1 files changed, 12 insertions, 0 deletions
diff --git a/Expression.h b/Expression.h
new file mode 100644
index 0000000..105ad28
--- /dev/null
+++ b/Expression.h
@@ -0,0 +1,12 @@
+#ifndef EXPRESSION_H
+#define EXPRESSION_H
+
+#include <string>
+#include <map>
+
+template<class T>
+struct Expression {
+  virtual T eval(const std::map<std::string, T>&) const = 0;
+};
+
+#endif