scala.collection.convert.impl.StringStepper.scala Maven / Gradle / Ivy
/*
* Scala (https://www.scala-lang.org)
*
* Copyright EPFL and Lightbend, Inc.
*
* Licensed under Apache License 2.0
* (http://www.apache.org/licenses/LICENSE-2.0).
*
* See the NOTICE file distributed with this work for
* additional information regarding copyright ownership.
*/
package scala.collection.convert
package impl
import java.lang.Character.{charCount, isLowSurrogate}
import java.util.Spliterator
import scala.collection.Stepper.EfficientSplit
import scala.collection.{IntStepper, Stepper}
/** Implements `Stepper` on a `String` where you step through chars packed into `Int`.
*/
private[collection] final class CharStringStepper(underlying: String, _i0: Int, _iN: Int)
extends IndexedStepperBase[IntStepper, CharStringStepper](_i0, _iN)
with IntStepper {
def nextStep(): Int =
if (hasStep) { val j = i0; i0 += 1; underlying.charAt(j) }
else Stepper.throwNSEE()
def semiclone(half: Int): CharStringStepper = new CharStringStepper(underlying, i0, half)
}
/** Implements `Stepper` on a `String` where you step through code points.
*/
private[collection] final class CodePointStringStepper(underlying: String, private var i0: Int, private var iN: Int)
extends IntStepper with EfficientSplit {
def characteristics: Int = Spliterator.IMMUTABLE | Spliterator.NONNULL | Spliterator.ORDERED
def estimateSize: Long = iN - i0
def hasStep: Boolean = i0 < iN
def nextStep(): Int = {
if (hasStep) {
val cp = underlying.codePointAt(i0)
i0 += charCount(cp)
cp
}
else Stepper.throwNSEE()
}
def trySplit(): CodePointStringStepper =
if (iN - 3 > i0) {
var half = (i0 + iN) >>> 1
if (isLowSurrogate(underlying.charAt(half))) half -= 1
val ans = new CodePointStringStepper(underlying, i0, half)
i0 = half
ans
}
else null
}