add Modify::replace_fix() convenience function

src/modify.cpp

@@ -998,6 +998,23 @@ void Modify::replace_fix(const char *replaceID,
   add_fix(narg,arg,trysuffix);
 }
 
+/* ----------------------------------------------------------------------
+   convenience function to allow replacing a fix from a single string
+------------------------------------------------------------------------- */
+
+void Modify::replace_fix(const std::string &oldfix,
+                         const std::string &fixcmd, int trysuffix)
+{
+  auto args = utils::split_words(fixcmd);
+  char **newarg = new char*[args.size()];
+  int i=0;
+  for (const auto &arg : args) {
+    newarg[i++] = (char *)arg.c_str();
+  }
+  replace_fix(oldfix.c_str(),args.size(),newarg,trysuffix);
+  delete[] newarg;
+}
+
 /* ----------------------------------------------------------------------
    one instance per fix in style_fix.h
 ------------------------------------------------------------------------- */

src/modify.h

@@ -101,6 +101,7 @@ class Modify : protected Pointers {
   void add_fix(int, char **, int trysuffix=1);
   void add_fix(const std::string &, int trysuffix=1);
   void replace_fix(const char *, int, char **, int trysuffix=1);
+  void replace_fix(const std::string &, const std::string &, int trysuffix=1);
   void modify_fix(int, char **);
   void delete_fix(const std::string &);
   void delete_fix(int);