avl.h

   1 /*
   2  * Copyright (C) 2010 Joseph Adams <joeyadams3.14159@gmail.com>
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a copy
   5  * of this software and associated documentation files (the "Software"), to deal
   6  * in the Software without restriction, including without limitation the rights
   7  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   8  * copies of the Software, and to permit persons to whom the Software is
   9  * furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice shall be included in
  12  * all copies or substantial portions of the Software.
  13  *
  14  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  15  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  17  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  18  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  19  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  20  * THE SOFTWARE.
  21  */
  22
  23 #ifndef CCAN_AVL_H
  24 #define CCAN_AVL_H
  25
  26 #include <stdbool.h>
  27 #include <stddef.h>
  28
  29 struct sm_state;
  30
  31 typedef struct AvlNode       AvlNode;
  32 typedef struct AvlIter       AvlIter;
  33
  34 struct stree {
  35         AvlNode    *root;
  36         size_t      count;
  37 };
  38
  39 void avl_free(struct stree **avl);
  40         /* Free an stree tree. */
  41
  42 struct sm_state *avl_lookup(const struct stree *avl, const struct sm_state *sm);
  43         /* O(log n). Lookup a sm.  Return NULL if the sm is not present. */
  44
  45 #define avl_member(avl, sm) (!!avl_lookup_node(avl, sm))
  46         /* O(log n). See if a sm is present. */
  47
  48 size_t stree_count(const struct stree *avl);
  49         /* O(1). Return the number of elements in the tree. */
  50
  51 bool avl_insert(struct stree **avl, const struct sm_state *sm);
  52         /*
  53          * O(log n). Insert an sm or replace it if already present.
  54          *
  55          * Return false if the insertion replaced an existing sm.
  56          */
  57
  58 bool avl_remove(struct stree **avl, const struct sm_state *sm);
  59         /*
  60          * O(log n). Remove an sm (if present).
  61          *
  62          * Return true if it was removed.
  63          */
  64
  65 bool avl_check_invariants(struct stree *avl);
  66         /* For testing purposes.  This function will always return true :-) */
  67
  68
  69 /************************* Traversal *************************/
  70
  71 #define avl_foreach(iter, avl)         avl_traverse(iter, avl, FORWARD)
  72         /*
  73          * O(n). Traverse an stree tree in order.
  74          *
  75          * Example:
  76          *
  77          * AvlIter i;
  78          *
  79          * avl_foreach(i, avl)
  80          *     printf("%s -> %s\n", i.sm->name, i.sm->state->name);
  81          */
  82
  83 #define FOR_EACH_SM(avl, _sm) {                 \
  84         AvlIter _i;                             \
  85         avl_foreach(_i, avl) {                  \
  86                 _sm = _i.sm;
  87
  88 #define END_FOR_EACH_SM(_sm) }}
  89
  90 #define avl_foreach_reverse(iter, avl) avl_traverse(iter, avl, BACKWARD)
  91         /* O(n). Traverse an stree tree in reverse order. */
  92
  93 typedef enum AvlDirection {FORWARD = 0, BACKWARD = 1} AvlDirection;
  94
  95 struct AvlIter {
  96         struct sm_state *sm;
  97         AvlNode      *node;
  98
  99         /* private */
 100         AvlNode      *stack[100];
 101         int           stack_index;
 102         AvlDirection  direction;
 103 };
 104
 105 void avl_iter_begin(AvlIter *iter, struct stree *avl, AvlDirection dir);
 106 void avl_iter_next(AvlIter *iter);
 107 #define avl_traverse(iter, avl, direction)        \
 108         for (avl_iter_begin(&(iter), avl, direction); \
 109              (iter).node != NULL;                     \
 110              avl_iter_next(&iter))
 111
 112
 113 /***************** Internal data structures ******************/
 114
 115 struct AvlNode {
 116         const struct sm_state *sm;
 117
 118         AvlNode    *lr[2];
 119         int         balance; /* -1, 0, or 1 */
 120 };
 121
 122 AvlNode *avl_lookup_node(const struct stree *avl, const struct sm_state *sm);
 123         /* O(log n). Lookup an stree node by sm.  Return NULL if not present. */
 124
 125 struct stree *clone_stree(struct stree *orig);
 126
 127 #endif