Category: containers
Component type: concept
A Forward Arbitrary Access Container is a Forward Container whose iterator type is a Forward Arbitrary Access Iterator that can move forward by arbitrary amounts in amortized constant time.
A Forward Arbitrary Access Container provides amortized constant time access to arbitrary elements.
No specifications on reverse movement is determined here.
No additional types beyond those defined in Forward Container. However, the requirements for the iterator type are strengthened: it must be a Forward Arbitrary Access Iterator.
X | A type that is a model of Forward Arbitrary Access Container |
a | Object of type X |
T | The value type of X |
In addition to the expressions defined in Forward Container, the following expressions must be valid.
| Name | Expression | Type requirements | Return type |
|---|---|---|---|
| Element access | a[n] | n is convertible to size_type | reference if a is mutable, const_reference otherwise.With Pair Associative Containers, mapped_type if a is mutable, const mapped_type otherwise. |
| Element access | a.at(n) | n is convertible to size_type | reference if a is mutable, const_reference otherwise.With Pair Associative Containers, mapped_type if a is mutable, const mapped_type otherwise. |
Semantics of an expression is defined only where it is not defined in Forward Container, or where there is additional information.
| Name | Expression | Precondition | Semantics | Postcondition |
|---|---|---|---|---|
| Element access | a[n] | 0 <= n < a.size() | Returns the nth element from the beginning of the container. | |
| Element access | a.at(n) | 0 <= n < a.size() | Returns the nth element from the beginning of the container.Throws out_of_range exception if precondition not met. |
The run-time complexity of element access is amortized constant time.
| Element access | The element returned by a[n] is the same as the one obtained by incrementing a.begin() n times and then dereferencing the resulting iterator. |
Iterator Overview, Sequence, Forward Arbitrary Access Iterator, Forward Arbitrary Access Container LOGN, Forward Arbitrary Access Iterator LOGN, Reverse Arbitrary Access Container, Reverse Arbitrary Access Iterator, Reverse Arbitrary Access Container LOGN, Reverse Arbitrary Access Iterator LOGN, Random Access Container, Random Access Iterator, Random Access Container LOGN, Random Access Iterator LOGN, Arbitrary Access Container LOGN, Arbitrary Access Iterator LOGN
1.7.3
