/*
 *                         OpenSplice DDS
 *
 *   This software and documentation are Copyright 2006 to TO_YEAR PrismTech
 *   Limited, its affiliated companies and licensors. All rights reserved.
 *
 *   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.
 *
 */
#include <limits.h>

#include "os_defs.h"
#include "os_stdlib.h"

#include "ut_avl.h"

#define LOAD_DIRKEY(avlnode, tree) (((char *) (avlnode)) - (tree)->avlnodeoffset + (tree)->keyoffset)
#define LOAD_INDKEY(avlnode, tree) (*((char **) (((char *) (avlnode)) - (tree)->avlnodeoffset + (tree)->keyoffset)))

static int comparenk (const ut_avlTreedef_t *td, const ut_avlNode_t *a, const void *b)
{
    const void *ka;
    if (td->flags & UT_AVL_TREEDEF_FLAG_INDKEY) {
        ka = LOAD_INDKEY (a, td);
    } else {
        ka = LOAD_DIRKEY (a, td);
    }
    if (td->flags & UT_AVL_TREEDEF_FLAG_R) {
        return td->u.comparekk_r (ka, b, td->cmp_arg);
    } else {
        return td->u.comparekk (ka, b);
    }
}

#if 0
static int comparenn_direct (const ut_avlTreedef_t *td, const ut_avlNode_t *a, const ut_avlNode_t *b)
{
    return td->comparekk (LOAD_DIRKEY (a, td), LOAD_DIRKEY (b, td));
}

static int comparenn_indirect (const ut_avlTreedef_t *td, const ut_avlNode_t *a, const ut_avlNode_t *b)
{
    return td->comparekk (LOAD_INDKEY (a, td), LOAD_INDKEY (b, td));
}

static int comparenn (const ut_avlTreedef_t *td, const ut_avlNode_t *a, const ut_avlNode_t *b)
{
    if (IS_INDKEY (td->keyoffset)) {
        return comparenn_indirect (td, a, b);
    } else {
        return comparenn_direct (td, a, b);
    }
}
#endif

static ut_avlNode_t *node_from_onode (const ut_avlTreedef_t *td, char *onode)
{
    if (onode == NULL) {
        return NULL;
    } else {
        return (ut_avlNode_t *) (onode + td->avlnodeoffset);
    }
}

static const ut_avlNode_t *cnode_from_onode (const ut_avlTreedef_t *td, const char *onode)
{
    if (onode == NULL) {
        return NULL;
    } else {
        return (const ut_avlNode_t *) (onode + td->avlnodeoffset);
    }
}

static char *onode_from_node (const ut_avlTreedef_t *td, ut_avlNode_t *node)
{
    if (node == NULL) {
        return NULL;
    } else {
        return (char *) node - td->avlnodeoffset;
    }
}

static const char *conode_from_node (const ut_avlTreedef_t *td, const ut_avlNode_t *node)
{
    if (node == NULL) {
        return NULL;
    } else {
        return (const char *) node - td->avlnodeoffset;
    }
}

static void treedef_init_common (ut_avlTreedef_t *td, os_size_t avlnodeoffset, os_size_t keyoffset, int (*cmp) (void), ut_avlAugment_t augment, os_uint32 flags)
{
    assert (avlnodeoffset <= 0x7fffffff);
    assert (keyoffset <= 0x7fffffff);
    td->avlnodeoffset = avlnodeoffset;
    td->keyoffset = keyoffset;
    td->u.cmp = cmp;
    td->augment = augment;
    td->flags = flags;
}

void ut_avlTreedefInit (ut_avlTreedef_t *td, os_size_t avlnodeoffset, os_size_t keyoffset, ut_avlCompare_t comparekk, ut_avlAugment_t augment, os_uint32 flags)
{
    treedef_init_common (td, avlnodeoffset, keyoffset, (int (*) (void)) comparekk, augment, flags);
}

void ut_avlTreedefInit_r (ut_avlTreedef_t *td, os_size_t avlnodeoffset, os_size_t keyoffset, ut_avlCompare_r_t comparekk_r, void *cmp_arg, ut_avlAugment_t augment, os_uint32 flags)
{
    td->cmp_arg = cmp_arg;
    treedef_init_common (td, avlnodeoffset, keyoffset, (int (*) (void)) comparekk_r, augment, flags | UT_AVL_TREEDEF_FLAG_R);
}

void ut_avlInit (const ut_avlTreedef_t *td, ut_avlTree_t *tree)
{
    tree->root = NULL;
    (void) td;
}

static void treedestroy (const ut_avlTreedef_t *td, ut_avlNode_t *n, void (*freefun) (void *node))
{
    if (n) {
        n->parent = NULL;
        treedestroy (td, n->cs[0], freefun);
        treedestroy (td, n->cs[1], freefun);
        n->cs[0] = NULL;
        n->cs[1] = NULL;
        freefun (onode_from_node (td, n));
    }
}

static void treedestroy_arg (const ut_avlTreedef_t *td, ut_avlNode_t *n, void (*freefun) (void *node, void *arg), void *arg)
{
    if (n) {
        n->parent = NULL;
        treedestroy_arg (td, n->cs[0], freefun, arg);
        treedestroy_arg (td, n->cs[1], freefun, arg);
        n->cs[0] = NULL;
        n->cs[1] = NULL;
        freefun (onode_from_node (td, n), arg);
    }
}

void ut_avlFree (const ut_avlTreedef_t *td, ut_avlTree_t *tree, void (*freefun) (void *node))
{
    ut_avlNode_t *n = tree->root;
    tree->root = NULL;
    if (freefun) {
        treedestroy (td, n, freefun);
    }
}

void ut_avlFreeArg (const ut_avlTreedef_t *td, ut_avlTree_t *tree, void (*freefun) (void *node, void *arg), void *arg)
{
    ut_avlNode_t *n = tree->root;
    tree->root = NULL;
    if (freefun) {
        treedestroy_arg (td, n, freefun, arg);
    }
}

static void augment (const ut_avlTreedef_t *td, ut_avlNode_t *n)
{
    td->augment (onode_from_node (td, n), conode_from_node (td, n->cs[0]), conode_from_node (td, n->cs[1]));
}

static ut_avlNode_t *rotate_single (const ut_avlTreedef_t *td, ut_avlNode_t **pnode, ut_avlNode_t *node, int dir)
{
    /* rotate_single(N, dir) performs one rotation, e.g., for dir=1, a
       right rotation as depicted below, for dir=0 a left rotation:

                     N                      _ND'
            _ND          v     ==>    u             N'
         u    _ND_D                          _ND_D     v

       Since a right rotation is only ever done with the left side is
       overweight, _ND must be != NULL.  */
    ut_avlNode_t * const parent = node->parent;
    ut_avlNode_t * const node_ND = node->cs[1-dir];
    ut_avlNode_t * const node_ND_D = node_ND->cs[dir];
    assert (node_ND);
    node_ND->cs[dir] = node;
    node_ND->parent = parent;
    node->parent = node_ND;
    node->cs[1-dir] = node_ND_D;
    if (node_ND_D) {
        node_ND_D->parent = node;
    }
    node->height = node_ND_D ? (1 + node_ND_D->height) : 1;
    node_ND->height = node->height + 1;
    *pnode = node_ND;
    if (td->augment) {
        augment (td, node);
        augment (td, node_ND);
    }
    return parent;
}

static ut_avlNode_t *rotate_double (const ut_avlTreedef_t *td, ut_avlNode_t **pnode, ut_avlNode_t *node, int dir)
{
    /* rotate_double() performs one double rotation, which is slightly
       faster when written out than the equivalent:

         rotate_single(N->cs[1-dir], 1-dir)
         rotate_single(N, dir)

       A right double rotation therefore means:

                    N                    N'            _ND_D''
            _ND         v  =>    _ND_D'     v  =>   _ND''     N''
         u    _ND_D            _ND'    y           u    x    y   v
             x     y         u     x

       Since a right double rotation is only ever done with the N is
       overweight on the left side and _ND is overweight on the right
       side, both _ND and _ND_D must be != NULL. */
    ut_avlNode_t * const parent = node->parent;
    ut_avlNode_t * const node_ND = node->cs[1-dir];
    ut_avlNode_t * const node_ND_D = node_ND->cs[dir];
    assert (node_ND);
    assert (node_ND_D);
    node_ND->cs[dir] = node_ND_D->cs[1-dir];
    if (node_ND->cs[dir]) {
        node_ND->cs[dir]->parent = node_ND;
    }
    node->cs[1-dir] = node_ND_D->cs[dir];
    if (node->cs[1-dir]) {
        node->cs[1-dir]->parent = node;
    }
    node_ND_D->cs[1-dir] = node_ND;
    node_ND_D->cs[dir] = node;
    node_ND->parent = node_ND_D;
    node->parent = node_ND_D;
    node_ND_D->parent = parent;
    *pnode = node_ND_D;
    {
        const int h = node_ND->height;
        node->height = node_ND_D->height;
        node_ND->height = node_ND_D->height;
        node_ND_D->height = h;
    }
    if (td->augment) {
        augment (td, node);
        augment (td, node_ND);
        augment (td, node_ND_D);
    }
    return parent;
}

static ut_avlNode_t *rotate (const ut_avlTreedef_t *td, ut_avlNode_t **pnode, ut_avlNode_t *node, int dir)
{
    /* _D => child in the direction of rotation (1 for right, 0 for
       left); _ND => child in the opposite direction.  So in a right
       rotation, _ND_D means the grandchild that is the right child of
       the left child. */
    ut_avlNode_t * const node_ND = node->cs[1-dir];
    ut_avlNode_t * const node_ND_ND = node_ND->cs[1-dir];
    ut_avlNode_t * const node_ND_D = node_ND->cs[dir];
    int height_ND_ND, height_ND_D;
    assert (dir == !!dir);
    assert (node_ND != NULL);
    height_ND_ND = node_ND_ND ? node_ND_ND->height : 0;
    height_ND_D = node_ND_D ? node_ND_D->height : 0;
    if (height_ND_ND < height_ND_D) {
        return rotate_double (td, pnode, node, dir);
    } else {
        return rotate_single (td, pnode, node, dir);
    }
}

static ut_avlNode_t *rebalance_one (const ut_avlTreedef_t *td, ut_avlNode_t **pnode, ut_avlNode_t *node)
{
    ut_avlNode_t *node_L = node->cs[0];
    ut_avlNode_t *node_R = node->cs[1];
    int height_L = node_L ? node_L->height : 0;
    int height_R = node_R ? node_R->height : 0;
    if (height_L > height_R + 1) {
        return rotate (td, pnode, node, 1);
    } else if (height_L < height_R - 1) {
        return rotate (td, pnode, node, 0);
    } else {
        /* Rebalance happens only on insert & delete, and augment needs to
           be called during rotations.  Therefore, rebalancing integrates
           calling augment, and because of that, includes running all the
           way up to the root even when not needed for the rebalancing
           itself. */
        int height = (height_L < height_R ? height_R : height_L) + 1;
        if (td->augment == 0 && height == node->height) {
            return NULL;
        } else {
            node->height = height;
            if (td->augment) {
                augment (td, node);
            }
            return node->parent;
        }
    }
}

static void rebalance_path (const ut_avlTreedef_t *td, ut_avlPath_t *path, ut_avlNode_t *node)
{
    while (node) {
        assert (*path->pnode[path->depth] == node);
        node = rebalance_one (td, path->pnode[path->depth], node);
        path->depth--;
    }
}

static ut_avlNode_t **nodeptr_from_node (ut_avlTree_t *tree, ut_avlNode_t *node)
{
    ut_avlNode_t *parent = node->parent;
    return (parent == NULL) ? &tree->root
        : (node == parent->cs[0]) ? &parent->cs[0]
        : &parent->cs[1];
}

static void rebalance_nopath (const ut_avlTreedef_t *td, ut_avlTree_t *tree, ut_avlNode_t *node)
{
    while (node) {
        ut_avlNode_t **pnode = nodeptr_from_node (tree, node);
        node = rebalance_one (td, pnode, node);
    }
}

void *ut_avlLookup (const ut_avlTreedef_t *td, const ut_avlTree_t *tree, const void *key)
{
    const ut_avlNode_t *cursor = tree->root;
    int c;
    while (cursor && (c = comparenk (td, cursor, key)) != 0) {
        const int dir = (c <= 0);
        cursor = cursor->cs[dir];
    }
    return (void *) conode_from_node (td, cursor);
}

static const ut_avlNode_t *lookup_path (const ut_avlTreedef_t *td, const ut_avlTree_t *tree, const void *key, ut_avlPath_t *path)
{
    const ut_avlNode_t *cursor = tree->root;
    const ut_avlNode_t *prev = NULL;
    int c;
    path->depth = 0;
    path->pnode[0] = (ut_avlNode_t **) &tree->root;
    while (cursor && (c = comparenk (td, cursor, key)) != 0) {
        const int dir = (c <= 0);
        prev = cursor;
        path->pnode[++path->depth] = (ut_avlNode_t **) &cursor->cs[dir];
        cursor = cursor->cs[dir];
    }
    path->pnodeidx = path->depth;
    path->parent = (ut_avlNode_t *) prev;
    return cursor;
}

void *ut_avlLookupDPath (const ut_avlTreedef_t *td, const ut_avlTree_t *tree, const void *key, ut_avlDPath_t *path)
{
    const ut_avlNode_t *node = lookup_path (td, tree, key, &path->p);
    return (void *) conode_from_node (td, node);
}

void *ut_avlLookupIPath (const ut_avlTreedef_t *td, const ut_avlTree_t *tree, const void *key, ut_avlIPath_t *path)
{
    const ut_avlNode_t *node = lookup_path (td, tree, key, &path->p);
    /* If no duplicates allowed, path may not be used for insertion,
       and hence there is no need to continue descending the tree.
       Since we can invalidate it very efficiently, do so. */
    if (node) {
        if (!(td->flags & UT_AVL_TREEDEF_FLAG_ALLOWDUPS)) {
            path->p.pnode[path->p.depth] = NULL;
        } else {
            const ut_avlNode_t *cursor = node;
            const ut_avlNode_t *prev;
            int c, dir;
            do {
                c = comparenk (td, cursor, key);
                dir = (c <= 0);
                prev = cursor;
                path->p.pnode[++path->p.depth] = (ut_avlNode_t **) &cursor->cs[dir];
                cursor = cursor->cs[dir];
            } while (cursor);
            path->p.parent = (ut_avlNode_t *) prev;
        }
    }
    return (void *) conode_from_node (td, node);
}

void ut_avlInsertIPath (const ut_avlTreedef_t *td, ut_avlTree_t *tree, void *vnode, ut_avlIPath_t *path)
{
    ut_avlNode_t *node = node_from_onode (td, vnode);
    (void) tree;
    node->cs[0] = NULL;
    node->cs[1] = NULL;
    node->parent = path->p.parent;
    node->height = 1;
    if (td->augment) {
        augment (td, node);
    }
    assert (path->p.pnode[path->p.depth]);
    assert ((*path->p.pnode[path->p.depth]) == NULL);
    *path->p.pnode[path->p.depth] = node;
    path->p.depth--;
    rebalance_path (td, &path->p, node->parent);
}

void ut_avlInsert (const ut_avlTreedef_t *td, ut_avlTree_t *tree, void *vnode)
{
    const void *node = cnode_from_onode (td, vnode);
    const void *key;
    ut_avlIPath_t path;
    if (td->flags & UT_AVL_TREEDEF_FLAG_INDKEY) {
        key = LOAD_INDKEY (node, td);
    } else {
        key = LOAD_DIRKEY (node, td);
    }
    ut_avlLookupIPath (td, tree, key, &path);
    ut_avlInsertIPath (td, tree, vnode, &path);
}

static void delete_generic (const ut_avlTreedef_t *td, ut_avlTree_t *tree, void *vnode, ut_avlDPath_t *path)
{
    ut_avlNode_t *node = node_from_onode (td, vnode);
    ut_avlNode_t **pnode;
    ut_avlNode_t *whence;

    if (path) {
        assert (tree == NULL);
        pnode = path->p.pnode[path->p.pnodeidx];
    } else {
        pnode = nodeptr_from_node (tree, node);
    }

    if (node->cs[0] == NULL)
    {
        if (node->cs[1]) {
            node->cs[1]->parent = node->parent;
        }
        *pnode = node->cs[1];
        whence = node->parent;
    }
    else if (node->cs[1] == NULL)
    {
        node->cs[0]->parent = node->parent;
        *pnode = node->cs[0];
        whence = node->parent;
    }
    else
    {
        ut_avlNode_t *subst;

        assert (node->cs[0] != NULL);
        assert (node->cs[1] != NULL);

        /* Use predecessor as substitute */
        if (path) {
            path->p.pnode[++path->p.depth] = &node->cs[0];
        }
        subst = node->cs[0];
        if (subst->cs[1] == NULL) {
            whence = subst;
        } else {
            do {
                if (path) {
                    path->p.pnode[++path->p.depth] = &subst->cs[1];
                }
                subst = subst->cs[1];
            } while (subst->cs[1]);
            whence = subst->parent;

            whence->cs[1] = subst->cs[0];
            if (whence->cs[1]) {
                whence->cs[1]->parent = whence;
            }
            subst->cs[0] = node->cs[0];
            if (subst->cs[0]) {
                subst->cs[0]->parent = subst;
            }
            if (path) {
                path->p.pnode[path->p.pnodeidx+1] = &subst->cs[0];
            }
        }

        subst->parent = node->parent;
        subst->height = node->height;
        subst->cs[1] = node->cs[1];
        if (subst->cs[1]) {
            subst->cs[1]->parent = subst;
        }
        *pnode = subst;
    }

    if (td->augment && whence) {
        augment (td, whence);
    }
    if (path) {
        path->p.depth--;
        rebalance_path (td, &path->p, whence);
    } else {
        rebalance_nopath (td, tree, whence);
    }
}

void ut_avlDeleteDPath (const ut_avlTreedef_t *td, ut_avlTree_t *tree, void *vnode, ut_avlDPath_t *path)
{
    (void) tree;
    delete_generic (td, NULL, vnode, path);
}

void ut_avlDelete (const ut_avlTreedef_t *td, ut_avlTree_t *tree, void *vnode)
{
    delete_generic (td, tree, vnode, NULL);
}

void ut_avlSwapNode (const ut_avlTreedef_t *td, ut_avlTree_t *tree, void *vold, void *vnew)
{
    ut_avlNode_t *old = node_from_onode (td, vold);
    ut_avlNode_t *new = node_from_onode (td, vnew);
    *nodeptr_from_node (tree, old) = new;
    /* use memmove so partially overlap between old & new is allowed
       (yikes!, but exploited by the memory allocator, and not a big
       deal to get right) */
    memmove (new, old, sizeof (*new));
    if (new->cs[0]) {
        new->cs[0]->parent = new;
    }
    if (new->cs[1]) {
        new->cs[1]->parent = new;
    }
    if (td->augment) {
        augment (td, new);
    }
}

static ut_avlNode_t *find_neighbour (const ut_avlNode_t *n, int dir)
{
    /* dir = 0 => pred; dir = 1 = succ */
    if (n->cs[dir]) {
        n = n->cs[dir];
        while (n->cs[1-dir]) {
            n = n->cs[1-dir];
        }
        return (ut_avlNode_t *) n;
    } else {
        const ut_avlNode_t *p = n->parent;
        while (p && n == p->cs[dir]) {
            n = p;
            p = p->parent;
        }
        return (ut_avlNode_t *) p;
    }
}

static ut_avlNode_t *find_extremum (const ut_avlTree_t *tree, int dir)
{
    const ut_avlNode_t *n = tree->root;
    if (n) {
        while (n->cs[dir]) {
            n = n->cs[dir];
        }
    }
    return (ut_avlNode_t *) n;
}

void *ut_avlFindMin (const ut_avlTreedef_t *td, const ut_avlTree_t *tree)
{
    return (void *) conode_from_node (td, find_extremum (tree, 0));
}

void *ut_avlFindMax (const ut_avlTreedef_t *td, const ut_avlTree_t *tree)
{
    return (void *) conode_from_node (td, find_extremum (tree, 1));
}

void *ut_avlFindPred (const ut_avlTreedef_t *td, const ut_avlTree_t *tree, const void *vnode)
{
    const ut_avlNode_t *n = cnode_from_onode (td, vnode);
    if (n == NULL) {
        return ut_avlFindMax (td, tree);
    } else {
        return (void *) conode_from_node (td, find_neighbour (n, 0));
    }
}

void *ut_avlFindSucc (const ut_avlTreedef_t *td, const ut_avlTree_t *tree, const void *vnode)
{
    const ut_avlNode_t *n = cnode_from_onode (td, vnode);
    if (n == NULL) {
        return ut_avlFindMin (td, tree);
    } else {
        return (void *) conode_from_node (td, find_neighbour (n, 1));
    }
}

static void avl_iter_downleft (ut_avlIter_t *iter)
{
    if (*iter->todop) {
        ut_avlNode_t *n;
        n = (*iter->todop)->cs[0];
        while (n) {
            assert ((int) (iter->todop - iter->todo) < (int) (sizeof (iter->todo) / sizeof (*iter->todo)));
            *++iter->todop = n;
            n = n->cs[0];
        }
        iter->right = (*iter->todop)->cs[1];
    }
}

void *ut_avlIterFirst (const ut_avlTreedef_t *td, const ut_avlTree_t *tree, ut_avlIter_t *iter)
{
    iter->td = td;
    iter->todop = iter->todo+1;
    *iter->todop = (ut_avlNode_t *) tree->root;
    avl_iter_downleft (iter);
    return onode_from_node (td, *iter->todop);
}

void *ut_avlIterNext (ut_avlIter_t *iter)
{
    if (iter->todop-- > iter->todo+1 && iter->right == NULL) {
        iter->right = (*iter->todop)->cs[1];
    } else {
        assert ((int) (iter->todop - iter->todo) < (int) (sizeof (iter->todo) / sizeof (*iter->todo)));
        *++iter->todop = iter->right;
        avl_iter_downleft (iter);
    }
    return onode_from_node (iter->td, *iter->todop);
}

void ut_avlWalk (const ut_avlTreedef_t *td, ut_avlTree_t *tree, ut_avlWalk_t f, void *a)
{
    const ut_avlNode_t *todo[1+UT_AVL_MAX_TREEHEIGHT];
    const ut_avlNode_t **todop = todo+1;
    *todop = tree->root;
    while (*todop) {
        ut_avlNode_t *right, *n;
        /* First locate the minimum value in this subtree */
        n = (*todop)->cs[0];
        while (n) {
            *++todop = n;
            n = n->cs[0];
        }
        /* Then process it and its parents until a node N is hit that has
           a right subtree, with (by definition) key values in between N
           and the parent of N */
        do {
            right = (*todop)->cs[1];
            f ((void *) conode_from_node (td, *todop), a);
        } while (todop-- > todo+1 && right == NULL);
        /* Continue with right subtree rooted at 'right' before processing
           the parent node of the last node processed in the loop above */
        *++todop = right;
    }
}

void ut_avlConstWalk (const ut_avlTreedef_t *td, const ut_avlTree_t *tree, ut_avlConstWalk_t f, void *a)
{
    ut_avlWalk (td, (ut_avlTree_t *) tree, (ut_avlWalk_t) f, a);
}

int ut_avlIsEmpty (const ut_avlTree_t *tree)
{
    return tree->root == NULL;
}

int ut_avlIsSingleton (const ut_avlTree_t *tree)
{
    int r = (tree->root && tree->root->height == 1);
    assert (!r || (tree->root->cs[0] == NULL && tree->root->cs[1] == NULL));
    return r;
}

void ut_avlAugmentUpdate (const ut_avlTreedef_t *td, void *vnode)
{
    if (td->augment) {
        ut_avlNode_t *node = node_from_onode (td, vnode);
        while (node) {
            augment (td, node);
            node = node->parent;
        }
    }
}

static const ut_avlNode_t *fixup_predsucceq (const ut_avlTreedef_t *td, const void *key, const ut_avlNode_t *tmp, const ut_avlNode_t *cand, int dir)
{
    if (tmp == NULL) {
        return cand;
    } else if (!(td->flags & UT_AVL_TREEDEF_FLAG_ALLOWDUPS)) {
        return tmp;
    } else {
        /* key exists - but it there's no guarantee we hit the first
           one in the in-order enumeration of the tree */
        cand = tmp;
        tmp = tmp->cs[1-dir];
        while (tmp) {
            if (comparenk (td, tmp, key) != 0) {
                tmp = tmp->cs[dir];
            } else {
                cand = tmp;
                tmp = tmp->cs[1-dir];
            }
        }
        return cand;
    }
}

static const ut_avlNode_t *lookup_predeq (const ut_avlTreedef_t *td, const ut_avlTree_t *tree, const void *key)
{
    const ut_avlNode_t *tmp = tree->root;
    const ut_avlNode_t *cand = NULL;
    int c;
    while (tmp && (c = comparenk (td, tmp, key)) != 0) {
        if (c < 0) {
            cand = tmp;
            tmp = tmp->cs[1];
        } else {
            tmp = tmp->cs[0];
        }
    }
    return fixup_predsucceq (td, key, tmp, cand, 0);
}

static const ut_avlNode_t *lookup_succeq (const ut_avlTreedef_t *td, const ut_avlTree_t *tree, const void *key)
{
    const ut_avlNode_t *tmp = tree->root;
    const ut_avlNode_t *cand = NULL;
    int c;
    while (tmp && (c = comparenk (td, tmp, key)) != 0) {
        if (c > 0) {
            cand = tmp;
            tmp = tmp->cs[0];
        } else {
            tmp = tmp->cs[1];
        }
    }
    return fixup_predsucceq (td, key, tmp, cand, 1);
}

static const ut_avlNode_t *fixup_predsucc (const ut_avlTreedef_t *td, const void *key, const ut_avlNode_t *tmp, const ut_avlNode_t *cand, int dir)
{
    /* dir=0: pred, dir=1: succ */
    if (tmp == NULL || tmp->cs[dir] == NULL) {
        return cand;
    } else if (!(td->flags & UT_AVL_TREEDEF_FLAG_ALLOWDUPS)) {
        /* No duplicates, therefore the extremum in the subtree */
        tmp = tmp->cs[dir];
        while (tmp->cs[1-dir]) {
            tmp = tmp->cs[1-dir];
        }
        return tmp;
    } else {
        /* Duplicates allowed, therefore: if tmp has no right subtree,
           cand else scan the right subtree for the minimum larger
           than key, return cand if none can be found */
        tmp = tmp->cs[dir];
        while (tmp) {
            if (comparenk (td, tmp, key) != 0) {
                cand = tmp;
                tmp = tmp->cs[1-dir];
            } else {
                tmp = tmp->cs[dir];
            }
        }
        return cand;
    }
}

static const ut_avlNode_t *lookup_pred (const ut_avlTreedef_t *td, const ut_avlTree_t *tree, const void *key)
{
    const ut_avlNode_t *tmp = tree->root;
    const ut_avlNode_t *cand = NULL;
    int c;
    while (tmp && (c = comparenk (td, tmp, key)) != 0) {
        if (c < 0) {
            cand = tmp;
            tmp = tmp->cs[1];
        } else {
            tmp = tmp->cs[0];
        }
    }
    return fixup_predsucc (td, key, tmp, cand, 0);
}

static const ut_avlNode_t *lookup_succ (const ut_avlTreedef_t *td, const ut_avlTree_t *tree, const void *key)
{
    const ut_avlNode_t *tmp = tree->root;
    const ut_avlNode_t *cand = NULL;
    int c;
    while (tmp && (c = comparenk (td, tmp, key)) != 0) {
        if (c > 0) {
            cand = tmp;
            tmp = tmp->cs[0];
        } else {
            tmp = tmp->cs[1];
        }
    }
    return fixup_predsucc (td, key, tmp, cand, 1);
}

void *ut_avlLookupSuccEq (const ut_avlTreedef_t *td, const ut_avlTree_t *tree, const void *key)
{
    return (void *) conode_from_node (td, lookup_succeq (td, tree, key));
}

void *ut_avlLookupPredEq (const ut_avlTreedef_t *td, const ut_avlTree_t *tree, const void *key)
{
    return (void *) conode_from_node (td, lookup_predeq (td, tree, key));
}

void *ut_avlLookupSucc (const ut_avlTreedef_t *td, const ut_avlTree_t *tree, const void *key)
{
    return (void *) conode_from_node (td, lookup_succ (td, tree, key));
}

void *ut_avlLookupPred (const ut_avlTreedef_t *td, const ut_avlTree_t *tree, const void *key)
{
    return (void *) conode_from_node (td, lookup_pred (td, tree, key));
}

void *ut_avlIterSuccEq (const ut_avlTreedef_t *td, const ut_avlTree_t *tree, ut_avlIter_t *iter, const void *key)
{
    const ut_avlNode_t *tmp = tree->root;
    int c;
    iter->td = td;
    iter->todop = iter->todo;
    while (tmp && (c = comparenk (td, tmp, key)) != 0) {
        if (c > 0) {
            *++iter->todop = (ut_avlNode_t *) tmp;
            tmp = tmp->cs[0];
        } else {
            tmp = tmp->cs[1];
        }
    }
    if (tmp != NULL) {
        *++iter->todop = (ut_avlNode_t *) tmp;
        if (td->flags & UT_AVL_TREEDEF_FLAG_ALLOWDUPS) {
            /* key exists - but it there's no guarantee we hit the
               first one in the in-order enumeration of the tree */
            tmp = tmp->cs[0];
            while (tmp) {
                if (comparenk (td, tmp, key) != 0) {
                    tmp = tmp->cs[1];
                } else {
                    *++iter->todop = (ut_avlNode_t *) tmp;
                    tmp = tmp->cs[0];
                }
            }
        }
    }
    if (iter->todop == iter->todo) {
        return NULL;
    } else {
        iter->right = (*iter->todop)->cs[1];
        return onode_from_node (td, *iter->todop);
    }
}

void *ut_avlIterSucc (const ut_avlTreedef_t *td, const ut_avlTree_t *tree, ut_avlIter_t *iter, const void *key)
{
    const ut_avlNode_t *tmp = tree->root;
    int c;
    iter->td = td;
    iter->todop = iter->todo;
    while (tmp && (c = comparenk (td, tmp, key)) != 0) {
        if (c > 0) {
            *++iter->todop = (ut_avlNode_t *) tmp;
            tmp = tmp->cs[0];
        } else {
            tmp = tmp->cs[1];
        }
    }
    if (tmp != NULL) {
      if (!(td->flags & UT_AVL_TREEDEF_FLAG_ALLOWDUPS)) {
            tmp = tmp->cs[1];
            if (tmp) {
                do {
                    *++iter->todop = (ut_avlNode_t *) tmp;
                    tmp = tmp->cs[0];
                } while (tmp);
            }
        } else {
            tmp = tmp->cs[1];
            while (tmp) {
                if (comparenk (td, tmp, key) != 0) {
                    *++iter->todop = (ut_avlNode_t *) tmp;
                    tmp = tmp->cs[0];
                } else {
                    tmp = tmp->cs[1];
                }
            }
        }
    }
    if (iter->todop == iter->todo) {
        return NULL;
    } else {
        iter->right = (*iter->todop)->cs[1];
        return onode_from_node (td, *iter->todop);
    }
}

void ut_avlWalkRange (const ut_avlTreedef_t *td, ut_avlTree_t *tree, const void *min, const void *max, ut_avlWalk_t f, void *a)
{
    ut_avlNode_t *n, *nn;
    n = (ut_avlNode_t *) lookup_succeq (td, tree, min);
    while (n && comparenk (td, n, max) <= 0) {
        nn = find_neighbour (n, 1);
        f (onode_from_node (td, n), a);
        n = nn;
    }
}

void ut_avlConstWalkRange (const ut_avlTreedef_t *td, const ut_avlTree_t *tree, const void *min, const void *max, ut_avlConstWalk_t f, void *a)
{
    ut_avlWalkRange (td, (ut_avlTree_t *) tree, min, max, (ut_avlWalk_t) f, a);
}

void ut_avlWalkRangeReverse (const ut_avlTreedef_t *td, ut_avlTree_t *tree, const void *min, const void *max, ut_avlWalk_t f, void *a)
{
    ut_avlNode_t *n, *nn;
    n = (ut_avlNode_t *) lookup_predeq (td, tree, max);
    while (n && comparenk (td, n, min) >= 0) {
        nn = find_neighbour (n, 0);
        f (onode_from_node (td, n), a);
        n = nn;
    }
}

void ut_avlConstWalkRangeReverse (const ut_avlTreedef_t *td, const ut_avlTree_t *tree, const void *min, const void *max, ut_avlConstWalk_t f, void *a)
{
    ut_avlWalkRangeReverse (td, (ut_avlTree_t *) tree, min, max, (ut_avlWalk_t) f, a);
}

void *ut_avlRoot (const ut_avlTreedef_t *td, const ut_avlTree_t *tree)
{
    return (void *) conode_from_node (td, tree->root);
}

/**************************************************************************************
 ****
 ****  Wrappers for counting trees
 ****
 **************************************************************************************/

void ut_avlCTreedefInit (ut_avlCTreedef_t *td, os_size_t avlnodeoffset, os_size_t keyoffset, ut_avlCompare_t comparekk, ut_avlAugment_t augment, os_uint32 flags)
{
    treedef_init_common (&td->t, avlnodeoffset, keyoffset, (int (*) (void)) comparekk, augment, flags);
}

void ut_avlCTreedefInit_r (ut_avlCTreedef_t *td, os_size_t avlnodeoffset, os_size_t keyoffset, ut_avlCompare_r_t comparekk_r, void *cmp_arg, ut_avlAugment_t augment, os_uint32 flags)
{
    td->t.cmp_arg = cmp_arg;
    treedef_init_common (&td->t, avlnodeoffset, keyoffset, (int (*) (void)) comparekk_r, augment, flags | UT_AVL_TREEDEF_FLAG_R);
}

void ut_avlCInit (const ut_avlCTreedef_t *td, ut_avlCTree_t *tree)
{
    ut_avlInit (&td->t, &tree->t);
    tree->count = 0;
}

void ut_avlCFree (const ut_avlCTreedef_t *td, ut_avlCTree_t *tree, void (*freefun) (void *node))
{
    tree->count = 0;
    ut_avlFree (&td->t, &tree->t, freefun);
}

void ut_avlCFreeArg (const ut_avlCTreedef_t *td, ut_avlCTree_t *tree, void (*freefun) (void *node, void *arg), void *arg)
{
    tree->count = 0;
    ut_avlFreeArg (&td->t, &tree->t, freefun, arg);
}

void *ut_avlCRoot (const ut_avlCTreedef_t *td, const ut_avlCTree_t *tree)
{
    return ut_avlRoot (&td->t, &tree->t);
}

void *ut_avlCLookup (const ut_avlCTreedef_t *td, const ut_avlCTree_t *tree, const void *key)
{
    return ut_avlLookup (&td->t, &tree->t, key);
}

void *ut_avlCLookupIPath (const ut_avlCTreedef_t *td, const ut_avlCTree_t *tree, const void *key, ut_avlIPath_t *path)
{
    return ut_avlLookupIPath (&td->t, &tree->t, key, path);
}

void *ut_avlCLookupDPath (const ut_avlCTreedef_t *td, const ut_avlCTree_t *tree, const void *key, ut_avlDPath_t *path)
{
    return ut_avlLookupDPath (&td->t, &tree->t, key, path);
}

void *ut_avlCLookupPredEq (const ut_avlCTreedef_t *td, const ut_avlCTree_t *tree, const void *key)
{
    return ut_avlLookupPredEq (&td->t, &tree->t, key);
}

void *ut_avlCLookupSuccEq (const ut_avlCTreedef_t *td, const ut_avlCTree_t *tree, const void *key)
{
    return ut_avlLookupSuccEq (&td->t, &tree->t, key);
}

void *ut_avlCLookupPred (const ut_avlCTreedef_t *td, const ut_avlCTree_t *tree, const void *key)
{
    return ut_avlLookupPred (&td->t, &tree->t, key);
}

void *ut_avlCLookupSucc (const ut_avlCTreedef_t *td, const ut_avlCTree_t *tree, const void *key)
{
    return ut_avlLookupSucc (&td->t, &tree->t, key);
}

void ut_avlCInsert (const ut_avlCTreedef_t *td, ut_avlCTree_t *tree, void *node)
{
    tree->count++;
    ut_avlInsert (&td->t, &tree->t, node);
}

void ut_avlCDelete (const ut_avlCTreedef_t *td, ut_avlCTree_t *tree, void *node)
{
    assert (tree->count > 0);
    tree->count--;
    ut_avlDelete (&td->t, &tree->t, node);
}

void ut_avlCInsertIPath (const ut_avlCTreedef_t *td, ut_avlCTree_t *tree, void *node, ut_avlIPath_t *path)
{
    tree->count++;
    ut_avlInsertIPath (&td->t, &tree->t, node, path);
}

void ut_avlCDeleteDPath (const ut_avlCTreedef_t *td, ut_avlCTree_t *tree, void *node, ut_avlDPath_t *path)
{
    assert (tree->count > 0);
    tree->count--;
    ut_avlDeleteDPath (&td->t, &tree->t, node, path);
}

void ut_avlCSwapNode (const ut_avlCTreedef_t *td, ut_avlCTree_t *tree, void *old, void *new)
{
    ut_avlSwapNode (&td->t, &tree->t, old, new);
}

void ut_avlCAugmentUpdate (const ut_avlCTreedef_t *td, void *node)
{
    ut_avlAugmentUpdate (&td->t, node);
}

int ut_avlCIsEmpty (const ut_avlCTree_t *tree)
{
    return ut_avlIsEmpty (&tree->t);
}

int ut_avlCIsSingleton (const ut_avlCTree_t *tree)
{
    return ut_avlIsSingleton (&tree->t);
}

os_size_t ut_avlCCount (const ut_avlCTree_t *tree)
{
    return tree->count;
}

void *ut_avlCFindMin (const ut_avlCTreedef_t *td, const ut_avlCTree_t *tree)
{
    return ut_avlFindMin (&td->t, &tree->t);
}

void *ut_avlCFindMax (const ut_avlCTreedef_t *td, const ut_avlCTree_t *tree)
{
    return ut_avlFindMax (&td->t, &tree->t);
}

void *ut_avlCFindPred (const ut_avlCTreedef_t *td, const ut_avlCTree_t *tree, const void *vnode)
{
    return ut_avlFindPred (&td->t, &tree->t, vnode);
}

void *ut_avlCFindSucc (const ut_avlCTreedef_t *td, const ut_avlCTree_t *tree, const void *vnode)
{
    return ut_avlFindSucc (&td->t, &tree->t, vnode);
}

void ut_avlCWalk (const ut_avlCTreedef_t *td, ut_avlCTree_t *tree, ut_avlWalk_t f, void *a)
{
    ut_avlWalk (&td->t, &tree->t, f, a);
}

void ut_avlCConstWalk (const ut_avlCTreedef_t *td, const ut_avlCTree_t *tree, ut_avlConstWalk_t f, void *a)
{
    ut_avlConstWalk (&td->t, &tree->t, f, a);
}

void ut_avlCWalkRange (const ut_avlCTreedef_t *td, ut_avlCTree_t *tree, const void *min, const void *max, ut_avlWalk_t f, void *a)
{
    ut_avlWalkRange (&td->t, &tree->t, min, max, f, a);
}

void ut_avlCConstWalkRange (const ut_avlCTreedef_t *td, const ut_avlCTree_t *tree, const void *min, const void *max, ut_avlConstWalk_t f, void *a)
{
    ut_avlConstWalkRange (&td->t, &tree->t, min, max, f, a);
}

void ut_avlCWalkRangeReverse (const ut_avlCTreedef_t *td, ut_avlCTree_t *tree, const void *min, const void *max, ut_avlWalk_t f, void *a)
{
    ut_avlWalkRangeReverse (&td->t, &tree->t, min, max, f, a);
}

void ut_avlCConstWalkRangeReverse (const ut_avlCTreedef_t *td, const ut_avlCTree_t *tree, const void *min, const void *max, ut_avlConstWalk_t f, void *a)
{
    ut_avlConstWalkRangeReverse (&td->t, &tree->t, min, max, f, a);
}

void *ut_avlCIterFirst (const ut_avlCTreedef_t *td, const ut_avlCTree_t *tree, ut_avlCIter_t *iter)
{
    return ut_avlIterFirst (&td->t, &tree->t, &iter->t);
}

void *ut_avlCIterSuccEq (const ut_avlCTreedef_t *td, const ut_avlCTree_t *tree, ut_avlCIter_t *iter, const void *key)
{
    return ut_avlIterSuccEq (&td->t, &tree->t, &iter->t, key);
}

void *ut_avlCIterSucc (const ut_avlCTreedef_t *td, const ut_avlCTree_t *tree, ut_avlCIter_t *iter, const void *key)
{
    return ut_avlIterSucc (&td->t, &tree->t, &iter->t, key);
}

void *ut_avlCIterNext (ut_avlCIter_t *iter)
{
    return ut_avlIterNext (&iter->t);
}
