166 lines
4.6 KiB
ReStructuredText
166 lines
4.6 KiB
ReStructuredText
.. Sequences/Intrinsic Metafunctions//erase
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erase
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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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, typename First
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, typename Last = |unspecified|
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>
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struct erase
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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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``erase`` performs a removal of one or more adjacent elements in the sequence
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starting from an arbitrary position.
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Header
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------
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.. parsed-literal::
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#include <boost/mpl/erase.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`` | |Extensible Sequence| or | A sequence to erase from. |
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| | |Extensible Associative Sequence| | |
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+---------------+-----------------------------------+-----------------------------------------------+
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| ``First`` | |Forward Iterator| | An iterator to the beginning of the range to |
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| | | be erased. |
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+---------------+-----------------------------------+-----------------------------------------------+
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| ``Last`` | |Forward Iterator| | An iterator past-the-end of the range to be |
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| | | erased. |
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+---------------+-----------------------------------+-----------------------------------------------+
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Expression semantics
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--------------------
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.. compound::
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:class: expression-semantics
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For any |Extensible Sequence| ``s``, and iterators ``pos``, ``first`` and ``last`` into ``s``:
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.. parsed-literal::
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typedef erase<s,first,last>::type r;
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:Return type:
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|Extensible Sequence|.
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:Precondition:
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``[first,last)`` is a valid range in ``s``.
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:Semantics:
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``r`` is a new sequence, |concept-identical| to ``s``, of the following elements:
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[``begin<s>::type``, ``pos``), [``last``, ``end<s>::type``).
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:Postcondition:
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The relative order of the elements in ``r`` is the same as in ``s``;
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.. parsed-literal::
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size<r>::value == size<s>::value - distance<first,last>::value
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.. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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.. parsed-literal::
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typedef erase<s,pos>::type r;
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:Return type:
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|Extensible Sequence|.
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:Precondition:
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``pos`` is a dereferenceable iterator in ``s``.
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:Semantics:
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Equivalent to
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.. parsed-literal::
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typedef erase< s,pos,next<pos>::type >::type r;
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.. compound::
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:class: expression-semantics
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For any |Extensible Associative Sequence| ``s``, and iterator ``pos`` into ``s``:
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.. parsed-literal::
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typedef erase<s,pos>::type r;
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:Return type:
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|Extensible Sequence|.
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:Precondition:
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``pos`` is a dereferenceable iterator to ``s``.
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:Semantics:
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Erases the element at a specific position ``pos``; equivalent to
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``erase_key<s, deref<pos>::type >::type``.
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:Postcondition:
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``size<r>::value == size<s>::value - 1``.
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Complexity
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----------
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+---------------------------------------+-----------------------------------------------+
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| Sequence archetype | Complexity (the range form) |
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+=======================================+===============================================+
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| |Extensible Associative Sequence| | Amortized constant time. |
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+---------------------------------------+-----------------------------------------------+
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| |Extensible Sequence| | Quadratic in the worst case, linear at best. |
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+---------------------------------------+-----------------------------------------------+
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Example
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-------
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.. parsed-literal::
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typedef vector_c<int,1,0,5,1,7,5,0,5> values;
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typedef find< values, integral_c<int,7> >::type pos;
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typedef erase<values,pos>::type result;
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BOOST_MPL_ASSERT_RELATION( size<result>::value, ==, 7 );
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typedef find<result, integral_c<int,7> >::type iter;
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BOOST_MPL_ASSERT(( is_same< iter, end<result>::type > ));
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See also
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--------
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|Extensible Sequence|, |Extensible Associative Sequence|, |erase_key|, |pop_front|, |pop_back|, |insert|
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