Fix unlikely but possible race in `WeakValueDictionary`
It may happen that value in `valueArray` could have been already
collected by the GC but #clearDeadSlots have not yet been called.
When this happened, `#at:ifAbsentPut:` returned tombstone rather
than updating the dictionary with value from block.
This commit fixes this by checking whether `valueArray` contain
the tombstone and if so, clearing up the dead slots and restarting
the operation. HTH.
"
COPYRIGHT (c) 2003 by eXept Software AG
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.
"
"{ Package: 'stx:libbasic' }"
MetaNumber subclass:#NotANumber
instanceVariableNames:''
classVariableNames:'NaN'
poolDictionaries:''
category:'Magnitude-Numbers'
!
!NotANumber class methodsFor:'documentation'!
copyright
"
COPYRIGHT (c) 2003 by eXept Software AG
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.
"
!
documentation
"
Represents the two metaNumbers +INF and -INF for non-float classes.
[author:]
Claus Gittinger
[see also:]
Number Infinity NotANumber
Float ShortFloat Fraction FixedPoint Integer Complex
FloatArray DoubleArray
"
! !
!NotANumber class methodsFor:'instance creation'!
new
^ NaN
! !
!NotANumber class methodsFor:'class initialization'!
initialize
NaN := self basicNew
"
self initialize
"
! !
!NotANumber methodsFor:'arithmetic'!
* aNumber
"Multiply the receiver and the argument and answer with the result."
^ self
!
+ aNumber
"Add the receiver and the argument and answer with the result."
^ self
!
- aNumber
"Subtract the argument from the receiver and answer with the result."
^ self
!
/ aNumber
"Divide the receiver by the argument and answer with the result."
^ self
! !
!NotANumber methodsFor:'comparing'!
= something
"return true, if the argument represents the same numeric value
as the receiver, false otherwise."
something respondsToArithmetic ifTrue:[ ^ something isNaN ].
^ false.
! !
!NotANumber methodsFor:'double dispatching'!
differenceFromSomeNumber:aNumber
"sent from aNumber-self, if aNumber does not know how to handle this"
^ self
!
lessFromSomeNumber:aNumber
"sent from aNumber < self, if aNumber does not know how to handle this"
^ Number
raise: #undefinedResultSignal
receiver: self
selector: #lessFromSomeNumber:
errorString: 'Cannot compare against NaN'
!
productFromSomeNumber:aNumber
"sent from aNumber*self, if aNumber does not know how to handle this"
^ self
!
quotientFromSomeNumber:aNumber
"Return the quotient of the argument, aNumber and the receiver.
Sent when aNumber does not know how to divide by the receiver."
^ self
!
sumFromSomeNumber:aNumber
"sent from aNumber+self, if aNumber does not know how to handle this"
^ self
! !
!NotANumber methodsFor:'printing'!
printOn:aStream
aStream nextPutAll:'NAN'
! !
!NotANumber methodsFor:'testing'!
isFinite
^ false
!
isNaN
^ true
! !
!NotANumber class methodsFor:'documentation'!
version
^ '$Header: /cvs/stx/stx/libbasic/NotANumber.st,v 1.2 2003/07/02 09:52:32 cg Exp $'
! !
NotANumber initialize!