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

src/utils.h

@@ -291,6 +291,13 @@ namespace LAMMPS_NS {
 
     std::string path_basename(const std::string &path);
 
+    /** Return the directory part of a path. Return "." if empty
+     *
+     * \param path file path
+     * \return directory name */
+
+    std::string path_dirname(const std::string &path);
+
     /** Join two pathname segments
      *
      * This uses the forward slash '/' character unless LAMMPS is compiled

unittest/utils/test_utils.cpp

@@ -525,11 +525,26 @@ TEST(Utils, path_basename)
 {
 #if defined(_WIN32)
     ASSERT_THAT(utils::path_basename("c:\\parent\\folder\\filename"), Eq("filename"));
+    ASSERT_THAT(utils::path_basename("folder\\"), Eq(""));
+    ASSERT_THAT(utils::path_basename("c:/parent/folder/filename"), Eq("filename"));
 #else
     ASSERT_THAT(utils::path_basename("/parent/folder/filename"), Eq("filename"));
+    ASSERT_THAT(utils::path_basename("/parent/folder/"), Eq(""));
 #endif
 }
 
+TEST(Utils, path_dirname)
+{
+#if defined(_WIN32)
+    ASSERT_THAT(utils::path_dirname("c:/parent/folder/filename"), Eq("c:/parent/folder"));
+    ASSERT_THAT(utils::path_dirname("c:\\parent\\folder\\filename"), Eq("c:\\parent\\folder"));
+    ASSERT_THAT(utils::path_dirname("c:filename"), Eq("."));
+#else
+    ASSERT_THAT(utils::path_dirname("/parent/folder/filename"), Eq("/parent/folder"));
+#endif
+    ASSERT_THAT(utils::path_dirname("filename"), Eq("."));
+}
+
 TEST(Utils, getsyserror)
 {
 #if defined(__linux__)