B >: A]: ViewOptF[F, B] = self.asInstanceOf[ViewOptF[F, B]]
def unsafeNarrow[B <: A]: ViewOptF[F, B] =
zoom(_.asInstanceOf[B])(modB => a => modB(a.asInstanceOf[B]))
def mapValue[B](f: ViewF[F, A] => B)(using Monoid[F[Unit]]): Option[B] =
get.map(a =>
f(
ViewF[F, A](
a,
(mod, cb) =>
modCB(
mod,
(previous, current) => (previous, current).tupled.foldMap((p, c) => cb(p, c))
)
)
)
)
def toOptionView(using Monoid[F[Unit]]): Option[ViewF[F, A]] =
mapValue(identity)
override def toString(): String = s"ViewOptF($get, )"
}
abstract class ViewListF[F[_]: Monad, A](
val get: List[A],
val modCB: (A => A, (List[A], List[A]) => F[Unit]) => F[Unit]
) extends ViewOps[F, List, A] { self =>
def as[B](iso: Iso[A, B]): ViewListF[F, B] = zoom(iso.asLens)
def exists(cond: A => Boolean): Boolean = get.exists(cond)
def forall(cond: A => Boolean): Boolean = get.forall(cond)
def zoom[B](getB: A => B)(modB: (B => B) => A => A): ViewListF[F, B] =
new ViewListF(
get.map(getB),
(f: B => B, cb: (List[B], List[B]) => F[Unit]) =>
modCB(modB(f), (previous, current) => cb(previous.map(getB), current.map(getB)))
) {
def modAndGet(f: B => B)(using Async[F]): F[List[B]] =
self.modAndGet(modB(f)).map(_.map(getB))
}
def zoomOpt[B](
getB: A => Option[B]
)(modB: (B => B) => A => A): ViewListF[F, B] =
new ViewListF(
get.flatMap(getB),
(f: B => B, cb: (List[B], List[B]) => F[Unit]) =>
modCB(
modB(f),
(previous, current) => cb(previous.flatMap(getB), current.flatMap(getB))
)
) {
def modAndGet(f: B => B)(using Async[F]): F[List[B]] =
self.modAndGet(modB(f)).map(_.flatMap(getB))
}
def zoomList[B](
getB: A => List[B]
)(modB: (B => B) => A => A): ViewListF[F, B] =
new ViewListF(
get.flatMap(getB),
(f: B => B, cb: (List[B], List[B]) => F[Unit]) =>
modCB(
modB(f),
(previous, current) => cb(previous.flatMap(getB), current.flatMap(getB))
)
) {
def modAndGet(f: B => B)(using Async[F]): F[List[B]] =
self.modAndGet(modB(f)).map(_.flatMap(getB))
}
def zoom[B](lens: Lens[A, B]): ViewListF[F, B] =
zoom(lens.get)(lens.modify)
def zoom[B](optional: Optional[A, B]): ViewListF[F, B] =
zoomOpt(optional.getOption)(optional.modify)
def zoom[B](prism: Prism[A, B]): ViewListF[F, B] =
zoomOpt(prism.getOption)(prism.modify)
def zoom[B](
traversal: Traversal[A, B]
): ViewListF[F, B] =
zoomList(traversal.getAll)(traversal.modify)
def withOnMod(f: (List[A], List[A]) => F[Unit]): ViewListF[F, A] =
new ViewListF[F, A](
get,
(modF, cb) =>
modCB(modF, (previous, current) => f(previous, current) >> cb(previous, current))
) {
def modAndGet(f: A => A)(using Async[F]): F[List[A]] =
self.modAndGet(f)
}
def withOnMod(f: List[A] => F[Unit]): ViewListF[F, A] =
withOnMod((_, current) => f(current))
def widen[B >: A]: ViewListF[F, B] = self.asInstanceOf[ViewListF[F, B]]
override def toString(): String = s"ViewListF($get, )"
}
