Add filesystem utils functions

src/utils.cpp

@@ -397,6 +397,51 @@ bool utils::is_double(const std::string & str) {
   return true;
 }
 
+/* ----------------------------------------------------------------------
+   strip off leading part of path, return just the filename
+------------------------------------------------------------------------- */
+
+std::string utils::path_basename(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) {
+    start = 0;
+  } else {
+    start += 1;
+  }
+
+  return path.substr(start);
+}
+
+/* ----------------------------------------------------------------------
+   join two paths
+------------------------------------------------------------------------- */
+
+std::string utils::path_join(const std::string & a, const std::string & b) {
+  #if defined(_WIN32)
+    return fmt::format("{}\\{}", a, b);
+  #else
+    return fmt::format("{}/{}", a, b);
+  #endif
+}
+
+/* ----------------------------------------------------------------------
+   try to open file for reading
+------------------------------------------------------------------------- */
+
+bool utils::file_is_readable(const std::string & path) {
+  FILE * fp = fopen(path.c_str(), "r");
+  if(fp) {
+    fclose(fp);
+    return true;
+  }
+  return false;
+}
+
 /* ------------------------------------------------------------------ */
 
 extern "C" {

src/utils.h

@@ -163,6 +163,28 @@ namespace LAMMPS_NS {
      * \return true, if string contains valid floating-point number, false otherwise
      */
     bool is_double(const std::string & str);
+
+    /**
+     * \brief Strip off leading part of path, return just the filename
+     * \param path file path
+     * \return file name
+     */
+    std::string path_basename(const std::string & path);
+
+    /**
+     * \brief Join two paths
+     * \param a first path
+     * \param b second path
+     * \return combined path
+     */
+    std::string path_join(const std::string & a, const std::string & b);
+
+    /**
+     * \brief Check if file exists and is readable
+     * \param path file path
+     * \return true if file exists and is readable
+     */
+    bool file_is_readable(const std::string & path);
   }
 }
 

unittest/utils/test_utils.cpp

@@ -182,3 +182,19 @@ TEST(Utils, strmatch_char_range) {
 TEST(Utils, strmatch_opt_range) {
     ASSERT_TRUE(utils::strmatch("rigid","^[0-9]*[p-s]igid"));
 }
+
+TEST(Utils, path_join) {
+#if defined(_WIN32)
+    ASSERT_THAT(utils::path_join("c:\\parent\\folder", "filename"), Eq("c:\\parent\\folder\\filename"));
+#else
+    ASSERT_THAT(utils::path_join("/parent/folder", "filename"), Eq("/parent/folder/filename"));
+#endif
+}
+
+TEST(Utils, path_basename) {
+#if defined(_WIN32)
+    ASSERT_THAT(utils::path_basename("c:\\parent\\folder\\filename"), Eq("filename"));
+#else
+    ASSERT_THAT(utils::path_basename("/parent/folder/filename"), Eq("filename"));
+#endif
+}