Class TDblQueBase

class TDblQueBase;

Description

A base class that provides implementation for the doubly linked list header.

It also encapsulates the offset value of a link object.

The class is abstract and is not intended to be instantiated.

Members

Defined in TDblQueBase:

• DoAddFirst(TAny *)Implements the insertion of the specified list element at the front of the doubl...
• DoAddLast(TAny *)Implements the insertion of the specified list element at the back of the doubly...
• DoAddPriority(TAny *)Implements the insertion of the specified list element in priority order.
• IsEmpty()constTests whether the doubly linked list is empty, i.e. has no list elements.
• Reset()Empties the doubly linked list.
• SetOffset(TInt)Sets the offset of the link object from the start of a doubly linked list elemen...
• TDblQueBase()Default constructor.
• TDblQueBase(TInt)Constructor with specified offset.
• __DbgTestEmpty()constTests whether the queue is empty.
• iHeadThe head, or anchor point of the queue.
• iOffsetThe offset of a component link object within elements that form the list.

See also:

• TDblQueA templated class that provides the behaviour for managing a doubly linked list.

protected: IMPORT_C TDblQueBase();

Description

Default constructor.

It sets:

1. iHead to point to this object in both the forwards and backwards direction.

2. iOffset to zero.

See also:

• TDblQueBase::iHeadThe head, or anchor point of the queue.
• TDblQueBase::iOffsetThe offset of a component link object within elements that form the list.

protected: IMPORT_C TDblQueBase(TInt aOffset);

Description

Constructor with specified offset.

It sets:

1. iHead to point to this object in both the forwards and backwards direction.

2. iOffset to the specified value.

Parameters

TInt aOffset The offset of a link object within an element.

Panic codes

USER 78, if aOffset is not divisible by four

See also:

• TDblQueBase::iHeadThe head, or anchor point of the queue.
• TDblQueBase::iOffsetThe offset of a component link object within elements that form the list.

IMPORT_C TBool IsEmpty() const;

Description

Tests whether the doubly linked list is empty, i.e. has no list elements.

Return value

TBool True, if the doubly linked list is empty; false, otherwise.

IMPORT_C void SetOffset(TInt aOffset);

Description

Sets the offset of the link object from the start of a doubly linked list element.

Parameters

TInt aOffset The offset of the link object from the start of a doubly linked list element.

Panic codes

USER 78, if aOffset is not divisible by four.

See also:

• TDblQueA templated class that provides the behaviour for managing a doubly linked list.

IMPORT_C void Reset();

Description

Empties the doubly linked list.

After a call to this function, there are no elements queued from the header; the elements are orphaned. Special care must be taken when list elements are CBase derived objects, i.e. are allocated on the heap.

protected: IMPORT_C void DoAddFirst(TAny *aPtr);

Description

Implements the insertion of the specified list element at the front of the doubly linked list.

This function is called by TDblQue::AddFirst(T &).

Parameters

TAny *aPtr An untyped pointer to the element to be inserted.

See also:

• TDblQue::AddFirst(T &)Inserts the specified list element at the front of the doubly linked list.

protected: IMPORT_C void DoAddLast(TAny *aPtr);

Description

Implements the insertion of the specified list element at the back of the doubly linked list.

This function is called by TDblQue::AddLast(T &).

Parameters

TAny *aPtr An untyped pointer to the element to be inserted.

See also:

• TDblQue::AddLast(T &)Inserts the specified list element at the back of the doubly linked list.

protected: IMPORT_C void DoAddPriority(TAny *aPtr);

Description

Implements the insertion of the specified list element in priority order.

This function is called by TPriQue::Add(T &).

Parameters

TAny *aPtr An untyped pointer to the element to be inserted.

See also:

• TPriQue::Add(T &)Inserts the specified list element in descending priority order.

protected: IMPORT_C void __DbgTestEmpty() const;

Description

Tests whether the queue is empty.

The function is implemented as an __ASSERT_DEBUG.

Panic codes

USER 79, if the assertion fails.

protected: TDblQueLink iHead;

Description

The head, or anchor point of the queue.

protected: TInt iOffset;

Description

The offset of a component link object within elements that form the list.