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Source/Engine/Utilities/StateMachine.cpp

@@ -0,0 +1,62 @@
+// Copyright (c) 2012-2020 Wojciech Figat. All rights reserved.
+
+#include "StateMachine.h"
+
+State::State(StateMachine* parent)
+    : _parent(parent)
+{
+    _parent->_states.Add(this);
+}
+
+State::~State()
+{
+    if (_parent)
+        _parent->_states.Remove(this);
+}
+
+bool State::IsActive() const
+{
+    return _parent->_currentState == this;
+}
+
+StateMachine::StateMachine()
+    : _currentState(nullptr)
+{
+}
+
+StateMachine::~StateMachine()
+{
+    for (int32 i = 0; i < _states.Count(); i++)
+    {
+        _states[i]->_parent = nullptr;
+    }
+}
+
+void StateMachine::GoToState(State* state)
+{
+    // Prevent from entering the same state
+    if (state == _currentState)
+        return;
+
+    // Check if cannot leave current state
+    if (_currentState && !_currentState->CanExit(state))
+        return;
+
+    // Check if cannot enter new state
+    if (state && !state->CanEnter())
+        return;
+
+    // Change state
+    switchState(state);
+}
+
+void StateMachine::switchState(State* nextState)
+{
+    if (_currentState)
+        _currentState->exitState();
+
+    _currentState = nextState;
+
+    if (_currentState)
+        _currentState->enterState();
+}