Move common potentials opening code to utils

src/utils.cpp

@@ -17,6 +17,7 @@
 #include "lammps.h"
 #include "error.h"
 #include "tokenizer.h"
+#include "text_file_reader.h"
 #include "fmt/format.h"
 
 #if defined(__linux__)
@@ -450,6 +451,59 @@ bool utils::file_is_readable(const std::string & path) {
   return false;
 }
 
+/* ----------------------------------------------------------------------
+   try to find potential file as specified by name
+   search current directory and the LAMMPS_POTENTIALS directory if
+   specified
+------------------------------------------------------------------------- */
+
+std::string utils::get_potential_file_path(const std::string& path) {
+  std::string filepath = path;
+  std::string filename = utils::path_basename(path);
+
+  if(utils::file_is_readable(filepath)) {
+    return filepath;
+  } else {
+    // try the environment variable directory
+    const char *path = getenv("LAMMPS_POTENTIALS");
+
+    if (path != nullptr){
+      std::string pot = utils::path_basename(filepath);
+      filepath = utils::path_join(path, pot);
+
+      if (utils::file_is_readable(filepath)) {
+        return filepath;
+      }
+    }
+  }
+  return "";
+}
+
+/* ----------------------------------------------------------------------
+   read first line of potential file
+   if has DATE field, print following word
+------------------------------------------------------------------------- */
+
+std::string utils::get_potential_date(const std::string & path, const std::string & potential_name) {
+  TextFileReader reader(path, potential_name);
+  reader.ignore_comments = false;
+  char * line = nullptr;
+
+  while (line = reader.next_line()) {
+    ValueTokenizer values(line);
+    while (values.has_next()) {
+      std::string word = values.next_string();
+      if (word == "DATE:") {
+        if (values.has_next()) {
+          std::string date = values.next_string();
+          return date;
+        }
+      }
+    }
+  }
+  return "";
+}
+
 /* ------------------------------------------------------------------ */
 
 extern "C" {