131 lines
2.7 KiB
Smalltalk
131 lines
2.7 KiB
Smalltalk
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Extension { #name : 'PPParser' }
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{ #category : '*petitislands' }
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PPParser >> acceptsEpsilon [
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"
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return true, if parser can accepts epsilon without a failure.
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Use #neverFails if parser never fail, no matter what is the input.
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The #isNullable semantics is a mystery for me. I think it is something
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like acceptsEpsilon and is used for first/set computation.
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"
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^ self subclassResponsibility
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]
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{ #category : '*petitislands' }
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PPParser >> acceptsEpsilonOpenSet: set [
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"private helper for acceptsEmpsilon that makes sure to avoid cycles (using open set)"
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self children isEmpty ifTrue: [ ^ self acceptsEpsilon ].
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self shouldBeImplemented .
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]
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{ #category : '*petitislands' }
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PPParser >> isIslandBorder [
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^ self subclassResponsibility
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]
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{ #category : '*petitislands' }
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PPParser >> isIslandBorderOpenSet: set [
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"private helper for acceptsEmpsilon that makes sure to avoid cycles (using open set)"
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self children isEmpty ifTrue: [ ^ self isIslandBorder ].
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self shouldBeImplemented .
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]
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{ #category : '*petitislands' }
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PPParser >> isWater [
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^ false
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]
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{ #category : '*petitislands' }
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PPParser >> island [
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self halt: 'deprecated'.
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^ self sea
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]
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{ #category : '*petitislands' }
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PPParser >> island: water [
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self halt: 'deprecated'.
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^ self sea: water
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]
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{ #category : '*petitislands' }
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PPParser >> next: context [
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^ PPChoiceParser withAll: (self nextSet: context)
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]
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{ #category : '*petitislands' }
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PPParser >> nextSet: aPPContext [
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^ aPPContext root nextSets at: self.
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]
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{ #category : '*petitislands' }
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PPParser >> nextSets [
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| nextSets |
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nextSets := IdentityDictionary new.
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self allParsersDo: [ :each | nextSets at: each put: IdentitySet new ].
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(nextSets at: self) add: PPSentinel instance.
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[ | changed |
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changed := false.
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nextSets keysAndValuesDo: [:parser :next |
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changed := (parser
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nextSets: nextSets
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into: next) or: [ changed ].
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].
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changed ] whileTrue.
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^ nextSets
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]
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{ #category : '*petitislands' }
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PPParser >> nextSets: aNextDictionary into: aSet [
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"return true/false, if something has changed or not...."
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| childSet change tally |
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change := false.
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self children do: [:each |
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childSet := aNextDictionary at: each.
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tally := childSet size.
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childSet addAll: aSet.
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change := change or: [ tally ~= childSet size ].
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].
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^ change
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]
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{ #category : '*petitislands' }
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PPParser >> nonEmpty [
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^ PPNonEmptyParser on: self
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]
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{ #category : '*petitislands' }
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PPParser >> previous [
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^ PPPreviousParser on: self
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]
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{ #category : '*petitislands' }
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PPParser >> sea [
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| island |
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island := PPSea new
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island: self;
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yourself.
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^ island memoized
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]
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{ #category : '*petitislands' }
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PPParser >> sea: water [
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^ self sea
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water: water;
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yourself
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]
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