A Unique Associative Container is an Associative Container with
the property that each key in the container is unique: no two elements
in a Unique Associative Container have the same key.
i and j are Input Iterators whose value type is convertible
to X::value_type. [1]
void
Count
a.count(k)
size_type
Expression semantics
Name
Expression
Precondition
Semantics
Postcondition
Range constructor
X(i, j)
X a(i, j);
[i,j) is a valid range.
Creates an associative container that contains all of the elements in the range [i,j)
that have unique keys.
size() is less than or equal to the distance from i to j.
Insert element
a.insert(t)
Inserts t into a if and only if a does not already contain an
element whose key is the same as the key of t. The return value
is a pairP. P.first is an iterator pointing to the
element whose key is the same as the key of t. P.second is
a bool: it is true if t was actually inserted into a, and
false if t was not inserted into a, i.e. if a already
contained an element with the same key as t.
P.first is a dereferenceable iterator. *(P.first) has the same
key as t. The size of a is incremented by 1 if and only if
P.second is true.
Insert range
a.insert(i, j)
[i, j) is a valid range.
Equivalent to a.insert(t) for each object t that is pointed to
by an iterator in the range [i, j). Each element is inserted into
a if and only if a does not already contain an element with
the same key.
The size of a is incremented by at most j - i.
Count
a.count(k)
Returns the number of elements in a whose keys are the same as k.
The return value is either 0 or 1.
Complexity guarantees
Average complexity for insert element is at most logarithmic.
Average complexity for insert range is at most O(N * log(size() + N)),
where N is j - i.
Invariants
Uniqueness
No two elements have the same key. Equivalently, this means that
for every object k of type key_type, a.count(k) returns either
0 or 1.
[1]
At present (early 1998), not all compilers support
"member templates". If your compiler supports member
templates then i and j may be of any type that
conforms to the Input Iterator
requirements. If your compiler does not yet support member
templates, however, then i and j must be of type
const T* or of type X::const_iterator.