scala

trait Seq

[source: `scala/Seq.scala`]

`trait` Seq[+A]
` extends `PartialFunction[Int, A]` with `Collection[A]
Class `Seq[A]` represents finite sequences of elements of type `A`.
Author
Martin Odersky
Matthias Zenger
Version
1.0, 16/07/2003
Direct Known Subclasses:
List, RandomAccessSeq, Seq.Projection, SeqProxy, Stream, Queue, Stack, MutableSeq, Buffer, MutableList, SingleLinkedList, RichString, NodeSeq

 Method Summary `override def` ++ [B >: A](that : Iterable[B]) : Seq[B] Appends two iterable objects. `override def` concat [B >: A](that : Iterable[B]) : Seq[B] Appends two iterable objects. ` def` contains (elem : Any) : Boolean Tests if the given value `elem` is a member of this sequence. `override def` drop (n : Int) : Seq[A] Returns this sequence without its `n` first elements If this sequence has less than `n` elements, the empty sequence is returned. `override def` dropWhile (p : (A) => Boolean) : Seq[A] Returns the longest suffix of this sequence whose first element does not satisfy the predicate `p`. `override def` filter (p : (A) => Boolean) : Seq[A] Returns all the elements of this sequence that satisfy the predicate `p`. The order of the elements is preserved. `override def` flatMap [B](f : (A) => Iterable[B]) : Seq[B] Applies the given function `f` to each element of this sequence, then concatenates the results. ` def` isDefinedAt (x : Int) : Boolean Is this partial function defined for the index `x`? `override def` isEmpty : Boolean Returns true if length == 0 ` def` last : A Returns the last element of this list. ` def` lastIndexOf [B >: A](elem : B) : Int Returns the index of the last occurence of the specified element in this sequence, or -1 if the sequence does not contain this element. `abstract def` length : Int Returns the length of the sequence. `override def` map [B](f : (A) => B) : Seq[B] Returns the sequence resulting from applying the given function `f` to each element of this sequence. `override def` projection : Projection[A] returns a projection that can be used to call non-strict `filter`, `map`, and `flatMap` methods that build projections of the collection. ` def` reverse : Seq[A] A sequence consisting of all elements of this sequence in reverse order. ` def` size : Int should always be `length` ` def` slice (from : Int, len : Int) : Seq[A] Returns a subsequence starting from index `from` consisting of `len` elements. ` def` subseq (from : Int, end : Int) : Seq[A] Returns a subsequence starting from index `from` consisting of `len` elements. `override def` take (n : Int) : Seq[A] Returns a sequence consisting only over the first `n` elements of this sequence, or else the whole sequence, if it has less than `n` elements. `override def` takeWhile (p : (A) => Boolean) : Seq[A] Returns the longest prefix of this sequence whose elements satisfy the predicate `p`. `override def` toArray [B >: A] : Array[B] Converts this sequence to a fresh Array with `length` elements.
 Methods inherited from Collection toString, stringPrefix, equalWith
 Methods inherited from Iterable elements (abstract), foreach, forall, exists, find, findIndexOf, indexOf, foldLeft, foldRight, /:, :\, reduceLeft, reduceRight, copyToBuffer, sameElements, toList, mkString, mkString, addString, addString, copyToArray, hasDefiniteSize
 Methods inherited from PartialFunction orElse, andThen
 Methods inherited from Function1 apply (abstract), compose
 Methods inherited from AnyRef getClass, hashCode, equals, clone, notify, notifyAll, wait, wait, wait, finalize, ==, !=, eq, ne, synchronized
 Methods inherited from Any ==, !=, isInstanceOf, asInstanceOf
 Class Summary ` class` Filter (p : (A) => Boolean)` extends `Projection[A]
 Method Details
`abstract` `def` length : Int
Returns the length of the sequence.
Returns
the sequence length.

`def` size : Int
should always be `length`
Overrides
Collection.size

`override` `def` isEmpty : Boolean
Returns true if length == 0

@deprecated

`override` `def` concat[B >: A](that : Iterable[B]) : Seq[B]
Appends two iterable objects.
Returns
the new iterable object
Deprecated
use `++` instead

`def` last : A
Returns the last element of this list.
Returns
the last element of the list.
Throws
Predef.UnsupportedOperationException - if the list is empty.

`override` `def` ++[B >: A](that : Iterable[B]) : Seq[B]
Appends two iterable objects.

`def` isDefinedAt(x : Int) : Boolean
Is this partial function defined for the index `x`?
Parameters
`x - `..
Returns
`true`, iff `x` is a legal sequence index.
Overrides
PartialFunction.isDefinedAt

`def` lastIndexOf[B >: A](elem : B) : Int
Returns the index of the last occurence of the specified element in this sequence, or -1 if the sequence does not contain this element.
Parameters
`elem - `element to search for.
Returns
the index in this sequence of the last occurence of the specified element, or -1 if the sequence does not contain this element.

`override` `def` map[B](f : (A) => B) : Seq[B]
Returns the sequence resulting from applying the given function `f` to each element of this sequence.
Parameters
`f - `function to apply to each element.
Returns
`f(a0), ..., f(an)` if this sequence is `a0, ..., an`.

`override` `def` flatMap[B](f : (A) => Iterable[B]) : Seq[B]
Applies the given function `f` to each element of this sequence, then concatenates the results.
Parameters
`f - `the function to apply on each element.
Returns
`f(a0) ::: ... ::: f(an)` if this sequence is `a0, ..., an`.

`override` `def` filter(p : (A) => Boolean) : Seq[A]
Returns all the elements of this sequence that satisfy the predicate `p`. The order of the elements is preserved.
Parameters
`p - `the predicate used to filter the list.
Returns
the elements of this list satisfying `p`.

`override` `def` take(n : Int) : Seq[A]
Returns a sequence consisting only over the first `n` elements of this sequence, or else the whole sequence, if it has less than `n` elements.
Parameters
`n - `the number of elements to take
Returns
the new sequence

`override` `def` drop(n : Int) : Seq[A]
Returns this sequence without its `n` first elements If this sequence has less than `n` elements, the empty sequence is returned.
Parameters
`n - `the number of elements to drop
Returns
the new sequence

`override` `def` takeWhile(p : (A) => Boolean) : Seq[A]
Returns the longest prefix of this sequence whose elements satisfy the predicate `p`.
Parameters
`p - `the test predicate.
Returns
the longest prefix of this sequence whose elements satisfy the predicate `p`.

`override` `def` dropWhile(p : (A) => Boolean) : Seq[A]
Returns the longest suffix of this sequence whose first element does not satisfy the predicate `p`.
Parameters
`p - `the test predicate.
Returns
the longest suffix of the sequence whose first element does not satisfy the predicate `p`.

`def` reverse : Seq[A]
A sequence consisting of all elements of this sequence in reverse order.

`def` contains(elem : Any) : Boolean
Tests if the given value `elem` is a member of this sequence.
Parameters
`elem - `element whose membership has to be tested.
Returns
`true` iff there is an element of this sequence which is equal (w.r.t. `==`) to `elem`.

`def` slice(from : Int, len : Int) : Seq[A]
Returns a subsequence starting from index `from` consisting of `len` elements.

@deprecated

`def` subseq(from : Int, end : Int) : Seq[A]
Returns a subsequence starting from index `from` consisting of `len` elements.
Deprecated
use `slice` instead

`override` `def` toArray[B >: A] : Array[B]
Converts this sequence to a fresh Array with `length` elements.
Overrides
Collection.toArray

`override` `def` projection : Projection[A]
returns a projection that can be used to call non-strict `filter`, `map`, and `flatMap` methods that build projections of the collection.