add extract function to fix_property_atom

src/fix_property_atom.cpp

@@ -948,3 +948,27 @@ int FixPropertyAtom::size_restart(int /*nlocal*/)
 {
   return values_peratom + 1;
 }
+
+/* ----------------------------------------------------------------------
+   extract fix property/atom properties
+------------------------------------------------------------------------- */
+
+void *FixPropertyAtom::extract(const char *str, int &dim)
+{
+  dim=0;
+  if (strcmp(str, "nvalue") == 0) {
+    return &nvalue;
+  } else if (strcmp(str, "border") == 0) {
+    return &border;
+  }
+  dim=1;
+  if (strcmp(str, "styles") == 0) {
+    return &styles;
+  } else if (strcmp(str, "index") == 0) {
+    return &index;
+  } else if (strcmp(str, "cols") == 0) {
+    return &cols;
+  }
+  return nullptr;
+}
+

src/fix_property_atom.h

@@ -51,6 +51,7 @@ class FixPropertyAtom : public Fix {
   void unpack_restart(int, int) override;
   int size_restart(int) override;
   int maxsize_restart() override;
+  void *extract(const char *, int &) override;
   double memory_usage() override;
 
  protected: