上記を参考にCコンパイラを作成する
expr = equality
equality = relational ("==" relational | "!=" relational)*
relational = add ("<" add | "<=" add | ">" add | ">=" add)*
add = mul ("+" mul | "-" mul)*
mul = unary ("*" unary | "/" unary)*
unary = ("+" | "-")? primary
primary = num | "(" expr ")"
X*
: Xは0回以上の繰り返しX?
: Xは0回または1回