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front_insert_iterator& operator=(const FrontInsertionSequence::value_type&) | Output Iterator | Used to implement the output iterator expression *i = x. [3] |
front_insert_iterator& operator++() | Output Iterator | Preincrement. |
front_insert_iterator& operator++(int) | Output Iterator | Postincrement. |
output_iterator_tag iterator_category(const front_insert_iterator&) iterator tags | Returns the iterator's category. | This is a global function, not a member. |
template<class FrontInsertionSequence> front_insert_iterator<FrontInsertionSequence> front_inserter(FrontInsertionSequence& S) | front_insert_iterator | See below. |
New members. These members are not defined in the Output Iterator requirements, but are specific to front_insert_iterator.
| Member | Description |
front_insert_iterator(FrontInsertionSequence& S) | Constructs a front_insert_iterator that inserts objects before the first element of S. |
template<class FrontInsertionSequence> front_insert_iterator<FrontInsertionSequence> front_inserter(FrontInsertionSequence& S); | Equivalent to front_insert_iterator<FrontInsertionSequence> (S). [4] This is a global function, not a member function. |
Notes [1] Note the difference between assignment through a FrontInsertionSequence::iterator and assignment through an front_insert_iterator<FrontInsertionSequence>. If i is a valid FrontInsertionSequence::iterator, then it points to some particular element in the front insertion sequence; the expression *i = t replaces that element with t, and does not change the total number of elements in the sequence. If ii is a valid front_insert_iterator<FrontInsertionSequence>, however, then the expression *ii = t is equivalent, for some FrontInsertionSequence seq, to the expression seq.push_front(t). That is, it does not overwrite any of seq's elements and it does change seq's size.
[2] Note the difference between a front_insert_iterator and an insert_iterator. It may seem that a front_insert_iterator is the same as an insert_iterator constructed with an insertion point that is the beginning of a sequence. In fact, though, there is a very important difference: every assignment through afront_insert_iterator corresponds to an insertion before the first element of the sequence. If you are inserting elements at the beginning of a sequence using an insert_iterator, then the elements will appear in the order in which they were inserted. If, however, you are inserting elements at the beginning of a sequence using a front_insert_iterator, then the elements will appear in the reverse of the order in which they were inserted.
[3] Note how assignment through an front_insert_iterator is implemented. In general, unary operator* must be defined so that it returns a proxy object, where the proxy object defines operator= to perform the insert operation. In this case, for the sake of simplicity, the proxy object is the front_insert_iterator itself. That is, *i simply returns i, and *i = t is equivalent to i = t. You should not, however, rely on this behavior. It is an implementation detail, and it is not guaranteed to remain the same in future versions.
[4] This function exists solely for the sake of convenience: since it is a non-member function, the template parameters may be inferred and the type of the front_insert_iterator need not be declared explicitly. One easy way to reverse a range and insert it at the beginning of a Front Insertion Sequence S, for example, is copy(first, last, front_inserter(S)).
See also insert_iterator, back_insert_iterator, Output Iterator, Sequence, Front Insertion Sequence, Iterator overview
back_insert_iterator<BackInsertionSequence>
Categories: iterators, adaptors
Component type: type
Description Back_insert_iterator is an iterator adaptor that functions as an Output Iterator: assignment through a back_insert_iterator inserts an object after the last element of a
