Eliot Miranda uploaded a new version of Compiler to project The Trunk:
http://source.squeak.org/trunk/Compiler-eem.452.mcz

==================== Summary ====================

Name: Compiler-eem.452
Author: eem
Time: 2 December 2020, 9:41:04.063795 pm
UUID: 4799ba54-ed87-4188-a653-e36499d92994
Ancestors: Compiler-eem.451

Provide an acceptably accurate means to test if a SYmbol is probably a message selector, Scanner class>>isMessageSelector:.

=============== Diff against Compiler-eem.451 ===============

Item was added:
+ ----- Method: Scanner class>>isMessageSelector: (in category 'testing') -----
+ isMessageSelector: aSymbol
+ 	"Answer if the argument is a valid message selector.
+ 	 This is optimized for fast filtering."
+ 	| first last sz type |
+ 	(sz := aSymbol size) = 0 ifTrue: [^false].
+ 	first := aSymbol at: 1.
+ 	last := aSymbol at: sz.
+ 	type := TypeTable at: first asciiValue.
+ 
+ 	type == #xLetter ifTrue:
+ 		["Alas some people (myself included) do create selectors with an initial capital.
+ 		  But this is unusual, and it is even rarer for these to be unary selectors, so I think
+ 		  it is better to exclude class names than include the few exceptions."
+ 		 (first isUppercase and: [last ~~ $:]) ifTrue:
+ 			[^false].
+ 		 "Could be unary or keyword, may include underscores if AllowUnderscoreSelectors.
+ 		  It is possible to be more agressive here, filtering out two successive colons, but I'm lazy"
+ 		 ^aSymbol allSatisfy: (AllowUnderscoreSelectors
+ 								ifTrue:
+ 									[last == $:
+ 										ifTrue: [[:c| c == $: or: [c == $_ or: [c isAlphaNumeric]]]]
+ 										ifFalse: [[:c| c ~~ $: and: [c == $_ or: [c isAlphaNumeric]]]]]
+ 								ifFalse:
+ 									[last == $:
+ 										ifTrue: [[:c| c == $: or: [c isAlphaNumeric]]]
+ 										ifFalse: [[:c| c ~~ $: and: [c isAlphaNumeric]]]])].
+ 
+ 	type == #xBinary ifTrue:
+ 		[^aSymbol allSatisfy: [:c| c == $| or: [(TypeTable at: c asciiValue) == #xBinary]]].
+ 
+ 	^type == #xUnderscore
+ 	 and: [AllowUnderscoreSelectors
+ 	 and: [self isMessageSelector: aSymbol allButFirst]]
+ 
+ 	"| implemented |
+ 	implemented := Set new.
+ 	self systemNavigation allSelect: [:m| implemented add: m selector. false].
+ 	^Symbol allSubInstances select: [:s| (implemented includes: s) not and: [self isMessageSelector: s]]"
+ 
+ 	"| implemented |
+ 	implemented := Set new.
+ 	self systemNavigation allSelect: [:m| implemented add: m selector. false].
+ 	^implemented reject: [:s| self isMessageSelector: s]"!