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< title > Random
Access Sequence</ title >
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< div class = "titlepage" >< div >< div >< h4 class = "title" >
< a name = "fusion.sequences.concepts.random_access_sequence" ></ a >< a href = "random_access_sequence.html" title = "Random
Access Sequence" > Random
Access Sequence</ a ></ h4 ></ div ></ div ></ div >
< a name = "fusion.sequences.concepts.random_access_sequence.description" ></ a >< h5 >
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< a name = "id479045" ></ a >
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< a href = "random_access_sequence.html#fusion.sequences.concepts.random_access_sequence.description" > Description</ a >
</ h5 >
< p >
A Random Access Sequence is a < a href = "bidirectional_sequence.html" title = "Bidirectional
Sequence" > Bidirectional
Sequence</ a > whose iterators model < a href = "../../iterators/concepts/random_access_iterator.html" title = "Random
Access Iterator" > Random
Access Iterator</ a > . It guarantees constant time access to arbitrary
sequence elements.
</ p >
< a name = "fusion.sequences.concepts.random_access_sequence.refinement_of" ></ a >< h5 >
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< a name = "id479096" ></ a >
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< a href = "random_access_sequence.html#fusion.sequences.concepts.random_access_sequence.refinement_of" > Refinement
of</ a >
</ h5 >
< p >
< a href = "bidirectional_sequence.html" title = "Bidirectional
Sequence" > Bidirectional
Sequence</ a >
</ p >
< div class = "variablelist" >
< p class = "title" >< b > Notation</ b ></ p >
< dl >
< dt >< span class = "term" >< tt class = "computeroutput" >< span class = "identifier" > s</ span ></ tt ></ span ></ dt >
< dd >
A Random Access Sequence
</ dd >
< dt >< span class = "term" >< tt class = "computeroutput" >< span class = "identifier" > S</ span ></ tt ></ span ></ dt >
< dd >
A Random Access Sequence type
</ dd >
< dt >< span class = "term" >< tt class = "computeroutput" >< span class = "identifier" > N</ span ></ tt ></ span ></ dt >
< dd >
An integral constant
</ dd >
< dt >< span class = "term" >< tt class = "computeroutput" >< span class = "identifier" > o</ span ></ tt ></ span ></ dt >
< dd >
An arbitrary object
</ dd >
< dt >< span class = "term" >< tt class = "computeroutput" >< span class = "identifier" > e</ span ></ tt ></ span ></ dt >
< dd >
A Sequence element
</ dd >
</ dl >
</ div >
< a name = "fusion.sequences.concepts.random_access_sequence.valid_expressions" ></ a >< h5 >
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< a name = "id479233" ></ a >
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< a href = "random_access_sequence.html#fusion.sequences.concepts.random_access_sequence.valid_expressions" > Valid
Expressions</ a >
</ h5 >
< p >
In addition to the requirements defined in < a href = "bidirectional_sequence.html" title = "Bidirectional
Sequence" > Bidirectional
Sequence</ a > , for any Random Access Sequence the following must be met:
</ p >
< div class = "informaltable" >
< h4 >
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< a name = "id479271" ></ a >
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</ h4 >
< table class = "table" >
< colgroup >
< col >
< col >
< col >
< col >
</ colgroup >
< thead >< tr >
< th > Expression</ th >
< th > Return type</ th >
< th > Type Requirements</ th >
< th > Runtime
Complexity</ th >
</ tr ></ thead >
< tbody >
< tr >
< td >< tt class = "computeroutput" >< a href = "../intrinsics/functions/begin.html" title = "begin" >< tt class = "computeroutput" >< span class = "identifier" > begin</ span ></ tt ></ a >< span class = "special" > (</ span >< span class = "identifier" > s</ span >< span class = "special" > )</ span ></ tt ></ td >
< td >< a href = "../../iterators/concepts/random_access_iterator.html" title = "Random
Access Iterator" > Random
Access Iterator</ a ></ td >
< td > </ td >
< td > Constant</ td >
</ tr >
< tr >
< td >< tt class = "computeroutput" >< a href = "../intrinsics/functions/end.html" title = "end" >< tt class = "computeroutput" >< span class = "identifier" > end</ span ></ tt ></ a >< span class = "special" > (</ span >< span class = "identifier" > s</ span >< span class = "special" > )</ span ></ tt ></ td >
< td >< a href = "../../iterators/concepts/random_access_iterator.html" title = "Random
Access Iterator" > Random
Access Iterator</ a ></ td >
< td > </ td >
< td > Constant</ td >
</ tr >
< tr >
< td >< tt class = "computeroutput" >< a href = "../intrinsics/functions/at.html" title = "at" >< tt class = "computeroutput" >< span class = "identifier" > at</ span ></ tt ></ a >< span class = "special" > < </ span >< span class = "identifier" > N</ span >< span class = "special" > > (</ span >< span class = "identifier" > s</ span >< span class = "special" > )</ span ></ tt ></ td >
< td > Any
type</ td >
< td > </ td >
< td > Constant</ td >
</ tr >
< tr >
< td >< tt class = "computeroutput" >< a href = "../intrinsics/functions/at.html" title = "at" >< tt class = "computeroutput" >< span class = "identifier" > at</ span ></ tt ></ a >< span class = "special" > < </ span >< span class = "identifier" > N</ span >< span class = "special" > > (</ span >< span class = "identifier" > s</ span >< span class = "special" > )</ span > < span class = "special" > =</ span > < span class = "identifier" > o</ span ></ tt ></ td >
< td > Any
type</ td >
< td >
< tt class = "computeroutput" >< span class = "identifier" > s</ span ></ tt >
is mutable and < tt class = "computeroutput" >< span class = "identifier" > e</ span > < span class = "special" > =</ span > < span class = "identifier" > o</ span ></ tt > ,
where < tt class = "computeroutput" >< span class = "identifier" > e</ span ></ tt > is the first
element in the sequence, is a valid expression.</ td >
< td > Constant</ td >
</ tr >
</ tbody >
</ table >
</ div >
< a name = "fusion.sequences.concepts.random_access_sequence.result_type_expressions" ></ a >< h5 >
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< a name = "id479596" ></ a >
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< a href = "random_access_sequence.html#fusion.sequences.concepts.random_access_sequence.result_type_expressions" > Result
Type Expressions</ a >
</ h5 >
< div class = "informaltable" >
< h4 >
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< a name = "id479620" ></ a >
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</ h4 >
< table class = "table" >
< colgroup >
< col >
< col >
</ colgroup >
< thead >< tr >
< th > Expression</ th >
< th > Compile Time Complexity</ th >
</ tr ></ thead >
< tbody >
< tr >
< td >< tt class = "computeroutput" >< a href = "../intrinsics/metafunctions/begin.html" title = "begin" >< tt class = "computeroutput" >< span class = "identifier" > result_of</ span >< span class = "special" > ::</ span >< span class = "identifier" > begin</ span ></ tt ></ a >< span class = "special" > < </ span >< span class = "identifier" > S</ span >< span class = "special" > > ::</ span >< span class = "identifier" > type</ span ></ tt ></ td >
< td > Amortized constant
time</ td >
</ tr >
< tr >
< td >< tt class = "computeroutput" >< a href = "../intrinsics/metafunctions/end.html" title = "end" >< tt class = "computeroutput" >< span class = "identifier" > result_of</ span >< span class = "special" > ::</ span >< span class = "identifier" > end</ span ></ tt ></ a >< span class = "special" > < </ span >< span class = "identifier" > S</ span >< span class = "special" > > ::</ span >< span class = "identifier" > type</ span ></ tt ></ td >
< td > Amortized constant
time</ td >
</ tr >
< tr >
< td >< tt class = "computeroutput" >< a href = "../intrinsics/metafunctions/at.html" title = "at" >< tt class = "computeroutput" >< span class = "identifier" > result_of</ span >< span class = "special" > ::</ span >< span class = "identifier" > at</ span ></ tt ></ a >< span class = "special" > < </ span >< span class = "identifier" > S</ span >< span class = "special" > ,</ span > < span class = "identifier" > N</ span >< span class = "special" > > ::</ span >< span class = "identifier" > type</ span ></ tt ></ td >
< td > Amortized constant
time</ td >
</ tr >
< tr >
< td >< tt class = "computeroutput" >< a href = "../intrinsics/metafunctions/value_at.html" title = "value_at" >< tt class = "computeroutput" >< span class = "identifier" > result_of</ span >< span class = "special" > ::</ span >< span class = "identifier" > value_at</ span ></ tt ></ a >< span class = "special" > < </ span >< span class = "identifier" > S</ span >< span class = "special" > ,</ span > < span class = "identifier" > N</ span >< span class = "special" > > ::</ span >< span class = "identifier" > type</ span ></ tt ></ td >
< td > Amortized constant
time</ td >
</ tr >
</ tbody >
</ table >
</ div >
< p class = "blurb" >
< span class = "inlinemediaobject" >< img src = "../../../images/note.png" alt = "note" ></ span > < tt class = "computeroutput" >< a href = "../intrinsics/metafunctions/at.html" title = "at" >< tt class = "computeroutput" >< span class = "identifier" > result_of</ span >< span class = "special" > ::</ span >< span class = "identifier" > at</ span ></ tt ></ a >< span class = "special" > < </ span >< span class = "identifier" > S</ span >< span class = "special" > ,</ span > < span class = "identifier" > N</ span >< span class = "special" > > </ span ></ tt >
returns the actual type returned by < tt class = "computeroutput" >< a href = "../intrinsics/functions/at.html" title = "at" >< tt class = "computeroutput" >< span class = "identifier" > at</ span ></ tt ></ a >< span class = "special" > < </ span >< span class = "identifier" > N</ span >< span class = "special" > > (</ span >< span class = "identifier" > s</ span >< span class = "special" > )</ span ></ tt > . In
most cases, this is a reference. Hence, there is no way to know the exact
element type using < tt class = "computeroutput" >< a href = "../intrinsics/metafunctions/at.html" title = "at" >< tt class = "computeroutput" >< span class = "identifier" > result_of</ span >< span class = "special" > ::</ span >< span class = "identifier" > at</ span ></ tt ></ a >< span class = "special" > < </ span >< span class = "identifier" > S</ span >< span class = "special" > ,</ span > < span class = "identifier" > N</ span >< span class = "special" > > </ span ></ tt > .The
element at < tt class = "computeroutput" >< span class = "identifier" > N</ span ></ tt > may actually
be a reference to begin with. For this purpose, you can use < tt class = "computeroutput" >< a href = "../intrinsics/metafunctions/value_at.html" title = "value_at" >< tt class = "computeroutput" >< span class = "identifier" > result_of</ span >< span class = "special" > ::</ span >< span class = "identifier" > value_at</ span ></ tt ></ a >< span class = "special" > < </ span >< span class = "identifier" > S</ span >< span class = "special" > ,</ span > < span class = "identifier" > N</ span >< span class = "special" > > </ span ></ tt > .
</ p >
< a name = "fusion.sequences.concepts.random_access_sequence.expression_semantics" ></ a >< h5 >
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< a name = "id480171" ></ a >
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< a href = "random_access_sequence.html#fusion.sequences.concepts.random_access_sequence.expression_semantics" > Expression
Semantics</ a >
</ h5 >
< p >
The semantics of an expression are defined only where they differ from,
or are not defined in < a href = "bidirectional_sequence.html" title = "Bidirectional
Sequence" > Bidirectional
Sequence</ a > .
</ p >
< div class = "informaltable" >
< h4 >
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< a name = "id480209" ></ a >
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</ h4 >
< table class = "table" >
< colgroup >
< col >
< col >
</ colgroup >
< thead >< tr >
< th > Expression</ th >
< th > Semantics</ th >
</ tr ></ thead >
< tbody >< tr >
< td >< tt class = "computeroutput" >< a href = "../intrinsics/functions/at.html" title = "at" >< tt class = "computeroutput" >< span class = "identifier" > at</ span ></ tt ></ a >< span class = "special" > < </ span >< span class = "identifier" > N</ span >< span class = "special" > > (</ span >< span class = "identifier" > s</ span >< span class = "special" > )</ span ></ tt ></ td >
< td > The
Nth element from the beginning of the sequence; see < a href = "../intrinsics/functions/at.html" title = "at" >< tt class = "computeroutput" >< span class = "identifier" > at</ span ></ tt ></ a > .</ td >
</ tr ></ tbody >
</ table >
</ div >
< a name = "fusion.sequences.concepts.random_access_sequence.models" ></ a >< h5 >
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< a name = "id480316" ></ a >
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< a href = "random_access_sequence.html#fusion.sequences.concepts.random_access_sequence.models" > Models</ a >
</ h5 >
< div class = "itemizedlist" >< ul type = "disc" >
< li >< a href = "../adapted/std__pair.html" title = "std::pair" >< tt class = "computeroutput" >< span class = "identifier" > std</ span >< span class = "special" > ::</ span >< span class = "identifier" > pair</ span ></ tt ></ a ></ li >
< li >< a href = "../adapted/boost__array.html" title = "boost::array" >< tt class = "computeroutput" >< span class = "identifier" > boost</ span >< span class = "special" > ::</ span >< span class = "identifier" > array</ span ></ tt ></ a ></ li >
< li >< a href = "../containers/vector.html" title = "vector" >< tt class = "computeroutput" >< span class = "identifier" > vector</ span ></ tt ></ a ></ li >
< li >
< a href = "../views/iterator_range.html" title = "iterator_range" >< tt class = "computeroutput" >< span class = "identifier" > iterator_range</ span ></ tt ></ a >
(where adapted sequence is a Random Access Sequence)
</ li >
< li >
< a href = "../views/transform_view.html" title = "transform_view" >< tt class = "computeroutput" >< span class = "identifier" > transform_view</ span ></ tt ></ a >
(where adapted sequence is a Random Access Sequence)
</ li >
< li >< a href = "../views/reverse_view.html" title = "reverse_view" >< tt class = "computeroutput" >< span class = "identifier" > reverse_view</ span ></ tt ></ a ></ li >
</ ul ></ div >
</ div >
< table xmlns:rev = "http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width = "100%" >< tr >
< td align = "left" ></ td >
< td align = "right" >< small > Copyright © 2001-2005 Joel de Guzman, Dan Marsden</ small ></ td >
</ tr ></ table >
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