/usr/share/gnu-smalltalk/examples/Case.st is in gnu-smalltalk-common 3.2.4-2.1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 | "======================================================================
|
| Case syntax for Smalltalk
|
|
======================================================================"
"======================================================================
|
| Written by Ulf Dambacher.
|
| This file is part of GNU Smalltalk.
|
| GNU Smalltalk is free software; you can redistribute it and/or modify it
| under the terms of the GNU General Public License as published by the Free
| Software Foundation; either version 2, or (at your option) any later version.
|
| GNU Smalltalk 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 General Public License for more
| details.
|
| You should have received a copy of the GNU General Public License along with
| GNU Smalltalk; see the file COPYING. If not, write to the Free Software
| Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
|
======================================================================"
Object subclass: #Case
instanceVariableNames: 'test found result'
classVariableNames: ''
poolDictionaries: ''
category: 'Examples-Useful tools'
!
Case comment:
'A nice class for switch-like tests. Slower than cascaded ifs but clearer.
#case:do: uses identity for testing (useful since you''ll likely use Case
with symbols, integers, characters, and the like), #ifEqualTo:do: uses
equality.
e.g.
Case new test: myObject;
case: 5 do: [ ''got five'' printNl ];
when: [ :testVal | testVal isInteger ] do: [ ''an integer'' printNl ];
else: [ :testVal | testVal printNl ]
You can use (Case test: myObject) instead of the first line above. Which of
the two possibilities is clearer, it is a matter of taste.'!
!Case class methodsFor: 'instance creation'!
test: anObject
^self new test: anObject
! !
!Case methodsFor: 'testing'!
test: anObject
test := anObject.
found := false.
!
reset
found := false
!
else: aBlock
^found
ifFalse: [ self do: aBlock ]
ifTrue: [ result ].
!
case: anObject do: aBlock
^(found not and: [test == anObject])
ifTrue: [ self do: aBlock ]
ifFalse: [ result ].
!
ifEqualTo: anObject do: aBlock
^(found not and: [test = anObject])
ifTrue: [ self do: aBlock ]
ifFalse: [ result ].
!
when: aBlock do: aBlock2
^(found not and: [aBlock value: test])
ifTrue: [ self do: aBlock ]
ifFalse: [ result ].
! !
!Case methodsFor: 'private'!
do: aBlock
found := true.
^result := (aBlock cull: test)
! !
Object subclass: #Switch
instanceVariableNames: 'values defaultBlock'
classVariableNames: ''
poolDictionaries: ''
category: 'Examples-Useful tools'
!
Object subclass: #SwitchCase
instanceVariableNames: 'secondParameter evaluationBlock actionBlock result'
classVariableNames: ''
poolDictionaries: ''
category: 'Examples-Useful tools'
!
Switch comment:
'Another class for switch-like tests. This is reusable, i.e. an instance
stores its case-do pairs.
e.g.
(Switch new)
case: "value or Block" do: [...];
...
default: [...];
on: value. "#= equality matching of cases"
(Switch new)
case: "value or Block" do: [...];
...
default: [...];
exactlyOn: value. "#== identity matching of cases"
'!
!Switch class methodsFor: 'instance creation'!
new
^self basicNew values: (ReadWriteStream on: Array new: 5)
! !
!Switch methodsFor: 'initialization'!
values: aStream
values := aStream
!
default: aBlock
defaultBlock := aBlock
!
case: anObjectOrBlock do: aBlock
| block |
block := anObjectOrBlock class == BlockClosure
ifTrue: [
[ :object :block :identity | block value: object ]
ifFalse: [
[ :object :comparison :identity |
identity
ifTrue: [ object == comparison ]
ifFalse: [ object = comparison ]
]
].
values nextPut: (SwitchCase new
secondParameter: anObjectOrBlock
evaluationBlock: block
actionBlock: aBlock)
! !
!Switch methodsFor: 'evaluation'!
on: anObject
| done case |
done := false.
values reset.
[ values atEnd ] whileFalse: [
case := values next.
(case evaluateIfEqualTo: anObject) ifTrue: [ ^case result ].
].
^defaultBlock value! !
exactlyOn: anObject
| done case |
done := false.
values reset.
[ values atEnd ] whileFalse: [
case := values next.
(case evaluateIfIdenticalTo: anObject) ifTrue: [ ^case result ].
].
^defaultBlock value! !
identityOn: anObject
| done case |
done := false.
values reset.
[ values atEnd ] whileFalse: [
case := values next.
(case evaluateIfIdenticalTo: anObject) ifTrue: [ ^case result ].
].
^defaultBlock value! !
!SwitchCase methodsFor: 'evaluation'!
evaluateIfEqualTo: object
^(evaluationBlock value: object value: secondParameter value: false)
ifTrue: [ result := actionBlock value ];
yourself
!
evaluateIfIdenticalTo: object
^(evaluationBlock value: object value: secondParameter value: true)
ifTrue: [ result := actionBlock value ];
yourself
!
result
| answer |
answer := result.
result := nil.
^answer
! !
!SwitchCase methodsFor: 'initialization'!
secondParameter: sP evaluationBlock: eB actionBlock: aB
secondParameter := sP.
evaluationBlock := eB.
actionBlock := aB
! !
|