TKeyArrayVar Class Reference

Defines the characteristics of a key used to access the elements of arrays of variable length objects. More...

#include <e32base.h>

Inheritance diagram for TKeyArrayVar:

Public Member Functions
IMPORT_C	TKeyArrayVar (TInt anOffset, TKeyCmpText aType)
	Constructs the characteristics of a descriptor key.
IMPORT_C	TKeyArrayVar (TInt anOffset, TKeyCmpText aType, TInt aLength)
	Constructs the characteristics of a text key.
IMPORT_C	TKeyArrayVar (TInt anOffset, TKeyCmpNumeric aType)
	Constructs the characteristics of a numeric key.
Public Member Functions inherited from TKey
void	SetPtr (const TAny *aPtr)
	Sets the pointer to a sample element whose key is to be used for comparison.
virtual IMPORT_C TInt	Compare (TInt aLeft, TInt aRight) const
	Compares the keys of two array elements.

Protected Member Functions
virtual IMPORT_C void	Set (CBufBase *aBase)
IMPORT_C TAny *	At (TInt anIndex) const
	Gets a pointer to the key of a specified array element.
Protected Member Functions inherited from TKey
IMPORT_C	TKey ()
	Protected default constructor.
IMPORT_C	TKey (TInt aOffset, TKeyCmpText aType)
	Constructs the characteristics of a descriptor type key.
IMPORT_C	TKey (TInt aOffset, TKeyCmpText aType, TInt aLength)
	Constructs the characteristics of a text key.
IMPORT_C	TKey (TInt aOffset, TKeyCmpNumeric aType)
	Constructs the characteristics of a numeric key.

Protected Attributes
CBufBase *	iBase
Protected Attributes inherited from TKey
TInt	iKeyOffset
TInt	iKeyLength
TInt	iCmpType
const TAny *	iPtr

Friends
class	CArrayVarBase

Detailed Description

Defines the characteristics of a key used to access the elements of arrays of variable length objects.

An object of this type can represent three categories of key, depending on the constructor used:

1. a descriptor key
2. a text key
3. a numeric key.

The Sort(), InsertIsqL(), Find() and FindIsqL() member functions of the CArrayVarFlat and CArrayVarSeg class hierarchies need a TKeyArrayVar object as an argument to define the location and type of key within an array element.

A TKeyArrayVar object is also required for sorting a packed array. The implementation of the SortL() member function of the CArrayPakFlat class constructs a temporary CArrayVarFlat object which requires the TKeyArrayVar object.

See also

CArrayVarFlat

CArrayVarSeg

CArrayPakFlat

API status

Published to all clients. Released API.

Definition at line 712 of file e32base.h.

Constructor & Destructor Documentation

TKeyArrayVar() [1/3]

IMPORT_C TKeyArrayVar::TKeyArrayVar	(	TInt	anOffset,
		TKeyCmpText	aType
	)

Constructs the characteristics of a descriptor key.

No length value is passed as this is taken from the descriptor type key.

TKeyCmpText

Parameters

anOffset	The offset of the key from the start of an array element.
aType	An enumeration which defines the type of comparison to be made between two descriptor keys.

(generated from Symbian Developer Library)

TKeyArrayVar() [2/3]

IMPORT_C TKeyArrayVar::TKeyArrayVar	(	TInt	anOffset,
		TKeyCmpText	aType,
		TInt	aLength
	)

Constructs the characteristics of a text key.

TKeyCmpText

Parameters

anOffset	The offset of the key from the start of an array element.
aType	An enumeration which defines the type of comparison to be made between two text keys.
aLength	The length of the text key.

(generated from Symbian Developer Library)

TKeyArrayVar() [3/3]

IMPORT_C TKeyArrayVar::TKeyArrayVar	(	TInt	anOffset,
		TKeyCmpNumeric	aType
	)

Constructs the characteristics of a numeric key.

TKeyCmpNumeric

Parameters

anOffset	The offset of the key from the start of an array element.
aType	An enumeration which defines the type of the numeric key.

(generated from Symbian Developer Library)

Member Function Documentation

At()

IMPORT_C TAny * TKeyArrayVar::At ( TInt  anIndex ) const

protectedvirtual

Gets a pointer to the key of a specified array element.

The default implementation raises a USER 35 panic.

The function is called by TKey::Compare() to compare the keys of two elements.

The implementation provided by a derived class must convert the index to a pointer to the key within the corresponding element. The implementation depends on the design of the array but, as general rule, use the index value to get a pointer to the corresponding element and then add the TKey protected data member iKeyOffset to this pointer to get a pointer to the key itself.

By convention, the index value is relative to zero; i.e. a zero value refers to the first element in the array. By this convention, the index can take any value between zero and the number of elements within the array minus one.

The function must also handle the special index value KIndexPtr. When this value is passed, the function should return a pointer to the key within the sample element. A pointer to the sample element is held in the protected data member iPtr and can be set up using SetPtr().

The implementation of this function also assumes that the derived class has a pointer to the array itself or has a function for finding it.

Parameters

anIndex

The index of the array element or the special index value KIndexPtr.

Panic condition: USER 35, if no replacement function has been provided by a derived class.

(generated from Symbian Developer Library)

Reimplemented from TKey.

Set()

virtual IMPORT_C void TKeyArrayVar::Set ( CBufBase *  aBase )

protectedvirtual

Reimplemented in TKeyArrayPak.

Friends And Related Symbol Documentation

CArrayVarBase

friend class CArrayVarBase

friend

Definition at line 753 of file e32base.h.

Member Data Documentation

iBase

CBufBase* TKeyArrayVar::iBase

protected

Definition at line 752 of file e32base.h.

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

• e32base.h
• e32base.h.dox