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vector.scala
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vector.scala
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/*
* Copyright (c) 2015 Typelevel
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of
* this software and associated documentation files (the "Software"), to deal in
* the Software without restriction, including without limitation the rights to
* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
* the Software, and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
package cats
package instances
import cats.data.{Chain, Ior, ZipVector}
import cats.instances.StaticMethods.appendAll
import cats.kernel.compat.scalaVersionSpecific._
import scala.annotation.tailrec
import scala.collection.immutable.VectorBuilder
trait VectorInstances extends cats.kernel.instances.VectorInstances {
implicit val catsStdInstancesForVector
: Traverse[Vector] with Monad[Vector] with Alternative[Vector] with CoflatMap[Vector] with Align[Vector] =
new Traverse[Vector] with Monad[Vector] with Alternative[Vector] with CoflatMap[Vector] with Align[Vector] {
def empty[A]: Vector[A] = Vector.empty[A]
def combineK[A](x: Vector[A], y: Vector[A]): Vector[A] = x ++ y
override def combineAllOptionK[A](as: IterableOnce[Vector[A]]): Option[Vector[A]] = {
val iter = as.iterator
if (iter.isEmpty) None else Some(appendAll(iter, Vector.newBuilder[A]).result())
}
override def fromIterableOnce[A](as: IterableOnce[A]): Vector[A] =
as.iterator.toVector
override def prependK[A](a: A, fa: Vector[A]): Vector[A] = a +: fa
override def appendK[A](fa: Vector[A], a: A): Vector[A] = fa :+ a
def pure[A](x: A): Vector[A] = Vector(x)
override def map[A, B](fa: Vector[A])(f: A => B): Vector[B] =
fa.map(f)
def flatMap[A, B](fa: Vector[A])(f: A => Vector[B]): Vector[B] =
fa.flatMap(f)
override def map2[A, B, Z](fa: Vector[A], fb: Vector[B])(f: (A, B) => Z): Vector[Z] =
if (fb.isEmpty) Vector.empty // do O(1) work if either is empty
else fa.flatMap(a => fb.map(b => f(a, b))) // already O(1) if fa is empty
private[this] val evalEmpty: Eval[Vector[Nothing]] = Eval.now(Vector.empty)
override def map2Eval[A, B, Z](fa: Vector[A], fb: Eval[Vector[B]])(f: (A, B) => Z): Eval[Vector[Z]] =
if (fa.isEmpty) evalEmpty // no need to evaluate fb
else fb.map(fb => map2(fa, fb)(f))
def coflatMap[A, B](fa: Vector[A])(f: Vector[A] => B): Vector[B] = {
@tailrec def loop(builder: VectorBuilder[B], as: Vector[A]): Vector[B] =
as match {
case _ +: rest => loop(builder += f(as), rest)
case _ => builder.result()
}
loop(new VectorBuilder[B], fa)
}
def foldLeft[A, B](fa: Vector[A], b: B)(f: (B, A) => B): B =
fa.foldLeft(b)(f)
def foldRight[A, B](fa: Vector[A], lb: Eval[B])(f: (A, Eval[B]) => Eval[B]): Eval[B] = {
def loop(i: Int): Eval[B] =
if (i < fa.length) f(fa(i), Eval.defer(loop(i + 1))) else lb
Eval.defer(loop(0))
}
override def foldMap[A, B](fa: Vector[A])(f: A => B)(implicit B: Monoid[B]): B =
B.combineAll(fa.iterator.map(f))
def tailRecM[A, B](a: A)(fn: A => Vector[Either[A, B]]): Vector[B] = {
val buf = Vector.newBuilder[B]
var state = List(fn(a).iterator)
@tailrec
def loop(): Unit =
state match {
case Nil => ()
case h :: tail if h.isEmpty =>
state = tail
loop()
case h :: tail =>
h.next() match {
case Right(b) =>
buf += b
loop()
case Left(a) =>
state = (fn(a).iterator) :: h :: tail
loop()
}
}
loop()
buf.result()
}
override def size[A](fa: Vector[A]): Long = fa.size.toLong
override def get[A](fa: Vector[A])(idx: Long): Option[A] =
if (idx < Int.MaxValue && fa.size > idx && idx >= 0) Some(fa(idx.toInt)) else None
override def foldMapK[G[_], A, B](fa: Vector[A])(f: A => G[B])(implicit G: MonoidK[G]): G[B] = {
def loop(i: Int): Eval[G[B]] =
if (i < fa.length) G.combineKEval(f(fa(i)), Eval.defer(loop(i + 1))) else Eval.now(G.empty)
loop(0).value
}
final override def traverse[G[_], A, B](fa: Vector[A])(f: A => G[B])(implicit G: Applicative[G]): G[Vector[B]] =
G match {
case x: StackSafeMonad[G] => Traverse.traverseDirectly(fa)(f)(x)
case _ => G.map(Chain.traverseViaChain(fa)(f))(_.toVector)
}
final override def updated_[A, B >: A](fa: Vector[A], idx: Long, b: B): Option[Vector[B]] =
if (idx >= 0L && idx < fa.size.toLong) {
Some(fa.updated(idx.toInt, b))
} else {
None
}
/**
* This avoids making a very deep stack by building a tree instead
*/
override def traverse_[G[_], A, B](fa: Vector[A])(f: A => G[B])(implicit G: Applicative[G]): G[Unit] = {
G match {
case x: StackSafeMonad[G] => Traverse.traverse_Directly(fa)(f)(x)
case _ =>
// the cost of this is O(size)
// c(n) = 1 + 2 * c(n/2)
// invariant: size >= 1
def runHalf(size: Int, idx: Int): Eval[G[Unit]] =
if (size > 1) {
val leftSize = size / 2
val rightSize = size - leftSize
runHalf(leftSize, idx)
.flatMap { left =>
val right = runHalf(rightSize, idx + leftSize)
G.map2Eval(left, right) { (_, _) => () }
}
} else {
val a = fa(idx)
// we evaluate this at most one time,
// always is a bit cheaper in such cases
//
// Here is the point of the laziness using Eval:
// we avoid calling f(a) or G.void in the
// event that the computation has already
// failed. We do not use laziness to avoid
// traversing fa, which we will do fully
// in all cases.
Eval.always {
val gb = f(a)
G.void(gb)
}
}
val len = fa.length
if (len == 0) G.unit
else runHalf(len, 0).value
}
}
override def mapAccumulate[S, A, B](init: S, fa: Vector[A])(f: (S, A) => (S, B)): (S, Vector[B]) =
StaticMethods.mapAccumulateFromStrictFunctor(init, fa, f)(this)
override def mapWithIndex[A, B](fa: Vector[A])(f: (A, Int) => B): Vector[B] =
StaticMethods.mapWithIndexFromStrictFunctor(fa, f)(this)
override def mapWithLongIndex[A, B](fa: Vector[A])(f: (A, Long) => B): Vector[B] =
StaticMethods.mapWithLongIndexFromStrictFunctor(fa, f)(this)
override def zipWithIndex[A](fa: Vector[A]): Vector[(A, Int)] =
fa.zipWithIndex
override def exists[A](fa: Vector[A])(p: A => Boolean): Boolean =
fa.exists(p)
override def isEmpty[A](fa: Vector[A]): Boolean =
fa.isEmpty
override def foldM[G[_], A, B](fa: Vector[A], z: B)(f: (B, A) => G[B])(implicit G: Monad[G]): G[B] = {
val length = fa.length
G.tailRecM((z, 0)) { case (b, i) =>
if (i < length) G.map(f(b, fa(i)))(b => Left((b, i + 1)))
else G.pure(Right(b))
}
}
override def fold[A](fa: Vector[A])(implicit A: Monoid[A]): A = A.combineAll(fa)
override def toList[A](fa: Vector[A]): List[A] = fa.toList
override def toIterable[A](fa: Vector[A]): Iterable[A] = fa
override def reduceLeftOption[A](fa: Vector[A])(f: (A, A) => A): Option[A] =
fa.reduceLeftOption(f)
override def find[A](fa: Vector[A])(f: A => Boolean): Option[A] = fa.find(f)
override def algebra[A]: Monoid[Vector[A]] = kernel.instances.VectorMonoid[A]
def functor: Functor[Vector] = this
def align[A, B](fa: Vector[A], fb: Vector[B]): Vector[A Ior B] = {
val aLarger = fa.size >= fb.size
if (aLarger) {
cats.compat.Vector.zipWith(fa, fb)(Ior.both) ++ fa.drop(fb.size).map(Ior.left)
} else {
cats.compat.Vector.zipWith(fa, fb)(Ior.both) ++ fb.drop(fa.size).map(Ior.right)
}
}
override def collectFirst[A, B](fa: Vector[A])(pf: PartialFunction[A, B]): Option[B] = fa.collectFirst(pf)
override def collectFirstSome[A, B](fa: Vector[A])(f: A => Option[B]): Option[B] =
fa.collectFirst(Function.unlift(f))
}
implicit def catsStdShowForVector[A: Show]: Show[Vector[A]] =
_.iterator.map(Show[A].show).mkString("Vector(", ", ", ")")
implicit def catsStdNonEmptyParallelForVectorZipVector: NonEmptyParallel.Aux[Vector, ZipVector] =
new NonEmptyParallel[Vector] {
type F[x] = ZipVector[x]
def flatMap: FlatMap[Vector] = cats.instances.vector.catsStdInstancesForVector
def apply: Apply[ZipVector] = ZipVector.catsDataCommutativeApplyForZipVector
def sequential: ZipVector ~> Vector =
new (ZipVector ~> Vector) { def apply[A](a: ZipVector[A]): Vector[A] = a.value }
def parallel: Vector ~> ZipVector =
new (Vector ~> ZipVector) { def apply[A](v: Vector[A]): ZipVector[A] = new ZipVector(v) }
}
}
@suppressUnusedImportWarningForScalaVersionSpecific
private[instances] trait VectorInstancesBinCompat0 {
implicit val catsStdTraverseFilterForVector: TraverseFilter[Vector] = new TraverseFilter[Vector] {
val traverse: Traverse[Vector] = cats.instances.vector.catsStdInstancesForVector
override def mapFilter[A, B](fa: Vector[A])(f: (A) => Option[B]): Vector[B] =
fa.collect(Function.unlift(f))
override def filter[A](fa: Vector[A])(f: (A) => Boolean): Vector[A] = fa.filter(f)
override def filterNot[A](fa: Vector[A])(f: A => Boolean): Vector[A] = fa.filterNot(f)
override def collect[A, B](fa: Vector[A])(f: PartialFunction[A, B]): Vector[B] = fa.collect(f)
override def flattenOption[A](fa: Vector[Option[A]]): Vector[A] = fa.flatten
def traverseFilter[G[_], A, B](fa: Vector[A])(f: (A) => G[Option[B]])(implicit G: Applicative[G]): G[Vector[B]] =
G match {
case x: StackSafeMonad[G] => TraverseFilter.traverseFilterDirectly(fa)(f)(x)
case _ =>
G.map(Chain.traverseFilterViaChain(fa)(f))(_.toVector)
}
override def filterA[G[_], A](fa: Vector[A])(f: (A) => G[Boolean])(implicit G: Applicative[G]): G[Vector[A]] =
traverse
.foldRight(fa, Eval.now(G.pure(Vector.empty[A])))((x, xse) =>
G.map2Eval(f(x), xse)((b, vector) => if (b) x +: vector else vector)
)
.value
}
}