jinja : fix quadratic cost in gather_string_parts (#27034)

* jinja : fix quadratic cost in gather_string_parts * fix some comments * remove test
2026-08-14 23:34:40 +02:00
parent 7e4c0a9688
commit 9e40df63ba
5 changed files with 48 additions and 8 deletions
@@ -763,14 +763,22 @@ struct runtime {
        gather_string_parts_recursive(val, parts);
        // join consecutive parts with the same type
        auto & p = parts->val_str.parts;
-        for (size_t i = 1; i < p.size(); ) {
-            if (p[i].is_input == p[i - 1].is_input) {
-                p[i - 1].val += p[i].val;
-                p.erase(p.begin() + i);
+        if (p.empty()) {
+            return parts;
+        }
+        size_t w = 0;
+        for (size_t r = 1; r < p.size(); r++) {
+            if (p[w].is_input == p[r].is_input) {
+                p[w].val += p[r].val;
            } else {
-                i++;
+                w++;
+                if (w != r) {
+                    // the guard is needed, self-move leaves the string in an unspecified state
+                    p[w] = std::move(p[r]);
+                }
            }
        }
+        p.resize(w + 1);
        return parts;
    }