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/*
 * Copyright (c) 2014-2019 by The Monix Project Developers.
 * See the project homepage at: https://monix.io
 *
 * 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 monix.execution

import monix.execution.atomic.PaddingStrategy._
import monix.execution.internal.atomic.BoxPaddingStrategy

/** A small toolkit of classes that support compare-and-swap semantics
  * for safe mutation of variables.
  *
  * On top of the JVM, this means dealing with lock-free thread-safe
  * programming. Also works on top of Javascript, with ''Scala.js'',
  * for API compatibility purposes and because it's a useful way to
  * box a value.
  *
  * The backbone of Atomic references is this method:
  * {{{
  *   def compareAndSet(expect: T, update: T): Boolean
  * }}}
  *
  * This method atomically sets a variable to the `update` value if it
  * currently holds the `expect` value, reporting `true` on success or
  * `false` on failure. The classes in this package also contain
  * methods to get and unconditionally set values.
  *
  * Building a reference is easy with the provided constructor, which
  * will automatically return the most specific type needed (in the
  * following sample, that's an `AtomicDouble`, inheriting from
  * `AtomicNumber[A]`):
  *
  * {{{
  *   val atomicNumber = Atomic(12.2)
  *
  *   atomicNumber.incrementAndGet()
  *   // => 13.2
  * }}}
  *
  * These also provide useful helpers for atomically mutating of
  * values (i.e. `transform`, `transformAndGet`, `getAndTransform`,
  * etc...) or of numbers of any kind (`incrementAndGet`, `getAndAdd`,
  * etc...).
  */
package object atomic {
  /** Internal utility for converting between padding strategy representations. */
  private[execution] def boxStrategyToPaddingStrategy(s: PaddingStrategy): BoxPaddingStrategy =
    s match {
      case NoPadding =>
        BoxPaddingStrategy.NO_PADDING
      case Left64 =>
        BoxPaddingStrategy.LEFT_64
      case Right64 =>
        BoxPaddingStrategy.RIGHT_64
      case LeftRight128 =>
        BoxPaddingStrategy.LEFT_RIGHT_128
      case Left128 =>
        BoxPaddingStrategy.LEFT_128
      case Right128 =>
        BoxPaddingStrategy.RIGHT_128
      case LeftRight256 =>
        BoxPaddingStrategy.LEFT_RIGHT_256
    }
}