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prior

Synopsis

template<
      typename Iterator
    >
struct prior
{
    typedef unspecified type;
};

Description

Returns the previous iterator in the sequence. [Note: prior has a number of overloaded meanings, depending on the type of its argument. For instance, if X is an Integral Constant, prior<X> returns an decremented Integral Constant of the same type. The following specification is iterator-specific. Please refer to the corresponding concept's documentation for the details of the alternative semantics — end note].

Header

#include <boost/mpl/next_prior.hpp>

Parameters

Parameter Requirement Description
Iterator Forward Iterator. An iterator to decrement.

Expression semantics

For any Forward Iterators iter:

typedef prior<iter>::type j; 
Return type:Forward Iterator.
Precondition:iter is decrementable.
Semantics:

j is an iterator pointing to the previous element in the sequence. If iter is a user-defined iterator, the library-provided default implementation is equivalent to

typedef iter::prior j;

Complexity

Amortized constant time.

Example

typedef vector_c<int,1> v;
typedef begin<v>::type first;
typedef end<v>::type last;

BOOST_MPL_ASSERT(( is_same< prior<last>::type, first > ));

See also

Iterators, begin / end, next, deref