| .. Sequences/Intrinsic Metafunctions//erase_key |
| |
| erase_key |
| ========= |
| |
| Synopsis |
| -------- |
| |
| .. parsed-literal:: |
| |
| template< |
| typename AssocSeq |
| , typename Key |
| > |
| struct erase_key |
| { |
| typedef |unspecified| type; |
| }; |
| |
| |
| |
| Description |
| ----------- |
| |
| Erases elements associated with the key ``Key`` in the |Extensible Associative Sequence| |
| ``AssocSeq`` . |
| |
| Header |
| ------ |
| |
| .. parsed-literal:: |
| |
| #include <boost/mpl/erase_key.hpp> |
| |
| |
| Model of |
| -------- |
| |
| |Tag Dispatched Metafunction| |
| |
| |
| Parameters |
| ---------- |
| |
| +---------------+-----------------------------------+-----------------------------------------------+ |
| | Parameter | Requirement | Description | |
| +===============+===================================+===============================================+ |
| | ``AssocSeq`` | |Extensible Associative Sequence| | A sequence to erase elements from. | |
| +---------------+-----------------------------------+-----------------------------------------------+ |
| | ``Key`` | Any type | A key for the elements to be removed. | |
| +---------------+-----------------------------------+-----------------------------------------------+ |
| |
| |
| Expression semantics |
| -------------------- |
| |
| For any |Extensible Associative Sequence| ``s``, and arbitrary type ``key``: |
| |
| |
| .. parsed-literal:: |
| |
| typedef erase_key<s,key>::type r; |
| |
| :Return type: |
| |Extensible Associative Sequence|. |
| |
| :Semantics: |
| ``r`` is |concept-identical| and equivalent to ``s`` except that |
| ``has_key<r,k>::value == false``. |
| |
| :Postcondition: |
| ``size<r>::value == size<s>::value - 1``. |
| |
| |
| |
| Complexity |
| ---------- |
| |
| Amortized constant time. |
| |
| |
| Example |
| ------- |
| |
| .. parsed-literal:: |
| |
| typedef map< pair<int,unsigned>, pair<char,long> > m; |
| typedef erase_key<m,char>::type m1; |
| |
| BOOST_MPL_ASSERT_RELATION( size<m1>::type::value, ==, 1 ); |
| BOOST_MPL_ASSERT(( is_same< at<m1,char>::type,void\_ > )); |
| BOOST_MPL_ASSERT(( is_same< at<m1,int>::type,unsigned > )); |
| |
| |
| See also |
| -------- |
| |
| |Extensible Associative Sequence|, |erase|, |has_key|, |insert| |
| |
| |
| .. 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) |
