406 lines
9.4 KiB
Smalltalk
406 lines
9.4 KiB
Smalltalk
"
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A PPIsland allows for imprecise parsing. One can create it on a parser p by calling: 'p island' E.g.:
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p := x, a island, y accepts following inputs:
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x.....a.....b
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xab
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yet fails on:
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x....a....c
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xb
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xac
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x..b....a....b
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The input represented by dots is called water and water can appear before and after the island. Use it, if you don't want to define all the grammar rules and you want to skip something.
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I am still an experiment, but if you know how to improve me, please contact Jan Kurs at: kurs@iam.unibe.ch
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Instance Variables
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afterWaterParser: <Object>
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awp: <Object>
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beforeWaterParser: <Object>
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bwp: <Object>
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context: <Object>
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island: <Object>
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afterWaterParser
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- xxxxx
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awp
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- xxxxx
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beforeWaterParser
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- xxxxx
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bwp
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- xxxxx
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context
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- xxxxx
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island
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- xxxxx
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"
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Class {
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#name : 'PPSea',
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#superclass : 'PPParser',
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#instVars : [
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'island',
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'afterWaterParser',
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'beforeWaterParser',
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'water',
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'defaultBeforeWaterParser',
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'defaultAfterWaterParser',
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'contextIdentifier'
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],
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#category : 'PetitIslands-Parsers'
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}
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{ #category : 'queries' }
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PPSea >> acceptsEpsilon [
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^ island acceptsEpsilon
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]
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{ #category : 'queries' }
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PPSea >> acceptsEpsilonOpenSet: set [
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^ island acceptsEpsilonOpenSet: set
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]
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{ #category : 'parsing' }
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PPSea >> afterWaterParser: aPPContext [
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self check: aPPContext.
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afterWaterParser ifNil: [
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afterWaterParser := self createAfterWaterParser: aPPContext.
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].
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^ afterWaterParser
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]
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{ #category : 'parsing' }
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PPSea >> beforeWaterParser: aPPContext [
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self check: aPPContext.
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beforeWaterParser ifNil: [
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beforeWaterParser := self createBeforeWaterParser: aPPContext.
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].
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^ beforeWaterParser
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]
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{ #category : 'parsing' }
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PPSea >> check: aPPContext [
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(contextIdentifier == aPPContext identifier) ifFalse: [ self reset: aPPContext ].
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]
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{ #category : 'accessing' }
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PPSea >> children [
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self flag: 'HACK ???'.
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(beforeWaterParser isNotNil and: [afterWaterParser isNotNil]) ifTrue: [
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^ Array with: beforeWaterParser with: island with: afterWaterParser
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].
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^ Array with: water with: island with: water
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]
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{ #category : 'parsing' }
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PPSea >> createAfterWaterParser: aPPContext [
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^ self createAfterWaterParserFromNextSet: (self nextSet: aPPContext).
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]
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{ #category : 'parsing' }
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PPSea >> createAfterWaterParserFromNextSet: nextSet [
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| set p |
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set := nextSet copy.
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set := self filterOutNextSet: set.
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(set anySatisfy: [ :e | e acceptsEpsilon ]) ifTrue: [
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set := set collect: [ :e | e acceptsEpsilon ifTrue: [ e nonEmpty ] ifFalse: [ e ]].
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set add: PPEndOfFileParser new.
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].
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set := set reject: [ :e | e class = PPFailingParser ].
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p := (PPChoiceParser withAll: set) and.
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^ PPWater on: p waterToken: water
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]
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{ #category : 'parsing' }
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PPSea >> createBeforeWaterParser: aPPContext [
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^ self createBeforeWaterParserFromNextSet: (self nextSet: aPPContext).
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]
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{ #category : 'parsing' }
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PPSea >> createBeforeWaterParserFromNextSet: nextSet [
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| set p |
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set := nextSet copy.
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set := self filterOutNextSet: nextSet.
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set add: island.
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(set anySatisfy: [ :e | e acceptsEpsilon ]) ifTrue: [
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set := set collect: [ :e | e acceptsEpsilon ifTrue: [ e nonEmpty ] ifFalse: [ e ]].
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set add: PPEndOfFileParser new.
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].
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set := set reject: [ :e | e class = PPFailingParser ].
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p := (PPChoiceParser withAll: set) and.
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^ PPWater on: p waterToken: water.
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]
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{ #category : 'analysis' }
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PPSea >> createWaterForRoot: root [
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| nextSet |
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"
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Be careful, why you call this method.
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I guess this is usefull when only debugging island gramamrs
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"
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nextSet := root nextSets at: self.
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defaultBeforeWaterParser := beforeWaterParser := self createBeforeWaterParserFromNextSet: nextSet.
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defaultAfterWaterParser := afterWaterParser := self createAfterWaterParserFromNextSet: nextSet.
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]
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{ #category : 'parsing' }
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PPSea >> exampleOn: aStream [
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aStream nextPutAll: '~~~~ '.
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island exampleOn: aStream .
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aStream nextPutAll: ' ~~~~'.
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]
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{ #category : 'analysis' }
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PPSea >> filterOutNextSet: nextSet [
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| newNextSet |
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newNextSet := nextSet.
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"This should remove the most patological cases of exponential complexity of islands"
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"TODO JK: this is an adhoc approach that needs better solution"
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newNextSet := newNextSet collect: [ :e |
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((e isKindOf: PPSea)
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and: [e island == island ])
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ifTrue: [ island ]
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ifFalse: [ e ]].
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newNextSet := newNextSet collect: [ :e |
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((e isKindOf: PPActionParser)
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and: [ (e block == #second)
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and: [ (e child isKindOf: PPSea)
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and: [ e child island == island ]]])
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ifTrue: [ island ]
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ifFalse: [ e ]].
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newNextSet := newNextSet collect: [ :e |
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((e isKindOf: PPDelegateParser)
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and: [ (e child isKindOf: PPActionParser)
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and: [ (e child block == #second)
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and: [ (e child child isKindOf: PPSea)
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and: [ e child child island == island ]]]])
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ifTrue: [ island ]
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ifFalse: [ e ]].
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^ newNextSet
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]
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{ #category : 'analysis' }
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PPSea >> followSet: aPPContext [
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^ aPPContext root followSets at: self.
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]
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{ #category : 'accessing' }
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PPSea >> initialize [
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super initialize.
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water := #any asParser name: 'water'; yourself.
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]
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{ #category : 'queries' }
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PPSea >> isIslandBorder [
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^ false
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]
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{ #category : 'queries' }
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PPSea >> isIslandBorderOpenSet: set [
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^ false
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]
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{ #category : 'accessing' }
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PPSea >> island [
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^ island
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]
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{ #category : 'accessing' }
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PPSea >> island: anObject [
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island := anObject "memoized"
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]
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{ #category : 'memoization' }
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PPSea >> memoized [
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^ PPMemoizingSea new
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island: self island;
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water: water;
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yourself
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]
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{ #category : 'queries' }
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PPSea >> name [
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^ super name ifNil: [
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island name ifNil: ['unknown island'] ifNotNil: [ island name, ' island' ] ].
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]
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{ #category : 'analysis' }
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PPSea >> nextSet: aPPContext [
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^ aPPContext root nextSets at: self.
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]
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{ #category : 'analysis' }
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PPSea >> nextSets: aNextDictionary into: aSet [
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"return true/false, if something has changed or not...."
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| islandSet change tally |
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change := false.
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"
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I rewrite the super implementation in order not to avoid updates in the
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before/after water (that would be unfortunate...)
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"
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islandSet := aNextDictionary at: island.
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tally := islandSet size.
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islandSet addAll: aSet.
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change := tally ~= islandSet size.
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^ change
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]
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{ #category : 'parsing' }
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PPSea >> parseAfterWater: aPPContext [
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^ (self afterWaterParser: aPPContext) parseOn: aPPContext .
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]
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{ #category : 'parsing' }
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PPSea >> parseBeforeWater: aPPContext [
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^ (self beforeWaterParser: aPPContext) parseOn: aPPContext.
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]
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{ #category : 'parsing' }
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PPSea >> parseIslandOn: aPPContext [
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| tmp result |
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tmp := aPPContext waterPosition.
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aPPContext waterPosition: aPPContext position.
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result := island parseOn: aPPContext.
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aPPContext waterPosition: tmp.
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^ result
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]
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{ #category : 'parsing' }
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PPSea >> parseIslandOn_old: aPPContext [
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| result |
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"Do not allow empty parses, when searching for the island..."
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(aPPContext waterPosition == aPPContext position) ifTrue:[
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result := island "nonEmpty" parseOn: aPPContext.
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"But allow when boundary found"
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] ifFalse: [
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| tmp |
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"
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Oh, the thing is, if island starts with island parser B,
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which is nested in another parser A, where B is bounded
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by something else than A. Then the B is not allowed to
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skip over the boundary of A, but B has different boundary!
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Thus I disallow before water of any island parser that starts island
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by setting the water position!
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"
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tmp := aPPContext waterPosition.
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aPPContext waterPosition: aPPContext position.
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result := island parseOn: aPPContext.
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aPPContext waterPosition: tmp.
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].
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^ result
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]
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{ #category : 'parsing' }
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PPSea >> parseOn: aPPContext [
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| bwr awr result retval memento |
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aPPContext islandInvoke.
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memento := aPPContext remember.
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bwr := self parseBeforeWater: aPPContext.
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bwr isPetitFailure ifTrue:
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[
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retval := PPFailure message: 'Could not find neither the island nor the next' context: aPPContext.
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aPPContext restore: memento.
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^ retval.
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].
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result := self parseIslandOn: aPPContext.
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result isPetitFailure ifTrue: [
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retval := PPFailure message: 'Island not found between ', memento position asString, ' and ', aPPContext position asString context: aPPContext.
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aPPContext restore: memento.
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^ retval
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].
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awr := self parseAfterWater: aPPContext.
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awr isPetitFailure ifTrue:
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[
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retval := PPFailure message: 'Could not find the next' context: aPPContext.
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aPPContext restore: memento.
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^ retval.
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].
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retval := OrderedCollection with: bwr with: result with: awr.
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^ retval
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]
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{ #category : 'accessing' }
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PPSea >> replace: parser with: anotherParser [
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super replace: parser with: anotherParser.
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(beforeWaterParser == parser) ifTrue: [ beforeWaterParser := anotherParser ].
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(afterWaterParser == parser) ifTrue: [ afterWaterParser := anotherParser ].
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(defaultBeforeWaterParser == parser) ifTrue: [ defaultBeforeWaterParser := anotherParser ].
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(defaultAfterWaterParser == parser) ifTrue: [ defaultAfterWaterParser := anotherParser ].
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(water == parser) ifTrue: [ water := anotherParser ].
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(island == parser) ifTrue: [ island := anotherParser ].
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]
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{ #category : 'memoization' }
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PPSea >> reset: aPPContext [
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contextIdentifier := aPPContext identifier.
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beforeWaterParser := defaultBeforeWaterParser.
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afterWaterParser := defaultAfterWaterParser.
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]
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{ #category : 'accessing - private' }
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PPSea >> setAfterWaterParser: parser [
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defaultAfterWaterParser := parser
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]
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{ #category : 'accessing - private' }
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PPSea >> setBeforeWaterParser: parser [
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defaultBeforeWaterParser := parser
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]
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{ #category : 'accessing' }
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PPSea >> water [
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^ water
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]
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{ #category : 'accessing' }
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PPSea >> water: aPPParser [
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water := aPPParser
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]
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