jh::concepts::random_access_iterator Concept Reference

Concept for iterators supporting random access operations. More...

#include <jh/conceptual/iterator.h>

Concept definition

    template<typename I, typename S = I>
    concept random_access_iterator =
    bidirectional_iterator<I, S> &&
 
    // Can be compared
    requires(const I a, const I b) {
        { a < b }  -> std::convertible_to<bool>;
        { a > b }  -> std::convertible_to<bool>;
        { a <= b } -> std::convertible_to<bool>;
        { a >= b } -> std::convertible_to<bool>;
        // (forward) has already proven that == and != exist
    } &&
 
    
    requires(const I a, const I b) {
        typename jh::concepts::iterator_difference_t<I>;
        requires (!std::same_as<jh::concepts::iterator_difference_t<I>, void>);
        
    } &&
 
    
    requires(I i, const I j, const jh::concepts::iterator_difference_t<I> n) {
        { i += n } -> std::same_as<I &>;
        { i -= n } -> std::same_as<I &>;
        { j + n }  -> std::same_as<I>;
        { n + j }  -> std::same_as<I>;
        { j - n }  -> std::same_as<I>;
        { j[n] }   -> std::same_as<jh::concepts::iterator_reference_t<I>>;
    }

Detailed Description

Concept for iterators supporting random access operations.

• Refines bidirectional_iterator, extending capabilities to constant-time positional access and arithmetic offset operations.
• Requires full comparison support: <, >, <=, and >=. Equality and inequality are already guaranteed by forward_iterator.
• Requires a valid iterator_difference_t type for distance computation between iterators.
• Must support arithmetic and indexing: i += n, i -= n, j + n, n + j, j - n, and j[n].
• An optional sentinel type S can be provided to check range consistency between begin() and end().

Template Parameters

I	Iterator-like type supporting random access and arithmetic operations.
S	Sentinel type used to verify consistency (defaults to I).