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/*****************************************************************************/
/* */
/* LISTNODE.CC */
/* */
/* (C) 1993,94 Ullrich von Bassewitz */
/* Zwehrenbuehlstrasse 33 */
/* D-72070 Tuebingen */
/* EMail: uz@ibb.schwaben.com */
/* */
/*****************************************************************************/
// $Id$
//
// $Log$
//
//
#include "listnode.h"
/*****************************************************************************/
/* class _ListNode */
/*****************************************************************************/
_ListNode::_ListNode (void* DataPtr)
{
NextNode = PrevNode = this;
ContentsPtr = DataPtr;
}
_ListNode::~_ListNode ()
{
Unlink ();
}
void _ListNode::InsertAfter (_ListNode* N)
// inserts one node after another
{
// the node cannot be inserted after itself
PRECONDITION (N != this);
// switch pointers
NextNode = N->NextNode;
PrevNode = N;
N->NextNode = this;
NextNode->PrevNode = this;
}
void _ListNode::InsertBefore (_ListNode* N)
// inserts one node before another
{
// the node cannot be inserted before itself
PRECONDITION (N != this);
// switch pointers
PrevNode = N->PrevNode;
NextNode = N;
N->PrevNode = this;
PrevNode->NextNode = this;
}
void _ListNode::Unlink ()
// Unlinks a node from a list.
{
// If the list constists only of this element, no unlink is necessary
if (NextNode == this) {
return;
}
// unlink node
PrevNode->NextNode = NextNode;
NextNode->PrevNode = PrevNode;
// the unlinked node is a list with one node
NextNode = PrevNode = this;
}
_ListNode* _ListNode::Traverse (int Forward, int (*F) (_ListNode*, void*),
void *UserPtr)
// Traverse through a list, starting with the current node and calling the
// given function F with every node as argument. Ends if finally the current
// node is reached again (all nodes have been visited in this case) or if the
// called function returns a value != 0. In the former case, Traverse returns
// a NULL pointer, in the latter, a pointer to the node is returned.
{
_ListNode* N = this;
do {
if (F (N, UserPtr)) {
// function returned true
return N;
}
if (Forward) {
N = N->NextNode;
} else {
N = N->PrevNode;
}
} while (N != this);
// Walked through the whole list, return NULL
return NULL;
}
u16 _ListNode::NodeCount ()
// Returns the node count of the list
{
register u16 Count = 0;
_ListNode* N = this;
do {
Count++;
N = N->NextNode;
} while (N != this);
return Count;
}
_ListNode* _ListNode::NodeWithNumber (u16 X)
// Returns the node with number X. Counting begins with "this", (which has
// number 0) and proceeds in "Next" direction.
// Warning: If X is greater than the number of nodes in the list, the
// result is undefined (wraping around).
{
_ListNode* N = this;
while (X--) {
N = N->NextNode;
}
return N;
}
u16 _ListNode::NumberOfNode (_ListNode* N)
// Returns the number of node N. Counting begins with "this" node
// (which has number 0) and proceeds in "Next" direction.
{
register u16 Count = 0;
_ListNode* R = this;
while (R != N) {
Count++;
R = R->NextNode;
CHECK (R != this); // Means N is not in list
}
return Count;
}
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