BlitzArraySliceIterator. More...

#include <BlitzArraySliceIterator.h>

Inheritance diagram for blitzplusplus::basi::Iterator< RANK, V, IS_CONST >:

Collaboration diagram for blitzplusplus::basi::Iterator< RANK, V, IS_CONST >:

Public Types
typedef boost::mpl::if_c< RANK==1, details::BaseTrivial< V, IS_CONST >, typename boost::mpl::if_c< RANK==Size< V >::value, details::BaseSpecial< V, IS_CONST >, details::Base< RANK, V, IS_CONST > >::type >::type	Base

typedef Base::CcCA	CcCA
	ttd::ConditionalConstCArray

typedef boost::iterator_range< Iterator >	Range
	Boost.Range-compliant range.

Public Member Functions
Iterator &	operator++ ()
	For the ForwardIterator concept.

template<bool IS_END>
	Iterator (CcCA &array, boost::mpl::bool_< IS_END > isEnd)
	Can be initialized either to the beginning or the end of the sequence of dummy-index combinations. More...

Related Functions
(Note that these are not member functions.)
template<typename V , typename A >
const Iterator< Rank< A >::value, V, false >	begin (A &array)
	Iterator to the beginning of the (non-const) sequence. More...

template<typename V , typename A >
const Iterator< Rank< A >::value, V, false >	end (A &array)
	” for the end More...

template<typename V , typename A >
const Iterator< Rank< A >::value, V, true >	begin (const A &array)
	Iterator to the beginning of the (const) sequence. More...

template<typename V , typename A >
const Iterator< Rank< A >::value, V, true >	end (const A &array)
	“ for the end More...

template<typename V , typename A >
const boost::iterator_range< Iterator< Rank< A >::value, V, false > >	fullRange (A &array)
	Boost.Range-compliant full range of slice iterators More...

template<typename V , typename A >
const boost::iterator_range< Iterator< Rank< A >::value, V, true > >	fullRange (const A &array)
	” const version More...

Detailed Description

template<int RANK, typename V, bool IS_CONST>
class blitzplusplus::basi::Iterator< RANK, V, IS_CONST >

BlitzArraySliceIterator.

Template Parameters

RANK	positive integer standing for the number of elementary Hilbert spaces
V	compile-time vector holding the retained index positions like $\avr{3,6,1,9,7}$ here. (Cf. Specifying subsystems)
IS_CONST	governs the constness of the class

To understand the template parameters, cf. also The multi-array concept.

Model of ForwardIterator. Can be both const and non-const iterator depending on the last template argument.

This iterator is implemented in terms of a cpputils::MultiIndexIterator, and hence it can be initialized to either the beginning or the end of the “sequence”.

This class is at the absolute heart of the framework as it is indispensable to implement

composite quantum systems (Composite and BinarySystem)
iterations over (multi)matrix rows and columns to get (multi)vectors
quantumdata::ldo::DiagonalIterator

This said, it is never really used directly in the framework, but rather through the maker functions blitzplusplus::basi::begin, blitzplusplus::basi::end, and blitzplusplus::basi::fullRange in standard or Boost.Range algorithms.

Quite generally, by iterating through all the combinations of indices not belonging to the given subsystem (dummy indices) and when dereferenced returning the corresponding slice, it can be used to implement the action of operators in extended (and/or permutated) Hilbert spaces.

Semantics

Sticking to the example here, assume that the function

void actWithA(CArray<5>&);

implements the action of the operator $A$ on a state vector of rank 5. Then the action on the extended Hilbert space can be calculated as

void actOnExtended(CArray<11>& psi)
{
  boost::for_each(blitzplusplus::basi::fullRange<tmptools::Vector<3,6,1,9,7> >(psi),
                  actWithA);
}

See also: blitzplusplus::basi::fullRange and the for_each algorithm of Boost.Range.

For further basic examples of usage cf. utils/testsuite/BlitzArraySliceIterator.cc & utils/testsuite/BlitzArraySliceIteratorTMP.cc.

See also: Notes on the implementation of Iterator

Todo:: Implement a default version of Iterator for the case when neither slicing nor transposition is necessary, that is when V is equivalent to a range<0,RANK-1>. This will require further compile-time implementation selection.

Todo:: Refine the iterator category according to the New-Style Iterator concepts. The point is that a multi-array is not a container of slices, so Iterator is definitely not a standard iterator. It seems rather like a proxy iterator.

Definition at line 297 of file BlitzArraySliceIterator.h.

Constructor & Destructor Documentation

template<int RANK, typename V , bool IS_CONST>

template<bool IS_END>

blitzplusplus::basi::Iterator< RANK, V, IS_CONST >::Iterator	(	CcCA &	array,
		boost::mpl::bool_< IS_END >	isEnd
	)

inline

Can be initialized either to the beginning or the end of the sequence of dummy-index combinations.

Template Parameters

IS_END governs the end-ness

Definition at line 316 of file BlitzArraySliceIterator.h.