curl/lib/splay.c

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/***************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) 1997 - 2006, Daniel Stenberg, <daniel@haxx.se>, et al.
*
* This software is licensed as described in the file COPYING, which
* you should have received as part of this distribution. The terms
* are also available at http://curl.haxx.se/docs/copyright.html.
*
* You may opt to use, copy, modify, merge, publish, distribute and/or sell
* copies of the Software, and permit persons to whom the Software is
* furnished to do so, under the terms of the COPYING file.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
* $Id$
***************************************************************************/
#include <stdio.h>
#include <stdlib.h>
#include "splay.h"
#define compare(i,j) ((i)-(j))
/* Set this to a key value that will *NEVER* appear otherwise */
#define KEY_NOTUSED -1
/*
* Splay using the key i (which may or may not be in the tree.) The starting
* root is t.
*/
struct Curl_tree *Curl_splay(int i, struct Curl_tree *t)
{
struct Curl_tree N, *l, *r, *y;
int comp;
if (t == NULL)
return t;
N.smaller = N.larger = NULL;
l = r = &N;
for (;;) {
comp = compare(i, t->key);
if (comp < 0) {
if (t->smaller == NULL)
break;
if (compare(i, t->smaller->key) < 0) {
y = t->smaller; /* rotate smaller */
t->smaller = y->larger;
y->larger = t;
t = y;
if (t->smaller == NULL)
break;
}
r->smaller = t; /* link smaller */
r = t;
t = t->smaller;
}
else if (comp > 0) {
if (t->larger == NULL)
break;
if (compare(i, t->larger->key) > 0) {
y = t->larger; /* rotate larger */
t->larger = y->smaller;
y->smaller = t;
t = y;
if (t->larger == NULL)
break;
}
l->larger = t; /* link larger */
l = t;
t = t->larger;
}
else {
break;
}
}
l->larger = r->smaller = NULL;
l->larger = t->smaller; /* assemble */
r->smaller = t->larger;
t->smaller = N.larger;
t->larger = N.smaller;
return t;
}
/* Insert key i into the tree t. Return a pointer to the resulting tree or
NULL if something went wrong. */
struct Curl_tree *Curl_splayinsert(int i, struct Curl_tree *t,
struct Curl_tree *area)
{
if (area == NULL)
return t;
if (t != NULL) {
t = Curl_splay(i,t);
if (compare(i, t->key)==0) {
/* it already exists one of this size */
area->same = t;
area->key = i;
area->smaller = t->smaller;
area->larger = t->larger;
t->smaller = area;
t->key = KEY_NOTUSED;
return area; /* new root node */
}
}
if (t == NULL) {
area->smaller = area->larger = NULL;
}
else if (compare(i, t->key) < 0) {
area->smaller = t->smaller;
area->larger = t;
t->smaller = NULL;
}
else {
area->larger = t->larger;
area->smaller = t;
t->larger = NULL;
}
area->key = i;
area->same = NULL; /* no identical node (yet) */
return area;
}
/* Deletes 'i' from the tree if it's there (with an exact match). Returns a
pointer to the resulting tree. */
struct Curl_tree *Curl_splayremove(int i, struct Curl_tree *t,
struct Curl_tree **removed)
{
struct Curl_tree *x;
if (t==NULL)
return NULL;
t = Curl_splay(i,t);
if (compare(i, t->key) == 0) { /* found it */
/* FIRST! Check if there is a list with identical sizes */
if((x = t->same)) {
/* there is, pick one from the list */
/* 'x' is the new root node */
x->key = t->key;
x->larger = t->larger;
x->smaller = t->smaller;
*removed = t;
return x; /* new root */
}
if (t->smaller == NULL) {
x = t->larger;
}
else {
x = Curl_splay(i, t->smaller);
x->larger = t->larger;
}
*removed = t;
return x;
}
else {
*removed = NULL; /* no match */
return t; /* It wasn't there */
}
}
/* Finds and deletes the best-fit node from the tree. Return a pointer to the
resulting tree. best-fit means the node with the given or lower number */
struct Curl_tree *Curl_splaygetbest(int i, struct Curl_tree *t,
struct Curl_tree **removed)
{
struct Curl_tree *x;
if (!t) {
*removed = NULL; /* none removed since there was no root */
return NULL;
}
t = Curl_splay(i,t);
if(compare(i, t->key) < 0) {
/* too big node, try the smaller chain */
if(t->smaller)
t=Curl_splay(t->smaller->key, t);
else {
/* fail */
*removed = NULL;
return t;
}
}
if (compare(i, t->key) >= 0) { /* found it */
/* FIRST! Check if there is a list with identical sizes */
x = t->same;
if(x) {
/* there is, pick one from the list */
/* 'x' is the new root node */
x->key = t->key;
x->larger = t->larger;
x->smaller = t->smaller;
*removed = t;
return x; /* new root */
}
if (t->smaller == NULL) {
x = t->larger;
}
else {
x = Curl_splay(i, t->smaller);
x->larger = t->larger;
}
*removed = t;
return x;
}
else {
*removed = NULL; /* no match */
return t; /* It wasn't there */
}
}
/* Deletes the node we point out from the tree if it's there. Return a pointer
to the resulting tree. */
struct Curl_tree *Curl_splayremovebyaddr(struct Curl_tree *t,
struct Curl_tree *remove)
{
struct Curl_tree *x;
if (!t || !remove)
return NULL;
if(KEY_NOTUSED == remove->key) {
/* just unlink ourselves nice and quickly: */
remove->smaller->same = remove->same;
if(remove->same)
remove->same->smaller = remove->smaller;
/* voila, we're done! */
return t;
}
t = Curl_splay(remove->key, t);
/* Check if there is a list with identical sizes */
x = t->same;
if(x) {
/* 'x' is the new root node */
x->key = t->key;
x->larger = t->larger;
x->smaller = t->smaller;
return x; /* new root */
}
/* Remove the actualy root node: */
if (t->smaller == NULL)
x = t->larger;
else {
x = Curl_splay(remove->key, t->smaller);
x->larger = t->larger;
}
return x;
}
#ifdef CURLDEBUG
int Curl_splayprint(struct Curl_tree * t, int d, char output)
{
int distance=0;
struct Curl_tree *node;
int i;
if (t == NULL)
return 0;
distance += Curl_splayprint(t->larger, d+1, output);
for (i=0; i<d; i++)
if(output)
printf(" ");
if(output) {
printf("%d[%d]", t->key, i);
}
for(node = t->same; node; node = node->same) {
distance += i; /* this has the same "virtual" distance */
if(output)
printf(" [+]");
}
if(output)
puts("");
distance += i;
distance += Curl_splayprint(t->smaller, d+1, output);
return distance;
}
#endif
#ifdef TEST_SPLAY
/*#define TEST2 */
#define MAX 50
#define OUTPUT 0 /* 1 enables, 0 disables */
/* A sample use of these functions. Start with the empty tree, insert some
stuff into it, and then delete it */
int main(int argc, char **argv)
{
struct Curl_tree *root, *t;
void *ptrs[MAX];
long sizes[]={
50, 60, 50, 100, 60, 200, 120, 300, 400, 200, 256, 122, 60, 120, 200, 300,
220, 80, 90, 50, 100, 60, 200, 120, 300, 400, 200, 256, 122, 60, 120, 200,
300, 220, 80, 90, 50, 100, 60, 200, 120, 300, 400, 200, 256, 122, 60, 120,
200, 300, 220, 80, 90};
int i;
root = NULL; /* the empty tree */
for (i = 0; i < MAX; i++) {
ptrs[i] = t = (struct Curl_tree *)malloc(sizeof(struct Curl_tree));
if(!t) {
puts("out of memory!");
return 0;
}
#ifdef TEST2
root = Curl_splayinsert(sizes[i], root, t);
#else
root = Curl_splayinsert((541*i)&1023, root, t);
#endif
}
#if 0
puts("Result:");
printtree(root, 0, 1);
#endif
#if 1
for (i=0; root; i+=30) {
Curl_splayprint(root, 0, 1);
do {
root = Curl_splaygetbest(i, root, &t);
if(t)
printf("bestfit %d became %d\n", i, t->key);
else
printf("bestfit %d failed!\n", i);
} while(t && root);
}
#endif
#if 0
for (i = 0; i < MAX; i++) {
printf("remove pointer %d size %d\n", i, sizes[i]);
root = removebyaddr(root, (struct Curl_tree *)ptrs[i]);
Curl_splayprint(root, 0, 1);
}
#endif
#if 0
#ifdef WEIGHT
for (i = -1; i<=root->weight; i++) {
t = find_rank(i, root);
if (t == NULL) {
printf("could not find a node of rank %d.\n", i);
} else {
printf("%d is of rank %d\n", t->key, i);
}
}
#endif
#endif
#if 0
#ifdef TEST2
for (i = 0; i < MAX; i++) {
printf("remove size %d\n", sizes[i]);
root = Curl_splayremove(sizes[i], root, &t);
free(t);
Curl_splayprint(root, 0, 1);
}
#endif
#endif
return 0;
}
#endif /* TEST_SPLAY */