Issue 691: const_local_iterator cbegin, cend missing from TR1

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691. const_local_iterator cbegin, cend missing from TR1

Section: 23.5 [unord], 99 [tr.hash] Status: CD1 Submitter: Joaquín M López Muñoz Opened: 2007-06-14 Last modified: 2016-01-28

Priority: Not Prioritized

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Discussion:

The last version of TR1 does not include the following member functions for unordered containers:

const_local_iterator cbegin(size_type n) const;
const_local_iterator cend(size_type n) const;

which looks like an oversight to me. I've checked th TR1 issues lists and the latest working draft of the C++0x std (N2284) and haven't found any mention to these menfuns or to their absence.

Is this really an oversight, or am I missing something?

Proposed resolution:

Add the following two rows to table 93 (unordered associative container requirements) in section 23.2.8 [unord.req]:

Unordered associative container requirements (in addition to container)
expression return type assertion/note pre/post-condition complexity

b.cbegin(n) const_local_iterator n shall be in the range [0, bucket_count()). Note: [b.cbegin(n), b.cend(n)) is a valid range containing all of the elements in the n^th bucket. Constant

b.cend(n) const_local_iterator n shall be in the range [0, bucket_count()). Constant

Unordered associative container requirements (in addition to container)
expression	return type	assertion/note pre/post-condition	complexity
`b.cbegin(n)`	`const_local_iterator`	`n` shall be in the range `[0, bucket_count())`. Note: `[b.cbegin(n), b.cend(n))` is a valid range containing all of the elements in the `n`^th bucket.	Constant
`b.cend(n)`	`const_local_iterator`	`n` shall be in the range `[0, bucket_count())`.	Constant

Add to the synopsis in 23.5.3 [unord.map]:

const_local_iterator cbegin(size_type n) const;
const_local_iterator cend(size_type n) const;

Add to the synopsis in 23.5.4 [unord.multimap]:

const_local_iterator cbegin(size_type n) const;
const_local_iterator cend(size_type n) const;

Add to the synopsis in 23.5.6 [unord.set]:

const_local_iterator cbegin(size_type n) const;
const_local_iterator cend(size_type n) const;

Add to the synopsis in 23.5.7 [unord.multiset]:

const_local_iterator cbegin(size_type n) const;
const_local_iterator cend(size_type n) const;