forked from boostorg/mpl
71 lines
1.6 KiB
ReStructuredText
71 lines
1.6 KiB
ReStructuredText
.. Sequences/Views//empty_sequence
|
|
|
|
empty_sequence
|
|
==============
|
|
|
|
Synopsis
|
|
--------
|
|
|
|
.. parsed-literal::
|
|
|
|
struct empty_sequence
|
|
{
|
|
// |unspecified|
|
|
// |...|
|
|
};
|
|
|
|
|
|
Description
|
|
-----------
|
|
|
|
Represents a sequence containing no elements.
|
|
|
|
|
|
Header
|
|
------
|
|
|
|
.. parsed-literal::
|
|
|
|
#include <boost/mpl/empty_sequence.hpp>
|
|
|
|
|
|
Expression semantics
|
|
--------------------
|
|
|
|
|Semantics disclaimer...| |Random Access Sequence|.
|
|
|
|
In the following table, ``s`` is an instance of ``empty_sequence``.
|
|
|
|
+-------------------------------+-----------------------------------------------------------+
|
|
| Expression | Semantics |
|
|
+===============================+===========================================================+
|
|
| ``empty_sequence`` | An empty |Random Access Sequence|. |
|
|
+-------------------------------+-----------------------------------------------------------+
|
|
| ``size<s>::type`` | ``size<s>::value == 0``; see |Random Access Sequence|. |
|
|
+-------------------------------+-----------------------------------------------------------+
|
|
|
|
|
|
Example
|
|
-------
|
|
|
|
.. parsed-literal::
|
|
|
|
typedef begin<empty_sequence>::type first;
|
|
typedef end<empty_sequence>::type last;
|
|
|
|
BOOST_MPL_ASSERT(( is_same<first,last> ));
|
|
BOOST_MPL_ASSERT_RELATION( size<empty_sequence>::value, ==, 0 );
|
|
|
|
typedef transform_view<
|
|
empty_sequence
|
|
, add_pointer<_>
|
|
> empty_view;
|
|
|
|
BOOST_MPL_ASSERT_RELATION( size<empty_sequence>::value, ==, 0 );
|
|
|
|
|
|
See also
|
|
--------
|
|
|
|
|Sequences|, |Views|, |vector|, |list|, |single_view|
|