1 files changed, 55 insertions, 0 deletions
diff --git a/Source/Core/InputCommon/ControlReference/FunctionExpression.h b/Source/Core/InputCommon/ControlReference/FunctionExpression.h
new file mode 100644
index 0000000000..f5332a0d25
--- /dev/null
+++ b/Source/Core/InputCommon/ControlReference/FunctionExpression.h
@@ -0,0 +1,55 @@
+// Copyright 2019 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <memory>
+#include <string>
+#include <variant>
+#include <vector>
+
+#include "InputCommon/ControlReference/ExpressionParser.h"
+#include "InputCommon/ControlReference/FunctionExpression.h"
+
+namespace ciface
+{
+namespace ExpressionParser
+{
+class FunctionExpression : public Expression
+{
+public:
+  struct ArgumentsAreValid
+  {
+  };
+
+  struct ExpectedArguments
+  {
+    std::string text;
+  };
+
+  using ArgumentValidation = std::variant<ArgumentsAreValid, ExpectedArguments>;
+
+  int CountNumControls() const override;
+  void UpdateReferences(ControlEnvironment& env) override;
+
+  ArgumentValidation SetArguments(std::vector<std::unique_ptr<Expression>>&& args);
+
+  void SetValue(ControlState value) override;
+
+protected:
+  virtual ArgumentValidation
+  ValidateArguments(const std::vector<std::unique_ptr<Expression>>& args) = 0;
+
+  Expression& GetArg(u32 number);
+  const Expression& GetArg(u32 number) const;
+  u32 GetArgCount() const;
+
+private:
+  std::vector<std::unique_ptr<Expression>> m_args;
+};
+
+std::unique_ptr<FunctionExpression> MakeFunctionExpression(std::string name);
+
+}  // namespace ExpressionParser
+}  // namespace ciface