| .. Iterators/Iterator Metafunctions//deref |50 |
| |
| deref |
| ===== |
| |
| Synopsis |
| -------- |
| |
| .. parsed-literal:: |
| |
| template< |
| typename Iterator |
| > |
| struct deref |
| { |
| typedef |unspecified| type; |
| }; |
| |
| |
| |
| Description |
| ----------- |
| |
| Dereferences an iterator. |
| |
| |
| Header |
| ------ |
| |
| .. parsed-literal:: |
| |
| #include <boost/mpl/deref.hpp> |
| |
| |
| |
| Parameters |
| ---------- |
| |
| +---------------+---------------------------+-----------------------------------+ |
| | Parameter | Requirement | Description | |
| +===============+===========================+===================================+ |
| | ``Iterator`` | |Forward Iterator| | The iterator to dereference. | |
| +---------------+---------------------------+-----------------------------------+ |
| |
| |
| Expression semantics |
| -------------------- |
| |
| For any |Forward Iterator|\ s ``iter``: |
| |
| |
| .. parsed-literal:: |
| |
| typedef deref<iter>::type t; |
| |
| :Return type: |
| A type. |
| |
| :Precondition: |
| ``iter`` is dereferenceable. |
| |
| :Semantics: |
| ``t`` is identical to the element referenced by ``iter``. If ``iter`` is |
| a user-defined iterator, the library-provided default implementation is |
| equivalent to |
| |
| .. parsed-literal:: |
| |
| typedef iter::type t; |
| |
| |
| |
| |
| Complexity |
| ---------- |
| |
| Amortized constant time. |
| |
| |
| Example |
| ------- |
| |
| .. parsed-literal:: |
| |
| typedef vector<char,short,int,long> types; |
| typedef begin<types>::type iter; |
| |
| BOOST_MPL_ASSERT(( is_same< deref<iter>::type, char > )); |
| |
| |
| See also |
| -------- |
| |
| |Iterators|, |begin| / |end|, |next| |
| |
| |
| .. 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) |
