"
COPYRIGHT (c) 1993 by Claus Gittinger
All Rights Reserved
This software is furnished under a license and may be used
only in accordance with the terms of that license and with the
inclusion of the above copyright notice. This software may not
be provided or otherwise made available to, or used by, any
other person. No title to or ownership of the software is
hereby transferred.
"
Set subclass:#IdentitySet
instanceVariableNames:''
classVariableNames:''
poolDictionaries:''
category:'Collections-Unordered'
!
IdentitySet comment:'
COPYRIGHT (c) 1993 by Claus Gittinger
All Rights Reserved
same as a Set but compares elements using == (i.e. they must be identical
- not just equal in structure).
Since compare is on identity, hashing is also done via
identityHash instead of hash.
$Header: /cvs/stx/stx/libbasic/IdentitySet.st,v 1.7 1994-06-02 11:20:33 claus Exp $
written jan 93 by claus
'!
!IdentitySet methodsFor:'private'!
find:key ifAbsent:aBlock
"Look for the key in the receiver. If it is found, return
the index of the slot containing the key, otherwise
return the value of evaluating aBlock.
Redefined to compare for identity instead of equality"
|index "{ Class:SmallInteger }"
length startIndex probe |
length := keyArray basicSize.
length < 10 ifTrue:[
"assuming, that for small sets the overhead of hashing
is large ..."
^ keyArray identityIndexOf:key ifAbsent:aBlock.
].
startIndex := key identityHash \\ length + 1.
index := startIndex.
[true] whileTrue:[
probe := (keyArray basicAt:index).
probe == key ifTrue:[^ index].
probe isNil ifTrue:[^ aBlock value].
index == length ifTrue:[
index := 1
] ifFalse:[
index := index + 1
].
index == startIndex ifTrue:[
^ aBlock value
]
]
!
findKeyOrNil:key
"Look for the key in the receiver. Redefined to compare for
identity instead of equality"
|index "{ Class:SmallInteger }"
length startIndex probe |
length := keyArray basicSize.
startIndex := key identityHash \\ length + 1.
index := startIndex.
[true] whileTrue:[
probe := keyArray basicAt:index.
(probe isNil or: [key == probe]) ifTrue:[^ index].
probe == DeletedEntry ifTrue:[
keyArray basicAt:index put:nil.
^ index
].
"/ (probe isNil or: [key == probe]) ifTrue:[^ index].
index == length ifTrue:[
index := 1
] ifFalse:[
index := index + 1
].
index == startIndex ifTrue: [
^ self grow findElementOrNil:key
]
]
!
findNil:key
"Look for the next slot usable for key. This method assumes that
key is not already in the receiver - used only while growing/rehashing"
|index "{ Class:SmallInteger }"
length|
length := keyArray basicSize.
index := key identityHash \\ length + 1.
[(keyArray basicAt:index) notNil] whileTrue:[
index == length ifTrue:[
index := 1
] ifFalse:[
index := index + 1
].
"notice: no check for no nil found - we must find one since
this is only called after growing"
].
^ index
! !