"

 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.

"

Collection subclass:#SequenceableCollection

       instanceVariableNames:''

       classVariableNames:''

       poolDictionaries:''

       category:'Collections-Abstract'

!

SequenceableCollection comment:'

COPYRIGHT (c) 1989 by Claus Gittinger

	      All Rights Reserved

'!

!SequenceableCollection 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.

"

!

version

"

"

!

documentation

"

    SequenceableCollections have ordered elements which can be accessed via

    a numeric index. 

    SequenceableCollection is an abstract class - there are no instances of 

    it in the system. See concrete subclasses (such as OrderedCollection).

"

! !

!SequenceableCollection class methodsFor:'instance creation'!

new:size withAll:element

    "return a new Collection of size, where all elements are

     initialized to element"

    |newCollection|

    newCollection := self new:size.

    newCollection atAllPut:element.

    ^ newCollection

! !

!SequenceableCollection methodsFor:'accessing'!

first

    "return the first element"

    ^ self at:1

!

last

    "return the last element"

    ^ self at:(self size)

!

at:index ifAbsent:exceptionBlock

    "return the element at index if valid. 

     If the index is invalid, return the result of evaluating 

     the exceptionblock."

    ((index < 1) or:[index > self size]) ifTrue:[

	^ exceptionBlock value

    ].

    ^ self at:index

    "

     #(1 2 3) at:4 ifAbsent:['no such index']

     (Dictionary with:(#foo -> #bar)

		 with:(#frob -> #baz)) 

	 at:#foobar ifAbsent:['no such index']

    "

! !

!SequenceableCollection methodsFor:'queries'!

isSequenceable

    "return true, if the receiver is some kind of sequenceableCollection"

    ^ true

!

isSequenceableCollection

    "OBSOLETE: use isSequenceable for ST-80 compatibility.

     This method is a historic leftover and will be removed."

    ^ true

!

firstIndex

    "return the first elements index"

    ^ 1

!

lastIndex

    "return the last elements index"

    ^ self size

!

size

    "return the number of elements in the collection.

     concrete implementations must define this"

    ^ self subclassResponsibility

!

keys

    "return a collection with all keys in the Smalltalk dictionary"

    |sz|

    sz := self size.

    sz == 0 ifTrue:[

	^ #()

    ].

    ^ 1 to:sz

! !

!SequenceableCollection methodsFor:'comparing'!

= aCollection

    "return true if the receiver and aCollection represent collections

     with equal contents."

    |index "{ Class: SmallInteger }"

     stop  "{ Class: SmallInteger }" |

    (aCollection == self) ifTrue:[^true].

    (aCollection isSequenceableCollection) ifFalse:[^false].

    stop := self size.

    stop == (aCollection size) ifFalse:[^false].

    index := 1.

    [index <= stop] whileTrue:[

	(self at:index) = (aCollection at:index) ifFalse:[^false].

	index := index + 1

    ].

    ^ true

    "

     #(1 2 3 4 5) = #(1 2 3 4 5)                        

     #($1 $2 $3 $4 $5) = #(1 2 3 4 5)                   

     #($1 $2 $3 $4 $5) = '12345'                       

     #($1 $2 $3 $4 $5) = '54321' asSortedCollection   

    "

!

hash

    "return a hash key for the receiver"

    "this hash is stupid - but for larger collections, the hashing

     time can become much bigger than the time lost in added probing.

     Time will show ..."

    ^ (self at:1 ifAbsent:[0]) hash * self size

    "

     #(1 2 3 4 5) hash

     #(1 2 3 4 5.0) asOrderedCollection hash

    "

!

startsWith:aCollection

    "return true, if the receivers first elements match those

     of aCollection"

    |index "{ Class: SmallInteger }"

     stop  "{ Class: SmallInteger }" |

    (aCollection == self) ifTrue:[^true].

    (aCollection isSequenceableCollection) ifFalse:[^false].

    stop := aCollection size.

    stop > self size ifTrue:[^false].

    index := 1.

    [index <= stop] whileTrue:[

	(self at:index) = (aCollection at:index) ifFalse:[^false].

	index := index + 1

    ].

    ^ true

    "

     'abcde' startsWith:#($a $b $c)

     #[1 2 3 4] startsWith:#(1 2 3)

     #(1 2 3 4) asOrderedCollection startsWith:#(1 2 3)

    "

!

endsWith:aCollection

    "return true, if the receivers last elements match those

     of aCollection"

    |index1 "{ Class: SmallInteger }"

     index2 "{ Class: SmallInteger }" 

     stop   "{ Class: SmallInteger }" 

     sz     "{ Class: SmallInteger }"|

    (aCollection == self) ifTrue:[^ true].

    (aCollection isSequenceableCollection) ifFalse:[^ false].

    stop := aCollection size.

    sz := self size.

    stop > sz ifTrue:[^false].

    index1 := sz.

    index2 := stop.

    [index2 > 0] whileTrue:[

	(self at:index1) = (aCollection at:index2) ifFalse:[^ false].

	index1 := index1 - 1.

	index2 := index2 - 1

    ].

    ^ true

    "

     'abcde' endsWith:#($d $e)

     #[1 2 3 4] endsWith:#(3 4)    

     #(1 2 3 4) asOrderedCollection endsWith:#(3 4)

    "

! !

!SequenceableCollection methodsFor:'copying'!

, aCollection

    "return a new collection formed from concatenating the receiver with

     the argument. The class of the new collection is determined by the

     receivers class, so mixing classes is possible, if the second collections

     elements can be stored into instances of the receivers class."

    |newCollection 

     mySize    "{ Class: SmallInteger }"

     newSize   "{ Class: SmallInteger }"

     otherSize "{ Class: SmallInteger }"

     dstIndex  "{ Class: SmallInteger }"|

    mySize := self size.

    otherSize := aCollection size.

    newSize := mySize + otherSize.

    newCollection := self copyEmptyAndGrow:newSize.   "must grow, otherwise replace fails"

    newCollection replaceFrom:1 to:mySize with:self startingAt:1.

    dstIndex := mySize + 1.

    aCollection isSequenceable ifTrue:[

	"

	 yes, aCollection has indexed elements

	"

	newCollection replaceFrom:dstIndex to:newSize

			     with:aCollection startingAt:1.

	^ newCollection

    ] ifFalse:[

	"

	 no, enumerate aCollection

	"

	aCollection do:[:element |

	    newCollection at:dstIndex put:element.

	    dstIndex := dstIndex + 1

	]

    ].

    ^ newCollection

    "

     #($a $b $c) , #(1 2 3)

     #($a $b $c) , '123'

     'abc' , '123'

     'abc' , #($q $w $e $r $t $y) asSortedCollection

     'abc' , #(1 2 3 4 5)"  "-- will fail, since strings cannot store integers

     'abc' asArray , #(1 2 3 4 5)

    "

!

copyWith:newElement

    "return a new collection containing the receivers elements

     and the single new element, newElement. 

     This is different from concatentation, which expects another collection

     as argument, but equivalent to copy-and-addLast."

    |newCollection mySize newSize|

    mySize := self size.

    newSize := mySize + 1.

    newCollection := self copyEmptyAndGrow:newSize.

    newCollection replaceFrom:1 to:mySize with:self startingAt:1.

    newCollection at:newSize put:newElement.

    ^newCollection

    "

     #(1 2 3 4 5) copyWith:$a

     'abcdefg' copyWith:$h

     'abcdefg' copyWith:'123'   -- will fail: string cannot be stored into string

     'abcdefg' copyWith:1       -- will fail: integer cannot be stored into string

    "

!

copyWithoutFirst:elementToSkip

    "return a new collection consisting of a copy of the receivers elements

     without the first elementToSkip, if it was present. 

     No error is reported, if elementToSkip is not in the collection."

    |copy skipIndex sz|

    skipIndex := self indexOf:elementToSkip startingAt:1.

    (skipIndex == 0) ifTrue:[^ self copy].

    sz := self size - 1.

    copy := self copyEmptyAndGrow:sz.