Allow CANTERA_DATA to include multiple directories

doc/sphinx/cython/tutorial.rst

@@ -302,10 +302,11 @@ Files\\Cantera\\data`` on Windows or ``/usr/local/cantera/data/`` on
 Unix/Linux/Mac OS X machines, depending on how you installed Cantera and the
 options you specified.
 
-If for some reason Cantera has difficulty finding where these files are on
-your system, set environment variable ``CANTERA_DATA`` to the directory where
-they are located. Alternatively, you can call function `add_directory` to add
-a directory to the Cantera search path::
+If for some reason Cantera has difficulty finding where these files are on your
+system, set environment variable ``CANTERA_DATA`` to the directory or
+directories (separated using ``;`` on Windows or ``:`` on other operating
+systems) where they are located. Alternatively, you can call function
+`add_directory` to add a directory to the Cantera search path::
 
     >>> ct.add_directory('/usr/local/cantera/my_data_files')
 

doc/sphinx/matlab/input-tutorial.rst

@@ -31,9 +31,10 @@ reaction mechanism, and a few surface reaction mechanisms.  These files are kept
 in the ``data`` subdirectory within the Cantera installation directory.
 
 If for some reason Cantera has difficulty finding where these files are on your
-system, set environment variable ``CANTERA_DATA`` to the directory where they
-are located. Alternatively, you can call function ``addDirectory`` to add a
-directory to the Cantera search path::
+system, set environment variable ``CANTERA_DATA`` to the directory or
+directories (separated using ``;`` on Windows or ``:`` on other operating
+systems) where they are located. Alternatively, you can call function
+`add_directory` to add a directory to the Cantera search path::
 
     addDirectory('/usr/local/cantera/my_data_files');
 

include/cantera/base/global.h

@@ -75,8 +75,10 @@ void popError();
  * On the Mac, directory '/Applications/Cantera/data' is added to the
  * search path.
  *
- * On any platform, if environment variable CANTERA_DATA is set to a
- * directory name, then this directory is added to the search path.
+ * On any platform, if environment variable CANTERA_DATA is set to a directory
+ * name or a list of directory names separated with the OS-dependent path
+ * separator (i.e. ";" on Windows, ":" elsewhere), then these directories will
+ * be added to the search path.
  *
  * Finally, the location where the data files were installed when
  * %Cantera was built is added to the search path.

src/base/application.cpp

@@ -446,13 +446,26 @@ void Application::setDefaultDirectories()
     dirs.push_back("/Applications/Cantera/data");
 #endif
 
-    //
-    // if environment variable CANTERA_DATA is defined, then add
-    // it to the search path
-    //
+    // if environment variable CANTERA_DATA is defined, then add it to the
+    // search path. CANTERA_DATA may include multiple directory, separated by
+    // the OS-dependent path separator (in the same manner as the PATH
+    // environment variable).
+#ifdef _WIN32
+    std::string pathsep = ";";
+#else
+    std::string pathsep = ":";
+#endif
+
     if (getenv("CANTERA_DATA") != 0) {
-        string datadir = string(getenv("CANTERA_DATA"));
-        dirs.push_back(datadir);
+        string s = string(getenv("CANTERA_DATA"));
+        size_t start = 0;
+        size_t end = s.find(pathsep);
+        while(end != npos) {
+            dirs.push_back(s.substr(start, end-start));
+            start = end + 1;
+            end = s.find(pathsep, start);
+        }
+        dirs.push_back(s.substr(start,end));
     }
 
     // CANTERA_DATA is defined in file config.h. This file is written