decaf::util::Comparator< T > Class Template Reference

A comparison function, which imposes a total ordering on some collection of objects. More...

#include <src/main/decaf/util/Comparator.h>

Public Member Functions
virtual	~Comparator ()
virtual bool	operator() (const T &left, const T &right) const =0
	Implementation of the Binary function interface as a means of allowing a Comparator to be passed to an STL Map for use as the sorting criteria.
virtual int	compare (const T &o1, const T &o2) const =0
	Compares its two arguments for order.

---

Detailed Description

template<typename T>
class decaf::util::Comparator< T >

A comparison function, which imposes a total ordering on some collection of objects.

Comparators can be passed to a sort method (such as Collections.sort) to allow precise control over the sort order. Comparators can also be used to control the order of certain data structures.

The ordering imposed by a Comparator c on a set of elements S is said to be consistent with equals if and only if ( compare( e1, e2) == 0 ) has the same boolean value as ( e1 == e2 ) for every e1 and e2 in S.

Since:

1.0

---

Constructor & Destructor Documentation

template<typename T>

virtual decaf::util::Comparator< T >::~Comparator

(

)

[inline, virtual]

---

Member Function Documentation

template<typename T>

virtual int decaf::util::Comparator< T >::compare	(	const T &	o1,
		const T &	o2
	)		const [pure virtual]

Compares its two arguments for order.

Returns a negative integer, zero, or a positive integer as the first argument is less than, equal to, or greater than the second.

The implementor must ensure that sgn( compare(x, y)) == -sgn(compare(y, x) ) for all x and y. (This implies that compare(x, y) must throw an exception if and only if compare(y, x) throws an exception.)

The implementor must also ensure that the relation is transitive: ((compare(x, y)>0) && (compare(y, z)>0)) implies compare(x, z)>0.

Finally, the implementer must ensure that compare(x, y)==0 implies that sgn(compare(x, z))==sgn(compare(y, z)) for all z.

It is generally the case, but not strictly required that (compare(x, y)==0) == ( x == y) ). Generally speaking, any comparator that violates this condition should clearly indicate this fact. The recommended language is "Note: this comparator imposes orderings that are inconsistent with equals."

Parameters:

o1	The first object to be compared
o2	The second object to be compared

Returns:

a negative integer, zero, or a positive integer as the first argument is less than, equal to, or greater than the second.

Implemented in decaf::util::comparators::Less< E >.

template<typename T>

virtual bool decaf::util::Comparator< T >::operator()	(	const T &	left,
		const T &	right
	)		const [pure virtual]

Implementation of the Binary function interface as a means of allowing a Comparator to be passed to an STL Map for use as the sorting criteria.

Parameters:

left	The Left hand side operand.
right	The Right hand side operand.

Returns:

true if the vale of left is less than the value of right.

Implemented in decaf::util::comparators::Less< E >.

---

The documentation for this class was generated from the following file:

• src/main/decaf/util/Comparator.h