89 lines
2.5 KiB
Smalltalk
89 lines
2.5 KiB
Smalltalk
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"
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I can recognize the deterministic choices, i.e. the choices, where based on the first token, one can decide if to take the choice or not.
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This simplifies the generated code and this migth improve performance as well (not yet implemented, as far as I know..)
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I need to be revisited and reimplemented...
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"
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Class {
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#name : 'PPCDeterministicChoiceVisitor',
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#superclass : 'PPCRewritingVisitor',
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#category : 'PetitCompiler-Visitors'
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}
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{ #category : 'as yet unclassified' }
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PPCDeterministicChoiceVisitor >> isDeterministicChoice: node [
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| predicates firstIndexes |
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predicates := self predicates: node.
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firstIndexes := OrderedCollection new.
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predicates do: [ :predicate |
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predicate classification withIndexDo: [ :bool :index |
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bool ifTrue: [firstIndexes add: index]
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]
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].
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^ firstIndexes size = firstIndexes asIdentitySet size
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]
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{ #category : 'as yet unclassified' }
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PPCDeterministicChoiceVisitor >> mergeFirstCharSets: firstSet [
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| firstCharSetsOfFirstSet blocks mergedBlock |
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firstCharSetsOfFirstSet := firstSet collect: [:e | e firstCharSet ].
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blocks := firstCharSetsOfFirstSet collect: [ :e | e block ].
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mergedBlock := [ :input | blocks anySatisfy: [ :block | block value: input ] ].
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^ PPCharSetPredicate on: mergedBlock.
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]
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{ #category : 'as yet unclassified' }
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PPCDeterministicChoiceVisitor >> predicates: node [
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| firstSets mergedSets |
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(node startsWithTrimmingTokens) ifTrue: [
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| tokensPerChild |
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tokensPerChild := node children collect: [:child | child firstSetWithTokens "firstSet" ].
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firstSets := tokensPerChild collect: [ :childTokensOrTerminal |
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| firstSet |
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firstSet := IdentitySet new.
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childTokensOrTerminal do: [ :tokenOrTerminal |
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tokenOrTerminal isTokenNode ifTrue: [
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firstSet addAll: tokenOrTerminal child firstSet
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] ifFalse: [
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firstSet addAll: tokenOrTerminal firstSet.
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]
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].
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firstSet
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].
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] ifFalse: [
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firstSets := node children collect: [:child | child firstSet ].
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].
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mergedSets := firstSets collect: [ :fs | self mergeFirstCharSets: fs ].
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node children with: mergedSets do: [ :child :merged |
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child mergedFirstCharSet: merged
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].
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^ mergedSets
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]
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{ #category : 'as yet unclassified' }
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PPCDeterministicChoiceVisitor >> visitChoiceNode: node [
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self visitChildren: node.
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(self isDeterministicChoice: node) ifTrue: [
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^ PPCDeterministicChoiceNode new
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children: node children;
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name: node name;
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firstFollowCache: node firstFollowCache;
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properties: node properties;
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yourself.
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].
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^ super visitChoiceNode: node.
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]
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