pear.sergiocarvalho.com

 <S>   ::= <sum>
 <sum> ::= <product>(a) '\+' <number>(b)
<<<
$result = $a->getValue() + $b->getValue();
>>>



 <sum> ::= <product>(A)
<<<
$result = (int) $A->getValue();
>>>




 <product> ::= <number>(a) '\*' <number>(b)
<<<
$result = $a->getValue() * $b->getValue();
>>>



 <product> ::= <number>(N)
<<<
$result = $N->getValue();
>>>


 <number> ::= <digit>(A)
<<<
$result = (int) $A->getValue();


>>>


 <number> ::= <number>(number) <digit>(digit)
<<<
$result = $number->getValue() * 10 + (int) $digit->getValue();
>>>


 <number> ::= <number>(A) '\.' <digit>(B)
<<<
$result = (float) ((string) $A->getValue() . '.' . (string) $B->getValue());
>>>