From 40005e1ea370513ae9b32ff94f028b0d87b61e6a Mon Sep 17 00:00:00 2001
From: Ian Bell <ian.bell@nist.gov>
Date: Tue, 7 Jan 2025 13:30:14 -0500
Subject: [PATCH] Use the cache to avoid writing the disabling file each time

Saves time with incremental builds because teqp does not have to recompile since the generated header is not newer
---
 CMakeLists.txt | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 7cfc719..af39b82 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -158,16 +158,20 @@ set(preprocessors)
 ## set(TEQP_DISABLED_FACTORIES "CPA,SAFTVRMIE,GENERICSAFT,SQUAREWELL,EXP6,2CLJF,MIE,MULTIFLUIDACTIVITY,PCSAFT,GERG200X,MULTIFLUIDASSOCIATION,LKP") # as an example
 if (TEQP_DISABLED_FACTORIES)
     string(REGEX MATCHALL "[^,]+" disabled_factories "${TEQP_DISABLED_FACTORIES}")
-    message(STATUS "${disabled_factories}")
+    message(STATUS "These model factories are disabled: ${disabled_factories}")
     foreach (factory ${disabled_factories})
       string(TOUPPER "${factory}" factory)
       string(STRIP "${factory}" factory)
       list(APPEND preprocessors "#define DISABLE_${factory}")
     endforeach()
+    set(PREPROCESSORS_SEMICOLON "${preprocessors}") # CMake requires strings to not contain newlines, so we store with ; instead of newlines
     string (REPLACE ";" "\n" preprocessors "${preprocessors}")
-    message(STATUS "Generated this ${CMAKE_CURRENT_BINARY_DIR}/generated_headers/model_flags.hpp:\n${preprocessors}")
-    # Generate the model_flags.hpp header
-    file(WRITE "${CMAKE_CURRENT_BINARY_DIR}/generated_headers/model_flags.hpp" "${preprocessors}")
+    if (NOT ("${PREPROCESSORS_SEMICOLON}" STREQUAL "$CACHE{TEQP_DISABLED_FACTORIES_PREPROCESSORS}"))
+      # Generate the model_flags.hpp header
+      message(STATUS "Writing to ${CMAKE_CURRENT_BINARY_DIR}/generated_headers/model_flags.hpp:\n${preprocessors}")
+      file(WRITE "${CMAKE_CURRENT_BINARY_DIR}/generated_headers/model_flags.hpp" "${preprocessors}")
+    endif()
+    SET(TEQP_DISABLED_FACTORIES_PREPROCESSORS ${PREPROCESSORS_SEMICOLON} CACHE INTERNAL "" FORCE)
 else()
     # Only write the HPP file the if it doesn't exist; thereafter, do nothing
     if (NOT EXISTS "${CMAKE_CURRENT_BINARY_DIR}/generated_headers/model_flags.hpp")