| .. Metafunctions/Comparisons//equal_to |50 |
| |
| equal_to |
| ======== |
| |
| Synopsis |
| -------- |
| |
| .. parsed-literal:: |
| |
| template< |
| typename T1 |
| , typename T2 |
| > |
| struct equal_to |
| { |
| typedef |unspecified| type; |
| }; |
| |
| |
| |
| Description |
| ----------- |
| |
| Returns a true-valued |Integral Constant| if ``T1`` and ``T2`` are equal. |
| |
| |
| Header |
| ------ |
| |
| .. parsed-literal:: |
| |
| #include <boost/mpl/equal_to.hpp> |
| #include <boost/mpl/comparison.hpp> |
| |
| |
| Model of |
| -------- |
| |
| |Numeric Metafunction| |
| |
| |
| Parameters |
| ---------- |
| |
| +---------------+---------------------------+-----------------------------------------------+ |
| | Parameter | Requirement | Description | |
| +===============+===========================+===============================================+ |
| | ``T1``, ``T2``| |Integral Constant| | Operation's arguments. | |
| +---------------+---------------------------+-----------------------------------------------+ |
| |
| |Note:| |numeric metafunction note| |-- end note| |
| |
| |
| Expression semantics |
| -------------------- |
| |
| |
| For any |Integral Constant|\ s ``c1`` and ``c2``: |
| |
| .. parsed-literal:: |
| |
| typedef equal_to<c1,c2>::type r; |
| |
| :Return type: |
| |Integral Constant|. |
| |
| :Semantics: |
| Equivalent to |
| |
| .. parsed-literal:: |
| |
| typedef bool_< (c1::value == c2::value) > r; |
| |
| |
| .. .......................................................................... |
| |
| .. parsed-literal:: |
| |
| typedef equal_to<c1,c2> r; |
| |
| :Return type: |
| |Integral Constant|. |
| |
| :Semantics: |
| Equivalent to |
| |
| .. parsed-literal:: |
| |
| struct r : equal_to<c1,c2>::type {}; |
| |
| |
| |
| Complexity |
| ---------- |
| |
| Amortized constant time. |
| |
| |
| Example |
| ------- |
| |
| .. parsed-literal:: |
| |
| BOOST_MPL_ASSERT_NOT(( equal_to< int_<0>, int_<10> > )); |
| BOOST_MPL_ASSERT_NOT(( equal_to< long_<10>, int_<0> > )); |
| BOOST_MPL_ASSERT(( equal_to< long_<10>, int_<10> > )); |
| |
| |
| See also |
| -------- |
| |
| |Comparisons|, |Numeric Metafunction|, |numeric_cast|, |not_equal_to|, |less| |
| |
| |
| .. copyright:: Copyright © 2001-2009 Aleksey Gurtovoy and David Abrahams |
| 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) |