1 files changed, 9 insertions, 10 deletions
diff --git a/Source/Core/InputCommon/ControlReference/ExpressionParser.h b/Source/Core/InputCommon/ControlReference/ExpressionParser.h
index f07c9a1326..398b273e0f 100644
--- a/Source/Core/InputCommon/ControlReference/ExpressionParser.h
+++ b/Source/Core/InputCommon/ControlReference/ExpressionParser.h
@@ -6,6 +6,7 @@
 
 #include <memory>
 #include <string>
+#include <utility>
 #include "InputCommon/ControllerInterface/Device.h"
 
 namespace ciface
@@ -46,26 +47,24 @@ private:
   bool is_input;
 };
 
-class ExpressionNode;
 class Expression
 {
 public:
-  Expression() : node(nullptr) {}
-  Expression(ExpressionNode* node);
-  ~Expression();
-  ControlState GetValue() const;
-  void SetValue(ControlState state);
-  int num_controls;
-  ExpressionNode* node;
+  virtual ~Expression() = default;
+  virtual ControlState GetValue() const = 0;
+  virtual void SetValue(ControlState state) = 0;
+  virtual int CountNumControls() const = 0;
+  virtual void UpdateReferences(ControlFinder& finder) = 0;
+  virtual operator std::string() const = 0;
 };
 
 enum class ParseStatus
 {
   Successful,
   SyntaxError,
-  NoDevice,
+  EmptyExpression,
 };
 
-ParseStatus ParseExpression(const std::string& expr, ControlFinder& finder, Expression** expr_out);
+std::pair<ParseStatus, std::unique_ptr<Expression>> ParseExpression(const std::string& expr);
 }
 }