124 lines
2.5 KiB
ReStructuredText
124 lines
2.5 KiB
ReStructuredText
.. Metafunctions/Bitwise Operations//shift_left
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shift_left
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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 T
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, typename Shift
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>
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struct shift_left
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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 result of bitwise *shift left* (``<<``) operation on ``T``.
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Header
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------
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.. parsed-literal::
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#include <boost/mpl/shift_left.hpp>
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#include <boost/mpl/bitwise.hpp>
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Model of
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--------
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|Numeric 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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| ``T`` | |Integral Constant| | A value to shift. |
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+---------------+-------------------------------+---------------------------+
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| ``Shift`` | Unsigned |Integral Constant| | A shift distance. |
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+---------------+-------------------------------+---------------------------+
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|Note:| |numeric metafunction note| |-- end note|
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Expression semantics
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--------------------
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For arbitrary |Integral Constant| ``c`` and unsigned |Integral Constant| ``shift``:
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.. parsed-literal::
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typedef shift_left<c,shift>::type r;
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:Return type:
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|Integral Constant|.
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:Semantics:
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Equivalent to
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.. parsed-literal::
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typedef integral_c<
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c::value_type
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, ( c::value << shift::value )
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> r;
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.. ..........................................................................
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.. parsed-literal::
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typedef shift_left<c,shift> r;
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:Return type:
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|Integral Constant|.
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:Semantics:
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Equivalent to
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.. parsed-literal::
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struct r : shift_left<c,shift>::type {};
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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 integral_c<unsigned,0> u0;
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typedef integral_c<unsigned,1> u1;
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typedef integral_c<unsigned,2> u2;
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typedef integral_c<unsigned,8> u8;
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BOOST_MPL_ASSERT_RELATION( (shift_left<u0,u0>::value), ==, 0 );
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BOOST_MPL_ASSERT_RELATION( (shift_left<u1,u0>::value), ==, 1 );
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BOOST_MPL_ASSERT_RELATION( (shift_left<u1,u1>::value), ==, 2 );
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BOOST_MPL_ASSERT_RELATION( (shift_left<u2,u1>::value), ==, 4 );
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BOOST_MPL_ASSERT_RELATION( (shift_left<u8,u1>::value), ==, 16 );
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See also
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--------
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|Bitwise Operations|, |Numeric Metafunction|, |numeric_cast|, |shift_right|, |bitand_|
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