Refactor folder (#10475)

Move many third-party components' source codes from the src folder to a new folder called deps_src. The goal is to make the code structure clearer and easier to navigate.

deps_src/libigl/igl/is_dir.cpp

@@ -0,0 +1,30 @@
+// This file is part of libigl, a simple c++ geometry processing library.
+// 
+// Copyright (C) 2013 Alec Jacobson <alecjacobson@gmail.com>
+// 
+// This Source Code Form is subject to the terms of the Mozilla Public License 
+// v. 2.0. If a copy of the MPL was not distributed with this file, You can 
+// obtain one at http://mozilla.org/MPL/2.0/.
+#include "is_dir.h"
+
+#include <sys/stat.h>
+
+#ifndef S_ISDIR
+#define S_ISDIR(mode)  (((mode) & S_IFMT) == S_IFDIR)
+#endif
+
+#ifndef S_ISREG
+#define S_ISREG(mode)  (((mode) & S_IFMT) == S_IFREG)
+#endif
+
+IGL_INLINE bool igl::is_dir(const char * filename)
+{
+  struct stat status;
+  if(stat(filename,&status)!=0)
+  {
+    // path does not exist
+    return false;
+  }
+  // Tests whether existing path is a directory
+  return S_ISDIR(status.st_mode);
+}