lval *lval_read_double(mpc_ast_t *t) {
errno = 0;
double x = strtof(t->contents, NULL);
if (errno == ERANGE) {
return lval_err("invalid double");
} else {
return lval_double(x);
}
}
lval eval(mpc_ast_t* t) {
if (strstr(t->tag, "number")) {
errno = 0;
if (strstr(t->contents, ".")) {
double d = strtod(t->contents, NULL);
return errno != ERANGE ? lval_double(d) : lval_err(LERR_BAD_NUM);
} else {
long x = strtol(t->contents, NULL, 10);
return errno != ERANGE ? lval_num(x) : lval_err(LERR_BAD_NUM);
}
}
char *op = t->children[1]->contents;
lval x = eval(t->children[2]);
int i = 3;
while (strstr(t->children[i]->tag, "expr")) {
x = eval_op(x, op, eval(t->children[i]));
i++;
}
return x;
}
lval eval_op(lval x, char* op, lval y) {
if (x.type == LVAL_ERR) {
return x;
}
if (y.type == LVAL_ERR) {
return y;
}
if (strcmp(op, "+") == 0) {
if (x.type == y.type) {
if (x.type == LVAL_NUM) {
return lval_num(x.l + y.l);
} else {
return lval_double(x.d + y.d);
}
} else if (x.type == LVAL_DOUBLE) {
return lval_double(x.d + y.l);
} else if (y.type == LVAL_DOUBLE) {
return lval_double(x.l + y.d);
}
}
if (strcmp(op, "-") == 0) {
if (x.type == y.type) {
if (x.type == LVAL_NUM) {
return lval_num(x.l - y.l);
} else {
return lval_double(x.d - y.d);
}
} else if (x.type == LVAL_DOUBLE) {
return lval_double(x.d - y.l);
} else if (y.type == LVAL_DOUBLE) {
return lval_double(x.l - y.d);
}
}
if (strcmp(op, "*") == 0) {
if (x.type == y.type) {
if (x.type == LVAL_NUM) {
return lval_num(x.l * y.l);
} else {
return lval_double(x.d * y.d);
}
} else if (x.type == LVAL_DOUBLE) {
return lval_double(x.d * y.l);
} else if (y.type == LVAL_DOUBLE) {
return lval_double(x.l * y.d);
}
}
if (strcmp(op, "/") == 0) {
if ((y.type == LVAL_NUM && y.l == 0) || (y.type == LVAL_DOUBLE && y.d == 0)) {
return lval_err(LERR_DIV_ZERO);
} else {
if (x.type == y.type) {
if (x.type == LVAL_NUM) {
return lval_num(x.l / y.l);
} else {
return lval_double(x.d / y.d);
}
} else if (x.type == LVAL_DOUBLE) {
return lval_double(x.d / y.l);
} else if (y.type == LVAL_DOUBLE) {
return lval_double(x.l / y.d);
}
}
}
if (strcmp(op, "%") == 0) {
if (! (x.type == LVAL_NUM && y.type == LVAL_NUM)) {
return lval_err(LERR_BAD_OP);
} else {
if (y.l == 0) {
return lval_err(LERR_DIV_ZERO);
} else {
return lval_num(x.l % y.l);
}
}
}
return lval_err(LERR_BAD_OP);
}
