[DeckList] Extract deck-node sort helpers (#7320)

Co-authored-by: Lukas Brübach <Bruebach.Lukas@bdosecurity.de>

libcockatrice_deck_list/libcockatrice/deck_list/tree/inner_deck_list_node.cpp

@@ -192,31 +192,35 @@ void InnerDecklistNode::writeElement(QXmlStreamWriter *xml)
     xml->writeEndElement(); // zone
 }
 
-QVector<QPair<int, int>> InnerDecklistNode::sort(Qt::SortOrder order)
+QVector<QPair<int, AbstractDecklistNode *>> InnerDecklistNode::indexedSnapshot() const
+{
+    QVector<QPair<int, AbstractDecklistNode *>> snapshot(size());
+    for (int i = size() - 1; i >= 0; --i) {
+        snapshot[i].first = i;
+        snapshot[i].second = at(i);
+    }
+    return snapshot;
+}
+
+QVector<QPair<int, int>> InnerDecklistNode::applySortedOrder(const QVector<QPair<int, AbstractDecklistNode *>> &sorted)
 {
     QVector<QPair<int, int>> result(size());
-
-    // Initialize temporary list with contents of current list
-    QVector<QPair<int, AbstractDecklistNode *>> tempList(size());
     for (int i = size() - 1; i >= 0; --i) {
-        tempList[i].first = i;
-        tempList[i].second = at(i);
+        result[i].first = sorted[i].first;
+        result[i].second = i;
+        replace(i, sorted[i].second);
     }
+    return result;
+}
+
+QVector<QPair<int, int>> InnerDecklistNode::sort(Qt::SortOrder order)
+{
+    auto snapshot = indexedSnapshot();
 
-    // Sort temporary list
     auto cmp = [order](const auto &a, const auto &b) {
         return (order == Qt::AscendingOrder) ? (b.second->compare(a.second)) : (a.second->compare(b.second));
     };
+    std::sort(snapshot.begin(), snapshot.end(), cmp);
 
-    std::sort(tempList.begin(), tempList.end(), cmp);
-
-    // Map old indexes to new indexes and
-    // copy temporary list to the current one
-    for (int i = size() - 1; i >= 0; --i) {
-        result[i].first = tempList[i].first;
-        result[i].second = i;
-        replace(i, tempList[i].second);
-    }
-
-    return result;
+    return applySortedOrder(snapshot);
 }

libcockatrice_deck_list/libcockatrice/deck_list/tree/inner_deck_list_node.h

@@ -223,6 +223,20 @@ public:
      */
     QVector<QPair<int, int>> sort(Qt::SortOrder order = Qt::AscendingOrder);
 
+private:
+    /**
+     * @brief Snapshots the current children as (old index, node) pairs.
+     */
+    QVector<QPair<int, AbstractDecklistNode *>> indexedSnapshot() const;
+
+    /**
+     * @brief Replaces this node's children with @p sorted and maps old indexes to new ones.
+     *
+     * @return A list of (old index, new index) pairs for each reordered child.
+     */
+    QVector<QPair<int, int>> applySortedOrder(const QVector<QPair<int, AbstractDecklistNode *>> &sorted);
+
+public:
     /**
      * @brief Deserialize this node and its children from XML.
      * @param xml Reader positioned at this element.