jh::concepts::is_iterator Concept Reference

Concept for detecting iterator-like types based on behavior. More...

#include <jh/conceptual/iterator.h>

Concept definition

    template<typename I>
    concept is_iterator =requires(I it) {
        *it;
        { ++it } -> std::same_as<I &>;
        it++;
    } &&
                         (
                                 
                                 (!requires { typename I::difference_type; }) ||
                                 (requires { typename I::difference_type; } &&
                                  !std::same_as<typename I::difference_type, void> &&
                                  std::signed_integral<typename I::difference_type>
                                 )
                         ) &&
                         (
                                 
                                 (!requires { typename I::difference_type; } || !requires(I a, I b) { a - b; }) ||
                                 (requires(I a, I b) {
                                     typename I::difference_type;
                                     { a - b } -> std::convertible_to<typename I::difference_type>;
                                 }
                                 )
                         )

Detailed Description

Concept for detecting iterator-like types based on behavior.

• Supports basic iteration operations: *it, ++it, and it++.
• If difference_type is defined, it must be a signed integral type.
• If both difference_type and operator- are defined, the result of a - b must be convertible to difference_type.
• difference_type may be omitted, but its definition must not conflict with iterator arithmetic semantics.

Template Parameters

I	Type to be tested for iterator-like behavior.

Note

Conceptually equivalent to std::input_or_output_iterator but implemented through pure behavioral (duck-typed) validation.