DataSource: Allow destruction of listeners during Notify...() callbacks, see #132.

Include/RmlUi/Core/Elements/DataSource.h

@@ -31,6 +31,7 @@
 
 #include "../Header.h"
 #include "../Types.h"
+#include "../ObserverPtr.h"
 
 namespace Rml {
 
@@ -100,7 +101,7 @@ class RMLUICORE_API DataSource
 	private:
 		String name;
 
-		using ListenerList = List< DataSourceListener* >;
+		using ListenerList = Vector< ObserverPtr<DataSourceListener> >;
 		ListenerList listeners;
 };
 

Include/RmlUi/Core/Elements/DataSourceListener.h

@@ -31,6 +31,7 @@
 
 #include "../Header.h"
 #include "../Types.h"
+#include "../ObserverPtr.h"
 
 namespace Rml {
 
@@ -43,7 +44,7 @@ class DataSource;
 	@author Robert Curry
  */
 
-class RMLUICORE_API DataSourceListener
+class RMLUICORE_API DataSourceListener : public EnableObserverPtr<DataSourceListener>
 {
 public:
 	DataSourceListener();

Include/RmlUi/Core/ObserverPtr.h

@@ -97,6 +97,10 @@ public:
 	// Returns true if we can dereference the pointer.
 	explicit operator bool() const noexcept { return block && block->pointed_to_object; }
 
+	// Comparison operators return true when they point to the same object, or they are both nullptr or expired.
+	bool operator==(const T* other) const noexcept { return get() == other; }
+	bool operator==(const ObserverPtr<T>& other) const noexcept { return get() == other.get(); }
+
 	// Retrieve the pointer to the observed object if we have one and it's still alive.
 	T* get() const noexcept {
 		return block ? static_cast<T*>(block->pointed_to_object) : nullptr;

Source/Core/Elements/DataSource.cpp

@@ -57,9 +57,10 @@ DataSource::DataSource(const String& _name)
 DataSource::~DataSource()
 {
 	ListenerList listeners_copy = listeners;
-	for (ListenerList::iterator i = listeners_copy.begin(); i != listeners_copy.end(); ++i)
+	for (auto& listener : listeners_copy)
 	{
-		(*i)->OnDataSourceDestroy(this);
+		if (listener)
+			listener->OnDataSourceDestroy(this);
 	}
 
 	DataSourceMap::iterator iterator = data_sources.find(name);
@@ -88,17 +89,17 @@ DataSource* DataSource::GetDataSource(const String& data_source_name)
 
 void DataSource::AttachListener(DataSourceListener* listener)
 {
-	if (find(listeners.begin(), listeners.end(), listener) != listeners.end())
+	if (std::find(listeners.begin(), listeners.end(), listener) != listeners.end())
 	{
 		RMLUI_ERROR;
 		return;
 	}
-	listeners.push_back(listener);
+	listeners.push_back(listener->GetObserverPtr());
 }
 
 void DataSource::DetachListener(DataSourceListener* listener)
 {
-	ListenerList::iterator i = find(listeners.begin(), listeners.end(), listener);
+	ListenerList::iterator i = std::find(listeners.begin(), listeners.end(), listener);
 	RMLUI_ASSERT(i != listeners.end());
 	if (i != listeners.end())
 	{
@@ -114,36 +115,40 @@ void* DataSource::GetScriptObject() const
 void DataSource::NotifyRowAdd(const String& table, int first_row_added, int num_rows_added)
 {
 	ListenerList listeners_copy = listeners;
-	for (ListenerList::iterator i = listeners_copy.begin(); i != listeners_copy.end(); ++i)
+	for (auto& listener : listeners_copy)
 	{
-		(*i)->OnRowAdd(this, table, first_row_added, num_rows_added);
+		if (listener)
+			listener->OnRowAdd(this, table, first_row_added, num_rows_added);
 	}
 }
 
 void DataSource::NotifyRowRemove(const String& table, int first_row_removed, int num_rows_removed)
 {
 	ListenerList listeners_copy = listeners;
-	for (ListenerList::iterator i = listeners_copy.begin(); i != listeners_copy.end(); ++i)
+	for (auto& listener : listeners_copy)
 	{
-		(*i)->OnRowRemove(this, table, first_row_removed, num_rows_removed);
+		if (listener)
+			listener->OnRowRemove(this, table, first_row_removed, num_rows_removed);
 	}
 }
 
 void DataSource::NotifyRowChange(const String& table, int first_row_changed, int num_rows_changed)
 {
 	ListenerList listeners_copy = listeners;
-	for (ListenerList::iterator i = listeners_copy.begin(); i != listeners_copy.end(); ++i)
+	for (auto& listener : listeners_copy)
 	{
-		(*i)->OnRowChange(this, table, first_row_changed, num_rows_changed);
+		if (listener)
+			listener->OnRowChange(this, table, first_row_changed, num_rows_changed);
 	}
 }
 
 void DataSource::NotifyRowChange(const String& table)
 {
 	ListenerList listeners_copy = listeners;
-	for (ListenerList::iterator i = listeners_copy.begin(); i != listeners_copy.end(); ++i)
+	for (auto& listener : listeners_copy)
 	{
-		(*i)->OnRowChange(this, table);
+		if (listener)
+			listener->OnRowChange(this, table);
 	}
 }