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Front Page / Metafunctions / Bitwise Operations / shift_left

shift_left

Synopsis

template<
      typename T
    , typename Shift
    >
struct shift_left
{
    typedef unspecified type;
};

Description

Returns the result of bitwise shift left (<<) operation on T.

Header

#include <boost/mpl/shift_left.hpp>
#include <boost/mpl/bitwise.hpp>

Model of

Numeric Metafunction

Parameters

Parameter Requirement Description
T Integral Constant A value to shift.
Shift Unsigned Integral Constant A shift distance.

[Note: The requirements listed in this specification are the ones imposed by the default implementation. See Numeric Metafunction concept for the details on how to provide an implementation for a user-defined numeric type that does not satisfy the Integral Constant requirements. — end note]

Expression semantics

For arbitrary Integral Constant c and unsigned Integral Constant shift:

typedef shift_left<c,shift>::type r;
Return type:

Integral Constant.

Semantics:

Equivalent to

typedef integral_c<
      c::value_type
    , ( c::value << shift::value )
    > r;
typedef shift_left<c,shift> r;
Return type:

Integral Constant.

Semantics:

Equivalent to

struct r : shift_left<c,shift>::type {};

Complexity

Amortized constant time.

Example

typedef integral_c<unsigned,0> u0;
typedef integral_c<unsigned,1> u1;
typedef integral_c<unsigned,2> u2;
typedef integral_c<unsigned,8> u8;

BOOST_MPL_ASSERT_RELATION( (shift_left<u0,u0>::value), ==, 0 );
BOOST_MPL_ASSERT_RELATION( (shift_left<u1,u0>::value), ==, 1 );
BOOST_MPL_ASSERT_RELATION( (shift_left<u1,u1>::value), ==, 2 );
BOOST_MPL_ASSERT_RELATION( (shift_left<u2,u1>::value), ==, 4 );
BOOST_MPL_ASSERT_RELATION( (shift_left<u8,u1>::value), ==, 16 );

See also

Bitwise Operations, Numeric Metafunction, numeric_cast, shift_right, bitand_