Exercise Of Modern Compiler Implementation in C

1. Write a function int maxargs(A_stm) that tells the maximum number of argument of any print statement within any subexpression of a given statement. For example, maxargs(prog) is 2.

int bigger(int first, int second) { return first > second ? first : second; }

int argsOfExp(A_exp exp) {
  if (NULL == exp)
    return 0;
  switch (exp->kind) {
  case A_idExp:
    return 0;
  case A_numExp:
    return 0;
  case A_opExp:
    return bigger(argsOfExp(exp->u.op.left), argsOfExp(exp->u.op.right));
  case A_eseqExp:
    return bigger(maxargs(exp->u.eseq.stm), argsOfExp(exp->u.eseq.exp));
  }
  return 0;
}

int argsOfExps(A_expList exps) {
  if (NULL == exps)
    return 0;
  switch (exps->kind) {
  case A_lastExpList:
    return 1;
  case A_pairExpList:
    return bigger(argsOfExp(exps->u.pair.head),
                  1 + argsOfExps(exps->u.pair.tail));
  }
  return 0;
}

int maxargs(A_stm a_stm) {
  if (NULL == a_stm)
    return 0;
  switch (a_stm->kind) {
  case A_compoundStm:
    return bigger(maxargs(a_stm->u.compound.stm1),
                  maxargs(a_stm->u.compound.stm2));
  case A_assignStm:
    return argsOfExp(a_stm->u.assign.exp);
  case A_printStm:
    return argsOfExps(a_stm->u.print.exps);
  }
  return 0;
}