sbt.internal.inc.text.EnumSetSerializer.scala Maven / Gradle / Ivy

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/*
 * Zinc - The incremental compiler for Scala.
 * Copyright Scala Center, Lightbend, and Mark Harrah
 *
 * Licensed under Apache License 2.0
 * SPDX-License-Identifier: Apache-2.0
 *
 * See the NOTICE file distributed with this work for
 * additional information regarding copyright ownership.
 */

package sbt.internal.inc.text

import java.util

import scala.reflect.ClassTag

case class EnumSetSerializer[E <: Enum[E]: ClassTag](allValues: Array[E]) {
  assert(
    allValues.size <= 6,
    s"EnumSetSerializer can only support up to 6 values (but got $allValues)."
  )

  private val enumClass = implicitly[ClassTag[E]].runtimeClass.asInstanceOf[Class[E]]

  private val masks = allValues.zipWithIndex.map {
    case (v, i) =>
      v -> (1 << i)
  }

  private val OffsetInASCII = 33 // byte value of '!'

  def serialize(set: util.EnumSet[E]): Char = {
    var flags = 0
    for ((v, mask) <- masks if set.contains(v)) flags |= mask
    (flags + OffsetInASCII).toChar
  }

  def deserialize(c: Char): util.EnumSet[E] = {
    val set = util.EnumSet.noneOf(enumClass)
    val bits = c.toInt - OffsetInASCII
    for ((v, mask) <- masks if (bits & mask) != 0) set.add(v)
    set
  }
}