pkarashchenko commented on a change in pull request #5690:
URL: https://github.com/apache/incubator-nuttx/pull/5690#discussion_r821546914
##########
File path: libs/libc/locale/lib_gettext.c
##########
@@ -195,6 +213,272 @@ static FAR char *molookup(FAR char *p, size_t size, FAR
const char *s)
return NULL;
}
+static FAR const char *skipspace(FAR const char *s)
+{
+ while (isspace(*s))
+ {
+ s++;
+ }
+
+ return s;
+}
+
+/* Grammar:
+ *
+ * Start = Expr ';'
+ * Expr = Or | Or '?' Expr ':' Expr
+ * Or = And | Or '||' And
+ * And = Eq | And '&&' Eq
+ * Eq = Rel | Eq '==' Rel | Eq '!=' Rel
+ * Rel = Add | Rel '<=' Add | Rel '>=' Add | Rel '<' Add | Rel '>' Add
+ * Add = Mul | Add '+' Mul | Add '-' Mul
+ * Mul = Prim | Mul '*' Prim | Mul '/' Prim | Mul '%' Prim
+ * Prim = '(' Expr ')' | '!' Prim | decimal | 'n'
+ *
+ * Internals:
+ *
+ * Recursive descent expression evaluator with stack depth limit.
+ * for binary operators an operator-precedence parser is used.
+ * eval* functions store the result of the parsed subexpression
+ * and return a pointer to the next non-space character.
+ */
+
+static FAR const char *evalprim(FAR struct eval_s *ev,
+ FAR const char *s, int d)
+{
+ FAR char *e;
+
+ if (--d < 0)
+ {
+ return "";
+ }
+
+ s = skipspace(s);
+ if (isdigit(*s))
+ {
+ ev->r = strtoul(s, &e, 10);
+ if (e == s || ev->r == -1)
+ {
+ return "";
+ }
+
+ return skipspace(e);
+ }
+
+ if (*s == 'n')
+ {
+ ev->r = ev->n;
+ return skipspace(s + 1);
+ }
+
+ if (*s == '(')
+ {
+ s = evalexpr(ev, s + 1, d);
+ if (*s != ')')
+ {
+ return "";
+ }
+
+ return skipspace(s + 1);
+ }
+
+ if (*s == '!')
+ {
+ s = evalprim(ev, s + 1, d);
+ ev->r = !ev->r;
+ return s;
+ }
+
+ return "";
+}
+
+static bool binop(FAR struct eval_s *ev, int op, unsigned long left)
+{
+ unsigned long a = left;
+ unsigned long b = ev->r;
+
+ switch (op)
+ {
+ case 0:
+ ev->r = a || b;
+ return true;
+
+ case 1:
+ ev->r = a && b;
+ return true;
+
+ case 2:
+ ev->r = a == b;
+ return true;
+
+ case 3:
+ ev->r = a != b;
+ return true;
+
+ case 4:
+ ev->r = a >= b;
+ return true;
+
+ case 5:
+ ev->r = a <= b;
+ return true;
+
+ case 6:
+ ev->r = a > b;
+ return true;
+
+ case 7:
+ ev->r = a < b;
+ return true;
+
+ case 8:
+ ev->r = a + b;
+ return true;
+
+ case 9:
+ ev->r = a - b;
+ return true;
+
+ case 10:
+ ev->r = a * b;
+ return true;
+
+ case 11:
+ if (b)
+ {
+ ev->r = a % b;
+ return true;
+ }
+
+ return false;
+
+ case 12:
+ if (b)
+ {
+ ev->r = a / b;
+ return true;
+ }
+
+ return false;
Review comment:
should we add a `default:` case? Or there is not compilation warning
generated?
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