Random Access Iterator

Description

A Random Access Iterator is a Bidirectional Iterator that provides constant-time guarantees on moving the iterator an arbitrary number of positions forward or backward and for measuring the distance to another iterator in the same sequence.

Refinement of

Bidirectional Iterator

Expression requirements

In addition to the requirements defined in Bidirectional Iterator, the following requirements must be met.

Expression	Type	Complexity
`next<i>::type`	Random Access Iterator	Amortized constant time
`prior<i>::type`	Random Access Iterator	Amortized constant time
`i::category`	Integral Constant, convertible to `random_access_iterator_tag`	Constant time
`advance<i,n>::type`	Random Access Iterator	Amortized constant time
`distance<i,j>::type`	Integral Constant	Amortized constant time

Expression semantics

typedef advance<i,n>::type j;

Semantics:	See `advance` specification

typedef distance<i,j>::type n;

Semantics:	See `distance` specification

Invariants

For any random access iterators i and j the following invariants always hold:

If advance<i,n>::type is well-defined, then advance< advance<i,n>::type, negate<n>::type >::type is a null operation.