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				.. Sequences/Intrinsic Metafunctions//empty								.. Copyright Aleksey Gurtovoy, David Abrahams 2007.				.. Distributed under the Boost				.. Software License, Version 1.0. (See accompanying				.. file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)								empty				=====								Synopsis				--------								.. parsed-literal::				    				    template				          typename Sequence				        >				    struct empty				    {				        typedef |unspecified| type;				    };																Description				-----------								Returns an |Integral Constant| ``c`` such that ``c::value == true`` if 				and only if the sequence is empty.												Header				------								.. parsed-literal::				    				    #include 												Model of				--------								|Tag Dispatched Metafunction|												Parameters				----------								+---------------+-----------------------+-----------------------------------+				| Parameter     | Requirement           | Description                       |				+===============+=======================+===================================+				| ``Sequence``  | |Forward Sequence|    | A sequence to test.               |				+---------------+-----------------------+-----------------------------------+												Expression semantics				--------------------								For any |Forward Sequence| ``s``:												.. parsed-literal::								    typedef empty::type c; 								:Return type:				    Boolean |Integral Constant|.								:Semantics:				    Equivalent to ``typedef is_same< begin::type,end::type >::type c;``.								:Postcondition:				    ``empty::value == ( size::value == 0 )``.																Complexity				----------								Amortized constant time.												Example				-------								.. parsed-literal::				    				    typedef range_c empty_range;				    typedef vector types;				    				    BOOST_MPL_ASSERT( empty );				    BOOST_MPL_ASSERT_NOT( empty );												See also				--------								|Forward Sequence|, |Integral Constant|, |size|, |begin| / |end|