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/*
* Copyright (c) 2019 Cisco and/or its affiliates.
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*
* Algorithm from:
* Cormen, T. H., Leiserson, C. E., Rivest, R. L., & Stein, C. (2009).
* Introduction to algorithms. MIT press, 3rd Edition, Ch. 13
*/
#include <vppinfra/rbtree.h>
static inline void
rb_tree_rotate_left (rb_tree_t * rt, rb_node_t * x)
{
rb_node_t *y, *tmp, *xp;
rb_node_index_t xi, yi;
xi = rb_node_index (rt, x);
yi = x->right;
y = rb_node_right (rt, x);
x->right = y->left;
if (y->left != RBTREE_TNIL_INDEX)
{
tmp = rb_node_left (rt, y);
tmp->parent = xi;
}
xp = rb_node_parent (rt, x);
y->parent = x->parent;
if (x->parent == RBTREE_TNIL_INDEX)
rt->root = rb_node_index (rt, y);
else if (xp->left == xi)
xp->left = yi;
else
xp->right = yi;
y->left = xi;
x->parent = yi;
}
static inline void
rb_tree_rotate_right (rb_tree_t * rt, rb_node_t * y)
{
rb_node_index_t yi, xi;
rb_node_t *x, *yp;
yi = rb_node_index (rt, y);
xi = y->left;
x = rb_node_left (rt, y);
y->left = x->right;
if (x->right != RBTREE_TNIL_INDEX)
{
rb_node_t *tmp = rb_node_right (rt, x);
tmp->parent = yi;
}
yp = rb_node_parent (rt, y);
x->parent = y->parent;
if (y->parent == RBTREE_TNIL_INDEX)
rt->root = rb_node_index (rt, x);
else if (yp->right == yi)
yp->right = xi;
else
yp->left = xi;
x->right = yi;
y->parent = xi;
}
static inline void
rb_tree_fixup_inline (rb_tree_t * rt, rb_node_t * y, rb_node_t * z)
{
rb_node_t *zpp, *zp;
rb_node_index_t zi;
while (y->color == RBTREE_RED)
{
zi = rb_node_index (rt, z);
zp = rb_node_parent (rt, z);
zpp = rb_node_parent (rt, zp);
if (z->parent == zpp->left)
{
y = rb_node_right (rt, zpp);
if (y->color == RBTREE_RED)
{
zp->color = RBTREE_BLACK;
y->color = RBTREE_BLACK;
zpp->color = RBTREE_RED;
z = zpp;
}
else
{
if (zi == zp->right)
{
z = zp;
rb_tree_rotate_left (rt, z);
zp = rb_node (rt, z->parent);
zpp = rb_node (rt, zp->parent);
}
zp->color = RBTREE_BLACK;
zpp->color = RBTREE_RED;
rb_tree_rotate_right (rt, zpp);
}
}
else
{
y = rb_node (rt, zpp->left);
if (y->color == RBTREE_RED)
{
zp->color = RBTREE_BLACK;
y->color = RBTREE_BLACK;
zpp->color = RBTREE_RED;
z = zpp;
}
else
{
if (zi == zp->left)
{
z = zp;
rb_tree_rotate_right (rt, z);
zp = rb_node (rt, z->parent);
zpp = rb_node (rt, zp->parent);
}
zp->color = RBTREE_BLACK;
zpp->color = RBTREE_RED;
rb_tree_rotate_left (rt, zpp);
}
}
}
rb_node (rt, rt->root)->color = RBTREE_BLACK;
}
static void
rb_tree_insert (rb_tree_t * rt, rb_node_t * z)
{
rb_node_index_t yi = 0, xi = rt->root;
rb_node_t *y, *x;
y = rb_node (rt, RBTREE_TNIL_INDEX);
while (xi != RBTREE_TNIL_INDEX)
{
x = rb_node (rt, xi);
y = x;
if (z->key < x->key)
xi = x->left;
else
xi = x->right;
}
yi = rb_node_index (rt, y);
z->parent = yi;
if (yi == RBTREE_TNIL_INDEX)
rt->root = rb_node_index (rt, z);
else if (z->key < y->key)
y->left = rb_node_index (rt, z);
else
y->right = rb_node_index (rt, z);
/* Tree fixup stage */
rb_tree_fixup_inline (rt, y, z);
}
__clib_export rb_node_index_t
rb_tree_add (rb_tree_t * rt, u32 key)
{
rb_node_t *n;
pool_get_zero (rt->nodes, n);
n->key = key;
n->color = RBTREE_RED;
rb_tree_insert (rt, n);
return rb_node_index (rt, n);
}
__clib_export rb_node_index_t
rb_tree_add2 (rb_tree_t * rt, u32 key, uword opaque)
{
rb_node_t *n;
pool_get_zero (rt->nodes, n);
n->key = key;
n->color = RBTREE_RED;
n->opaque = opaque;
rb_tree_insert (rt, n);
return rb_node_index (rt, n);
}
__clib_export rb_node_index_t
rb_tree_add_custom (rb_tree_t * rt, u32 key, uword opaque, rb_tree_lt_fn ltfn)
{
rb_node_index_t yi = 0, xi = rt->root;
rb_node_t *z, *y, *x;
pool_get_zero (rt->nodes, z);
z->key = key;
z->color = RBTREE_RED;
z->opaque = opaque;
y = rb_node (rt, RBTREE_TNIL_INDEX);
while (xi != RBTREE_TNIL_INDEX)
{
x = rb_node (rt, xi);
y = x;
ASSERT (z->key != x->key);
if (ltfn (z->key, x->key))
xi = x->left;
else
xi = x->right;
}
yi = rb_node_index (rt, y);
z->parent = yi;
if (yi == RBTREE_TNIL_INDEX)
rt->root = rb_node_index (rt, z);
else if (ltfn (z->key, y->key))
y->left = rb_node_index (rt, z);
else
y->right = rb_node_index (rt, z);
rb_tree_fixup_inline (rt, y, z);
return rb_node_index (rt, z);
}
__clib_export rb_node_t *
rb_tree_search_subtree (rb_tree_t * rt, rb_node_t * x, u32 key)
{
while (rb_node_index (rt, x) != RBTREE_TNIL_INDEX && key != x->key)
if (key < x->key)
x = rb_node_left (rt, x);
else
x = rb_node_right (rt, x);
return x;
}
__clib_export rb_node_t *
rb_tree_search_subtree_custom (rb_tree_t * rt, rb_node_t * x, u32 key,
rb_tree_lt_fn ltfn)
{
while (rb_node_index (rt, x) != RBTREE_TNIL_INDEX && key != x->key)
if (ltfn (key, x->key))
x = rb_node_left (rt, x);
else
x = rb_node_right (rt, x);
return x;
}
__clib_export rb_node_t *
rb_tree_min_subtree (rb_tree_t * rt, rb_node_t * x)
{
while (x->left != RBTREE_TNIL_INDEX)
x = rb_node_left (rt, x);
return x;
}
__clib_export rb_node_t *
rb_tree_max_subtree (rb_tree_t * rt, rb_node_t * x)
{
while (x->right != RBTREE_TNIL_INDEX)
x = rb_node_right (rt, x);
return x;
}
__clib_export rb_node_t *
rb_tree_successor (rb_tree_t * rt, rb_node_t * x)
{
rb_node_t *y;
if (x->right != RBTREE_TNIL_INDEX)
return rb_tree_min_subtree (rt, rb_node_right (rt, x));
y = rb_node_parent (rt, x);
while (!rb_node_is_tnil (rt, y) && y->right == rb_node_index (rt, x))
{
x = y;
y = rb_node_parent (rt, y);
}
return y;
}
__clib_export rb_node_t *
rb_tree_predecessor (rb_tree_t * rt, rb_node_t * x)
{
rb_node_t *y;
if (x->left != RBTREE_TNIL_INDEX)
return rb_tree_max_subtree (rt, rb_node_left (rt, x));
y = rb_node_parent (rt, x);
while (!rb_node_is_tnil (rt, y) && y->left == rb_node_index (rt, x))
{
x = y;
y = rb_node_parent (rt, y);
}
return y;
}
static inline void
rb_tree_transplant (rb_tree_t * rt, rb_node_t * u, rb_node_t * v)
{
rb_node_t *up;
up = rb_node_parent (rt, u);
if (u->parent == RBTREE_TNIL_INDEX)
rt->root = rb_node_index (rt, v);
else if (rb_node_index (rt, u) == up->left)
up->left = rb_node_index (rt, v);
else
up->right = rb_node_index (rt, v);
v->parent = u->parent;
}
static void
rb_tree_del_node_internal (rb_tree_t * rt, rb_node_t * z)
{
rb_node_color_t y_original_color;
rb_node_t *x, *y, *yr, *yl, *xp, *w, *wl, *wr;
rb_node_index_t xi, yi;
y = z;
y_original_color = y->color;
if (z->left == RBTREE_TNIL_INDEX)
{
x = rb_node_right (rt, z);
rb_tree_transplant (rt, z, x);
}
else if (z->right == RBTREE_TNIL_INDEX)
{
x = rb_node_left (rt, z);
rb_tree_transplant (rt, z, x);
}
else
{
y = rb_tree_min_subtree (rt, rb_node_right (rt, z));
y_original_color = y->color;
x = rb_node_right (rt, y);
yi = rb_node_index (rt, y);
if (y->parent == rb_node_index (rt, z))
x->parent = yi;
else
{
rb_tree_transplant (rt, y, x);
y->right = z->right;
yr = rb_node_right (rt, y);
yr->parent = yi;
}
rb_tree_transplant (rt, z, y);
y->left = z->left;
yl = rb_node_left (rt, y);
yl->parent = yi;
y->color = z->color;
}
if (y_original_color == RBTREE_RED)
return;
/* Tree fixup needed */
xi = rb_node_index (rt, x);
while (xi != rt->root && x->color == RBTREE_BLACK)
{
xp = rb_node_parent (rt, x);
if (xi == xp->left)
{
w = rb_node_right (rt, xp);
if (w->color == RBTREE_RED)
{
w->color = RBTREE_BLACK;
xp->color = RBTREE_RED;
rb_tree_rotate_left (rt, xp);
w = rb_node_right (rt, xp);
}
wl = rb_node_left (rt, w);
wr = rb_node_right (rt, w);
if (wl->color == RBTREE_BLACK && wr->color == RBTREE_BLACK)
{
if (!rb_node_is_tnil (rt, w))
w->color = RBTREE_RED;
x = xp;
}
else
{
if (wr->color == RBTREE_BLACK)
{
wl->color = RBTREE_BLACK;
w->color = RBTREE_RED;
rb_tree_rotate_right (rt, w);
w = rb_node_right (rt, xp);
wr = rb_node_right (rt, w);
}
w->color = xp->color;
xp->color = RBTREE_BLACK;
wr->color = RBTREE_BLACK;
rb_tree_rotate_left (rt, xp);
x = rb_node (rt, rt->root);
}
}
else
{
w = rb_node_left (rt, xp);
if (w->color == RBTREE_RED)
{
w->color = RBTREE_BLACK;
xp->color = RBTREE_RED;
rb_tree_rotate_right (rt, xp);
w = rb_node_left (rt, xp);
}
wl = rb_node_left (rt, w);
wr = rb_node_right (rt, w);
if (wl->color == RBTREE_BLACK && wr->color == RBTREE_BLACK)
{
if (!rb_node_is_tnil (rt, w))
w->color = RBTREE_RED;
x = xp;
}
else
{
if (wl->color == RBTREE_BLACK)
{
wr->color = RBTREE_BLACK;
w->color = RBTREE_RED;
rb_tree_rotate_left (rt, w);
w = rb_node_left (rt, xp);
wl = rb_node_left (rt, w);
}
w->color = xp->color;
xp->color = RBTREE_BLACK;
wl->color = RBTREE_BLACK;
rb_tree_rotate_right (rt, xp);
x = rb_node (rt, rt->root);
}
}
xi = rb_node_index (rt, x);
}
x->color = RBTREE_BLACK;
}
__clib_export void
rb_tree_del_node (rb_tree_t * rt, rb_node_t * z)
{
rb_tree_del_node_internal (rt, z);
pool_put (rt->nodes, z);
}
__clib_export void
rb_tree_del (rb_tree_t * rt, u32 key)
{
rb_node_t *n;
n = rb_tree_search_subtree (rt, rb_node (rt, rt->root), key);
if (rb_node_index (rt, n) != RBTREE_TNIL_INDEX)
rb_tree_del_node (rt, n);
}
__clib_export void
rb_tree_del_custom (rb_tree_t * rt, u32 key, rb_tree_lt_fn ltfn)
{
rb_node_t *n;
n = rb_tree_search_subtree_custom (rt, rb_node (rt, rt->root), key, ltfn);
if (rb_node_index (rt, n) != RBTREE_TNIL_INDEX)
rb_tree_del_node (rt, n);
}
__clib_export u32
rb_tree_n_nodes (rb_tree_t * rt)
{
return pool_elts (rt->nodes);
}
__clib_export void
rb_tree_free_nodes (rb_tree_t * rt)
{
pool_free (rt->nodes);
rt->root = RBTREE_TNIL_INDEX;
}
__clib_export void
rb_tree_init (rb_tree_t * rt)
{
rb_node_t *tnil;
rt->nodes = 0;
rt->root = RBTREE_TNIL_INDEX;
/* By convention first node, index 0, is the T.nil sentinel */
pool_get_zero (rt->nodes, tnil);
tnil->color = RBTREE_BLACK;
}
__clib_export int
rb_tree_is_init (rb_tree_t * rt)
{
if (pool_elts (rt->nodes) == 0)
return 0;
return 1;
}
/*
* fd.io coding-style-patch-verification: ON
*
* Local Variables:
* eval: (c-set-style "gnu")
* End:
*/
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