"{ Package: 'squeak:petitparser' }"

PPCompositeParser subclass:#PPArithmeticParser
	instanceVariableNames:'terms addition factors multiplication power primary parentheses
		number'
	classVariableNames:''
	poolDictionaries:''
	category:'PetitTests-Examples'
!


!PPArithmeticParser methodsFor:'accessing'!

start
	^ terms end
! !

!PPArithmeticParser methodsFor:'grammar'!

addition
	^ (factors separatedBy: ($+ asParser / $- asParser) token trim) 
		foldLeft: [ :a :op :b | a perform: op value asSymbol with: b ]
!

factors
	^ multiplication / power
!

multiplication
	^ (power separatedBy: ($* asParser / $/ asParser) token trim)
		foldLeft: [ :a :op :b | a perform: op value asSymbol with: b ]
!

number
	^ ($- asParser optional , #digit asParser plus , ($. asParser , #digit asParser plus) optional) token trim ==> [ :token | token value asNumber ]
!

parentheses
	^ $( asParser flatten trim , terms , $) asParser flatten trim ==> #second
!

power
	^ (primary separatedBy: $^ asParser token trim) foldRight: [ :a :op :b | a raisedTo: b ]
!

primary
	^ number / parentheses
!

terms
	^ addition / factors
! !

!PPArithmeticParser class methodsFor:'documentation'!

version_SVN
    ^ '$Id: PPArithmeticParser.st,v 1.1 2011-08-18 18:56:17 cg Exp $'
! !