add utils::path_dirname() to complement utils::path_basename()

src/utils.cpp

@@ -772,6 +772,22 @@ std::string utils::path_basename(const std::string &path) {
   return path.substr(start);
 }
 
+/* ----------------------------------------------------------------------
+   Return only the leading part of a path, return just the directory
+------------------------------------------------------------------------- */
+
+std::string utils::path_dirname(const std::string &path) {
+#if defined(_WIN32)
+  size_t start = path.find_last_of("/\\");
+#else
+  size_t start = path.find_last_of("/");
+#endif
+
+  if (start == std::string::npos) return ".";
+
+  return path.substr(0,start);
+}
+
 /* ----------------------------------------------------------------------
    join two paths
 ------------------------------------------------------------------------- */