support that LAMMPS_POTENTIALS is a real path variable with multiple entries, not just a single folder

src/tokenizer.h

@@ -33,7 +33,7 @@ class Tokenizer {
     size_t start;
     size_t ntokens;
 public:
-    Tokenizer(const std::string & str, const std::string & separators = TOKENIZER_DEFAULT_SEPARATORS);
+    Tokenizer(const std::string &str, const std::string &separators = TOKENIZER_DEFAULT_SEPARATORS);
     Tokenizer(Tokenizer &&);
     Tokenizer(const Tokenizer &);
     Tokenizer& operator=(const Tokenizer&) = default;
@@ -42,7 +42,7 @@ public:
     void reset();
     void skip(int n);
     bool has_next() const;
-    bool contains(const std::string & str) const;
+    bool contains(const std::string &str) const;
     std::string next();
 
     size_t count();
@@ -52,7 +52,7 @@ public:
 class TokenizerException : public std::exception {
   std::string message;
 public:
-  TokenizerException(const std::string & msg, const std::string & token);
+  TokenizerException(const std::string &msg, const std::string &token);
 
   ~TokenizerException() throw() {
   }
@@ -64,20 +64,20 @@ public:
 
 class InvalidIntegerException : public TokenizerException {
 public:
-    InvalidIntegerException(const std::string & token) : TokenizerException("Not a valid integer number", token) {
+    InvalidIntegerException(const std::string &token) : TokenizerException("Not a valid integer number", token) {
     }
 };
 
 class InvalidFloatException : public TokenizerException {
 public:
-    InvalidFloatException(const std::string & token) : TokenizerException("Not a valid floating-point number", token) {
+    InvalidFloatException(const std::string &token) : TokenizerException("Not a valid floating-point number", token) {
     }
 };
 
 class ValueTokenizer {
     Tokenizer tokens;
 public:
-    ValueTokenizer(const std::string & str, const std::string & separators = TOKENIZER_DEFAULT_SEPARATORS);
+    ValueTokenizer(const std::string &str, const std::string &separators = TOKENIZER_DEFAULT_SEPARATORS);
     ValueTokenizer(const ValueTokenizer &);
     ValueTokenizer(ValueTokenizer &&);
     ValueTokenizer& operator=(const ValueTokenizer&) = default;
@@ -90,7 +90,7 @@ public:
     double next_double();
 
     bool has_next() const;
-    bool contains(const std::string & value) const;
+    bool contains(const std::string &value) const;
     void skip(int ntokens);
 
     size_t count();

src/utils.cpp

@@ -16,6 +16,7 @@
 #include <cstdlib>
 #include <cerrno>
 #include "lammps.h"
+#include "comm.h"
 #include "compute.h"
 #include "error.h"
 #include "fix.h"
@@ -23,6 +24,7 @@
 #include "modify.h"
 #include "tokenizer.h"
 #include "text_file_reader.h"
+#include "update.h"
 #include "fmt/format.h"
 
 #if defined(__linux__)
@@ -822,6 +824,11 @@ bool utils::file_is_readable(const std::string &path) {
    search current directory and the LAMMPS_POTENTIALS directory if
    specified
 ------------------------------------------------------------------------- */
+#if defined(_WIN32)
+#define OS_PATH_VAR_SEP ";"
+#else
+#define OS_PATH_VAR_SEP ":"
+#endif
 
 std::string utils::get_potential_file_path(const std::string &path) {
   std::string filepath = path;
@@ -831,19 +838,25 @@ std::string utils::get_potential_file_path(const std::string &path) {
     return filepath;
   } else {
     // try the environment variable directory
-    const char *path = getenv("LAMMPS_POTENTIALS");
+    const char *var = getenv("LAMMPS_POTENTIALS");
 
-    if (path != nullptr){
-      std::string pot = utils::path_basename(filepath);
-      filepath = utils::path_join(path, pot);
+    if (var != nullptr){
+      Tokenizer dirs(var,OS_PATH_VAR_SEP);
 
-      if (utils::file_is_readable(filepath)) {
-        return filepath;
+      while (dirs.has_next()) {
+        auto pot = utils::path_basename(filepath);
+        auto path = dirs.next();
+        filepath = utils::path_join(path, pot);
+
+        if (utils::file_is_readable(filepath)) {
+          return filepath;
+        }
       }
     }
   }
   return "";
 }
+#undef OS_PATH_VAR_SEP
 
 /* ----------------------------------------------------------------------
    read first line of potential file