100 lines
1.6 KiB
ReStructuredText
100 lines
1.6 KiB
ReStructuredText
.. Sequences/Intrinsic Metafunctions//back
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back
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====
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Synopsis
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--------
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.. parsed-literal::
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template<
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typename Sequence
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>
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struct back
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{
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typedef |unspecified| type;
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};
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Description
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-----------
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Returns the last element in the sequence.
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Header
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------
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.. parsed-literal::
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#include <boost/mpl/back.hpp>
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Model of
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--------
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|Tag Dispatched Metafunction|
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Parameters
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----------
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+---------------+---------------------------+-----------------------------------+
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| Parameter | Requirement | Description |
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+===============+===========================+===================================+
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| ``Sequence`` | |Bidirectional Sequence| | A sequence to be examined. |
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+---------------+---------------------------+-----------------------------------+
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Expression semantics
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--------------------
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For any |Bidirectional Sequence| ``s``:
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.. parsed-literal::
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typedef back<s>::type t;
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:Return type:
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A type.
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:Precondition:
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``empty<s>::value == false``.
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:Semantics:
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Equivalent to
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.. parsed-literal::
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typedef deref< prior< end<s>::type >::type >::type t;
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Complexity
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----------
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Amortized constant time.
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Example
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-------
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.. parsed-literal::
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typedef range_c<int,0,1> range1;
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typedef range_c<int,0,10> range2;
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typedef range_c<int,-10,0> range3;
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BOOST_MPL_ASSERT_RELATION( back<range1>::value, ==, 0 );
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BOOST_MPL_ASSERT_RELATION( back<range2>::value, ==, 9 );
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BOOST_MPL_ASSERT_RELATION( back<range3>::value, ==, -1 );
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See also
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--------
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|Bidirectional Sequence|, |front|, |push_back|, |end|, |deref|, |at|
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