diff --git a/Source/Core/InputCommon/Src/ControllerInterface/ExpressionParser.cpp b/Source/Core/InputCommon/Src/ControllerInterface/ExpressionParser.cpp
diff --git a/Source/Core/InputCommon/Src/ControllerInterface/ExpressionParser.h b/Source/Core/InputCommon/Src/ControllerInterface/ExpressionParser.h
@@ -0,0 +1,73 @@
+
+#ifndef _EXPRESSIONPARSER_H_
+#define _EXPRESSIONPARSER_H_
+
+#include <string>
+#include "Device.h"
+
+namespace ciface
+{
+namespace ExpressionParser
+{
+
+class ControlQualifier
+{
+public:
+	bool has_device;
+	Core::DeviceQualifier device_qualifier;
+	std::string control_name;
+
+	ControlQualifier() : has_device(false) {}
+
+	operator std::string()
+	{
+		if (has_device)
+			return device_qualifier.ToString() + ":" + control_name;
+		else
+			return control_name;
+	}
+};
+
+class ControlFinder
+{
+public:
+	ControlFinder(const Core::DeviceContainer &container_, const Core::DeviceQualifier &default_, const bool is_input_) : container(container_), default_device(default_), is_input(is_input_) {}
+	Core::Device::Control *FindControl(ControlQualifier qualifier);
+
+private:
+	Core::Device *FindDevice(ControlQualifier qualifier);
+	const Core::DeviceContainer &container;
+	const Core::DeviceQualifier &default_device;
+	bool is_input;
+};
+
+class Parser;
+class ExpressionNode;
+class Expression
+{
+	friend class Parser;
+
+public:
+	Expression() : expr(NULL) {}
+	~Expression();
+	ControlState GetValue();
+	void SetValue (ControlState state);
+	int num_controls;
+
+private:
+	ExpressionNode *expr;
+};
+
+enum ExpressionParseStatus
+{
+	EXPRESSION_PARSE_SUCCESS = 0,
+	EXPRESSION_PARSE_SYNTAX_ERROR,
+	EXPRESSION_PARSE_NO_DEVICE,
+};
+
+ExpressionParseStatus ParseExpression(std::string expr, ControlFinder &finder, Expression **expr_out);
+
+}
+}
+
+#endif