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1210. Iterator reachability should not require a container

Section: 24.3[iterator.requirements]Status:ResolvedSubmitter: Alisdair MeredithOpened: 2009-09-18Last modified: 2016-01-28

Priority:Not Prioritized

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Discussion:

p6 Iterator requirements 24.3[iterator.requirements]

An iteratorj is called reachable from an iteratori if and only ifthere is a finite sequence of applications of the expression++i thatmakesi == j. Ifj is reachable fromi, they refer to the samecontainer.

A good example would be stream iterators, which do not refer to acontainer. Typically, the end iterator from a range of stream iteratorswill compare equal for many such ranges. I suggest striking the secondsentence.

An alternative wording might be:

Ifj is reachable fromi, and bothi andj are dereferencable iterators, then they refer to the samerange.

[2010 Pittsburgh: Moved toNAD EditorialResolved. Rationale added below.]

Rationale:

Solved byN3066.

Proposed resolution:

Change 24.3[iterator.requirements], p6:

An iteratorj is calledreachable from an iteratori if and only if there is a finite sequence of applications ofthe expression++i that makesi == j.Ifj is reachable fromi, they refer to the samecontainer.