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Element iteration

This section refers to element iteration over interval containers. Element iterators are available as associated types on interval sets and interval maps.

Variant

Associated element iterator type for interval container T

forward

T::element_iterator

const forward

T::element_const_iterator

reverse

T::element_reverse_iterator

const reverse

T::element_const_reverse_iterator

There are also associated iterators types T::iterator, T::const_iterator, T::reverse_iterator and T::reverse_const_iterator on interval containers. These are segment iterators. Segment iterators are "first citizen iterators". Iteration over segments is fast, compared to an iteration over elements, particularly if intervals are large. But if we want to view our interval containers as containers of elements that are usable with std::algoritms, we need to iterate over elements.

Iteration over elements . . .

On the other hand, sometimes iteration over interval containers on the element level might be desired, if you have some interface that works for std::SortedAssociativeContainers of elements and you need to quickly use it with an interval container. Accepting the poorer performance might be less bothersome at times than adjusting your whole interface for segment iteration.

[Caution] Caution

So we advice you to choose element iteration over interval containers judiciously. Do not use element iteration by default or habitual. Always try to achieve results using member functions, global functions or operators (preferably inplace versions) or iteration over segments first.

Synopsis Complexities

interval
sets

interval
maps

J elements_begin(T&)

O(1)

O(1)

J elements_end(T&)

O(1)

O(1)

J elements_rbegin(T&)

O(1)

O(1)

J elements_rend(T&)

O(1)

O(1)

Element iteration

Description

      element_iterator elements_begin(T&)
element_const_iterator elements_begin(const T&)

Returns an element iterator to the first element of the container.

      element_iterator elements_end(T&)
element_const_iterator elements_end(const T&)

Returns an element iterator to a position elements_end(c) after the last element of the container.

      element_reverse_iterator elements_rbegin(T&)
element_const_reverse_iterator elements_rbegin(const T&)

Returns a reverse element iterator to the last element of the container.

      element_reverse_iterator elements_rend(T&)
element_const_reverse_iterator elements_rend(const T&)

Returns a reverse element iterator to a position elements_rend(c) before the first element of the container.

Example

interval_set<int> inter_set;
inter_set.add(interval<int>::right_open(0,3))
         .add(interval<int>::right_open(7,9));

for(interval_set<int>::element_const_iterator creeper = elements_begin(inter_set); 
    creeper != elements_end(inter_set); ++creeper)
    cout << *creeper << " ";
cout << endl;
//Program output: 0 1 2 7 8

for(interval_set<int>::element_reverse_iterator repeerc = elements_rbegin(inter_set); 
    repeerc != elements_rend(inter_set); ++repeerc)
    cout << *repeerc << " ";
cout << endl;
//Program output: 8 7 2 1 0

See also . . .

Segment iteration

Back to section . . .

Function Synopsis

Interface


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