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no-throw-input-iterator, no-throw-forward-iterator, no-throw-sentinel-for, no-throw-input-range, no-throw-forward-range

template< class I >
concept no-throw-input-iterator =
    std::input_iterator<I> &&
    std::is_lvalue_reference_v<std::iter_reference_t<I>> &&
    std::same_as<std::remove_cvref_t<std::iter_reference_t<I>>, std::iter_value_t<I>>;
 (1) (exposition only*) 
template< class I >
concept no-throw-forward-iterator =
    no-throw-input-iterator<I> &&
    std::forward_iterator<I> &&
    no-throw-sentinel-for<I, I>;
 (2) (exposition only*) 
template< class S, class I >
concept no-throw-sentinel-for = std::sentinel_for<S, I>;
 (3) (exposition only*) 
template< class R >
concept no-throw-input-range =
    ranges::range<R> &&
    no-throw-input-iterator<ranges::iterator_t<R>> &&
    no-throw-sentinel-for<ranges::sentinel_t<R>, ranges::iterator_t<R>>;
 (4) (exposition only*) 
template< class R >
concept no-throw-forward-range =
    no-throw-input-range<R> &&
    no-throw-forward-iterator<ranges::iterator_t<R>>;
 (5) (exposition only*)

These exposition-only concepts specify that no exceptions are thrown from operations required by algorithms on iterators, sentinels, and ranges.

1) The no-throw-input-iterator concept requires that dereferencing the iterator yields an lvalue, like contiguous_iterator and LegacyForwardIterator.

Semantic requirements

Like all standard concepts, every concept listed here is modeled only if all concepts it subsumes are modeled.

1) A type I models no-throw-input-iterator only if no exceptions are thrown from increment, copy construction, move construction, copy assignment, move assignment, or indirection through valid iterators.
3) Types S and I model no-throw-sentinel-for only if no exceptions are thrown from copy construction, move construction, copy assignment, move assignment, or comparisons between valid values of type I and S.
4) A type R models no-throw-input-range only if no exceptions are thrown from calls to ranges::begin and ranges::end on an object of type R.

Notes

These concepts allow some operations on iterators and sentinels to throw exceptions, e.g. operations on invalid values.

See also

(C++20)
specifies that a type is an input iterator, that is, its referenced values can be read and it can be both pre- and post-incremented
(concept)
(C++20)
specifies that an input_iterator is a forward iterator, supporting equality comparison and multi-pass
(concept)
(C++20)
specifies a type is a sentinel for an input_or_output_iterator type
(concept)
(C++20)
specifies a range whose iterator type satisfies input_iterator
(concept)
(C++20)
specifies a range whose iterator type satisfies forward_iterator
(concept)

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https://en.cppreference.com/w/cpp/memory/ranges/nothrow_concepts