support that LAMMPS_POTENTIALS is a real path variable with multiple entries,...

#include <cstdlib>

#include <cerrno>

#include "lammps.h"

#include "comm.h"

#include "compute.h"

#include "error.h"

#include "fix.h"

#include "modify.h"

#include "tokenizer.h"

#include "text_file_reader.h"

#include "update.h"

#include "fmt/format.h"

#if defined(__linux__)

   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;

    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);

    if (var != nullptr){

      Tokenizer dirs(var,OS_PATH_VAR_SEP);

      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 "";

}

#undef OS_PATH_VAR_SEP

/* ----------------------------------------------------------------------

   read first line of potential file