add Interpreter class

Change-Id: I4786b925c8cd1e7baba2c0e24cf785a7c53c09ec
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 7513c87..3819930 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -60,6 +60,7 @@
     src/ast.cpp
     src/utils.cpp
     src/parser_context.cpp
+    src/interpreter.cpp
     )
 
 add_library(parser STATIC ${parser_SRCS})