27 Algorithms library [algorithms]

27.10 Generalized numeric operations [numeric.ops]

27.10.11 Transform inclusive scan [transform.inclusive.scan]

template<class InputIterator, class OutputIterator,
         class BinaryOperation, class UnaryOperation>
  constexpr OutputIterator
    transform_inclusive_scan(InputIterator first, InputIterator last,
                             OutputIterator result,
                             BinaryOperation binary_op, UnaryOperation unary_op);
template<class ExecutionPolicy,
         class ForwardIterator1, class ForwardIterator2,
         class BinaryOperation, class UnaryOperation>
  ForwardIterator2
    transform_inclusive_scan(ExecutionPolicy&& exec,
                             ForwardIterator1 first, ForwardIterator1 last,
                             ForwardIterator2 result,
                             BinaryOperation binary_op, UnaryOperation unary_op);
template<class InputIterator, class OutputIterator,
         class BinaryOperation, class UnaryOperation, class T>
  constexpr OutputIterator
    transform_inclusive_scan(InputIterator first, InputIterator last,
                             OutputIterator result,
                             BinaryOperation binary_op, UnaryOperation unary_op,
                             T init);
template<class ExecutionPolicy,
         class ForwardIterator1, class ForwardIterator2,
         class BinaryOperation, class UnaryOperation, class T>
  ForwardIterator2
    transform_inclusive_scan(ExecutionPolicy&& exec,
                             ForwardIterator1 first, ForwardIterator1 last,
                             ForwardIterator2 result,
                             BinaryOperation binary_op, UnaryOperation unary_op,
                             T init);

Let U be the value type of decltype(first).

Mandates: If init is provided, all of

(2.1)
binary_op(init, init),
(2.2)
binary_op(init, unary_op(*first)), and
(2.3)
binary_op(unary_op(*first), unary_op(*first))

are convertible to T; otherwise, binary_op(unary_op(*first), unary_op(*first)) is convertible to U.

Preconditions:

(3.1)
If init is provided, T meets the Cpp17MoveConstructible (Table 31) requirements; otherwise, U meets the Cpp17MoveConstructible requirements.
(3.2)
Neither unary_op nor binary_op invalidates iterators or subranges, nor modifies elements in the ranges [first, last] or [result, result + (last - first)].

Effects: For each integer K in [0, last - first) assigns through result + K the value of

(4.1)
GENERALIZED_NONCOMMUTATIVE_SUM(
binary_op, init,
unary_op(*(first + 0)), unary_op(*(first + 1)), ..., unary_op(*(first + K)))

if init is provided, or
(4.2)
GENERALIZED_NONCOMMUTATIVE_SUM(
binary_op,
unary_op(*(first + 0)), unary_op(*(first + 1)), ..., unary_op(*(first + K)))

otherwise.

Returns: The end of the resulting range beginning at result.

Complexity:

O (last - first)

applications each of unary_op and binary_op.

Remarks: result may be equal to first.

[Note 1:

The difference between transform_exclusive_scan and transform_inclusive_scan is that transform_inclusive_scan includes the

i^{th}

input element in the

i^{th}

sum.

If binary_op is not mathematically associative, the behavior of transform_inclusive_scan can be nondeterministic.

transform_inclusive_scan does not apply unary_op to init.

— end note]