1 files changed, 26 insertions, 8 deletions

diff --git a/src/ui/style/StyleRuleSet.cpp b/src/ui/style/StyleRuleSet.cpp
index 537d1956..88109350 100644
--- a/src/ui/style/StyleRuleSet.cpp
+++ b/src/ui/style/StyleRuleSet.cpp
@@ -6,12 +6,30 @@
 #include <unordered_set>
 
 namespace cru::ui::style {
-StyleRuleSet::StyleRuleSet(StyleRuleSet* parent) { SetParent(parent); }
+namespace {
+bool CheckCycle(StyleRuleSet* t, StyleRuleSet* p) {
+  while (p != nullptr) {
+    if (p == t) {
+      return true;
+    }
+    p = p->GetParent().get();
+  }
+
+  return false;
+}
+}  // namespace
 
-void StyleRuleSet::SetParent(StyleRuleSet* parent) {
+StyleRuleSet::StyleRuleSet(std::shared_ptr<StyleRuleSet> parent) {
+  SetParent(std::move(parent));
+}
+
+void StyleRuleSet::SetParent(std::shared_ptr<StyleRuleSet> parent) {
   if (parent == parent_) return;
+  if (CheckCycle(this, parent.get())) {
+    throw Exception(u"Cycle detected in StyleRuleSet parent.");
+  }
   parent_change_event_guard_.Reset();
-  parent_ = parent;
+  parent_ = std::move(parent);
   if (parent != nullptr) {
     parent_change_event_guard_.Reset(parent->ChangeEvent()->AddSpyOnlyHandler(
         [this] { this->RaiseChangeEvent(); }));
@@ -44,12 +62,12 @@ void StyleRuleSet::Set(const StyleRuleSet& other, bool set_parent) {
 }
 
 StyleRuleSetBind::StyleRuleSetBind(controls::Control* control,
-                                   StyleRuleSet* ruleset)
-    : control_(control), ruleset_(ruleset) {
+                                   std::shared_ptr<StyleRuleSet> ruleset)
+    : control_(control), ruleset_(std::move(ruleset)) {
   Expects(control);
-  Expects(ruleset);
+  Expects(ruleset_);
 
-  ruleset->ChangeEvent()->AddSpyOnlyHandler([this] {
+  ruleset_->ChangeEvent()->AddSpyOnlyHandler([this] {
     UpdateRuleSetChainCache();
     UpdateChangeListener();
     UpdateStyle();
@@ -60,7 +78,7 @@ void StyleRuleSetBind::UpdateRuleSetChainCache() {
   ruleset_chain_cache_.clear();
   auto parent = ruleset_;
   while (parent != nullptr) {
-    ruleset_chain_cache_.push_back(parent);
+    ruleset_chain_cache_.push_back(parent.get());
     parent = parent->GetParent();
   }
 }