Standard C++ Library User Guide and Tutorial

typedef Allocator::types<T>::pointer iterator;
typedef Allocator::types<T>const_pointer iterator;
protected:
Allocator the_allocator; // copy of the allocator
private:
size_type buffer_size;
iterator buffer_start;
iterator current_end;
iterator end_of_buffer;
public:
// A constructor that initializes the set using a range
// from some other container or array
template <class Iterator>
set(Iterator start, Iterator finish,
Allocator alloc = Allocator());
iterator begin() { return buffer_start; }
iterator end() { return current_end; }
};
Given this class interface, here's a definition of a possible constructor that uses the allocator. The
numbered comments following this code briefly describe the allocator's role. For a fuller
treatment of allocators take a look at the Tutorial and Class Reference sections for allocators.
template <class T, class Allocator>
template <class Iterator>
set<T,Allocator>::set(Iterator start, Iterator finish,
Allocator alloc)
: buffer_size(finish-start + DEFAULT_CUSHION),
buffer_start(0),
current_end(0), end_of_buffer(0)
{
// copy the argument to our internal object
the_allocator = alloc; // 1
// Create an initial buffer
buffer_start = the_allocator.allocate(buffer_size); // 2
end_of_buffer = buffer_start + buffer_size;
// construct new values from iterator range on the buffer
for (current_end = buffer_start;
start != finish;
current_end++, start++)