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/*
* Filters: utility functions
*
* Copyright 1998 Pavel Machek <pavel@ucw.cz>
*
* Can be freely distributed and used under the terms of the GNU GPL.
*/
#include "lib/alloca.h"
#include "nest/bird.h"
#include "conf/conf.h"
#include "filter/filter.h"
/**
* find_tree
* @t: tree to search in
* @val: value to find
*
* Search for given value in the tree. I relies on fact that sorted tree is populated
* by &f_val structures (that can be compared by val_compare()). In each node of tree,
* either single value (then t->from==t->to) or range is present.
*
* Both set matching and |switch() { }| construction is implemented using this function,
* thus both are as fast as they can be.
*/
struct f_tree *
find_tree(struct f_tree *t, struct f_val val)
{
if (!t)
return NULL;
if ((val_compare(t->from, val) != 1) &&
(val_compare(t->to, val) != -1))
return t;
if (val_compare(t->from, val) == -1)
return find_tree(t->right, val);
else
return find_tree(t->left, val);
}
static struct f_tree *
build_tree_rec(struct f_tree **buf, int l, int h)
{
struct f_tree *n;
int pos;
if (l >= h)
return NULL;
pos = (l+h)/2;
n = buf[pos];
n->left = build_tree_rec(buf, l, pos);
n->right = build_tree_rec(buf, pos+1, h);
return n;
}
/**
* build_tree
* @from: degenerated tree (linked by @tree->left) to be transformed into form suitable for find_tree()
*
* Transforms denerated tree into balanced tree.
*/
struct f_tree *
build_tree(struct f_tree *from)
{
struct f_tree *tmp, *root;
struct f_tree **buf;
int len, i;
if (from == NULL)
return NULL;
len = 0;
for (tmp = from; tmp != NULL; tmp = tmp->left)
len++;
if (len <= 1024)
buf = alloca(len * sizeof(struct f_tree *));
else
buf = malloc(len * sizeof(struct f_tree *));
/* Convert a degenerated tree into an sorted array */
i = 0;
for (tmp = from; tmp != NULL; tmp = tmp->left)
buf[i++] = tmp;
qsort(buf, len, sizeof(struct f_tree *), tree_compare);
root = build_tree_rec(buf, 0, len);
if (len > 1024)
free(buf);
return root;
}
struct f_tree *
f_new_tree(void)
{
struct f_tree * ret;
ret = cfg_alloc(sizeof(struct f_tree));
ret->left = ret->right = NULL;
ret->from.type = ret->to.type = T_VOID;
ret->from.val.i = ret->to.val.i = 0;
ret->data = NULL;
return ret;
}
/**
* same_tree
* @t1: first tree to be compared
* @t2: second one
*
* Compares two trees and returns 1 if they are same
*/
int
same_tree(struct f_tree *t1, struct f_tree *t2)
{
if ((!!t1) != (!!t2))
return 0;
if (!t1)
return 1;
if (val_compare(t1->from, t2->from))
return 0;
if (val_compare(t1->to, t2->to))
return 0;
if (!same_tree(t1->left, t2->left))
return 0;
if (!same_tree(t1->right, t2->right))
return 0;
if (!i_same(t1->data, t2->data))
return 0;
return 1;
}
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