6.0 KiB
[transform.reduce]
26 Algorithms library [algorithms]
26.10 Generalized numeric operations [numeric.ops]
26.10.6 Transform reduce [transform.reduce]
template<class InputIterator1, class InputIterator2, class T> constexpr T transform_reduce(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, T init);
Effects: Equivalent to:return transform_reduce(first1, last1, first2, init, plus<>(), multiplies<>());
template<class ExecutionPolicy, class ForwardIterator1, class ForwardIterator2, class T> T transform_reduce(ExecutionPolicy&& exec, ForwardIterator1 first1, ForwardIterator1 last1, ForwardIterator2 first2, T init);
Effects: Equivalent to:return transform_reduce(std::forward(exec), first1, last1, first2, init, plus<>(), multiplies<>());
template<class InputIterator1, class InputIterator2, class T, class BinaryOperation1, class BinaryOperation2> constexpr T transform_reduce(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, T init, BinaryOperation1 binary_op1, BinaryOperation2 binary_op2); template<class ExecutionPolicy, class ForwardIterator1, class ForwardIterator2, class T, class BinaryOperation1, class BinaryOperation2> T transform_reduce(ExecutionPolicy&& exec, ForwardIterator1 first1, ForwardIterator1 last1, ForwardIterator2 first2, T init, BinaryOperation1 binary_op1, BinaryOperation2 binary_op2);
Mandates: All of
binary_op1(init, init),
binary_op1(init, binary_op2(*first1, *first2)),
binary_op1(binary_op2(*first1, *first2), init), and
binary_op1(binary_op2(*first1, *first2), binary_op2(*first1, *first2))
are convertible to T.
Preconditions:
-
T meets the Cpp17MoveConstructible (Table 31) requirements.
-
Neither binary_op1 nor binary_op2 invalidates subranges, nor modifies elements in the ranges [first1, last1] and [first2, first2 + (last1 - first1)].
Returns: GENERALIZED_SUM(binary_op1, init, binary_op2(*i, *(first2 + (i - first1))), …) for every iterator i in [first1, last1).
Complexity: O(last1 - first1) applications each of binary_op1 and binary_op2.
template<class InputIterator, class T, class BinaryOperation, class UnaryOperation> constexpr T transform_reduce(InputIterator first, InputIterator last, T init, BinaryOperation binary_op, UnaryOperation unary_op); template<class ExecutionPolicy, class ForwardIterator, class T, class BinaryOperation, class UnaryOperation> T transform_reduce(ExecutionPolicy&& exec, ForwardIterator first, ForwardIterator last, T init, BinaryOperation binary_op, UnaryOperation unary_op);
Mandates: All of
binary_op(init, init),
binary_op(init, unary_op(*first)),
binary_op(unary_op(*first), init), and
binary_op(unary_op(*first), unary_op(*first))
are convertible to T.
Preconditions:
-
T meets the Cpp17MoveConstructible (Table 31) requirements.
-
Neither unary_op nor binary_op invalidates subranges, nor modifies elements in the range [first, last].
Returns: GENERALIZED_SUM(binary_op, init, unary_op(*i), …) for every iterator i in [first, last).
Complexity: O(last - first) applications each of unary_op andbinary_op.
[Note 1:
transform_reduce does not apply unary_op to init.
â end note]