A type Body satisfies ParallelForBody if it meets the Function Objects requirements from the [function.objects] ISO C++ Standard section. It should also meet one of the following requirements:

ParallelForEachBody Requirements: Pseudo-Signature, Semantics

Body::operator()(ItemType item) const

Process the received item.

Body::operator()(ItemType item, tbb::feeder<ItemType> &feeder) const

Process the received item. May invoke the feeder.add(T) function to spawn additional items.


ItemType may be optionally passed to Body::operator() by reference. const and volatile type qualifiers are also applicable.


The argument type ItemType should either satisfy the CopyConstructibe, MoveConstructibe or both requirements from the ISO C++ [utility.arg.requirements] section. If the type is not CopyConstructibe, there are additional usage restrictions:

  • If Body::operator() accepts an argument by value, or if the InputIterator type from parallel_for_each algorithm does not satisfy the Forward Iterator requirements from the [forward.iterators] ISO C++ Standard section, dereferencing an InputIterator must produce an rvalue reference.

  • Additional work items should be passed to the feeder as rvalues, for example, via the std::move function.

See also: