Class Body implementing the concept of parallel_scan body must define:

Body::Body( Body&, split );

tbb::split
Dummy type that distinguishes splitting constructor from copy constructor.
Definition: tbb_stddef.h:416

Splitting constructor. Split b so that this and b can accumulate separately
Body::~Body();

Destructor
void Body::operator()( const Range& r, pre_scan_tag );

tbb::pre_scan_tag
Used to indicate that the initial scan is being performed.
Definition: parallel_scan.h:32

Preprocess iterations for range r
void Body::operator()( const Range& r, final_scan_tag );

tbb::final_scan_tag
Used to indicate that the final scan is being performed.
Definition: parallel_scan.h:39

Do final processing for iterations of range r
void Body::reverse_join( Body& a );

Merge preprocessing state of a into this, where a was created earlier from b by b's splitting constructor