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Random Access Sequence

Description

A Random Access Sequence is a Bidirectional Sequence whose iterators model Random Access Iterator. It guarantees constant time access to arbitrary sequence elements.

Refinement of

Bidirectional Sequence

Notation

s: A Random Access Sequence
S: A Random Access Sequence type
N: An MPL Integral Constant
o: An arbitrary object
e: A Sequence element

Valid Expressions

In addition to the requirements defined in Bidirectional Sequence, for any Random Access Sequence the following must be met:

Expression	Return type	Type Requirements	Runtime Complexity
`begin(s)`	Random Access Iterator		Constant
`end(s)`	Random Access Iterator		Constant
`at<N>(s)`	Any type		Constant
`at<N>(s) = o`	Any type	`s` is mutable and `e = o`, where `e` is the first element in the sequence, is a valid expression.	Constant

Result Type Expressions

Expression	Compile Time Complexity
`result_of::begin<S>::type`	Amortized constant time
`result_of::end<S>::type`	Amortized constant time
`result_of::at<S, N>::type`	Amortized constant time
`result_of::value_at<S, N>::type`	Amortized constant time

Expression Semantics

The semantics of an expression are defined only where they differ from, or are not defined in Bidirectional Sequence.

Expression	Semantics
`at<N>(s)`	The Nth element from the beginning of the sequence; see `at`.

Models

std::pair
boost::array
vector
reverse_view
iterator_range (where adapted sequence is a Random Access Sequence)
transform_view (where adapted sequence is a Random Access Sequence)
zip_view (where adapted sequences are models of Random Access Sequence)