diff options
Diffstat (limited to 'src/library/scala/collection/immutable/Range.scala')
| -rw-r--r-- | src/library/scala/collection/immutable/Range.scala | 73 |
1 files changed, 42 insertions, 31 deletions
diff --git a/src/library/scala/collection/immutable/Range.scala b/src/library/scala/collection/immutable/Range.scala index ca6720da19..82203b3d1a 100644 --- a/src/library/scala/collection/immutable/Range.scala +++ b/src/library/scala/collection/immutable/Range.scala @@ -33,7 +33,7 @@ import scala.collection.parallel.immutable.ParRange * `init`) are also permitted on overfull ranges. * * @param start the start of this range. - * @param end the end of the range. For exclusive ranges, e.g. + * @param end the end of the range. For exclusive ranges, e.g. * `Range(0,3)` or `(0 until 3)`, this is one * step past the last one in the range. For inclusive * ranges, e.g. `Range.inclusive(0,3)` or `(0 to 3)`, @@ -57,8 +57,7 @@ import scala.collection.parallel.immutable.ParRange * and its complexity is O(1). */ @SerialVersionUID(7618862778670199309L) -@deprecatedInheritance("The implementation details of Range makes inheriting from it unwise.", "2.11.0") -class Range(val start: Int, val end: Int, val step: Int) +sealed class Range(val start: Int, val end: Int, val step: Int) extends scala.collection.AbstractSeq[Int] with IndexedSeq[Int] with scala.collection.CustomParallelizable[Int, ParRange] @@ -81,8 +80,8 @@ extends scala.collection.AbstractSeq[Int] || (start < end && step < 0) || (start == end && !isInclusive) ) - @deprecated("This method will be made private, use `length` instead.", "2.11") - final val numRangeElements: Int = { + + private val numRangeElements: Int = { if (step == 0) throw new IllegalArgumentException("step cannot be 0.") else if (isEmpty) 0 else { @@ -91,21 +90,17 @@ extends scala.collection.AbstractSeq[Int] else len.toInt } } - @deprecated("This method will be made private, use `last` instead.", "2.11") - final val lastElement = - if (isEmpty) start - step - else step match { - case 1 => if (isInclusive) end else end-1 - case -1 => if (isInclusive) end else end+1 - case _ => - val remainder = (gap % step).toInt - if (remainder != 0) end - remainder - else if (isInclusive) end - else end - step - } - - @deprecated("This method will be made private.", "2.11") - final val terminalElement = lastElement + step + + // This field has a sensible value only for non-empty ranges + private val lastElement = step match { + case 1 => if (isInclusive) end else end-1 + case -1 => if (isInclusive) end else end+1 + case _ => + val remainder = (gap % step).toInt + if (remainder != 0) end - remainder + else if (isInclusive) end + else end - step + } /** The last element of this range. This method will return the correct value * even if there are too many elements to iterate over. @@ -199,6 +194,23 @@ extends scala.collection.AbstractSeq[Int] } ) + /** Creates a new range containing the elements starting at `from` up to but not including `until`. + * + * $doesNotUseBuilders + * + * @param from the element at which to start + * @param until the element at which to end (not included in the range) + * @return a new range consisting of a contiguous interval of values in the old range + */ + override def slice(from: Int, until: Int): Range = + if (from <= 0) take(until) + else if (until >= numRangeElements && numRangeElements >= 0) drop(from) + else { + val fromValue = locationAfterN(from) + if (from >= until) newEmptyRange(fromValue) + else new Range.Inclusive(fromValue, locationAfterN(until-1), step) + } + /** Creates a new range containing all the elements of this range except the last one. * * $doesNotUseBuilders @@ -380,22 +392,20 @@ extends scala.collection.AbstractSeq[Int] case _ => super.equals(other) } - /** Note: hashCode can't be overridden without breaking Seq's - * equals contract. - */ - override def toString() = { - val endStr = - if (numRangeElements > Range.MAX_PRINT || (!isEmpty && numRangeElements < 0)) ", ... )" else ")" - take(Range.MAX_PRINT).mkString("Range(", ", ", endStr) + /* Note: hashCode can't be overridden without breaking Seq's equals contract. */ + + override def toString = { + val preposition = if (isInclusive) "to" else "until" + val stepped = if (step == 1) "" else s" by $step" + val prefix = if (isEmpty) "empty " else if (!isExact) "inexact " else "" + s"${prefix}Range $start $preposition $end$stepped" } } /** A companion object for the `Range` class. */ object Range { - private[immutable] val MAX_PRINT = 512 // some arbitrary value - /** Counts the number of range elements. * @pre step != 0 * If the size of the range exceeds Int.MaxValue, the @@ -427,7 +437,7 @@ object Range { def count(start: Int, end: Int, step: Int): Int = count(start, end, step, isInclusive = false) - class Inclusive(start: Int, end: Int, step: Int) extends Range(start, end, step) { + final class Inclusive(start: Int, end: Int, step: Int) extends Range(start, end, step) { // override def par = new ParRange(this) override def isInclusive = true override protected def copy(start: Int, end: Int, step: Int): Range = new Inclusive(start, end, step) @@ -496,8 +506,9 @@ object Range { // As there is no appealing default step size for not-really-integral ranges, // we offer a partially constructed object. - class Partial[T, U](f: T => U) { + class Partial[T, U](private val f: T => U) extends AnyVal { def by(x: T): U = f(x) + override def toString = "Range requires step" } // Illustrating genericity with Int Range, which should have the same behavior |