The MPL Reference Manual: erase

erase

Synopsis

template<
      typename Sequence
    , typename First
    , typename Last = unspecified
    >
struct erase
{
    typedef unspecified type;
};

Description

erase performs a removal of one or more adjacent elements in the sequence starting from an arbitrary position.

Header

#include <boost/mpl/erase.hpp>

Model of

Tag Dispatched Metafunction

Parameters

Parameter	Requirement	Description
`Sequence`	Extensible Sequence or Extensible Associative Sequence	A sequence to erase from.
`First`	Forward Iterator	An iterator to the beginning of the range to be erased.
`Last`	Forward Iterator	An iterator past-the-end of the range to be erased.

Expression semantics

For any Extensible Sequence s, and iterators pos, first and last into s:

typedef erase::type r;

Return type:	Extensible Sequence.
Precondition:	`[first,last)` is a valid range in `s`.
Semantics:	`r` is a new sequence, concept-identical to `s`, of the following elements: [`begin::type`~~, `pos`), [`last`, `end::type`).~~
Postcondition:	The relative order of the elements in `r` is the same as in `s`; size::value == size~~::value - distance::value~~

typedef erase::type r;

Return type: Extensible Sequence.

Precondition: pos is a dereferenceable iterator in s.

Semantics:

Equivalent to

typedef erase< s,pos,next::type >::type r;

For any Extensible Associative Sequence s, and iterator pos into s:

typedef erase::type r;

Return type:	Extensible Sequence.
Precondition:	`pos` is a dereferenceable iterator to `s`.
Semantics:	Erases the element at a specific position `pos`; equivalent to `erase_key deref::type >::type`.
Postcondition:	`size::value == size::value - 1`.

Complexity

Sequence archetype	Complexity (the range form)
Extensible Associative Sequence	Amortized constant time.
Extensible Sequence	Quadratic in the worst case, linear at best.

Example

typedef vector_c values;
typedef find< values, integral_c >::type pos;
typedef erase::type result;

BOOST_MPL_ASSERT_RELATION( size::value, ==, 7 );

typedef findintegral_c >::type iter;
BOOST_MPL_ASSERT(( is_same< iter, end::type > ));

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