LComparator

LComparator is a PowerPlant class that is used for comparing objects. Comparators are objects that know how to compare to other objects or structures.

Methods :

The methods in this class are:

LComparator()	~LComparator()
Clone()	Compare()
CompareToKey()	GetComparator()
IsEqualTo()	IsEqualToKey()

Data Members:

The data members in this class are:

sComparator

Operation:

Subclasses will need to implement the Compare() method. The compare Compare() result should be one of the following:

• < 0 - object/data item 1 is less than object/data item 2
• 0 - object/data item 1 is equal to object/data item 2
• > 0 -þobject/data item 1 is greater than object/data item 2 Source files:

(Array Classes)

LComparator.h

LComparator.cp

LComparator()

Purpose:

The constructor is a placeholder, it doesn't do anything for this class.

Access:

Public

Prototype:

LComparator();

None

~LComparator()

Purpose:

The destructor is a placeholder, it doesn't do anything for this class.

Access:

Virtual, Public

Prototype:

~LComparator();

Clone()

Purpose:

This method simply creates this object by calling new.

Access:

Virtual, Public

Prototype:

virtual LComparator* Clone();

None

Return:

A pointer to a new comparator object.

Compare()

Purpose:

This method takes two pointers to data blocks, and their sizes, and determines what the result of the comparison should be.

Access:

Virtual, Public

Prototype:

virtual SInt32 Compare(

 const void* inItemOne,

 const void* inItemTwo,

 USInt32 inSizeOne,

 USInt32 inSizeTwo ) const;

This method has the following parameters:

const void*	inItemOne	A data pointer to the first item.
const void*	inItemTwo	A data pointer to the second item.
USInt32	inSizeOne	The size of the first item.
USInt32	inSizeTwo	The size of the second item.

Return:

SInt32 that indicates one of the following:

< 0 - object/data item 1 is less than object/data item 2 0 - object/data item 1 is equal to object/data item 2 > 0 -þobject/data item 1 is greater than object/data item 2

CompareToKey()

Purpose:

This method is not yet implemented.

Access:

Virtual, Public

Prototype:

virtual SInt32 CompareToKey(

 const void* inItem,

 USInt32 inSize,

 const void* inKey) const;

This method has the following parameters:

const void*	inItem	The pointer to the first item.
USInt32	inSize	The size of the first item.
const void*	inKey	The key to compare with.

Return:

SInt32

GetComparator()

Purpose:

This method is an accessor for sComparator. If sComparator does not yet exist, the object is created before returning from this method.

Access:

Static, Public

Prototype:

static LComparator* GetComparator();

None

Return:

A pointer to sComparator.

IsEqualTo()

Purpose:

This method detects whether two objects are equal.

Access:

Virtual, Public

Prototype:

virtual Boolean IsEqualTo(

 const void* inItemOne,

 const void* inItemTwo,

 USInt32 inSizeOne,

 USInt32 inSizeTwo) const;

This method has the following parameters:

const void*	inItemOne	A data pointer to the first item.
const void*	inItemTwo	A data pointer to the second item.
USInt32	inSizeOne	The size of the first item.
USInt32	inSizeTwo	The size of the second item.

Return:

Boolean indicating true if the items are equal, false otherwise.

IsEqualToKey()

Purpose:

This method compares an item to the key to see if they are identical.

Access:

Virtual, Public

Prototype:

virtual Boolean IsEqualToKey(

 const void* inItem,

 USInt32 inSize,

 const void* inKey) const;

This method has the following parameters:

const void*	inItem	The pointer to the first item.
USInt32	inSize	The size of the first item.
const void*	inKey	The key to compare with.

Return:

Boolean indicating true if the items are equal, false otherwise.

sComparator

Purpose:

This data member stores the pointer to the object we use as a standard for comparisons.

Access:

Static, Protected

Prototype:

static LComparator* sComparator;