"{ Package: 'stx:goodies/petitparser/compiler' }"

"{ NameSpace: Smalltalk }"

PPCRewritingVisitor subclass:#PPCLL1Visitor

	instanceVariableNames:''

	classVariableNames:''

	poolDictionaries:''

	category:'PetitCompiler-Visitors'

!

!PPCLL1Visitor methodsFor:'as yet unclassified'!

isDeterministicChoice: node

    | firsts |

    firsts := OrderedCollection new.

    node children do: [ :child |

        (self startsWithToken: child) ifFalse: [ ^ false ].

        firsts addAll: child firstSetWithTokens.

    ].

    (firsts asIdentitySet size = firsts size) ifFalse: [ ^ false ].

    firsts do:[:e1 |

        firsts do:[:e2 |     

            e1 == e2 ifFalse: [

                (e1 overlapsWith: e2) ifTrue: [ ^ false ] ].

        ].

    ].

    ^ true

    "Modified: / 10-05-2015 / 07:27:05 / Jan Vrany <jan.vrany@fit.cvut.cz>"

!

startsWithToken: node

    | firstSet terminal total |

    total := 0.

    firstSet := node firstSetWithTokens.

    terminal := (firstSet detect: [ :e | e isTerminal ] ifNone: [ nil ]).

    terminal isNil ifFalse: [ ^ false ].

    ^ true

!

visitChoiceNode: node

    super visitChoiceNode: node.

    (self isDeterministicChoice: node) ifTrue: [ 

        self change.

        ^ PPCDeterministicChoiceNode new

            children: node children;

            name: node name;

            firstFollowCache: node firstFollowCache;

            yourself

    ].

    ^ node

! !