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|
"======================================================================
|
| Link 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.
|
======================================================================"
Object subclass: Link [
| nextLink |
<category: 'Collections-Sequenceable'>
<comment: 'I represent simple linked lists. Generally, I am not used by myself, but
rather a subclass adds other instance variables that hold the information
for each node, and I hold the glue that keeps them together.'>
Link class >> nextLink: aLink [
"Create an instance with the given next link"
<category: 'instance creation'>
^self new nextLink: aLink
]
at: index [
"Retrieve a node (instance of Link) that is at a distance of `index'
after the receiver."
<category: 'iteration'>
| i element |
i := 1.
element := self.
[i = index ifTrue: [^element].
i := i + 1.
(element := element nextLink) isNil]
whileFalse.
SystemExceptions.IndexOutOfRange signalOn: self withIndex: index
]
at: index put: object [
<category: 'iteration'>
self shouldNotImplement
]
do: aBlock [
"Evaluate aBlock for each element in the list"
<category: 'iteration'>
| item |
item := self.
[aBlock value: item.
(item := item nextLink) isNil] whileFalse
]
size [
"Answer the number of elements in the list. Warning: this is O(n)"
<category: 'iteration'>
| item count |
item := self.
count := 1.
[(item := item nextLink) isNil] whileFalse: [count := count + 1].
^count
]
nextLink [
"Answer the next item in the list"
<category: 'basic'>
^nextLink
]
nextLink: aLink [
"Set the next item in the list"
<category: 'basic'>
nextLink := aLink
]
]
|
