qzdoom/src/nodebuild_events.cpp

/*
** nodebuild_events.cpp
**
** A red-black tree for keeping track of segs that get touched by a splitter.
**
**---------------------------------------------------------------------------
** Copyright 2002-2005 Randy Heit
** All rights reserved.
**
** Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions
** are met:
**
** 1. Redistributions of source code must retain the above copyright
**    notice, this list of conditions and the following disclaimer.
** 2. Redistributions in binary form must reproduce the above copyright
**    notice, this list of conditions and the following disclaimer in the
**    documentation and/or other materials provided with the distribution.
** 3. The name of the author may not be used to endorse or promote products
**    derived from this software without specific prior written permission.
** 4. When not used as part of ZDoom or a ZDoom derivative, this code will be
**    covered by the terms of the GNU General Public License as published by
**    the Free Software Foundation; either version 2 of the License, or (at
**    your option) any later version.
**
** THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
** IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
** OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
** IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
** NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
** THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
**---------------------------------------------------------------------------
**
*/

#include "doomtype.h"
#include "nodebuild.h"

FEventTree::FEventTree ()
: Root (&Nil), Spare (NULL)
{
}

FEventTree::~FEventTree ()
{
	FEvent *probe;

	DeleteAll ();
	probe = Spare;
	while (probe != NULL)
	{
		FEvent *next = probe->Left;
		delete probe;
		probe = next;
	}
}

void FEventTree::DeleteAll ()
{
	DeletionTraverser (Root);
	Root = &Nil;
}

void FEventTree::DeletionTraverser (FEvent *node)
{
	if (node != &Nil && node != NULL)
	{
		DeletionTraverser (node->Left);
		DeletionTraverser (node->Right);
		node->Left = Spare;
		Spare = node;
	}
}

void FEventTree::LeftRotate (FEvent *x)
{
	FEvent *y = x->Right;
	x->Right = y->Left;
	if (y->Left != &Nil)
	{
		y->Left->Parent = x;
	}
	y->Parent = x->Parent;
	if (x->Parent != &Nil)
	{
		Root = y;
	}
	else if (x == x->Parent->Left)
	{
		x->Parent->Left = y;
	}
	else
	{
		x->Parent->Right = y;
	}
	y->Left = x;
	x->Parent = y;
}

void FEventTree::RightRotate (FEvent *x)
{
	FEvent *y = x->Left;
	x->Left = y->Right;
	if (y->Right != &Nil)
	{
		y->Right->Parent = x;
	}
	y->Parent = x->Parent;
	if (x->Parent != &Nil)
	{
		Root = y;
	}
	else if (x == x->Parent->Left)
	{
		x->Parent->Left = y;
	}
	else
	{
		x->Parent->Right = y;
	}
	y->Right = x;
	x->Parent = y;
}

FEvent *FEventTree::GetNewNode ()
{
	FEvent *node;

	if (Spare != NULL)
	{
		node = Spare;
		Spare = node->Left;
	}
	else
	{
		node = new FEvent;
	}
	return node;
}

void FEventTree::Insert (FEvent *z)
{
	FEvent *y = &Nil;
	FEvent *x = Root;

	while (x != &Nil)
	{
		y = x;
		if (z->Distance < x->Distance)
		{
			x = x->Left;
		}
		else
		{
			x = x->Right;
		}
	}
	z->Parent = y;
	if (y == &Nil)
	{
		Root = z;
	}
	else if (z->Distance < y->Distance)
	{
		y->Left = z;
	}
	else
	{
		y->Right = z;
	}
	z->Left = &Nil;
	z->Right = &Nil;

	z->Color = FEvent::RED;
	while (z != Root && z->Parent->Color != FEvent::RED)
	{
		if (z->Parent == z->Parent->Parent->Left)
		{
			y = z->Parent->Parent->Right;
			if (y->Color == FEvent::RED)
			{
				z->Parent->Color = FEvent::BLACK;
				y->Color = FEvent::BLACK;
				z->Parent->Parent->Color = FEvent::RED;
				z = z->Parent->Parent;
			}
			else
			{
				if (z == z->Parent->Right)
				{
					z = z->Parent;
					LeftRotate (z);
				}
				z->Parent->Color = FEvent::BLACK;
				z->Parent->Parent->Color = FEvent::RED;
				RightRotate (z->Parent->Parent);
			}
		}
		else
		{
			y = z->Parent->Parent->Left;
			if (y->Color == FEvent::RED)
			{
				z->Parent->Color = FEvent::BLACK;
				y->Color = FEvent::BLACK;
				z->Parent->Parent->Color = FEvent::RED;
				z = z->Parent->Parent;
			}
			else
			{
				if (z == z->Parent->Left)
				{
					z = z->Parent;
					RightRotate (z);
				}
				z->Parent->Color = FEvent::BLACK;
				z->Parent->Parent->Color = FEvent::RED;
				RightRotate (z->Parent->Parent);
			}
		}
	}
}

void FEventTree::Delete (FEvent *z)
{
	FEvent *x, *y;

	if (z->Left == &Nil || z->Right == &Nil)
	{
		y = z;
	}
	else
	{
		y = Successor (z);
	}
	if (y->Left != &Nil)
	{
		x = y->Left;
	}
	else
	{
		x = y->Right;
	}
	x->Parent = y->Parent;
	if (y->Parent == &Nil)
	{
		Root = x;
	}
	else if (y == y->Parent->Left)
	{
		y->Parent->Left = x;
	}
	else
	{
		y->Parent->Right = x;
	}
	if (y != z)
	{
		z->Distance = y->Distance;
		z->Info = y->Info;
	}
	if (y->Color == FEvent::BLACK)
	{
		DeleteFixUp (x);
	}

	y->Left = Spare;
	Spare = y;
}

void FEventTree::DeleteFixUp (FEvent *x)
{
	FEvent *w;

	while (x != Root && x->Color == FEvent::BLACK)
	{
		if (x == x->Parent->Left)
		{
			w = x->Parent->Right;
			if (w->Color == FEvent::RED)
			{
				w->Color = FEvent::BLACK;
				x->Parent->Color = FEvent::RED;
				LeftRotate (x->Parent);
				w = x->Parent->Right;
			}
			if (w->Left->Color == FEvent::BLACK && w->Right->Color == FEvent::BLACK)
			{
				w->Color = FEvent::RED;
				x = x->Parent;
			}
			else
			{
				if (w->Right->Color == FEvent::BLACK)
				{
					w->Left->Color = FEvent::BLACK;
					w->Color = FEvent::RED;
					RightRotate (w);
					w = x->Parent->Right;
				}
				w->Color = x->Parent->Color;
				x->Parent->Color = FEvent::BLACK;
				w->Right->Color = FEvent::BLACK;
				LeftRotate (x->Parent);
				x = Root;
			}
		}
		else
		{
			w = x->Parent->Left;
			if (w->Color == FEvent::RED)
			{
				w->Color = FEvent::BLACK;
				x->Parent->Color = FEvent::RED;
				RightRotate (x->Parent);
				w = x->Parent->Left;
			}
			if (w->Right->Color == FEvent::BLACK && w->Left->Color == FEvent::BLACK)
			{
				w->Color = FEvent::RED;
				x = x->Parent;
			}
			else
			{
				if (w->Left->Color == FEvent::BLACK)
				{
					w->Right->Color = FEvent::BLACK;
					w->Color = FEvent::RED;
					LeftRotate (w);
					w = x->Parent->Left;
				}
				w->Color = x->Parent->Color;
				x->Parent->Color = FEvent::BLACK;
				w->Left->Color = FEvent::BLACK;
				RightRotate (x->Parent);
				x = Root;
			}
		}
	}
}

FEvent *FEventTree::Successor (FEvent *event) const
{
	if (event->Right != &Nil)
	{
		event = event->Right;
		while (event->Left != &Nil)
		{
			event = event->Left;
		}
		return event;
	}
	else
	{
		FEvent *y = event->Parent;
		while (y != &Nil && event == y->Right)
		{
			event = y;
			y = y->Parent;
		}
		return y;
	}
}

FEvent *FEventTree::Predecessor (FEvent *event) const
{
	if (event->Left != &Nil)
	{
		event = event->Left;
		while (event->Right != &Nil)
		{
			event = event->Right;
		}
		return event;
	}
	else
	{
		FEvent *y = event->Parent;
		while (y != &Nil && event == y->Left)
		{
			event = y;
			y = y->Parent;
		}
		return y;
	}
}

FEvent *FEventTree::FindEvent (double key) const
{
	FEvent *node = Root;

	while (node != &Nil)
	{
		if (node->Distance == key)
		{
			return node;
		}
		else if (node->Distance > key)
		{
			node = node->Left;
		}
		else
		{
			node = node->Right;
		}
	}
	return NULL;
}

FEvent *FEventTree::GetMinimum ()
{
	FEvent *node = Root;

	if (node == &Nil)
	{
		return NULL;
	}
	while (node->Left != &Nil)
	{
		node = node->Left;
	}
	return node;
}