Expr* factor_tail(const char* string, Expr* expr) {
Expr* new_expr;
switch(string[VAL_STRING]) {
case '*':
case '/':
if(NULL == (new_expr = (Expr*)malloc(sizeof(Expr)))) {
exit(1);
}
if(NULL == (new_expr->data.expr[1] = (Expr*)malloc(sizeof(Expr)))) {
exit(1);
}
new_expr->op = eat_char(string, string[VAL_STRING]);
new_expr->data.expr[0] = expr;
new_expr->data.expr[1] = factor(string, new_expr->data.expr[1]);
new_expr = factor_tail(string, new_expr);
return new_expr;
case '+':
case '-':
case ')':
case 0:
return expr;
default:
error_message(string);return NULL;
}
}
Expr* term(const char* string, Expr* expr) {
if(string[VAL_STRING] == '(' || isdigit(string[VAL_STRING])) {
expr = factor(string, expr);
expr = factor_tail(string, expr);
return expr;
} else {
error_message(string);return NULL;
}
}
static term_node *term(void){
term_node *termn = newTermNode();
if(match(TOKEN_LBRA, NO_CONSUME) ||
match(TOKEN_IDENTIFIER, NO_CONSUME) ||
match(TOKEN_LITERAL, NO_CONSUME))
if((termn->facn = factor()) != NULL)
if((termn->factln = factor_tail()) != error)
return termn;
freeTerm(termn);
return NULL;
}
static fac_tail_node *factor_tail(void){
fac_tail_node *factln = newFacTailNode();
if((factln->mulOp = match(TOKEN_MULOP, CONSUME)) != NULL){
if((factln->facn = factor()) != NULL)
if((factln->factln = factor_tail()) != error)
return factln;
}
else if(match(TOKEN_SCOL, NO_CONSUME) ||
match(TOKEN_ADDOP, NO_CONSUME) ||
match(TOKEN_RBRA, NO_CONSUME) ||
match(TOKEN_COMPOP, NO_CONSUME)){
freeFacTail(factln);
return NULL;
}
freeFacTail(factln);
return error;
}
