"{ Encoding: utf8 }"

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

"{ NameSpace: Smalltalk }"

PPDelegateParser subclass:#PPExpressionParser

	instanceVariableNames:'operators'

	classVariableNames:''

	poolDictionaries:''

	category:'PetitParser-Tools'

!

!PPExpressionParser methodsFor:'private'!

build: aParser left: aChoiceParser

	^ (aParser separatedBy: aChoiceParser) foldLeft: [ :a :op :b | op first value: a value: op second value: b ]

!

build: aParser postfix: aChoiceParser

	^ aParser , aChoiceParser star map: [ :term :ops | ops inject: term into: [ :result :operator | operator first value: result value: operator second ] ]

!

build: aParser prefix: aChoiceParser

	^ aChoiceParser star , aParser map: [ :ops :term | ops reversed inject: term into: [ :result :operator | operator first value: operator second value: result ] ]

!

build: aParser right: aChoiceParser

	^ (aParser separatedBy: aChoiceParser) foldRight: [ :a :op :b | op first value: a value: op second value: b ]

!

buildOn: aParser

        ^ self buildSelectors inject: aParser into: [ :term :selector |

                | list |

                list := operators at: selector ifAbsent: [ #() ].

                list isEmpty

                        ifTrue: [ term ]

                        ifFalse: [

                                self

                                        perform: selector with: term 

                                        with: (list size == 1

                                                ifTrue: [ list first first ==> [ :operator | Array with: list first second with: operator ] ]

                                                ifFalse: [ 

                                                        list

                                                                inject: PPChoiceParser new

                                                                into: [ :choice :each | choice / (each first ==> [ :operator | Array with: each second with: operator ]) ] ]) ] ]

!

buildSelectors

	^ #(build:prefix: build:postfix: build:right: build:left:)

!

operator: aSymbol parser: aParser do: aBlock

	parser isNil

		ifTrue: [ ^ self error: 'You did not specify a term when creating the receiver.' ].

	operators isNil

		ifTrue: [ ^ self error: 'Use #group: to define precedence groups in descending order.' ].

	(operators at: aSymbol ifAbsentPut: [ OrderedCollection new ])

		addLast: (Array with: aParser asParser with: aBlock)

! !

!PPExpressionParser methodsFor:'specifying'!

group: aOneArgumentBlock

	"Defines a priority group by evaluating aOneArgumentBlock."

	operators := Dictionary new.

	parser := [ 

		aOneArgumentBlock value: self.

	 	self buildOn: parser ]

			ensure: [ operators := nil ]

!

left: aParser do: aThreeArgumentBlock

	"Define an operator aParser that is left-associative. Evaluate aThreeArgumentBlock with the first term, the operator, and the second term."

	self operator: #build:left: parser: aParser do: aThreeArgumentBlock

!

postfix: aParser do: aTwoArgumentBlock

	"Define a postfix operator aParser. Evaluate aTwoArgumentBlock with the term and the operator."

	self operator: #build:postfix: parser: aParser do: aTwoArgumentBlock

!

prefix: aParser do: aTwoArgumentBlock

	"Define a prefix operator aParser. Evaluate aTwoArgumentBlock with the operator and the term."

	self operator: #build:prefix: parser: aParser do: aTwoArgumentBlock

!

right: aParser do: aThreeArgumentBlock

	"Define an operator aParser that is right-associative. Evaluate aThreeArgumentBlock with the first term, the operator, and the second term."

	self operator: #build:right: parser: aParser do: aThreeArgumentBlock

!

term: aParser

	"Defines the initial term aParser of the receiver."

	parser isNil

		ifTrue: [ parser := aParser ]

		ifFalse: [ self error: 'Unable to redefine the term.' ]

! !

!PPExpressionParser class methodsFor:'documentation'!

version

    ^ '$Header$'

!

version_CVS

    ^ '$Header$'

!

version_SVN

    ^ '$Id$'

! !