Compilers: Principles and Practice by Pearson

Worked-out Problems 465

1. E -> T {+T} 4. P -> (E) | a | b | empty

2. T -> F {F}

3. F -> P {*P}

A skeleton RDP for the grammar:

pE(){pT(); while(next() == ’+’){pplus(); pT();}}

pT(){pF(); while(strchr(next(),"(ab+"){pF();}}

pF(){pP(); while(next() == ’*’{past();pP();}}

pP(){if(next() == ’(’){plp(); pE(); prp();}

else if(next() == ’a’) pa();

else if(next() == ’b’) pb();

else error("unexpected token");

}

pplus(){if(symbol() != ’+’) error("+ expected");}

past(){if(symbol() != ’*’) error("* expected");}

plp(){if(symbol() != ’(’) error("( expected");}

prp(){if(symbol() != ’)’) error(") expected");}

pa(){if(symbol() != ’a’) error("a or b expected");} ...