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[core] remove size maint in algo_splaytree

remove size maintenance tracking in algo_splaytree; not used in lighttpd
master
Glenn Strauss 5 months ago
parent
commit
0329e765a3
  1. 61
      src/algo_splaytree.c
  2. 7
      src/algo_splaytree.h

61
src/algo_splaytree.c

@ -10,6 +10,8 @@
operations are illustrated in the code below. The remainder of this
introduction is taken from top-down-splay.c.
[[ XXX: size maintenance has been removed; not used in lighttpd ]]
"Splay trees", or "self-adjusting search trees" are a simple and
efficient data structure for storing an ordered set. The data
structure consists of a binary tree, with no additional fields. It
@ -54,19 +56,16 @@
/* This is the comparison. */
/* Returns <0 if i<j, =0 if i=j, and >0 if i>j */
#define node_size splaytree_size
/* Splay using the key i (which may or may not be in the tree.)
* The starting root is t, and the tree used is defined by rat
* size fields are maintained */
*/
splay_tree * splaytree_splay (splay_tree *t, int i) {
splay_tree N, *l, *r, *y;
int comp, l_size, r_size;
int comp;
if (t == NULL) return t;
N.left = N.right = NULL;
l = r = &N;
l_size = r_size = 0;
for (;;) {
comp = compare(i, t->key);
@ -76,49 +75,28 @@ splay_tree * splaytree_splay (splay_tree *t, int i) {
y = t->left; /* rotate right */
t->left = y->right;
y->right = t;
t->size = node_size(t->left) + node_size(t->right) + 1;
t = y;
if (t->left == NULL) break;
}
r->left = t; /* link right */
r = t;
t = t->left;
r_size += 1+node_size(r->right);
} else if (comp > 0) {
if (t->right == NULL) break;
if (compare(i, t->right->key) > 0) {
y = t->right; /* rotate left */
t->right = y->left;
y->left = t;
t->size = node_size(t->left) + node_size(t->right) + 1;
t = y;
if (t->right == NULL) break;
}
l->right = t; /* link left */
l = t;
t = t->right;
l_size += 1+node_size(l->left);
} else {
break;
}
}
l_size += node_size(t->left); /* Now l_size and r_size are the sizes of */
r_size += node_size(t->right); /* the left and right trees we just built.*/
t->size = l_size + r_size + 1;
l->right = r->left = NULL;
/* The following two loops correct the size fields of the right path */
/* from the left child of the root and the right path from the left */
/* child of the root. */
for (y = N.right; y != NULL; y = y->right) {
y->size = l_size;
l_size -= 1+node_size(y->left);
}
for (y = N.left; y != NULL; y = y->left) {
y->size = r_size;
r_size -= 1+node_size(y->right);
}
l->right = t->left; /* assemble */
r->left = t->right;
@ -147,16 +125,13 @@ splay_tree * splaytree_insert(splay_tree * t, int i, void *data) {
new->left = t->left;
new->right = t;
t->left = NULL;
t->size = 1+node_size(t->right);
} else {
new->right = t->right;
new->left = t;
t->right = NULL;
t->size = 1+node_size(t->left);
}
new->key = i;
new->data = data;
new->size = 1 + node_size(new->left) + node_size(new->right);
return new;
}
@ -164,10 +139,7 @@ splay_tree * splaytree_delete(splay_tree *t, int i) {
/* Deletes i from the tree if it's there. */
/* Return a pointer to the resulting tree. */
splay_tree * x;
int tsize;
if (t==NULL) return NULL;
tsize = t->size;
t = splaytree_splay(t, i);
if (compare(i, t->key) == 0) { /* found it */
if (t->left == NULL) {
@ -177,33 +149,8 @@ splay_tree * splaytree_delete(splay_tree *t, int i) {
x->right = t->right;
}
free(t);
if (x != NULL) {
x->size = tsize-1;
}
return x;
} else {
return t; /* It wasn't there */
}
}
#if 0
static splay_tree *find_rank(int r, splay_tree *t) {
/* Returns a pointer to the node in the tree with the given rank. */
/* Returns NULL if there is no such node. */
/* Does not change the tree. To guarantee logarithmic behavior, */
/* the node found here should be splayed to the root. */
int lsize;
if ((r < 0) || (r >= node_size(t))) return NULL;
for (;;) {
lsize = node_size(t->left);
if (r < lsize) {
t = t->left;
} else if (r > lsize) {
r = r - lsize -1;
t = t->right;
} else {
return t;
}
}
}
#endif

7
src/algo_splaytree.h

@ -5,8 +5,6 @@
typedef struct tree_node {
struct tree_node * left, * right;
int key;
int size; /* maintained to be the number of nodes rooted here */
void *data;
} splay_tree;
@ -15,11 +13,6 @@ splay_tree * splaytree_splay (splay_tree *t, int key);
splay_tree * splaytree_insert(splay_tree *t, int key, void *data);
splay_tree * splaytree_delete(splay_tree *t, int key);
#define splaytree_size(x) (((x)==NULL) ? 0 : ((x)->size))
/* This macro returns the size of a node. Unlike "x->size", */
/* it works even if x=NULL. The test could be avoided by using */
/* a special version of NULL which was a real node with size 0. */
#include "algo_md.h"

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