CODEWITHSUNDEEP
c++pointersiterator
Björn Pollex
Björn Pollex

Reputation: 76778

How to define pointer for a custom input iterator

I am writing a custom input iterator that adapts an underlying sequence and yields transformed values (I know about boost::transform_iterator, but this is special).

I am unsure how to define pointer-type for this iterator. Since the iterator generates values on the fly, reference is defined as an alias for value_type (which is allowed for input iterators, reference must merely be convertible to value_type). My intuition is that it would still just be value_type *, and I can't really think of anything else that would make sense.

However, I haven't found any information about the context in which pointer is expected to be used, and hence don't know what requirements are placed on it, and the documentation of boost::transform_iterator (which usually offers useful advice) is silent on this issue.

So my question is, is it generally safe to just define pointer as value_type *? If not, what are the alternatives?

Upvotes: 2

Views: 119

Answers (1)

NathanOliver
NathanOliver

Reputation: 180424

The only thing I can find in the standard that calls out what they should refers to comes from [iterator.traits]

[...]In addition, the types

iterator_traits<Iterator>::reference
iterator_traits<Iterator>::pointer

shall be defined as the iterator’s reference and pointer types, that is, for an iterator object a, the same type as the type of *a and a->, respectively.

Upvotes: 2

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