C++ key-value container with variable type values

What I need is a key-value container for keeping some well-known parameters of objects. All possible keys are known on compile time. Values are belong to differnt types: POD (integers, pointers) and non-POD (some small structures with contructors).

Current implementation uses very big structure and tons of code to initialize, fill and copy values. So I want to replace this structure with container. Container m开发者_如何学编程ust provide: 1) quick access by key (constant time). 2) the possibility to iterate over all values to copy them.

I tried to think up some array based approach, but coldn't make it. I can make some hash table, but I don't know what to do with different value types.

sounds like std::unordered_map (or boost::unordered_map) is the right solution. Just use boost::any for the objects so they can be any type.

You might want to look at Boost.Variant for storing the values. Then you can just use a std::map<Key, boost::variant> or std::unordered_map<Key, boost::variant> for your container.

sounds like the std::map is the right way to go.

While your keys are known at compile time, you may just populate the std::map structure with the data as part of the initialization.

For the value, you probably want to implement a wrapper objects which can hold int, pointers, and some of your simple-non-POD objects, and then make that your second (value) object in the std::hash table.

std::map, inplements .find(key) for fast lookup and .begin() and .end() for ::iterator's

You said:

All possible keys are known on compile time.

then you must be knowing the type as well.

If the type is integral type, then array or pointer of boost::any is the best choice.

//if the size is known at compile time!
boost::any objmap[size]; 

//if the size isn't known at compile time
boost::any *objmap = new boost::any[size];

Whatever you use (array or pointer), the key will be the index of objmap and objmap[key] will be the value associated with the key.