Intel Threading Building Blocks

Name

blocked_range<Value> Template Class — Template class for a recursively divisible half-open interval.

Synopsis

#include "tbb/blocked_range.h"

template<typename Value> class blocked_range;

Description

A blocked_range<Value> represents a half-open range [i,j) that can be recursively split. The types i and j must model the requirements in Table 3-3. Because the requirements are pseudosignatures, signatures that differ in ways that can be implicitly converted are allowed. For example, a blocked_range<int> is allowed because the difference of two int values can be implicitly converted to a size_t. Examples that model the Value requirements are integral types, pointers, and STL random-access iterators whose difference can be implicitly converted to a size_t.

A blocked_range models the Range Concept.

Table 3-3. Value Concept for block_range

Pseudosignature	Semantics
Value::Value( const Value& )	Copy constructor
Value::~Value()	Destructor
bool operator<( const Value& i, const Value& j )	Value i precedes value j
size_t operator-( const Value& i, const Value& j )	Number of values in range [i,j)
Value operator+( const Value& i, size_t k )	kth value after i

A blocked_range<Value> specifies a grainsize of type size_t. A blocked_range is splittable into two subranges if the size of the range exceeds grainsize. The ideal grain size depends upon the context of the blocked_range<Value>, which is typically the range argument to the loop templates parallel_for, parallel_reduce