NAME¶

std::experimental::ranges::Incrementable - std::experimental::ranges::Incrementable

Synopsis¶

Defined in header <experimental/ranges/iterator>
template< class I >

concept bool Incrementable =
Regular<I> &&
WeaklyIncrementable<I> && (ranges TS)
requires(I i) {
{ i++ } -> Same<I>&&;

};

The concept Incrementable<I> specifies the requirements on a type that can be
incremented (with the pre- and post-increment operators). The increment operations
(including those required by WeaklyIncrementable) are required to be
equality-preserving, and the type is required to be EqualityComparable.

Let a and b be incrementable objects of type I. Incrementable<I> is satisfied only
if:

* If bool(a == b) then bool(a++ == b).
* If bool(a == b) then bool(void(a++), a) == ++b).

Equality preservation

An expression is equality preserving if it results in equal outputs given equal
inputs.

* The inputs to an expression consist of its operands.
* The outputs of an expression consist of its result and all operands modified by
the expression (if any).

Every expression required to be equality preserving is further required to be
stable: two evaluations of such an expression with the same input objects must have
equal outputs absent any explicit intervening modification of those input objects.

Unless noted otherwise, every expression used in a requires-expression is required
to be equality preserving and stable, and the evaluation of the expression may only
modify its non-constant operands. Operands that are constant must not be modified.

Notes¶

The requirement that a equals b implies ++a equals ++b allows the use of multi-pass
algorithms with Incrementable types.