What is the aim of the OneCharacterSymbols class?

On Wed, 4 Sep 2013 00:21:42.547 0000, commits at source.squeak.org
<commits at source.squeak.org> wrote:
> A new version of Collections was added to project The Inbox:
> http://source.squeak.org/inbox/Collections-nice.530.mcz
>
> ==================== Summary ====================
>
> Name: Collections-nice.530
> Author: nice
> Time: 4 September 2013, 2:21:28.852 am
> UUID: d732aa23-1c77-4c1e-abc0-d8d4506b7f9f
> Ancestors: Collections-ul.529
>
> Fix this:
>   self assert: (allSymbols select: [:s | s = '+']) size = 1.
>
> 1) It is un-necessary to enumerate the 1-char symbols, they already are in
> SymbolTable (the first time they were created via #findIntern: or by virtue
> of last #rehash) !
>
> 2) We can use a WeekArray rather than an Array because there is no point in
> keeping a reference to unused 1-char symbols.
>
> Maybe we should get rid of OneCharacterSymbols class var, but I didn't
> dare...
>
> =============== Diff against Collections-ul.529 ===============
>
> Item was changed:
>   ----- Method: Symbol class>>allSymbols (in category 'access') -----
>   allSymbols
>   	"Answer all interned symbols"
>   	^Array streamContents:[:s|
>   		s nextPutAll: NewSymbols.
> - 		s nextPutAll: OneCharacterSymbols.
>   		s nextPutAll: SymbolTable.
>   	].
>   !
>
> Item was changed:
>   ----- Method: Symbol class>>initialize (in category 'class
> initialization') -----
>   initialize
>
>   	"Symbol initialize"
>
>   	Symbol rehash.
> + 	OneCharacterSymbols := WeakArray new: 256.
> + 	(0 to: 255) do: [ :byte | byte asCharacter asSymbol].
> - 	OneCharacterSymbols := nil.
> - 	OneCharacterSymbols := (1 to: 256) collect: [ :i | (i - 1) asCharacter
> asSymbol].
>   	Smalltalk addToShutDownList: self.
>   !
>
> Item was changed:
>   ----- Method: Symbol class>>internCharacter: (in category 'instance
> creation') -----
>   internCharacter: aCharacter
>   	aCharacter asciiValue > 256 ifTrue:[^self intern: aCharacter asString].
> + 	^(OneCharacterSymbols at: aCharacter asciiValue + 1) ifNil:
> [OneCharacterSymbols at: aCharacter asciiValue + 1 put: (self intern:
> aCharacter asString)]
> - 	OneCharacterSymbols ifNil: [^self intern: aCharacter asString].
> - 	^OneCharacterSymbols at: aCharacter asciiValue + 1
>   !
>
> Item was changed:
>   ----- Method: Symbol class>>selectorsContaining: (in category 'access')
> -----
>   selectorsContaining: aString
>   	"Answer a list of selectors that contain aString within them.
> Case-insensitive.  Does return symbols that begin with a capital letter."
>
>   	| size selectorList ascii |
>
>   	selectorList := OrderedCollection new.
>   	(size := aString size) = 0 ifTrue: [^selectorList].
>
>   	aString size = 1 ifTrue:
>   		[
>   			ascii := aString first asciiValue.
> + 			ascii < 128 ifTrue: [(OneCharacterSymbols at: ascii+1) ifNotNil: [:s |
> selectorList add: s]]
> - 			ascii < 128 ifTrue: [selectorList add: (OneCharacterSymbols at:
> ascii+1)]
>   		].
>
>   	(aString first isLetter or: [aString first isDigit]) ifFalse:
>   		[
>   			aString size = 2 ifTrue:
>   				[Symbol hasInterned: aString ifTrue:
>   					[:s | selectorList add: s]].
>   			^selectorList
>   		].
>
>   	selectorList := selectorList copyFrom: 2 to: selectorList size.
>
>   	self allSymbolTablesDo: [:each |
>   		each size >= size ifTrue:
>   			[(each findSubstring: aString in: each startingAt: 1
>   				matchTable: CaseInsensitiveOrder) > 0
>   						ifTrue: [selectorList add: each]]].
>
>   	^selectorList reject: [:each | "reject non-selectors, but keep ones that
> begin with an uppercase"
>   		each numArgs < 0 and: [each asString withFirstCharacterDownshifted
> numArgs < 0]].
>
>   "Symbol selectorsContaining: 'scon'"!
>
>
>