1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
|
/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2003-2013, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
package scala
package collection
package mutable
import generic._
import immutable.List
/**
* This class is used internally to represent mutable lists. It is the
* basis for the implementation of the class `Queue`.
*
* @author Matthias Zenger
* @author Martin Odersky
* @version 2.8
* @since 1
* @define Coll `mutable.MutableList`
* @define coll mutable list
* @see [[http://docs.scala-lang.org/overviews/collections/concrete-mutable-collection-classes.html#mutable_lists "Scala's Collection Library overview"]]
* section on `Mutable Lists` for more information.
*/
@SerialVersionUID(5938451523372603072L)
class MutableList[A]
extends AbstractSeq[A]
with LinearSeq[A]
with LinearSeqOptimized[A, MutableList[A]]
with GenericTraversableTemplate[A, MutableList]
with Builder[A, MutableList[A]]
with Serializable
{
override def companion: GenericCompanion[MutableList] = MutableList
override protected[this] def newBuilder: Builder[A, MutableList[A]] = new MutableList[A]
protected var first0: LinkedList[A] = new LinkedList[A]
protected var last0: LinkedList[A] = first0
protected var len: Int = 0
def toQueue = new Queue(first0, last0, len)
/** Is the list empty?
*/
override def isEmpty = len == 0
/** Returns the first element in this list
*/
override def head: A = if (nonEmpty) first0.head else throw new NoSuchElementException
/** Returns the rest of this list
*/
override def tail: MutableList[A] = {
val tl = new MutableList[A]
tailImpl(tl)
tl
}
protected final def tailImpl(tl: MutableList[A]) {
require(nonEmpty, "tail of empty list")
tl.first0 = first0.tail
tl.len = len - 1
tl.last0 = if (tl.len == 0) tl.first0 else last0
}
/** Prepends a single element to this list. This operation takes constant
* time.
* @param elem the element to prepend.
* @return this $coll.
*/
def +=: (elem: A): this.type = { prependElem(elem); this }
/** Returns the length of this list.
*/
override def length: Int = len
/** Returns the `n`-th element of this list.
* @throws IndexOutOfBoundsException if index does not exist.
*/
override def apply(n: Int): A = first0.apply(n)
/** Updates the `n`-th element of this list to a new value.
* @throws IndexOutOfBoundsException if index does not exist.
*/
def update(n: Int, x: A): Unit = first0.update(n, x)
/** Returns the `n`-th element of this list or `None`
* if index does not exist.
*/
def get(n: Int): Option[A] = first0.get(n)
protected def prependElem(elem: A) {
first0 = new LinkedList[A](elem, first0)
if (len == 0) last0 = first0
len = len + 1
}
protected def appendElem(elem: A) {
if (len == 0) {
prependElem(elem)
} else {
last0.next = new LinkedList[A]
last0 = last0.next
last0.elem = elem
last0.next = new LinkedList[A] // for performance, use sentinel `object` instead?
len = len + 1
}
}
/** Returns an iterator over up to `length` elements of this list.
*/
override def iterator: Iterator[A] = if (isEmpty) Iterator.empty else
new AbstractIterator[A] {
var elems = first0
var count = len
def hasNext = count > 0 && elems.nonEmpty
def next() = {
if (!hasNext) throw new NoSuchElementException
count = count - 1
val e = elems.elem
elems = if (count == 0) null else elems.next
e
}
}
override def last = {
if (isEmpty) throw new NoSuchElementException("MutableList.empty.last")
last0.elem
}
/** Returns an instance of [[scala.List]] containing the same
* sequence of elements.
*/
override def toList: List[A] = first0.toList
/** Returns the current list of elements as a linked List
* sequence of elements.
*/
private[mutable] def toLinkedList: LinkedList[A] = first0
/** Appends a single element to this buffer. This takes constant time.
*
* @param elem the element to append.
*/
def +=(elem: A): this.type = { appendElem(elem); this }
def clear() {
first0 = new LinkedList[A]
last0 = first0
len = 0
}
def result = this
override def clone(): MutableList[A] = {
val bf = newBuilder
bf ++= seq
bf.result()
}
}
object MutableList extends SeqFactory[MutableList] {
implicit def canBuildFrom[A]: CanBuildFrom[Coll, A, MutableList[A]] =
ReusableCBF.asInstanceOf[GenericCanBuildFrom[A]]
def newBuilder[A]: Builder[A, MutableList[A]] = new MutableList[A]
}
|
