Hi,


I recently uploaded to versions of the Collections package to the Inbox 
for review and testing before adding them to the Trunk. These changes 
affect only rare, but important use-cases of OrderedCollection (and 
it's subclasses). After evaluating the following snippet:

Installer squeak
 	project: 'inbox';
 	install: 'Collections-ul.359.mcz'

from your up-to-date Trunk image, you can expect the following speedups:

"Add elements without growing to the end."
(1 to: 5) collect: [ :run |
 	[
 		| o |
 		o := OrderedCollection new: 100000.
 		1 to: 100000 do: [ :each | o addLast: each ] ] timeToRun 
].
#old -> #(19 19 20 19 20).
#new -> #(13 14 14 14 14).

"Add elements without growing to the front."
(1 to: 5) collect: [ :run |
 	[
 		| o |
 		o := OrderedCollection new: 100000.
 		1 to: 100000 do: [ :each | o addFirst: each ] ] timeToRun 
].
#old -> #(14 14 14 14 14).
#new -> #(10 11 10 10 10).

"Add elements to both ends with growing."
data := Array streamContents: [ :stream |
 	10000 timesRepeat: [ stream nextPut: 2 atRandom ] ].
(1 to: 5) collect: [ :run |
 	[
 		| o input each |
 		o := OrderedCollection new.
 		input := data readStream.
 		[ (each := input next) == nil ] whileFalse: [
 			each = 1
 				ifTrue: [ o addFirst: each ]
 				ifFalse: [ o addLast: each ] ] ] timeToRun 
].
#old -> #(2367 2393 2377 2426 2404).
#new -> #(2 2 2 2 2)

Feedback is welcome, as usual.


Cheers,
Levente