| .. Sequences/Intrinsic Metafunctions//push_front |
| |
| push_front |
| ========== |
| |
| Synopsis |
| -------- |
| |
| .. parsed-literal:: |
| |
| template< |
| typename Sequence |
| , typename T |
| > |
| struct push_front |
| { |
| typedef |unspecified| type; |
| }; |
| |
| |
| |
| Description |
| ----------- |
| |
| ``push_front`` performs an insertion at the beginning of the sequence with guaranteed |O(1)| |
| complexity. |
| |
| |
| Header |
| ------ |
| |
| .. parsed-literal:: |
| |
| #include <boost/mpl/push_front.hpp> |
| |
| |
| Model of |
| -------- |
| |
| |Tag Dispatched Metafunction| |
| |
| |
| Parameters |
| ---------- |
| |
| +---------------+-------------------------------+-----------------------------------------------+ |
| | Parameter | Requirement | Description | |
| +===============+===============================+===============================================+ |
| | ``Sequence`` | |Front Extensible Sequence| | A sequence to insert into. | |
| +---------------+-------------------------------+-----------------------------------------------+ |
| | ``T`` | Any type | The element to be inserted. | |
| +---------------+-------------------------------+-----------------------------------------------+ |
| |
| |
| |
| Expression semantics |
| -------------------- |
| |
| |
| For any |Front Extensible Sequence| ``s`` and arbitrary type ``x``: |
| |
| |
| .. parsed-literal:: |
| |
| typedef push_front<s,x>::type r; |
| |
| :Return type: |
| |Front Extensible Sequence|. |
| |
| :Semantics: |
| Equivalent to |
| |
| .. parsed-literal:: |
| |
| typedef insert< s,begin<s>::type,x >::type r; |
| |
| |
| :Postcondition: |
| ``size<r>::value == size<s>::value + 1``; |
| ``front<r>::type`` is identical to ``x``. |
| |
| |
| Complexity |
| ---------- |
| |
| Amortized constant time. |
| |
| |
| Example |
| ------- |
| |
| .. parsed-literal:: |
| |
| typedef vector_c<int,1,2,3,5,8,13,21> v; |
| BOOST_MPL_ASSERT_RELATION( size<v>::value, ==, 7 ); |
| |
| typedef push_front< v,integral_c<int,1> >::type fibonacci; |
| BOOST_MPL_ASSERT_RELATION( size<fibonacci>::value, ==, 8 ); |
| |
| BOOST_MPL_ASSERT(( equal< |
| fibonacci |
| , vector_c<int,1,1,2,3,5,8,13,21> |
| , equal_to<_,_> |
| > )); |
| |
| |
| See also |
| -------- |
| |
| |Front Extensible Sequence|, |insert|, |pop_front|, |front|, |push_back| |
| |
| |
| .. 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) |