/
NonEmptySet.scala
51 lines (43 loc) · 1.52 KB
/
NonEmptySet.scala
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/*
* Copyright 2020 Fabio Labella
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package dynosaur
import cats.syntax.all._
/** A Set that cannot be empty, to support DynamoDb number, string and
* binary sets.
*/
sealed abstract case class NonEmptySet[A](value: Set[A])
object NonEmptySet {
def of[A](head: A, tail: A*): NonEmptySet[A] =
create((head +: tail).toSet)
def fromSet[A](set: Set[A]): Option[NonEmptySet[A]] =
if (set.nonEmpty) create(set).some
else none
def fromCatsNonEmpty[A](set: cats.data.NonEmptySet[A]): NonEmptySet[A] =
create(set.toSortedSet.toSet)
/** Note:
* It's up to you to ensure the non empty invariant holds
*/
def unsafeFromSet[A](set: Set[A]): NonEmptySet[A] =
if (set.nonEmpty) create(set)
else
throw new IllegalArgumentException(
"Cannot create NonEmptySet from empty set"
)
def toSet[A](v: Option[NonEmptySet[A]]): Set[A] =
v.map(_.value).getOrElse(Set.empty)
private def create[A](set: Set[A]) =
new NonEmptySet(set) {}
}