"
 COPYRIGHT (c) 1989 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.
"

"{ Package: 'stx:libbasic' }"

LookupKey subclass:#Association
	instanceVariableNames:'value'
	classVariableNames:''
	poolDictionaries:''
	category:'Collections-Support'
!

!Association class methodsFor:'documentation'!

copyright
"
 COPYRIGHT (c) 1989 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.
"
!

documentation
"
    Associations are a key-value pair; conceptionally, they are the elements of 
    Dictionaries - storing value under the key. (However, the real implementation
    of Dictionary is different).
    Taken by itself, an association is not very useful.

    [Instance variables:]

        key             <Object>        the key (inherited)
        value           <Object>        the value

    [author:]
        Claus Gittinger

    [See also:]
        Dictionary IdentityDictionary
"
! !

!Association class methodsFor:'instance creation'!

key:aKey value:aValue
    "return a new Association"

    ^ self basicNew key:aKey value:aValue
! !

!Association methodsFor:'accessing'!

key:aKey value:aValue
    "set both the key and value of the receiver.
     Return the receiver"

    key := aKey.
    value := aValue
!

value
    "return the value of the association"

    ^ value
!

value:anObject
    "set the value of the receiver to be anObject.
     Return the receiver"

    value := anObject
! !

!Association methodsFor:'comparing'!

= anAssociation
    "return true if the receiver equals the argument.
     Notice, that this compares both key AND value.
     Time will show if this is ok."

    self species == anAssociation species ifTrue:[
	(anAssociation key = key) ifTrue:[
	    ^ anAssociation value = value
	]
    ].
    ^ false
!

hash
    "return an integer useful for hashing on the receiver;
     redefined since = is redefined here."

    ^ (key hash) bitXor:(value hash)
! !

!Association methodsFor:'printing & storing'!

displayString
    "return a string containing a printable representation
     of the receiver for displaying - redefined to use display string on
     the components for nicer look"

    ^ key displayString , '->' , value displayString
!

printOn:aStream
    "return a string containing a printable representation
     of the receiver"

    key printOn:aStream.
    aStream nextPutAll:'->'.
    value printOn:aStream
!

storeOn:aStream
    "append a string representing an expression to reconstruct the receiver
     to aStream."

    aStream nextPut:$(. 
    key storeOn:aStream.
    aStream nextPutAll:'->'. 
    value storeOn:aStream.
    aStream nextPut:$).

    "Created: / 3.2.2000 / 22:31:28 / cg"
! !

!Association methodsFor:'queries'!

isAssociation
    "return true, if the receiver is some kind of association;
     true is returned here - the method is redefined from Object."

    ^ true

    "Created: 14.5.1996 / 17:04:13 / cg"
! !

!Association class methodsFor:'documentation'!

version
    ^ '$Id: Association.st 10447 2009-06-14 13:09:55Z vranyj1 $'
! !