A Simple Associative Container is an Associative Container where
elements are their own keys. A key in a Simple Associative Container
is not associated with any additional value.
None, except for those described in the Associative Container
requirements. Simple Associative Container, however, introduces two
new type restrictions.
Key type
X::key_type
The type of the key associated with X::value_type. The types
key_type and value_type must be the same type.
Iterator
X::iterator
The type of iterator used to iterate through a Simple Associative
Container's elements. The types X::iterator and
X::const_iterator must be the same type. That is, a
Simple Associative Container does not provide mutable iterators. [1]
Notation
X
A type that is a model of Simple Associative Container
[1]
This is a consequence of the Immutability of Keys invariant of
Associative Container. Keys may never be modified; values in
a Simple Associative Container are themselves keys, so it immediately
follows that values in a Simple Associative Container may not be modified.