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Comparing value_type iterator in range constructor

I am writing a cosntructor range for a custom container:

MyContainer(const InputIterator& first, 
            const InputIterator& last, 
            const allocator_type& alloc = allocator_type())

and would like to check that it is InputIterator::value_type

compatible with the container value_type

. At first I tried:

static_assert(!(std::is_convertible<InputIterator::value_type, value_type>::value ||
        std::is_same<InputIterator::value_type, value_type>::value), "error");

and went as far as:

using InputIteratorType = typename std::decay<InputIterator>::type;
using InputValueType = typename std::decay<InputIteratorType::value_type>::type;
static_assert(!(std::is_convertible<InputValueType, value_type>::value ||
        std::is_same<InputValueType, value_type>::value), "error");

but it always asserts even when I use MyContainer::iterator

as an input iterator.

How can I check compatibility InputIterator

?

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1 answer


I guess you probably want std::is_constructible

:

static_assert(std::is_constructible<
    value_type,
    decltype(*first)
    >::value, "error");


Or alternatively, std::is_assignable

depending on whether you are creating or assigning it from input iterators.

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