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Moved Maximized back in universal trait IterableOnceOps #19446

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Jan 15, 2024
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Moved Maximized back in universal trait IterableOnceOps #19446

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53 changes: 23 additions & 30 deletions scala2-library-cc/src/scala/collection/IterableOnce.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -321,8 +321,6 @@ object IterableOnce {
trait IterableOnceOps[+A, +CC[_], +C] extends Any { this: IterableOnce[A]^ =>
/////////////////////////////////////////////////////////////// Abstract methods that must be implemented

import IterableOnceOps.Maximized

/** Produces a $coll containing cumulative results of applying the
* operator going left to right, including the initial value.
*
Expand Down Expand Up @@ -1052,6 +1050,29 @@ trait IterableOnceOps[+A, +CC[_], +C] extends Any { this: IterableOnce[A]^ =>
case _ => foldLeft(new Maximized[A, B]("maxBy")(f)(ord.gt))((m, a) => m(m, a)).result
}

private class Maximized[X, B](descriptor: String)(f: X -> B)(cmp: (B, B) -> Boolean) extends AbstractFunction2[Maximized[X, B], X, Maximized[X, B]] {
var maxElem: X = null.asInstanceOf[X]
var maxF: B = null.asInstanceOf[B]
var nonEmpty = false
def toOption: Option[X] = if (nonEmpty) Some(maxElem) else None
def result: X = if (nonEmpty) maxElem else throw new UnsupportedOperationException(s"empty.$descriptor")
def apply(m: Maximized[X, B], a: X): Maximized[X, B] =
if (m.nonEmpty) {
val fa = f(a)
if (cmp(fa, maxF)) {
maxF = fa
maxElem = a
}
m
}
else {
m.nonEmpty = true
m.maxElem = a
m.maxF = f(a)
m
}
}

/** Finds the first element which yields the largest value measured by function f.
*
* $willNotTerminateInf
Expand Down Expand Up @@ -1335,31 +1356,3 @@ trait IterableOnceOps[+A, +CC[_], +C] extends Any { this: IterableOnce[A]^ =>
xs
}
}

object IterableOnceOps:

// Moved out of trait IterableOnceOps to here, since universal traits cannot
// have nested classes in Scala 3
private class Maximized[X, B](descriptor: String)(f: X -> B)(cmp: (B, B) -> Boolean) extends AbstractFunction2[Maximized[X, B], X, Maximized[X, B]] {
var maxElem: X = null.asInstanceOf[X]
var maxF: B = null.asInstanceOf[B]
var nonEmpty = false
def toOption: Option[X] = if (nonEmpty) Some(maxElem) else None
def result: X = if (nonEmpty) maxElem else throw new UnsupportedOperationException(s"empty.$descriptor")
def apply(m: Maximized[X, B], a: X): Maximized[X, B] =
if (m.nonEmpty) {
val fa = f(a)
if (cmp(fa, maxF)) {
maxF = fa
maxElem = a
}
m
}
else {
m.nonEmpty = true
m.maxElem = a
m.maxF = f(a)
m
}
}
end IterableOnceOps