PAbstractSortedList Class Reference

This class is a collection of objects which are descendents of the PObject class. More...

#include <lists.h>

Inheritance diagram for PAbstractSortedList:

List of all members.

Public Types
typedef PSortedListElement	Element
Public Member Functions
Construction
	PAbstractSortedList ()
	Create a new, empty, sorted list.
Overrides from class PObject
virtual Comparison	Compare (const PObject &obj) const
	Get the relative rank of the two lists.
Overrides from class PContainer
virtual PBoolean	SetSize (PINDEX newSize)
	This function is meaningless for lists.
Overrides from class PCollection
virtual PINDEX	Append (PObject *obj)
	Add a new object to the collection.
virtual PINDEX	Insert (const PObject &before, PObject *obj)
	Add a new object to the collection.
virtual PINDEX	InsertAt (PINDEX index, PObject *obj)
	Add a new object to the collection.
virtual PBoolean	Remove (const PObject *obj)
	Remove the object from the collection.
virtual PObject *	RemoveAt (PINDEX index)
	Remove the object at the specified ordinal index from the collection.
virtual void	RemoveAll ()
	Remove all of the elements in the collection.
virtual PBoolean	SetAt (PINDEX index, PObject *val)
	This method simply returns false as the list order is mantained by the class.
virtual PObject *	GetAt (PINDEX index) const
	Get the object at the specified ordinal position.
virtual PINDEX	GetObjectsIndex (const PObject *obj) const
	Search the collection for the specific instance of the object.
virtual PINDEX	GetObjectsIndex (const PObject *obj, PSortedListElement *&lastElement) const
virtual PINDEX	GetValuesIndex (const PObject &obj) const
	Search the collection for the specified value of the object.
Protected Member Functions
void	RemoveElement (Element *node)
void	LeftRotate (Element *node)
void	RightRotate (Element *node)
void	DeleteSubTrees (Element *node, PBoolean deleteObject)
PINDEX	ValueSelect (const Element *node, const PObject &obj, const Element **lastElement) const
Protected Attributes
PSortedListInfo *	info

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Detailed Description

This class is a collection of objects which are descendents of the PObject class.

It is implemeted as a Red-Black binary tree to maintain the objects in rank order. Note that this requires that the PObject::Compare() function be fully implemented oin objects contained in the collection.

The implementation of a sorted list allows fast inserting and deleting as well as random access of objects in the collection. As the objects are being kept sorted, "fast" is a relative term. All operations take o(lg n) unless a particular object is repeatedly accessed.

The class remembers the last accessed element. This state information is used to optimise access by the "virtual array" model of collections. If repeated access via ordinal index is made there is little overhead. All other access incurs a minimum overhead, but not insignificant.

The PAbstractSortedList class would very rarely be descended from directly by the user. The PDECLARE_LIST and PLIST macros would normally be used to create descendent classes. They will instantiate the template based on PSortedList or directly declare and define the class (using inline functions) if templates are not being used.

The PSortedList class or PDECLARE_SORTED_LIST macro will define the correctly typed operators for subscript access (operator[]).

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Member Typedef Documentation

typedef PSortedListElement PAbstractSortedList::Element

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Constructor & Destructor Documentation

PAbstractSortedList::PAbstractSortedList

(

)

Create a new, empty, sorted list.

Note that by default, objects placed into the list will be deleted when removed or when all references to the list are destroyed.

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Member Function Documentation

virtual PINDEX PAbstractSortedList::Append

(

PObject *

obj

)

[virtual]

Add a new object to the collection.

The object is always placed in the correct ordinal position in the list. It is not placed at the "end".

Returns:

index of the newly added object.

Implements PCollection.

virtual Comparison PAbstractSortedList::Compare

(

const PObject &

obj

)

const [virtual]

Get the relative rank of the two lists.

The following algorithm is employed for the comparison:

• EqualTo if the two lists are identical in length and each objects values, not pointer, are equal.

• LessThan if the instances object value at an ordinal position is less than the corresponding objects value in the obj parameters list.

This is also returned if all objects are equal and the instances list length is less than the obj parameters list length.

• GreaterThan if the instances object value at an ordinal position is greater than the corresponding objects value in the obj parameters list.

This is also returned if all objects are equal and the instances list length is greater than the obj parameters list length.

Returns:

comparison of the two objects, EqualTo for same, LessThan for obj logically less than the object and GreaterThan for obj logically greater than the object.

Reimplemented from PObject.

void PAbstractSortedList::DeleteSubTrees	(	Element *	node,
		PBoolean	deleteObject
	)			[protected]

virtual PObject* PAbstractSortedList::GetAt

(

PINDEX

index

)

const [virtual]

Get the object at the specified ordinal position.

If the index was greater than the size of the collection then NULL is returned.

Returns:

pointer to object at the specified index.

Implements PCollection.

virtual PINDEX PAbstractSortedList::GetObjectsIndex	(	const PObject *	obj,
		PSortedListElement *&	lastElement
	)			const [virtual]

virtual PINDEX PAbstractSortedList::GetObjectsIndex

(

const PObject *

obj

)

const [virtual]

Search the collection for the specific instance of the object.

The object pointers are compared, not the values. A binary search is employed to locate the entry.

Note that that will require value comparisons to be made to find the equivalent entry and then a final check is made with the pointers to see if they are the same instance.

Returns:

ordinal index position of the object, or P_MAX_INDEX.

Implements PCollection.

virtual PINDEX PAbstractSortedList::GetValuesIndex

(

const PObject &

obj

)

const [virtual]

Search the collection for the specified value of the object.

The object values are compared, not the pointers. So the objects in the collection must correctly implement the PObject::Compare() function. A binary search is employed to locate the entry.

Returns:

ordinal index position of the object, or P_MAX_INDEX.

Implements PCollection.

virtual PINDEX PAbstractSortedList::Insert	(	const PObject &	before,
		PObject *	obj
	)			[virtual]

Add a new object to the collection.

The object is always placed in the correct ordinal position in the list. It is not placed at the specified position. The before parameter is ignored.

Returns:

index of the newly inserted object.

Implements PCollection.

virtual PINDEX PAbstractSortedList::InsertAt	(	PINDEX	index,
		PObject *	obj
	)			[virtual]

Add a new object to the collection.

The object is always placed in the correct ordinal position in the list. It is not placed at the specified position. The index parameter is ignored.

Returns:

index of the newly inserted object.

Implements PCollection.

void PAbstractSortedList::LeftRotate

(

Element *

node

)

[protected]

virtual PBoolean PAbstractSortedList::Remove

(

const PObject *

obj

)

[virtual]

Remove the object from the collection.

If the AllowDeleteObjects option is set then the object is also deleted.

Note that the comparison for searching for the object in collection is made by pointer, not by value. Thus the parameter must point to the same instance of the object that is in the collection.

Returns:

true if the object was in the collection.

Implements PCollection.

virtual void PAbstractSortedList::RemoveAll

(

)

[virtual]

Remove all of the elements in the collection.

This operates by continually calling RemoveAt() until there are no objects left.

The objects are removed from the last, at index (GetSize()-1) toward the first at index zero.

Reimplemented from PCollection.

virtual PObject* PAbstractSortedList::RemoveAt

(

PINDEX

index

)

[virtual]

Remove the object at the specified ordinal index from the collection.

If the AllowDeleteObjects option is set then the object is also deleted.

Note if the index is beyond the size of the collection then the function will assert.

Returns:

pointer to the object being removed, or NULL if it was deleted.

Implements PCollection.

void PAbstractSortedList::RemoveElement

(

Element *

node

)

[protected]

void PAbstractSortedList::RightRotate

(

Element *

node

)

[protected]

virtual PBoolean PAbstractSortedList::SetAt	(	PINDEX	index,
		PObject *	val
	)			[virtual]

This method simply returns false as the list order is mantained by the class.

Kept to mimic PAbstractList interface.

Returns:

false allways

Implements PCollection.

virtual PBoolean PAbstractSortedList::SetSize

(

PINDEX

newSize

)

[virtual]

This function is meaningless for lists.

The size of the collection is determined by the addition and removal of objects. The size cannot be set in any other way.

Returns:

Always true.

Implements PContainer.

PINDEX PAbstractSortedList::ValueSelect	(	const Element *	node,
		const PObject &	obj,
		const Element **	lastElement
	)			const [protected]

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Member Data Documentation

PSortedListInfo* PAbstractSortedList::info [protected]

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

• lists.h

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