MyCalculator

a simple calculator implemented by lexical and parser

support add sub mul div nag pow, but num can only have one '.', i don't check it actuclly, i nearly don't do too much wrong check

now, i give the grammar:

E->E+T | E-T | T
T->T* F | T/F | F
F->-N | N
N->M^N | M
M->(E) | id

eliminate left recursion:

E ->TE'
E'->+TE' | -TE' |$
T ->FT'
T'-> * FT' | /FT' |$
F ->-N | N
N ->MN'
N'->^N |$
M ->(E)|id

first and follow:

first(N) = first(M) = {(,id}
first(E) = first(T) = first(F) = {-,(,id}
first(E') = {+,-, $}
first(T') = {* ,/, $ }
first(N') = {^,$}
follow(E) = follow(E') = {), ~ }
follow(T) = follow(T') = {+,-,),$}
follow(F) = follow(N) = follow(N') = {* ,/,+,-,), $ }
follow(M) = {^,* ,/,+,-,),$}

Analysis table:

Tables	id	+	-	*	/	^	(	)	$
E	TE'		TE'				TE'
E'		+TE'	-TE'
T	FT'		FT'				FT'
T'				* FT'	/FT'
F	N		-N				N
N	MN						MN'
N'						^N
M	id						(

hope can help you