Question

i need to serialize directory tree.
i have no trouble with this type:

std::map<
   std::string, // string(path name)
   std::vector<std::string> // string array(file names in the path)
> tree;

but for the serialization the directory tree with the content i need other type:

std::map<
   std::string, // string(path name)
   std::vector< // files array
      std::pair<
         std::string, // file name
         std::vector< // array of file pieces
            std::pair< // <<<<<<<<<<<<<<<<<<<<<< for this i need lazy initialization
               std::string, // piece buf
               boost::uint32_t // crc32 summ on piece
            >
         >
      >
   >
> tree;

how can i initialize the object of type “std::pair” in the moment of its serialization?
i.e. read file piece/calculate crc32 summ.

up

Answer 1

I would replace the std::string in the vector by a custom class, let me say MyFileNames

class MyFileNames : std::string
{
// add forward constructors as needed

};

std::map<
   std::string, // string(path name)
   std::vector<MyFileNames> // string array(file names in the path)
> tree;

And define the save serialization function for MyFileNames by converting the std::string to a

std::pair<
     std::string, // file name
     std::vector< // array of file pieces
        std::pair< // <<<<<<<<<<<<<<<<<<<<<< for this i need lazy initialization
           std::string, // piece buf
           boost::uint32_t // crc32 summ on piece
        >
     >
>

and the serialize this type.
This let you evaluate the lazy part only the data is serialized. For the load you could ignore the lazy data, as I suppose that this data can be calculated.