mirror of
https://github.com/renbaoshuo/S2OJ.git
synced 2024-11-25 12:58:41 +00:00
768 lines
28 KiB
HTML
768 lines
28 KiB
HTML
<!doctype html>
|
|
|
|
<title>CodeMirror: Scala mode</title>
|
|
<meta charset="utf-8"/>
|
|
<link rel=stylesheet href="../../doc/docs.css">
|
|
|
|
<link rel="stylesheet" href="../../lib/codemirror.css">
|
|
<link rel="stylesheet" href="../../theme/ambiance.css">
|
|
<script src="../../lib/codemirror.js"></script>
|
|
<script src="../../addon/edit/matchbrackets.js"></script>
|
|
<script src="clike.js"></script>
|
|
<div id=nav>
|
|
<a href="http://codemirror.net"><img id=logo src="../../doc/logo.png"></a>
|
|
|
|
<ul>
|
|
<li><a href="../../index.html">Home</a>
|
|
<li><a href="../../doc/manual.html">Manual</a>
|
|
<li><a href="https://github.com/marijnh/codemirror">Code</a>
|
|
</ul>
|
|
<ul>
|
|
<li><a href="../index.html">Language modes</a>
|
|
<li><a class=active href="#">Scala</a>
|
|
</ul>
|
|
</div>
|
|
|
|
<article>
|
|
<h2>Scala mode</h2>
|
|
<form>
|
|
<textarea id="code" name="code">
|
|
|
|
/* __ *\
|
|
** ________ ___ / / ___ Scala API **
|
|
** / __/ __// _ | / / / _ | (c) 2003-2011, LAMP/EPFL **
|
|
** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ **
|
|
** /____/\___/_/ |_/____/_/ | | **
|
|
** |/ **
|
|
\* */
|
|
|
|
package scala.collection
|
|
|
|
import generic._
|
|
import mutable.{ Builder, ListBuffer }
|
|
import annotation.{tailrec, migration, bridge}
|
|
import annotation.unchecked.{ uncheckedVariance => uV }
|
|
import parallel.ParIterable
|
|
|
|
/** A template trait for traversable collections of type `Traversable[A]`.
|
|
*
|
|
* $traversableInfo
|
|
* @define mutability
|
|
* @define traversableInfo
|
|
* This is a base trait of all kinds of $mutability Scala collections. It
|
|
* implements the behavior common to all collections, in terms of a method
|
|
* `foreach` with signature:
|
|
* {{{
|
|
* def foreach[U](f: Elem => U): Unit
|
|
* }}}
|
|
* Collection classes mixing in this trait provide a concrete
|
|
* `foreach` method which traverses all the
|
|
* elements contained in the collection, applying a given function to each.
|
|
* They also need to provide a method `newBuilder`
|
|
* which creates a builder for collections of the same kind.
|
|
*
|
|
* A traversable class might or might not have two properties: strictness
|
|
* and orderedness. Neither is represented as a type.
|
|
*
|
|
* The instances of a strict collection class have all their elements
|
|
* computed before they can be used as values. By contrast, instances of
|
|
* a non-strict collection class may defer computation of some of their
|
|
* elements until after the instance is available as a value.
|
|
* A typical example of a non-strict collection class is a
|
|
* <a href="../immutable/Stream.html" target="ContentFrame">
|
|
* `scala.collection.immutable.Stream`</a>.
|
|
* A more general class of examples are `TraversableViews`.
|
|
*
|
|
* If a collection is an instance of an ordered collection class, traversing
|
|
* its elements with `foreach` will always visit elements in the
|
|
* same order, even for different runs of the program. If the class is not
|
|
* ordered, `foreach` can visit elements in different orders for
|
|
* different runs (but it will keep the same order in the same run).'
|
|
*
|
|
* A typical example of a collection class which is not ordered is a
|
|
* `HashMap` of objects. The traversal order for hash maps will
|
|
* depend on the hash codes of its elements, and these hash codes might
|
|
* differ from one run to the next. By contrast, a `LinkedHashMap`
|
|
* is ordered because it's `foreach` method visits elements in the
|
|
* order they were inserted into the `HashMap`.
|
|
*
|
|
* @author Martin Odersky
|
|
* @version 2.8
|
|
* @since 2.8
|
|
* @tparam A the element type of the collection
|
|
* @tparam Repr the type of the actual collection containing the elements.
|
|
*
|
|
* @define Coll Traversable
|
|
* @define coll traversable collection
|
|
*/
|
|
trait TraversableLike[+A, +Repr] extends HasNewBuilder[A, Repr]
|
|
with FilterMonadic[A, Repr]
|
|
with TraversableOnce[A]
|
|
with GenTraversableLike[A, Repr]
|
|
with Parallelizable[A, ParIterable[A]]
|
|
{
|
|
self =>
|
|
|
|
import Traversable.breaks._
|
|
|
|
/** The type implementing this traversable */
|
|
protected type Self = Repr
|
|
|
|
/** The collection of type $coll underlying this `TraversableLike` object.
|
|
* By default this is implemented as the `TraversableLike` object itself,
|
|
* but this can be overridden.
|
|
*/
|
|
def repr: Repr = this.asInstanceOf[Repr]
|
|
|
|
/** The underlying collection seen as an instance of `$Coll`.
|
|
* By default this is implemented as the current collection object itself,
|
|
* but this can be overridden.
|
|
*/
|
|
protected[this] def thisCollection: Traversable[A] = this.asInstanceOf[Traversable[A]]
|
|
|
|
/** A conversion from collections of type `Repr` to `$Coll` objects.
|
|
* By default this is implemented as just a cast, but this can be overridden.
|
|
*/
|
|
protected[this] def toCollection(repr: Repr): Traversable[A] = repr.asInstanceOf[Traversable[A]]
|
|
|
|
/** Creates a new builder for this collection type.
|
|
*/
|
|
protected[this] def newBuilder: Builder[A, Repr]
|
|
|
|
protected[this] def parCombiner = ParIterable.newCombiner[A]
|
|
|
|
/** Applies a function `f` to all elements of this $coll.
|
|
*
|
|
* Note: this method underlies the implementation of most other bulk operations.
|
|
* It's important to implement this method in an efficient way.
|
|
*
|
|
*
|
|
* @param f the function that is applied for its side-effect to every element.
|
|
* The result of function `f` is discarded.
|
|
*
|
|
* @tparam U the type parameter describing the result of function `f`.
|
|
* This result will always be ignored. Typically `U` is `Unit`,
|
|
* but this is not necessary.
|
|
*
|
|
* @usecase def foreach(f: A => Unit): Unit
|
|
*/
|
|
def foreach[U](f: A => U): Unit
|
|
|
|
/** Tests whether this $coll is empty.
|
|
*
|
|
* @return `true` if the $coll contain no elements, `false` otherwise.
|
|
*/
|
|
def isEmpty: Boolean = {
|
|
var result = true
|
|
breakable {
|
|
for (x <- this) {
|
|
result = false
|
|
break
|
|
}
|
|
}
|
|
result
|
|
}
|
|
|
|
/** Tests whether this $coll is known to have a finite size.
|
|
* All strict collections are known to have finite size. For a non-strict collection
|
|
* such as `Stream`, the predicate returns `true` if all elements have been computed.
|
|
* It returns `false` if the stream is not yet evaluated to the end.
|
|
*
|
|
* Note: many collection methods will not work on collections of infinite sizes.
|
|
*
|
|
* @return `true` if this collection is known to have finite size, `false` otherwise.
|
|
*/
|
|
def hasDefiniteSize = true
|
|
|
|
def ++[B >: A, That](that: GenTraversableOnce[B])(implicit bf: CanBuildFrom[Repr, B, That]): That = {
|
|
val b = bf(repr)
|
|
if (that.isInstanceOf[IndexedSeqLike[_, _]]) b.sizeHint(this, that.seq.size)
|
|
b ++= thisCollection
|
|
b ++= that.seq
|
|
b.result
|
|
}
|
|
|
|
@bridge
|
|
def ++[B >: A, That](that: TraversableOnce[B])(implicit bf: CanBuildFrom[Repr, B, That]): That =
|
|
++(that: GenTraversableOnce[B])(bf)
|
|
|
|
/** Concatenates this $coll with the elements of a traversable collection.
|
|
* It differs from ++ in that the right operand determines the type of the
|
|
* resulting collection rather than the left one.
|
|
*
|
|
* @param that the traversable to append.
|
|
* @tparam B the element type of the returned collection.
|
|
* @tparam That $thatinfo
|
|
* @param bf $bfinfo
|
|
* @return a new collection of type `That` which contains all elements
|
|
* of this $coll followed by all elements of `that`.
|
|
*
|
|
* @usecase def ++:[B](that: TraversableOnce[B]): $Coll[B]
|
|
*
|
|
* @return a new $coll which contains all elements of this $coll
|
|
* followed by all elements of `that`.
|
|
*/
|
|
def ++:[B >: A, That](that: TraversableOnce[B])(implicit bf: CanBuildFrom[Repr, B, That]): That = {
|
|
val b = bf(repr)
|
|
if (that.isInstanceOf[IndexedSeqLike[_, _]]) b.sizeHint(this, that.size)
|
|
b ++= that
|
|
b ++= thisCollection
|
|
b.result
|
|
}
|
|
|
|
/** This overload exists because: for the implementation of ++: we should reuse
|
|
* that of ++ because many collections override it with more efficient versions.
|
|
* Since TraversableOnce has no '++' method, we have to implement that directly,
|
|
* but Traversable and down can use the overload.
|
|
*/
|
|
def ++:[B >: A, That](that: Traversable[B])(implicit bf: CanBuildFrom[Repr, B, That]): That =
|
|
(that ++ seq)(breakOut)
|
|
|
|
def map[B, That](f: A => B)(implicit bf: CanBuildFrom[Repr, B, That]): That = {
|
|
val b = bf(repr)
|
|
b.sizeHint(this)
|
|
for (x <- this) b += f(x)
|
|
b.result
|
|
}
|
|
|
|
def flatMap[B, That](f: A => GenTraversableOnce[B])(implicit bf: CanBuildFrom[Repr, B, That]): That = {
|
|
val b = bf(repr)
|
|
for (x <- this) b ++= f(x).seq
|
|
b.result
|
|
}
|
|
|
|
/** Selects all elements of this $coll which satisfy a predicate.
|
|
*
|
|
* @param p the predicate used to test elements.
|
|
* @return a new $coll consisting of all elements of this $coll that satisfy the given
|
|
* predicate `p`. The order of the elements is preserved.
|
|
*/
|
|
def filter(p: A => Boolean): Repr = {
|
|
val b = newBuilder
|
|
for (x <- this)
|
|
if (p(x)) b += x
|
|
b.result
|
|
}
|
|
|
|
/** Selects all elements of this $coll which do not satisfy a predicate.
|
|
*
|
|
* @param p the predicate used to test elements.
|
|
* @return a new $coll consisting of all elements of this $coll that do not satisfy the given
|
|
* predicate `p`. The order of the elements is preserved.
|
|
*/
|
|
def filterNot(p: A => Boolean): Repr = filter(!p(_))
|
|
|
|
def collect[B, That](pf: PartialFunction[A, B])(implicit bf: CanBuildFrom[Repr, B, That]): That = {
|
|
val b = bf(repr)
|
|
for (x <- this) if (pf.isDefinedAt(x)) b += pf(x)
|
|
b.result
|
|
}
|
|
|
|
/** Builds a new collection by applying an option-valued function to all
|
|
* elements of this $coll on which the function is defined.
|
|
*
|
|
* @param f the option-valued function which filters and maps the $coll.
|
|
* @tparam B the element type of the returned collection.
|
|
* @tparam That $thatinfo
|
|
* @param bf $bfinfo
|
|
* @return a new collection of type `That` resulting from applying the option-valued function
|
|
* `f` to each element and collecting all defined results.
|
|
* The order of the elements is preserved.
|
|
*
|
|
* @usecase def filterMap[B](f: A => Option[B]): $Coll[B]
|
|
*
|
|
* @param pf the partial function which filters and maps the $coll.
|
|
* @return a new $coll resulting from applying the given option-valued function
|
|
* `f` to each element and collecting all defined results.
|
|
* The order of the elements is preserved.
|
|
def filterMap[B, That](f: A => Option[B])(implicit bf: CanBuildFrom[Repr, B, That]): That = {
|
|
val b = bf(repr)
|
|
for (x <- this)
|
|
f(x) match {
|
|
case Some(y) => b += y
|
|
case _ =>
|
|
}
|
|
b.result
|
|
}
|
|
*/
|
|
|
|
/** Partitions this $coll in two ${coll}s according to a predicate.
|
|
*
|
|
* @param p the predicate on which to partition.
|
|
* @return a pair of ${coll}s: the first $coll consists of all elements that
|
|
* satisfy the predicate `p` and the second $coll consists of all elements
|
|
* that don't. The relative order of the elements in the resulting ${coll}s
|
|
* is the same as in the original $coll.
|
|
*/
|
|
def partition(p: A => Boolean): (Repr, Repr) = {
|
|
val l, r = newBuilder
|
|
for (x <- this) (if (p(x)) l else r) += x
|
|
(l.result, r.result)
|
|
}
|
|
|
|
def groupBy[K](f: A => K): immutable.Map[K, Repr] = {
|
|
val m = mutable.Map.empty[K, Builder[A, Repr]]
|
|
for (elem <- this) {
|
|
val key = f(elem)
|
|
val bldr = m.getOrElseUpdate(key, newBuilder)
|
|
bldr += elem
|
|
}
|
|
val b = immutable.Map.newBuilder[K, Repr]
|
|
for ((k, v) <- m)
|
|
b += ((k, v.result))
|
|
|
|
b.result
|
|
}
|
|
|
|
/** Tests whether a predicate holds for all elements of this $coll.
|
|
*
|
|
* $mayNotTerminateInf
|
|
*
|
|
* @param p the predicate used to test elements.
|
|
* @return `true` if the given predicate `p` holds for all elements
|
|
* of this $coll, otherwise `false`.
|
|
*/
|
|
def forall(p: A => Boolean): Boolean = {
|
|
var result = true
|
|
breakable {
|
|
for (x <- this)
|
|
if (!p(x)) { result = false; break }
|
|
}
|
|
result
|
|
}
|
|
|
|
/** Tests whether a predicate holds for some of the elements of this $coll.
|
|
*
|
|
* $mayNotTerminateInf
|
|
*
|
|
* @param p the predicate used to test elements.
|
|
* @return `true` if the given predicate `p` holds for some of the
|
|
* elements of this $coll, otherwise `false`.
|
|
*/
|
|
def exists(p: A => Boolean): Boolean = {
|
|
var result = false
|
|
breakable {
|
|
for (x <- this)
|
|
if (p(x)) { result = true; break }
|
|
}
|
|
result
|
|
}
|
|
|
|
/** Finds the first element of the $coll satisfying a predicate, if any.
|
|
*
|
|
* $mayNotTerminateInf
|
|
* $orderDependent
|
|
*
|
|
* @param p the predicate used to test elements.
|
|
* @return an option value containing the first element in the $coll
|
|
* that satisfies `p`, or `None` if none exists.
|
|
*/
|
|
def find(p: A => Boolean): Option[A] = {
|
|
var result: Option[A] = None
|
|
breakable {
|
|
for (x <- this)
|
|
if (p(x)) { result = Some(x); break }
|
|
}
|
|
result
|
|
}
|
|
|
|
def scan[B >: A, That](z: B)(op: (B, B) => B)(implicit cbf: CanBuildFrom[Repr, B, That]): That = scanLeft(z)(op)
|
|
|
|
def scanLeft[B, That](z: B)(op: (B, A) => B)(implicit bf: CanBuildFrom[Repr, B, That]): That = {
|
|
val b = bf(repr)
|
|
b.sizeHint(this, 1)
|
|
var acc = z
|
|
b += acc
|
|
for (x <- this) { acc = op(acc, x); b += acc }
|
|
b.result
|
|
}
|
|
|
|
@migration(2, 9,
|
|
"This scanRight definition has changed in 2.9.\n" +
|
|
"The previous behavior can be reproduced with scanRight.reverse."
|
|
)
|
|
def scanRight[B, That](z: B)(op: (A, B) => B)(implicit bf: CanBuildFrom[Repr, B, That]): That = {
|
|
var scanned = List(z)
|
|
var acc = z
|
|
for (x <- reversed) {
|
|
acc = op(x, acc)
|
|
scanned ::= acc
|
|
}
|
|
val b = bf(repr)
|
|
for (elem <- scanned) b += elem
|
|
b.result
|
|
}
|
|
|
|
/** Selects the first element of this $coll.
|
|
* $orderDependent
|
|
* @return the first element of this $coll.
|
|
* @throws `NoSuchElementException` if the $coll is empty.
|
|
*/
|
|
def head: A = {
|
|
var result: () => A = () => throw new NoSuchElementException
|
|
breakable {
|
|
for (x <- this) {
|
|
result = () => x
|
|
break
|
|
}
|
|
}
|
|
result()
|
|
}
|
|
|
|
/** Optionally selects the first element.
|
|
* $orderDependent
|
|
* @return the first element of this $coll if it is nonempty, `None` if it is empty.
|
|
*/
|
|
def headOption: Option[A] = if (isEmpty) None else Some(head)
|
|
|
|
/** Selects all elements except the first.
|
|
* $orderDependent
|
|
* @return a $coll consisting of all elements of this $coll
|
|
* except the first one.
|
|
* @throws `UnsupportedOperationException` if the $coll is empty.
|
|
*/
|
|
override def tail: Repr = {
|
|
if (isEmpty) throw new UnsupportedOperationException("empty.tail")
|
|
drop(1)
|
|
}
|
|
|
|
/** Selects the last element.
|
|
* $orderDependent
|
|
* @return The last element of this $coll.
|
|
* @throws NoSuchElementException If the $coll is empty.
|
|
*/
|
|
def last: A = {
|
|
var lst = head
|
|
for (x <- this)
|
|
lst = x
|
|
lst
|
|
}
|
|
|
|
/** Optionally selects the last element.
|
|
* $orderDependent
|
|
* @return the last element of this $coll$ if it is nonempty, `None` if it is empty.
|
|
*/
|
|
def lastOption: Option[A] = if (isEmpty) None else Some(last)
|
|
|
|
/** Selects all elements except the last.
|
|
* $orderDependent
|
|
* @return a $coll consisting of all elements of this $coll
|
|
* except the last one.
|
|
* @throws `UnsupportedOperationException` if the $coll is empty.
|
|
*/
|
|
def init: Repr = {
|
|
if (isEmpty) throw new UnsupportedOperationException("empty.init")
|
|
var lst = head
|
|
var follow = false
|
|
val b = newBuilder
|
|
b.sizeHint(this, -1)
|
|
for (x <- this.seq) {
|
|
if (follow) b += lst
|
|
else follow = true
|
|
lst = x
|
|
}
|
|
b.result
|
|
}
|
|
|
|
def take(n: Int): Repr = slice(0, n)
|
|
|
|
def drop(n: Int): Repr =
|
|
if (n <= 0) {
|
|
val b = newBuilder
|
|
b.sizeHint(this)
|
|
b ++= thisCollection result
|
|
}
|
|
else sliceWithKnownDelta(n, Int.MaxValue, -n)
|
|
|
|
def slice(from: Int, until: Int): Repr = sliceWithKnownBound(math.max(from, 0), until)
|
|
|
|
// Precondition: from >= 0, until > 0, builder already configured for building.
|
|
private[this] def sliceInternal(from: Int, until: Int, b: Builder[A, Repr]): Repr = {
|
|
var i = 0
|
|
breakable {
|
|
for (x <- this.seq) {
|
|
if (i >= from) b += x
|
|
i += 1
|
|
if (i >= until) break
|
|
}
|
|
}
|
|
b.result
|
|
}
|
|
// Precondition: from >= 0
|
|
private[scala] def sliceWithKnownDelta(from: Int, until: Int, delta: Int): Repr = {
|
|
val b = newBuilder
|
|
if (until <= from) b.result
|
|
else {
|
|
b.sizeHint(this, delta)
|
|
sliceInternal(from, until, b)
|
|
}
|
|
}
|
|
// Precondition: from >= 0
|
|
private[scala] def sliceWithKnownBound(from: Int, until: Int): Repr = {
|
|
val b = newBuilder
|
|
if (until <= from) b.result
|
|
else {
|
|
b.sizeHintBounded(until - from, this)
|
|
sliceInternal(from, until, b)
|
|
}
|
|
}
|
|
|
|
def takeWhile(p: A => Boolean): Repr = {
|
|
val b = newBuilder
|
|
breakable {
|
|
for (x <- this) {
|
|
if (!p(x)) break
|
|
b += x
|
|
}
|
|
}
|
|
b.result
|
|
}
|
|
|
|
def dropWhile(p: A => Boolean): Repr = {
|
|
val b = newBuilder
|
|
var go = false
|
|
for (x <- this) {
|
|
if (!p(x)) go = true
|
|
if (go) b += x
|
|
}
|
|
b.result
|
|
}
|
|
|
|
def span(p: A => Boolean): (Repr, Repr) = {
|
|
val l, r = newBuilder
|
|
var toLeft = true
|
|
for (x <- this) {
|
|
toLeft = toLeft && p(x)
|
|
(if (toLeft) l else r) += x
|
|
}
|
|
(l.result, r.result)
|
|
}
|
|
|
|
def splitAt(n: Int): (Repr, Repr) = {
|
|
val l, r = newBuilder
|
|
l.sizeHintBounded(n, this)
|
|
if (n >= 0) r.sizeHint(this, -n)
|
|
var i = 0
|
|
for (x <- this) {
|
|
(if (i < n) l else r) += x
|
|
i += 1
|
|
}
|
|
(l.result, r.result)
|
|
}
|
|
|
|
/** Iterates over the tails of this $coll. The first value will be this
|
|
* $coll and the final one will be an empty $coll, with the intervening
|
|
* values the results of successive applications of `tail`.
|
|
*
|
|
* @return an iterator over all the tails of this $coll
|
|
* @example `List(1,2,3).tails = Iterator(List(1,2,3), List(2,3), List(3), Nil)`
|
|
*/
|
|
def tails: Iterator[Repr] = iterateUntilEmpty(_.tail)
|
|
|
|
/** Iterates over the inits of this $coll. The first value will be this
|
|
* $coll and the final one will be an empty $coll, with the intervening
|
|
* values the results of successive applications of `init`.
|
|
*
|
|
* @return an iterator over all the inits of this $coll
|
|
* @example `List(1,2,3).inits = Iterator(List(1,2,3), List(1,2), List(1), Nil)`
|
|
*/
|
|
def inits: Iterator[Repr] = iterateUntilEmpty(_.init)
|
|
|
|
/** Copies elements of this $coll to an array.
|
|
* Fills the given array `xs` with at most `len` elements of
|
|
* this $coll, starting at position `start`.
|
|
* Copying will stop once either the end of the current $coll is reached,
|
|
* or the end of the array is reached, or `len` elements have been copied.
|
|
*
|
|
* $willNotTerminateInf
|
|
*
|
|
* @param xs the array to fill.
|
|
* @param start the starting index.
|
|
* @param len the maximal number of elements to copy.
|
|
* @tparam B the type of the elements of the array.
|
|
*
|
|
*
|
|
* @usecase def copyToArray(xs: Array[A], start: Int, len: Int): Unit
|
|
*/
|
|
def copyToArray[B >: A](xs: Array[B], start: Int, len: Int) {
|
|
var i = start
|
|
val end = (start + len) min xs.length
|
|
breakable {
|
|
for (x <- this) {
|
|
if (i >= end) break
|
|
xs(i) = x
|
|
i += 1
|
|
}
|
|
}
|
|
}
|
|
|
|
def toTraversable: Traversable[A] = thisCollection
|
|
def toIterator: Iterator[A] = toStream.iterator
|
|
def toStream: Stream[A] = toBuffer.toStream
|
|
|
|
/** Converts this $coll to a string.
|
|
*
|
|
* @return a string representation of this collection. By default this
|
|
* string consists of the `stringPrefix` of this $coll,
|
|
* followed by all elements separated by commas and enclosed in parentheses.
|
|
*/
|
|
override def toString = mkString(stringPrefix + "(", ", ", ")")
|
|
|
|
/** Defines the prefix of this object's `toString` representation.
|
|
*
|
|
* @return a string representation which starts the result of `toString`
|
|
* applied to this $coll. By default the string prefix is the
|
|
* simple name of the collection class $coll.
|
|
*/
|
|
def stringPrefix : String = {
|
|
var string = repr.asInstanceOf[AnyRef].getClass.getName
|
|
val idx1 = string.lastIndexOf('.' : Int)
|
|
if (idx1 != -1) string = string.substring(idx1 + 1)
|
|
val idx2 = string.indexOf('$')
|
|
if (idx2 != -1) string = string.substring(0, idx2)
|
|
string
|
|
}
|
|
|
|
/** Creates a non-strict view of this $coll.
|
|
*
|
|
* @return a non-strict view of this $coll.
|
|
*/
|
|
def view = new TraversableView[A, Repr] {
|
|
protected lazy val underlying = self.repr
|
|
override def foreach[U](f: A => U) = self foreach f
|
|
}
|
|
|
|
/** Creates a non-strict view of a slice of this $coll.
|
|
*
|
|
* Note: the difference between `view` and `slice` is that `view` produces
|
|
* a view of the current $coll, whereas `slice` produces a new $coll.
|
|
*
|
|
* Note: `view(from, to)` is equivalent to `view.slice(from, to)`
|
|
* $orderDependent
|
|
*
|
|
* @param from the index of the first element of the view
|
|
* @param until the index of the element following the view
|
|
* @return a non-strict view of a slice of this $coll, starting at index `from`
|
|
* and extending up to (but not including) index `until`.
|
|
*/
|
|
def view(from: Int, until: Int): TraversableView[A, Repr] = view.slice(from, until)
|
|
|
|
/** Creates a non-strict filter of this $coll.
|
|
*
|
|
* Note: the difference between `c filter p` and `c withFilter p` is that
|
|
* the former creates a new collection, whereas the latter only
|
|
* restricts the domain of subsequent `map`, `flatMap`, `foreach`,
|
|
* and `withFilter` operations.
|
|
* $orderDependent
|
|
*
|
|
* @param p the predicate used to test elements.
|
|
* @return an object of class `WithFilter`, which supports
|
|
* `map`, `flatMap`, `foreach`, and `withFilter` operations.
|
|
* All these operations apply to those elements of this $coll which
|
|
* satisfy the predicate `p`.
|
|
*/
|
|
def withFilter(p: A => Boolean): FilterMonadic[A, Repr] = new WithFilter(p)
|
|
|
|
/** A class supporting filtered operations. Instances of this class are
|
|
* returned by method `withFilter`.
|
|
*/
|
|
class WithFilter(p: A => Boolean) extends FilterMonadic[A, Repr] {
|
|
|
|
/** Builds a new collection by applying a function to all elements of the
|
|
* outer $coll containing this `WithFilter` instance that satisfy predicate `p`.
|
|
*
|
|
* @param f the function to apply to each element.
|
|
* @tparam B the element type of the returned collection.
|
|
* @tparam That $thatinfo
|
|
* @param bf $bfinfo
|
|
* @return a new collection of type `That` resulting from applying
|
|
* the given function `f` to each element of the outer $coll
|
|
* that satisfies predicate `p` and collecting the results.
|
|
*
|
|
* @usecase def map[B](f: A => B): $Coll[B]
|
|
*
|
|
* @return a new $coll resulting from applying the given function
|
|
* `f` to each element of the outer $coll that satisfies
|
|
* predicate `p` and collecting the results.
|
|
*/
|
|
def map[B, That](f: A => B)(implicit bf: CanBuildFrom[Repr, B, That]): That = {
|
|
val b = bf(repr)
|
|
for (x <- self)
|
|
if (p(x)) b += f(x)
|
|
b.result
|
|
}
|
|
|
|
/** Builds a new collection by applying a function to all elements of the
|
|
* outer $coll containing this `WithFilter` instance that satisfy
|
|
* predicate `p` and concatenating the results.
|
|
*
|
|
* @param f the function to apply to each element.
|
|
* @tparam B the element type of the returned collection.
|
|
* @tparam That $thatinfo
|
|
* @param bf $bfinfo
|
|
* @return a new collection of type `That` resulting from applying
|
|
* the given collection-valued function `f` to each element
|
|
* of the outer $coll that satisfies predicate `p` and
|
|
* concatenating the results.
|
|
*
|
|
* @usecase def flatMap[B](f: A => TraversableOnce[B]): $Coll[B]
|
|
*
|
|
* @return a new $coll resulting from applying the given collection-valued function
|
|
* `f` to each element of the outer $coll that satisfies predicate `p` and concatenating the results.
|
|
*/
|
|
def flatMap[B, That](f: A => GenTraversableOnce[B])(implicit bf: CanBuildFrom[Repr, B, That]): That = {
|
|
val b = bf(repr)
|
|
for (x <- self)
|
|
if (p(x)) b ++= f(x).seq
|
|
b.result
|
|
}
|
|
|
|
/** Applies a function `f` to all elements of the outer $coll containing
|
|
* this `WithFilter` instance that satisfy predicate `p`.
|
|
*
|
|
* @param f the function that is applied for its side-effect to every element.
|
|
* The result of function `f` is discarded.
|
|
*
|
|
* @tparam U the type parameter describing the result of function `f`.
|
|
* This result will always be ignored. Typically `U` is `Unit`,
|
|
* but this is not necessary.
|
|
*
|
|
* @usecase def foreach(f: A => Unit): Unit
|
|
*/
|
|
def foreach[U](f: A => U): Unit =
|
|
for (x <- self)
|
|
if (p(x)) f(x)
|
|
|
|
/** Further refines the filter for this $coll.
|
|
*
|
|
* @param q the predicate used to test elements.
|
|
* @return an object of class `WithFilter`, which supports
|
|
* `map`, `flatMap`, `foreach`, and `withFilter` operations.
|
|
* All these operations apply to those elements of this $coll which
|
|
* satisfy the predicate `q` in addition to the predicate `p`.
|
|
*/
|
|
def withFilter(q: A => Boolean): WithFilter =
|
|
new WithFilter(x => p(x) && q(x))
|
|
}
|
|
|
|
// A helper for tails and inits.
|
|
private def iterateUntilEmpty(f: Traversable[A @uV] => Traversable[A @uV]): Iterator[Repr] = {
|
|
val it = Iterator.iterate(thisCollection)(f) takeWhile (x => !x.isEmpty)
|
|
it ++ Iterator(Nil) map (newBuilder ++= _ result)
|
|
}
|
|
}
|
|
|
|
|
|
</textarea>
|
|
</form>
|
|
|
|
<script>
|
|
var editor = CodeMirror.fromTextArea(document.getElementById("code"), {
|
|
lineNumbers: true,
|
|
matchBrackets: true,
|
|
theme: "ambiance",
|
|
mode: "text/x-scala"
|
|
});
|
|
</script>
|
|
</article>
|