CGAL::Combination_enumerator< CombinationElement > Class Template Reference

#include <CGAL/Combination_enumerator.h>

Definition

template<class CombinationElement>
class CGAL::Combination_enumerator< CombinationElement >

The class Combination_enumerator is used to enumerate all fixed-size combinations (subsets) of a source range of elements.

For example, it can enumerate all the combinations of 2 elements from the source range [3,7) (7 excluded) which gives the enumeration {3,4}, {3,5}, {3,6}, {4,5}, {4,6}, {5,6}. The source range consists of elements of type CombinationElement and is specified by its first element and the element just beyond its last one.

Template Parameters

CombinationElement

should be a model of the concept CombinationElement.

Each combination is uniquely represented as an increasing sequence of elements. Thus, the combinations can be lexicographically ordered. They are enumerated in that order, so that we can talk about the first or last combination.

Examples

Generator/combination_enumerator.cpp, and Generator/name_pairs.cpp.

Creation
	Combination_enumerator (int k, const CombinationElement &first, const CombinationElement &beyond)
	This constructor initializes the object to enumerate the combinations of k elements from the source range [first, beyond).
	Combination_enumerator (const Combination_enumerator &combi)
	The copy constructor.

Access to the Current Combination
const CombinationElement &	operator[] (int i)
	Returns the i-th element of the current combination.

Access to the Enumeration
int	number_of_elements ()
	Returns the size of the enumerated combinations (the parameter k from the class' constructor).
const CombinationElement &	min_element ()
	Returns the smallest element of the source range.
const CombinationElement &	beyond_element ()
	Returns the successor to the largest element of the source range (the parameter beyond of the constructor of the class).
bool	finished ()
	Returns true if and only if all combinations have been enumerated.

Operations
void	reset ()
	Resets the enumerator.
void	operator++ ()
	Moves *this to the next combination.
Combination_enumerator	operator++ (int)
	Post-incrementation.

Constructor & Destructor Documentation

Combination_enumerator()

template<class CombinationElement >

CGAL::Combination_enumerator< CombinationElement >::Combination_enumerator	(	int	k,
		const CombinationElement &	first,
		const CombinationElement &	beyond
	)

This constructor initializes the object to enumerate the combinations of k elements from the source range [first, beyond).

The current combination is set to the first combination of the enumeration.

Precondition

1 <= k <= beyond - first

Member Function Documentation

min_element()

template<class CombinationElement >

const CombinationElement & CGAL::Combination_enumerator< CombinationElement >::min_element

(

)

Returns the smallest element of the source range.

(the parameter first of the constructor of the class).

operator++()

template<class CombinationElement >

Combination_enumerator CGAL::Combination_enumerator< CombinationElement >::operator++

(

int

)

Post-incrementation.

Same as the pre-incrementation above, but returns the original value of *this.

operator[]()

template<class CombinationElement >

const CombinationElement & CGAL::Combination_enumerator< CombinationElement >::operator[]

(

int

i

)

Returns the i-th element of the current combination.

Precondition

0 <= i < number_of_elements()

reset()

template<class CombinationElement >

void CGAL::Combination_enumerator< CombinationElement >::reset

(

)

Resets the enumerator.

The current combination is set to the first one of the enumeration.