akka.persistence.r2dbc.journal.CollectionUtils.scala Maven / Gradle / Ivy

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Reactive Akka Journal, Snapshot Store, and Persistence Query plugin

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/*
 * Copyright 2020-2021 Borislav Borisov.
 *
 * 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
 *
 *     https://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 akka.persistence.r2dbc.journal

import java.util.function
import java.util.stream.Collector
import scala.collection.immutable
import scala.collection.mutable.Buffer

object CollectionUtils {

  def toSeq[T]: Collector[T, Buffer[T], collection.Seq[T]] = {
    val accumulator = new function.BiConsumer[Buffer[T], T] {
      override def accept(t: Buffer[T], u: T): Unit = t += u
    }
    val combiner = new function.BinaryOperator[Buffer[T]] {
      override def apply(t: Buffer[T], u: Buffer[T]): Buffer[T] = t ++= u
    }
    val finisher = new function.Function[Buffer[T], collection.Seq[T]] {
      override def apply(t: Buffer[T]): collection.Seq[T] = t.toSeq
    }
    Collector.of(() => Buffer.empty[T], accumulator, combiner, finisher, Collector.Characteristics.IDENTITY_FINISH)
  }

}