Grammar for Boolean Equations

Question

Could anyone show me a grammar for boolean equation with 3 variables x,y.z
that i could use to help build a parser.
thanks
podger

Answer 1

Equation := '(' 'equal' Expression Expression ')';
Expression := Var | AndEx | OrEx | NotEx;
NotEx := '(' 'not' Expression ')';
AndEx := '(' 'and' Expression+ ')';
OrEx := '(' 'or' Expression+ ')';
Var := 'x' | 'y' | 'z';
is probably the easiest complete one to build a parser for; if you want some other language (eg infix operators) then you need a more complicated parser; essentially the grammar morphs to
Equation := DisEx 'equal' DisEx;
DisEx := DisTerm ( 'or' DisTerm) *;
DisTerm := Var | ConEx | NotEx;
Var := 'x' | 'y' | 'z';
ConEx := ConTerm ( 'and' ConTerm ) +;
ConTerm := ExTerm | '(' Expression ')';
NotEx := 'not' ConTerm;
Which is harder to write a parser for.