Add keyexpr_was_declared api function

include/zenoh-pico/api/primitives.h

@@ -93,10 +93,23 @@ z_owned_str_t z_keyexpr_to_string(z_keyexpr_t keyexpr);
  *
  * Returns:
  *   The :c:type:`z_bytes_t` pointing to key expression string representation if it's possible
-
  */
 z_bytes_t z_keyexpr_as_bytes(z_keyexpr_t keyexpr);
 
+/**
+ * Indicates if the key expression has been declared but don't guarantee it's still in session.
+ *
+ * If given keyexpr was declared, to retrieve the keyexpr string representation the user must use
+ * :c:func:zp_keyexpr_resolve
+ *
+ * Parameters:
+ *   keyexpr: A loaned instance of :c:type:`z_keyexpr_t`
+ *
+ * Returns:
+ *   Returns ``true`` if the keyexpr was declared or ``false`` otherwise.
+ */
+_Bool zp_keyexpr_was_declared(const z_keyexpr_t *keyexpr);
+
 /**
  * Constructs a null-terminated string departing from a :c:type:`z_keyexpr_t` for a given :c:type:`z_session_t`.
  * The user is responsible of dropping the returned string using ``z_free``.

src/api/api.c

@@ -77,6 +77,14 @@
     }
 }
 
+_Bool zp_keyexpr_was_declared(const z_keyexpr_t *keyexpr) {
+    _Bool ret = false;
+    if (keyexpr->_id != Z_RESOURCE_ID_NONE) {
+        ret = true;
+    }
+    return ret;
+}
+
 z_owned_str_t zp_keyexpr_resolve(z_session_t zs, z_keyexpr_t keyexpr) {
     z_owned_str_t ret = {._value = NULL};