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/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2006-2009, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
// $Id$
package scala
import collection.immutable.Vector
import collection.generic.VectorView
/** <p>
* The <code>Range</code> class represents integer values in range
* <code>[start;end)</code> with non-zero step value <code>step</code>.
* Sort of acts like a sequence also (supports length and contains).
* For example:
* </p><pre>
* <b>val</b> r1 = 0 until 10
* <b>val</b> r2 = r1.start until r1.end by r1.step + 1
* println(r2.length) // = 5
* </pre>
*
* @author Martin Odersky
* @version 2.8
*/
class Range(val start: Int, val end: Int, val step: Int) extends VectorView[Int, Vector[Int]] {
require(step != 0)
protected def underlying = Vector.empty[Int]
/** Create a new range with the start and end values of this range and
* a new <code>step</code>.
*/
def by(step: Int): Range = new Range(start, end, step)
override def foreach(f: Int => Unit) {
var i = start
if (step > 0) {
while (i < end) {
f(i)
i += step
}
} else {
while (i > end) {
f(i)
i += step
}
}
}
lazy val length: Int = {
def plen(start: Int, end: Int, step: Int) =
if (end <= start) 0 else (end - start - 1) / step + 1
if (step > 0) plen(start, end, step)
else plen(end, start, -step)
}
def apply(idx: Int): Int = {
if (idx < 0 || idx >= length) throw new IndexOutOfBoundsException(idx.toString)
start + idx * step
}
def contains(x: Int): Boolean =
if (step > 0) start <= x && x < end
else start >= x && x > end
def inclusive = Range.inclusive(start, end, step)
}
object Range {
/** @deprecated use Range.inclusive instead */
class Inclusive(start: Int, end0: Int, step: Int)
extends Range(start, if (step > 0) end0 + 1 else end0 - 1, step) { self =>
override def by(step: Int): Range = new Inclusive(start, end0, step)
}
def apply(start: Int, end: Int, step: Int) =
new Range(start, end, step)
def inclusive(start: Int, end: Int, step: Int): Range =
new Range.Inclusive(start, end, step)
}
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