scala.compat.java8.converterImpl.StepsString.scala Maven / Gradle / Ivy

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package scala.compat.java8.converterImpl

import language.implicitConversions

import scala.compat.java8.collectionImpl._
import scala.compat.java8.runtime._

import Stepper._

////////////////////////////
// Stepper implementation //
////////////////////////////

private[java8] class StepperStringChar(underlying: String, _i0: Int, _iN: Int)
  extends StepsIntLikeIndexed[StepperStringChar](_i0, _iN) {
  def nextInt() = if (hasNext()) { val j = i0; i0 += 1; underlying.charAt(j) } else throwNSEE
  def semiclone(half: Int) = new StepperStringChar(underlying, i0, half)
}

private[java8] class StepperStringCodePoint(underlying: String, var i0: Int, var iN: Int) extends IntStepper with EfficientSubstep {
  def characteristics() = NonNull
  def estimateSize = iN - i0
  def hasNext = i0 < iN
  def nextInt() = {
    if (hasNext()) {
      val cp = underlying.codePointAt(i0)
      i0 += java.lang.Character.charCount(cp)
      cp
    }
    else throwNSEE
  }
  def substep() = {
    if (iN-3 > i0) {
      var half = (i0+iN) >>> 1
      if (java.lang.Character.isLowSurrogate(underlying.charAt(half))) half -= 1
      val ans = new StepperStringCodePoint(underlying, i0, half)
      i0 = half
      ans
    }
    else null
  }
}

/////////////////////////
// Value class adapter //
/////////////////////////

final class RichStringCanStep(private val underlying: String) extends AnyVal with MakesStepper[IntStepper with EfficientSubstep] {
  @inline def stepper: IntStepper with EfficientSubstep = charStepper
  @inline def charStepper: IntStepper with EfficientSubstep = new StepperStringChar(underlying, 0, underlying.length)
  @inline def codepointStepper: IntStepper with EfficientSubstep = new StepperStringCodePoint(underlying, 0, underlying.length)
}