Calculating the size of the serialized object

The number of bytes required to represent a serialized object cannot be easily known in advance. It is possible to calculate it, but it's an expensive process. The object gets serialized twice: the first time to count the number of bytes, and the second time for real. This is expensive, but can be convenient sometimes:

#include <x/serialize.H>

std::vector<std::string> strarray;

// ...
	
x::serialize::sizeof_iterator cnt;
	
cnt(strarray);
	
std::vector<char> buffer;
	
buffer.resize(cnt.counter());
	
char *ptr=&buffer[0];

x::serialize::iterator<char *> o_iter(ptr);
	
o_iter(strarray);
	

sizeof_iterator is a subclass of iterator that throws away the serialized bytes, after counting them. Its counter() method returns the resulting byte count. This example allocates a suitable buffer, then the object gets serialized for real, using a plain char * as an output iterator.

It goes without saying that the serialized objects cannot be modified between the first and the second serialization pass in a manner that affects their serialized representation.