SRB2/src/m_aatree.c

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// SONIC ROBO BLAST 2
//-----------------------------------------------------------------------------
// Copyright (C) 1993-1996 by id Software, Inc.
// Copyright (C) 1998-2000 by DooM Legacy Team.
// Copyright (C) 1999-2016 by Sonic Team Junior.
//
// This program is free software distributed under the
// terms of the GNU General Public License, version 2.
// See the 'LICENSE' file for more details.
//-----------------------------------------------------------------------------
/// \file m_aatree.h
/// \brief AA trees code
#include "m_aatree.h"
#include "z_zone.h"
// A partial implementation of AA trees,
// according to the algorithms given on Wikipedia.
// http://en.wikipedia.org/wiki/AA_tree
typedef struct aatree_node_s
{
INT32 level;
INT32 key;
void* value;
struct aatree_node_s *left, *right;
} aatree_node_t;
struct aatree_s
{
aatree_node_t *root;
UINT32 flags;
};
aatree_t *M_AATreeAlloc(UINT32 flags)
{
aatree_t *aatree = Z_Malloc(sizeof (aatree_t), PU_STATIC, NULL);
aatree->root = NULL;
aatree->flags = flags;
return aatree;
}
static void M_AATreeFree_Node(aatree_node_t *node)
{
if (node->left) M_AATreeFree_Node(node->left);
if (node->right) M_AATreeFree_Node(node->right);
Z_Free(node);
}
void M_AATreeFree(aatree_t *aatree)
{
if (aatree->root)
M_AATreeFree_Node(aatree->root);
Z_Free(aatree);
}
static aatree_node_t *M_AATreeSkew(aatree_node_t *node)
{
if (node && node->left && node->left->level == node->level)
{
// Not allowed: horizontal left-link. Reverse the
// horizontal link and hook the orphan back in.
aatree_node_t *oldleft = node->left;
node->left = oldleft->right;
oldleft->right = node;
return oldleft;
}
// No change needed.
return node;
}
static aatree_node_t *M_AATreeSplit(aatree_node_t *node)
{
if (node && node->right && node->right->right && node->level == node->right->right->level)
{
// Not allowed: two consecutive horizontal right-links.
// The middle one becomes the new root at this point,
// with suitable adjustments below.
aatree_node_t *oldright = node->right;
node->right = oldright->left;
oldright->left = node;
oldright->level++;
return oldright;
}
// No change needed.
return node;
}
static aatree_node_t *M_AATreeSet_Node(aatree_node_t *node, UINT32 flags, INT32 key, void* value)
{
if (!node)
{
// Nothing here, so just add where we are
node = Z_Malloc(sizeof (aatree_node_t), PU_STATIC, NULL);
node->level = 1;
node->key = key;
if (value && (flags & AATREE_ZUSER)) Z_SetUser(value, &node->value);
else node->value = value;
node->left = node->right = NULL;
}
else
{
if (key < node->key)
node->left = M_AATreeSet_Node(node->left, flags, key, value);
else if (key > node->key)
node->right = M_AATreeSet_Node(node->right, flags, key, value);
else
{
if (value && (flags & AATREE_ZUSER)) Z_SetUser(value, &node->value);
else node->value = value;
}
node = M_AATreeSkew(node);
node = M_AATreeSplit(node);
}
return node;
}
void M_AATreeSet(aatree_t *aatree, INT32 key, void* value)
{
aatree->root = M_AATreeSet_Node(aatree->root, aatree->flags, key, value);
}
// Caveat: we don't distinguish between nodes that don't exists
// and nodes with value == NULL.
static void *M_AATreeGet_Node(aatree_node_t *node, INT32 key)
{
if (node)
{
if (node->key == key)
return node->value;
else if(node->key < key)
return M_AATreeGet_Node(node->right, key);
else
return M_AATreeGet_Node(node->left, key);
}
return NULL;
}
void *M_AATreeGet(aatree_t *aatree, INT32 key)
{
return M_AATreeGet_Node(aatree->root, key);
}
static void M_AATreeIterate_Node(aatree_node_t *node, aatree_iter_t callback)
{
if (node->left) M_AATreeIterate_Node(node->left, callback);
callback(node->key, node->value);
if (node->right) M_AATreeIterate_Node(node->right, callback);
}
void M_AATreeIterate(aatree_t *aatree, aatree_iter_t callback)
{
if (aatree->root)
M_AATreeIterate_Node(aatree->root, callback);
}