dev.tauri.choam.data.Set.scala Maven / Gradle / Ivy
/*
* SPDX-License-Identifier: Apache-2.0
* Copyright 2016-2024 Daniel Urban and contributors listed in NOTICE.txt
*
* 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 dev.tauri.choam
package data
import cats.kernel.{ Hash, Order }
sealed trait Set[A] {
def contains: A =#> Boolean
/** @return `true` iff it did not already contain the element */
def add: A =#> Boolean
/** @return `true` iff it did contain the element */
def remove: A =#> Boolean
}
object Set {
final def hashSet[A](implicit A: Hash[A]): Axn[Set[A]] =
Map.hashMap[A, Unit].map(new SetFromMap(_))
final def orderedSet[A](implicit A: Order[A]): Axn[Set[A]] =
Map.orderedMap[A, Unit].map(new SetFromMap(_))
private[this] final class SetFromMap[A](m: Map[A, Unit]) extends Set[A] {
final override val contains: A =#> Boolean =
m.get.map(_.isDefined)
final override val add: A =#> Boolean =
m.putIfAbsent.contramap[A](a => (a, ())).map(_.isEmpty)
final override val remove: A =#> Boolean =
m.del
}
}