From dedd7df19cd01c14f5464a0c208434b084c6d8e9 Mon Sep 17 00:00:00 2001
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 <sergey.marinkevich@eltex.loc>
Date: Tue, 5 Aug 2025 19:49:58 +0700
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Примеров итератора с доступом на чтение я много оставил, а пример
модификации дерева только один. И тот я сразу забыл перевести на
итераторы (range-based for loop).

Т.к. проход теперь не по вектору (он давал экземпляр умного указателя),
а по обычному указателю (собственному прокси, если точнее), то узел
разрушался уже в процессе его отключения от дерева. Добавил удержание
ссылки в сам `unlinkParent()` (ну, нам действительно может быть нужно
только безвозвратное удаление поддерева) и пример в `main.cpp` расширил
и прокомментировал.
---
 include/mixins/BaseLinkMixin.h | 10 +++++++++-
 src/main.cpp                   | 29 +++++++++++++++++++++++++----
 2 files changed, 34 insertions(+), 5 deletions(-)

diff --git a/include/mixins/BaseLinkMixin.h b/include/mixins/BaseLinkMixin.h
index 5501a71..bbe6965 100644
--- a/include/mixins/BaseLinkMixin.h
+++ b/include/mixins/BaseLinkMixin.h
@@ -37,7 +37,15 @@ public:
 
 		auto parentLink = parent->getLink();
 
-		parentLink->removeChild(getNode());
+		/* NOTE:
+		 *
+		 * Keep a reference to the node we gonna to unlink.
+		 * Otherwise, we'll disappear between `removeChild` and
+		 * `setParent`. Do not rearrange these calls, because
+		 * we want to modify the tree top down.
+		 */
+		auto node = getNode();
+		parentLink->removeChild(node);
 		getLink()->setParent(nullptr);
 	}
 
diff --git a/src/main.cpp b/src/main.cpp
index 4e9ec49..2feb4e3 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -119,11 +119,32 @@ int main() {
 
 		logger.info("Unlinking ComplexChild1 and ComplexChild3...\n");
 		child1->unlinkParent();
-		for (auto child : root->getLink()->getChildren()) {
-			NodePtr childNode = std::dynamic_pointer_cast<INode>(child);
-			if (childNode->name() == "ComplexChild3") {
-				childNode->unlinkParent();
+		for (auto child : traversal::BFS(root)) {
+			if (child->name() == "ComplexChild3") {
+				/* Avoid of disconnecting a node of the tree
+				 * we're traversing. Method holds reference
+				 * to it's object itself. But iterator ignores
+				 * smart pointers, feeling free to dereference
+				 * the destroyed object.
+				 */
+#if 1
+				/* Keep in mind to keep your reference until
+				 * the cycle ends, if you want more than just
+				 * remove subtree.
+				 */
+				NodePtr node = *child;
+				node->unlinkParent();
+				std::cout << "Unlinked: "
+					  << node->name() << std::endl;
 				break;
+#else
+				/* Otherwise, just break immediately you
+				 * unlinked a node. The current pointer is not
+				 * a valid pointer anymore.
+				 */
+				child->unlinkParent();
+				break;
+#endif
 			}
 		}