Optimize subqueries

libursa/QueryOptimizer.cpp

@@ -2,12 +2,29 @@
 
 #include <vector>
 
+// Run the optimization pases on subqueries.
+// After this step, every subquery should be maximally optimized,
+// So I believe there's no need to run this in a loop.
+Query simplify_subqueries(Query &&q) {
+    // q_optimize ensures QueryType is not PRIMITIVE already
+    std::vector<Query> newqueries;
+    for (auto &&query : q.as_queries()) {
+        newqueries.emplace_back(q_optimize(std::move(query)));
+    }
+    if (q.get_type() == QueryType::MIN_OF) {
+        return q_min_of(q.as_count(), std::move(newqueries));
+    }
+    return std::move(Query(q.get_type(), std::move(newqueries)));
+}
+
 Query q_optimize(Query &&q) {
     if (q.get_type() == QueryType::PRIMITIVE) {
         // Nothing to improve here.
         return std::move(q);
     }
 
+    q = simplify_subqueries(std::move(q));
+
     // Optimization passes will be added here later.
 
     return std::move(q);