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/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2006-2009, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
// $Id$
package scala.collection
package generic
/** A template for companion objects of Traversable and subclasses thereof.
*
* @since 2.8
*/
abstract class TraversableFactory[CC[X] <: Traversable[X] with GenericTraversableTemplate[X, CC]]
extends GenericCompanion[CC] {
class GenericCanBuildFrom[A] extends CanBuildFrom[CC[_], A, CC[A]] {
def apply(from: Coll) = from.genericBuilder[A]
def apply() = newBuilder[A]
}
/** Concatenate all the argument collections into a single collection.
*
* @param xss the collections that are to be concatenated
* @return the concatenation of all the collections
*/
def concat[A](xss: Traversable[A]*): CC[A] = {
val b = newBuilder[A]
for (xs <- xss) b ++= xs
b.result
}
/** A traversable that contains the results of some element computation a number of times.
* @param n the number of elements returned
* @param elem the element computation
*/
def fill[A](n: Int)(elem: => A): CC[A] = {
val b = newBuilder[A]
var i = 0
while (i < n) {
b += elem
i += 1
}
b.result
}
/** A two-dimensional traversable that contains the results of some element computation a number of times.
* @param n1 the number of elements in the 1st dimension
* @param n2 the number of elements in the 2nd dimension
* @param elem the element computation
*/
def fill[A](n1: Int, n2: Int)(elem: => A): CC[CC[A]] =
tabulate(n1)(_ => fill(n2)(elem))
/** A three-dimensional traversable that contains the results of some element computation a number of times.
* @param n1 the number of elements in the 1st dimension
* @param n2 the number of elements in the 2nd dimension
* @param n3 the number of elements in the 3nd dimension
* @param elem the element computation
*/
def fill[A](n1: Int, n2: Int, n3: Int)(elem: => A): CC[CC[CC[A]]] =
tabulate(n1)(_ => fill(n2, n3)(elem))
/** A four-dimensional traversable that contains the results of some element computation a number of times.
* @param n1 the number of elements in the 1st dimension
* @param n2 the number of elements in the 2nd dimension
* @param n3 the number of elements in the 3nd dimension
* @param n4 the number of elements in the 4th dimension
* @param elem the element computation
*/
def fill[A](n1: Int, n2: Int, n3: Int, n4: Int)(elem: => A): CC[CC[CC[CC[A]]]] =
tabulate(n1)(_ => fill(n2, n3, n4)(elem))
/** A five-dimensional traversable that contains the results of some element computation a number of times.
* @param n1 the number of elements in the 1st dimension
* @param n2 the number of elements in the 2nd dimension
* @param n3 the number of elements in the 3nd dimension
* @param n4 the number of elements in the 4th dimension
* @param n5 the number of elements in the 5th dimension
* @param elem the element computation
*/
def fill[A](n1: Int, n2: Int, n3: Int, n4: Int, n5: Int)(elem: => A): CC[CC[CC[CC[CC[A]]]]] =
tabulate(n1)(_ => fill(n2, n3, n4, n5)(elem))
/** A traversable containing values of a given function over a range of integer values starting from 0.
* @param n The number of elements in the traversable
* @param f The function computing element values
* @return A traversable consisting of elements `f(0), ..., f(n -1)`
*/
def tabulate[A](n: Int)(f: Int => A): CC[A] = {
val b = newBuilder[A]
var i = 0
while (i < n) {
b += f(i)
i += 1
}
b.result
}
/** A two-dimensional traversable containing values of a given function over ranges of integer values starting from 0.
* @param n1 the number of elements in the 1st dimension
* @param n2 the number of elements in the 2nd dimension
* @param f The function computing element values
*/
def tabulate[A](n1: Int, n2: Int)(f: (Int, Int) => A): CC[CC[A]] =
tabulate(n1)(i1 => tabulate(n2)(f(i1, _)))
/** A three-dimensional traversable containing values of a given function over ranges of integer values starting from 0.
* @param n1 the number of elements in the 1st dimension
* @param n2 the number of elements in the 2nd dimension
* @param n3 the number of elements in the 3nd dimension
* @param f The function computing element values
*/
def tabulate[A](n1: Int, n2: Int, n3: Int)(f: (Int, Int, Int) => A): CC[CC[CC[A]]] =
tabulate(n1)(i1 => tabulate(n2, n3)(f(i1, _, _)))
/** A four-dimensional traversable containing values of a given function over ranges of integer values starting from 0.
* @param n1 the number of elements in the 1st dimension
* @param n2 the number of elements in the 2nd dimension
* @param n3 the number of elements in the 3nd dimension
* @param n4 the number of elements in the 4th dimension
* @param f The function computing element values
*/
def tabulate[A](n1: Int, n2: Int, n3: Int, n4: Int)(f: (Int, Int, Int, Int) => A): CC[CC[CC[CC[A]]]] =
tabulate(n1)(i1 => tabulate(n2, n3, n4)(f(i1, _, _, _)))
/** A five-dimensional traversable containing values of a given function over ranges of integer values starting from 0.
* @param n1 the number of elements in the 1st dimension
* @param n2 the number of elements in the 2nd dimension
* @param n3 the number of elements in the 3nd dimension
* @param n4 the number of elements in the 4th dimension
* @param n5 the number of elements in the 5th dimension
* @param f The function computing element values
*/
def tabulate[A](n1: Int, n2: Int, n3: Int, n4: Int, n5: Int)(f: (Int, Int, Int, Int, Int) => A): CC[CC[CC[CC[CC[A]]]]] =
tabulate(n1)(i1 => tabulate(n2, n3, n4, n5)(f(i1, _, _, _, _)))
/** A traversable containing a sequence of increasing integers in a range.
*
* @param from the start value of the traversable
* @param end the end value of the traversable (the first value NOT returned)
* @return the traversable with values in range `start, start + 1, ..., end - 1`
* up to, but exclusding, `end`.
*/
def range(start: Int, end: Int): CC[Int] = range(start, end, 1)
/** A traversable containing equally spaced values in some integer interval.
* @param start the start value of the traversable
* @param end the end value of the traversable (the first value NOT returned)
* @param step the increment value of the traversable (must be positive or negative)
* @return the traversable with values in `start, start + step, ...` up to, but excluding `end`
*/
def range(start: Int, end: Int, step: Int): CC[Int] = {
if (step == 0) throw new IllegalArgumentException("zero step")
val b = newBuilder[Int]
var i = start
while (if (step < 0) end < i else i < end) {
b += i
i += step
}
b.result
}
/** A traversable containing repeated applications of a function to a start value.
*
* @param start the start value of the traversable
* @param len the number of elements returned by the traversable
* @param f the function that's repeatedly applied
* @return the traversable returning `len` values in the sequence `start, f(start), f(f(start)), ...`
*/
def iterate[A](start: A, len: Int)(f: A => A): CC[A] = {
val b = newBuilder[A]
var acc = start
var i = 0
while (i < len) {
b += acc
acc = f(acc)
i += 1
}
b.result
}
}
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