/usr/share/gnu-smalltalk/kernel/LinkedList.st is in gnu-smalltalk-common 3.2.4-2.1.
This file is owned by root:root, with mode 0o644.
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| LinkedList Method Definitions
|
|
======================================================================"
"======================================================================
|
| Copyright 1988,92,94,95,99,2000,2001,2002
| Free Software Foundation, Inc.
| Written by Steve Byrne.
|
| This file is part of the GNU Smalltalk class library.
|
| The GNU Smalltalk class library is free software; you can redistribute it
| and/or modify it under the terms of the GNU Lesser General Public License
| as published by the Free Software Foundation; either version 2.1, or (at
| your option) any later version.
|
| The GNU Smalltalk class library is distributed in the hope that it will be
| useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
| General Public License for more details.
|
| You should have received a copy of the GNU Lesser General Public License
| along with the GNU Smalltalk class library; see the file COPYING.LIB.
| If not, write to the Free Software Foundation, 59 Temple Place - Suite
| 330, Boston, MA 02110-1301, USA.
|
======================================================================"
SequenceableCollection subclass: LinkedList [
| firstLink lastLink |
<category: 'Collections-Sequenceable'>
<comment: 'I provide methods that access and manipulate linked lists. I assume that
the elements of the linked list are subclasses of Link, because I use
the methods that class Link supplies to implement my methods.'>
at: index [
"Return the element that is index into the linked list."
<category: 'accessing'>
^firstLink at: index
]
at: index put: object [
<category: 'accessing'>
self shouldNotImplement
]
add: aLink [
"Add aLink at the end of the list; return aLink."
<category: 'adding'>
self addLast: aLink.
^aLink
]
addFirst: aLink [
"Add aLink at the head of the list; return aLink."
<category: 'adding'>
lastLink isNil ifTrue: [lastLink := aLink].
aLink nextLink: firstLink.
^firstLink := aLink
]
addLast: aLink [
"Add aLink at then end of the list; return aLink."
<category: 'adding'>
firstLink isNil ifTrue: [firstLink := aLink].
lastLink notNil ifTrue: [lastLink nextLink: aLink].
^lastLink := aLink
]
removeFirst [
"Remove the first element from the list and return it, or error if the
list is empty."
<category: 'adding'>
^self remove: firstLink
ifAbsent: [SystemExceptions.EmptyCollection signalOn: self]
]
removeLast [
"Remove the final element from the list and return it, or error if the
list is empty."
<category: 'adding'>
^self remove: lastLink
ifAbsent: [SystemExceptions.EmptyCollection signalOn: self]
]
remove: aLink ifAbsent: aBlock [
"Remove aLink from the list and return it, or invoke aBlock if it's not
found in the list."
<category: 'adding'>
| prev |
aLink == firstLink
ifTrue:
[firstLink isNil ifTrue: [^aBlock value].
firstLink := firstLink nextLink.
firstLink isNil ifTrue: [lastLink := nil].
aLink nextLink: nil.
^aLink].
prev := firstLink.
[prev isNil ifTrue: [^aBlock value].
prev nextLink == aLink]
whileFalse: [prev := prev nextLink].
prev nextLink: aLink nextLink.
aLink == lastLink ifTrue: [lastLink := prev].
aLink nextLink: nil.
^aLink
]
do: aBlock [
"Enumerate each object in the list, passing it to aBlock (actual
behavior might depend on the subclass of Link that is being used)."
<category: 'enumerating'>
self isEmpty ifFalse: [firstLink do: aBlock]
]
includes: anObject [
"Answer whether we include anObject"
"Blah, this is roughly the same implementation as in Collection."
<category: 'enumerating'>
self isEmpty ifTrue: [^false].
firstLink do: [:element | anObject = element ifTrue: [^true]].
^false
]
identityIncludes: anObject [
"Answer whether we include the anObject object"
"Blah, this is roughly the same implementation as in Collection."
<category: 'enumerating'>
self isEmpty ifTrue: [^false].
firstLink do: [:element | anObject == element ifTrue: [^true]].
^false
]
isEmpty [
"Returns true if the list contains no members"
<category: 'testing'>
^firstLink isNil
]
notEmpty [
"Returns true if the list contains at least a member"
<category: 'testing'>
^firstLink notNil
]
size [
"Answer the number of elements in the list. Warning: this is O(n)"
<category: 'testing'>
^self isEmpty ifTrue: [0] ifFalse: [firstLink size]
]
]
|