tree.c 3.47 KB
Newer Older
1 2 3 4 5 6 7 8
/*
 *	Filters: utility functions
 *
 *	Copyright 1998 Pavel Machek <pavel@ucw.cz>
 *
 *	Can be freely distributed and used under the terms of the GNU GPL.
 */

9
#include "lib/alloca.h"
10 11 12 13
#include "nest/bird.h"
#include "conf/conf.h"
#include "filter/filter.h"

14 15 16 17 18 19 20 21
/**
 * 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.
22
 *
Pavel Machek's avatar
Pavel Machek committed
23
 * Both set matching and |switch() { }| construction is implemented using this function,
24
 * thus both are as fast as they can be.
25
 */
26 27 28 29
struct f_tree *
find_tree(struct f_tree *t, struct f_val val)
{
  if (!t)
Pavel Machek's avatar
Pavel Machek committed
30
    return NULL;
31 32 33 34 35 36 37 38 39
  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);
}

40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55
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;
}

56 57 58 59 60
static int 
tree_compare(const void *p1, const void *p2)
{
  return val_compare((* (struct f_tree **) p1)->from, (* (struct f_tree **) p2)->from);
}
61

62 63
/**
 * build_tree
64
 * @from: degenerated tree (linked by @tree->left) to be transformed into form suitable for find_tree()
65 66 67
 *
 * Transforms denerated tree into balanced tree.
 */
68 69 70
struct f_tree *
build_tree(struct f_tree *from)
{
71 72 73
  struct f_tree *tmp, *root;
  struct f_tree **buf;
  int len, i;
74

75
  if (from == NULL)
76 77
    return NULL;

78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99
  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;
100 101 102 103 104 105 106 107 108 109 110 111 112
}

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;
}
113

114 115 116 117 118 119 120
/**
 * same_tree
 * @t1: first tree to be compared
 * @t2: second one
 *
 * Compares two trees and returns 1 if they are same
 */
121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139
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;
}
140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173


static void
tree_node_format(struct f_tree *t, buffer *buf)
{
  if (t == NULL)
    return;

  tree_node_format(t->left, buf);

  val_format(t->from, buf);
  if (val_compare(t->from, t->to) != 0)
  {
    buffer_puts(buf, "..");
    val_format(t->to, buf);
  }
  buffer_puts(buf, ", ");

  tree_node_format(t->right, buf);
}

void
tree_format(struct f_tree *t, buffer *buf)
{
  buffer_puts(buf, "[");
 
 tree_node_format(t, buf);

 /* Undo last separator */
  if (buf->pos[-1] != '[')
    buf->pos -= 2;
 
  buffer_puts(buf, "]");
}