1.. Sequences/Intrinsic Metafunctions//clear 2 3clear 4===== 5 6Synopsis 7-------- 8 9.. parsed-literal:: 10 11 template< 12 typename Sequence 13 > 14 struct clear 15 { 16 typedef |unspecified| type; 17 }; 18 19 20 21Description 22----------- 23 24Returns an empty sequence |concept-identical| to ``Sequence``. 25 26 27Header 28------ 29 30.. parsed-literal:: 31 32 #include <boost/mpl/clear.hpp> 33 34 35Model of 36-------- 37 38|Tag Dispatched Metafunction| 39 40 41Parameters 42---------- 43 44+---------------+-----------------------------------+---------------------------------------+ 45| Parameter | Requirement | Description | 46+===============+===================================+=======================================+ 47| ``Sequence`` | |Extensible Sequence| or | A sequence to get an empty "copy" of. | 48| | |Extensible Associative Sequence| | | 49+---------------+-----------------------------------+---------------------------------------+ 50 51 52Expression semantics 53-------------------- 54 55For any |Extensible Sequence| or |Extensible Associative Sequence| ``s``: 56 57 58.. parsed-literal:: 59 60 typedef clear<s>::type t; 61 62:Return type: 63 |Extensible Sequence| or |Extensible Associative Sequence|. 64 65:Semantics: 66 Equivalent to 67 68 .. parsed-literal:: 69 70 typedef erase< s, begin<s>::type, end<s>::type >::type t; 71 72 73:Postcondition: 74 ``empty<s>::value == true``. 75 76 77Complexity 78---------- 79 80Amortized constant time. 81 82 83Example 84------- 85 86.. parsed-literal:: 87 88 typedef vector_c<int,1,3,5,7,9,11> odds; 89 typedef clear<odds>::type nothing; 90 91 BOOST_MPL_ASSERT(( empty<nothing> )); 92 93 94See also 95-------- 96 97|Extensible Sequence|, |Extensible Associative Sequence|, |erase|, |empty|, |begin|, |end| 98 99 100.. copyright:: Copyright � 2001-2009 Aleksey Gurtovoy and David Abrahams 101 Distributed under the Boost Software License, Version 1.0. (See accompanying 102 file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) 103