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15 changes: 15 additions & 0 deletions
15
lenses/shared/src/main/scala/com/trueaccord/lenses/package.scala
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| package com.trueaccord | ||
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| package object lenses { | ||
| @deprecated("Use scalapb.lenses package instead of com.trueaccord.lenses", "0.7.0") | ||
| type Updatable[A] = scalapb.lenses.Updatable[A] | ||
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| @deprecated("Use scalapb.lenses package instead of com.trueaccord.lenses", "0.7.0") | ||
| type Lens[Container, A] = scalapb.lenses.Lens[Container, A] | ||
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| @deprecated("Use scalapb.lenses package instead of com.trueaccord.lenses", "0.7.0") | ||
| type ObjectLens[U, Container] = scalapb.lenses.ObjectLens[U, Container] | ||
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| @deprecated("Use scalapb.lenses package instead of com.trueaccord.lenses", "0.7.0") | ||
| val Lens = scalapb.lenses.Lens | ||
| } |
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lenses/shared/src/main/scala/scalapb/lenses/Lenses.scala
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| Original file line number | Diff line number | Diff line change |
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| package scalapb.lenses | ||
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| import scala.language.higherKinds | ||
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| trait Lens[Container, A] extends Any { | ||
| self => | ||
| /** get knows how to extract some field of type `A` from a container */ | ||
| def get(c: Container): A | ||
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| /** Represents an assignment operator. | ||
| * | ||
| * Given a value of type A, sets knows how to transform a container such that `a` is | ||
| * assigned to the field. | ||
| * | ||
| * We must have get(set(a)(c)) == a | ||
| */ | ||
| def set(a: A): Mutation[Container] | ||
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| /** alias to set */ | ||
| def :=(a: A) = set(a) | ||
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| /** Represent an update operator (like x.y += 1 ) */ | ||
| def modify(f: A => A): Mutation[Container] = c => set(f(get(c)))(c) | ||
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| /** Composes two lenses, this enables nesting. | ||
| * | ||
| * If our field of type A has a sub-field of type B, then given a lens for it | ||
| * (other: Lens[A, B]) we can create a single lens from Container to B. | ||
| */ | ||
| def compose[B](other: Lens[A, B]): Lens[Container, B] = new Lens[Container, B] { | ||
| def get(c: Container) = other.get(self.get(c)) | ||
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| def set(b: B) = self.modify(other.set(b)) | ||
| } | ||
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| /** Given two lenses with the same origin, returns a new lens that can mutate both values | ||
| * represented by both lenses through a tuple. | ||
| */ | ||
| def zip[B](other: Lens[Container, B]): Lens[Container, (A, B)] = new Lens[Container, (A,B)] { | ||
| def get(c: Container): (A,B) = (self.get(c), other.get(c)) | ||
| def set(t: (A, B)): Mutation[Container] = self.set(t._1).andThen(other.set(t._2)) | ||
| } | ||
| } | ||
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| object Lens { | ||
| /* Create a Lens from getter and setter. */ | ||
| def apply[Container, A](getter: Container => A)(setter: (Container, A) => Container): Lens[Container, A] = new Lens[Container, A] { | ||
| def get(c: Container) = getter(c) | ||
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| def set(a: A): Mutation[Container] = setter(_, a) | ||
| } | ||
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| /** This is the unit lens, with respect to the compose operation defined above. That is, | ||
| * len.compose(unit) == len == unit.compose(len) | ||
| * | ||
| * More practically, you can view it as a len that mutates the entire object, instead of | ||
| * just a field of it: get() gives the original object, and set() returns the assigned value, | ||
| * no matter what the original value was. | ||
| */ | ||
| def unit[U]: Lens[U, U] = Lens(identity[U])((c, v) => v) | ||
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| /** Implicit that adds some syntactic sugar if our lens watches a Seq-like collection. */ | ||
| implicit class SeqLikeLens[U, A, Coll[A] <: collection.SeqLike[A, Coll[A]]](val lens: Lens[U, Coll[A]]) extends AnyVal { | ||
| type CBF = collection.generic.CanBuildFrom[Coll[A], A, Coll[A]] | ||
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| private def field(getter: Coll[A] => A)(setter: (Coll[A], A) => Coll[A]): Lens[U, A] = | ||
| lens.compose[A](Lens[Coll[A], A](getter)(setter)) | ||
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| def apply(i: Int)(implicit cbf: CBF): Lens[U, A] = field(_.apply(i))((c, v) => c.updated(i, v)) | ||
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| def head(implicit cbf: CBF): Lens[U, A] = apply(0) | ||
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| def last(implicit cbf: CBF): Lens[U, A] = field(_.last)((c, v) => c.updated(c.size - 1, v)) | ||
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| def :+=(item: A)(implicit cbf: CBF) = lens.modify(_ :+ item) | ||
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| def :++=(item: scala.collection.GenTraversableOnce[A])(implicit cbf: CBF) = lens.modify(_ ++ item) | ||
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| def foreach(f: Lens[A, A] => Mutation[A])(implicit cbf: CBF): Mutation[U] = | ||
| lens.modify(s => s.map { | ||
| (m: A) => | ||
| val field: Lens[A, A] = Lens.unit[A] | ||
| val p: Mutation[A] = f(field) | ||
| p(m) | ||
| }) | ||
| } | ||
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| /** Implicit that adds some syntactic sugar if our lens watches a Set-like collection. */ | ||
| implicit class SetLikeLens[U, A, Coll[A] <: collection.SetLike[A, Coll[A]] with Set[A]](val lens: Lens[U, Coll[A]]) extends AnyVal { | ||
| type CBF = collection.generic.CanBuildFrom[Coll[A], A, Coll[A]] | ||
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| private def field(getter: Coll[A] => A)(setter: (Coll[A], A) => Coll[A]): Lens[U, A] = | ||
| lens.compose[A](Lens[Coll[A], A](getter)(setter)) | ||
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| def :+=(item: A)(implicit cbf: CBF) = lens.modify(_ + item) | ||
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| def :++=(item: scala.collection.GenTraversableOnce[A])(implicit cbf: CBF) = lens.modify(_ ++ item) | ||
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| def foreach(f: Lens[A, A] => Mutation[A])(implicit cbf: CBF): Mutation[U] = | ||
| lens.modify(s => s.map { | ||
| (m: A) => | ||
| val field: Lens[A, A] = Lens.unit[A] | ||
| val p: Mutation[A] = f(field) | ||
| p(m) | ||
| }) | ||
| } | ||
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| /** Implicit that adds some syntactic sugar if our lens watches an Option[_]. */ | ||
| implicit class OptLens[U, A](val lens: Lens[U, Option[A]]) extends AnyVal { | ||
| def inplaceMap(f: Lens[A, A] => Mutation[A]) = | ||
| lens.modify(opt => opt.map { | ||
| (m: A) => | ||
| val field: Lens[A, A] = Lens.unit[A] | ||
| val p: Mutation[A] = f(field) | ||
| p(m) | ||
| }) | ||
| } | ||
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| /** Implicit that adds some syntactic sugar if our lens watches a Map[_, _]. */ | ||
| implicit class MapLens[U, A, B](val lens: Lens[U, Map[A, B]]) extends AnyVal { | ||
| def apply(key: A): Lens[U, B] = lens.compose(Lens[Map[A, B], B](_.apply(key))((map, value) => map.updated(key, value))) | ||
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| def :+=(pair: (A, B)) = lens.modify(_ + pair) | ||
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| def :++=(item: Iterable[(A, B)]) = lens.modify(_ ++ item) | ||
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| def foreach(f: Lens[(A, B), (A, B)] => Mutation[(A, B)]): Mutation[U] = | ||
| lens.modify(s => s.map { | ||
| (pair: (A, B)) => | ||
| val field: Lens[(A, B), (A, B)] = Lens.unit[(A, B)] | ||
| val p: Mutation[(A, B)] = f(field) | ||
| p(pair) | ||
| }) | ||
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| def foreachValue(f: Lens[B, B] => Mutation[B]): Mutation[U] = | ||
| lens.modify(s => s.mapValues { | ||
| (m: B) => | ||
| val field: Lens[B, B] = Lens.unit[B] | ||
| val p: Mutation[B] = f(field) | ||
| p(m) | ||
| }) | ||
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| def mapValues(f: B => B) = foreachValue(_.modify(f)) | ||
| } | ||
| } | ||
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| /** Represents a lens that has sub-lenses. */ | ||
| class ObjectLens[U, Container](self: Lens[U, Container]) extends Lens[U, Container] { | ||
| /** Creates a sub-lens */ | ||
| def field[A](lens: Lens[Container, A]): Lens[U, A] = self.compose(lens) | ||
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| /** Creates a sub-lens */ | ||
| def field[A](getter: Container => A)(setter: (Container, A) => Container): Lens[U, A] = | ||
| field(Lens(getter)(setter)) | ||
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| override def get(u: U) = self.get(u) | ||
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| override def set(c: Container) = self.set(c) | ||
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| def update(ms: (Lens[Container, Container] => Mutation[Container])*): Mutation[U] = | ||
| u => set(ms.foldLeft[Container](get(u))((p, m) => m(Lens.unit[Container])(p)))(u) | ||
| } | ||
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| trait Updatable[A] extends Any { | ||
| self: A => | ||
| def update(ms: (Lens[A, A] => Mutation[A])*): A = ms.foldLeft[A](self)((p, m) => m(Lens.unit[A])(p)) | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,5 @@ | ||
| package scalapb | ||
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| package object lenses { | ||
| type Mutation[C] = C => C | ||
| } |
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