add new thirdparty lib, ExprTk

CMakeLists.txt

@@ -162,11 +162,13 @@ target_sources(nf7
     file/system_nfile.cc
     file/system_node.cc
     file/value_curve.cc
+    file/value_expr.cc
     file/value_imm.cc
     file/value_plot.cc
 )
 target_link_libraries(nf7
   PRIVATE
+    exprtk
     freetype
     glew
     glfw

thirdparty/CMakeLists.txt

@@ -10,8 +10,22 @@ else()
 endif()
 
 
+# ---- ExprTk ----
+# repository: https://github.com/ArashPartow/exprtk
+# license   : MIT
+
+FetchContent_Declare(
+  exprtk
+  URL "https://github.com/ArashPartow/exprtk/archive/refs/tags/0.0.1.zip"
+)
+FetchContent_Populate(exprtk)
+
+add_library(exprtk INTERFACE)
+target_include_directories(exprtk SYSTEM INTERFACE "${exprtk_SOURCE_DIR}")
+
+
 # ---- FreeType ----
-# repository:
+# repository: https://gitlab.freedesktop.org/freetype/freetype
 # license   : The FreeType License
 
 FetchContent_Declare(