I am wondering if it is possible to create something like a predicate for a std::map for all of its values so I don't have to edit the values before I insert them into the map.

What I would like is something like this:

mymap["username"] = " Marlon "; // notice the space on both sides of my name
assert(mymap["username"] == "Marlon"); // no more whitespace

The context is I am creating a std::map for a .ini file and I would like it to automatically remove leading/trailing whitespace from the values when I want to retrieve them. I've already created a predicate to ignore casing and whitespace from the key so I want to know if it is possible to do the same for the value.