config.nml paths can replace @GEMINI_SIMROOT@ with env var path

+gemini3d/+fileio/expand_simroot.m

@@ -0,0 +1,14 @@
+function p = expand_simroot(p)
+
+key = "@GEMINI_SIMROOT@";
+
+if startsWith(p, key)
+  r = getenv(extractBetween(key, 2, strlength(key)-1));
+  if isempty(r)
+    error("gemini3d:fileio:read_nml", p + " refers to undefined environment variable GEMINI_SIMROOT. Set it to location to store/load Gemini3D simulations.")
+  end
+
+  p = fullfile(r, extractAfter(p, key));
+end
+
+end

+gemini3d/+fileio/make_valid_paths.m

@@ -45,10 +45,12 @@
 function folder = make_valid_folder(folder, top)
 import gemini3d.fileio.*
 
+folder = gemini3d.fileio.expand_simroot(folder);
+
 folder = expanduser(folder);
 % in case absolute path was specified
 
-if ~isfolder(folder)  && ~is_absolute_path(folder)
+if ~isfolder(folder) && ~is_absolute_path(folder)
   folder = fullfile(top, folder);
 end
 
@@ -57,6 +59,8 @@
 
 function filename = make_valid_filename(filename, top)
 
+filename = gemini3d.fileio.expand_simroot(filename);
+
 filename = gemini3d.fileio.expanduser(filename);
 % in case absolute path was specified
 

+gemini3d/+tests/TestAUnit.m

@@ -94,6 +94,21 @@ function test_path_tail(tc)
 end
 end
 
+function test_nml_gemini_simroot(tc)
+old = getenv("GEMINI_SIMROOT");
+
+setenv("GEMINI_SIMROOT", "abc123")
+
+out = gemini3d.fileio.expand_simroot("@GEMINI_SIMROOT@/foo");
+
+setenv("GEMINI_SIMROOT", old)
+
+tc.verifyEqual(out, fullfile("abc123", "foo"))
+
+
+end
+
+
 function test_grid1d(tc)
 
 x = gemini3d.grid.grid1d(100., 5);