explicit map(const Pred& comp = Pred(), const A& al = A());
map(const map& x);
map(const value_type *first, const value_type *last,
const Pred& comp = Pred(), const A& al = A());
The constructors with an argument named comp store the function object so that it can be later returned by calling
key_comp(). All constructors also store the allocator object al (or, for the copy constructor, x.get_allocator())
in allocator and initialize the controlled sequence. The first constructor specifies an empty initial controlled sequence.
The second constructor specifies a copy of the sequence controlled by x. The last constructor specifies the sequence of
element values [first, last).
In this implementation, if a translator does not support member template functions, the template:
template<class InIt>
map(InIt first, InIt last,
const Pred& comp = Pred(), const A& al = A());
is replaced by:
map(const value_type *first, const value_type *last,
const Pred& comp = Pred(), const A& al = A());