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      1 /*
      2  *
      3  * Copyright 2015 gRPC authors.
      4  *
      5  * Licensed under the Apache License, Version 2.0 (the "License");
      6  * you may not use this file except in compliance with the License.
      7  * You may obtain a copy of the License at
      8  *
      9  *     http://www.apache.org/licenses/LICENSE-2.0
     10  *
     11  * Unless required by applicable law or agreed to in writing, software
     12  * distributed under the License is distributed on an "AS IS" BASIS,
     13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     14  * See the License for the specific language governing permissions and
     15  * limitations under the License.
     16  *
     17  */
     18 
     19 #ifndef GRPC_CORE_LIB_AVL_AVL_H
     20 #define GRPC_CORE_LIB_AVL_AVL_H
     21 
     22 #include <grpc/support/port_platform.h>
     23 
     24 #include <grpc/support/sync.h>
     25 
     26 /** internal node of an AVL tree */
     27 typedef struct grpc_avl_node {
     28   gpr_refcount refs;
     29   void* key;
     30   void* value;
     31   struct grpc_avl_node* left;
     32   struct grpc_avl_node* right;
     33   long height;
     34 } grpc_avl_node;
     35 
     36 /** vtable for the AVL tree
     37  * The optional user_data is propagated from the top level grpc_avl_XXX API.
     38  * From the same API call, multiple vtable functions may be called multiple
     39  * times.
     40  */
     41 typedef struct grpc_avl_vtable {
     42   /** destroy a key */
     43   void (*destroy_key)(void* key, void* user_data);
     44   /** copy a key, returning new value */
     45   void* (*copy_key)(void* key, void* user_data);
     46   /** compare key1, key2; return <0 if key1 < key2,
     47       >0 if key1 > key2, 0 if key1 == key2 */
     48   long (*compare_keys)(void* key1, void* key2, void* user_data);
     49   /** destroy a value */
     50   void (*destroy_value)(void* value, void* user_data);
     51   /** copy a value */
     52   void* (*copy_value)(void* value, void* user_data);
     53 } grpc_avl_vtable;
     54 
     55 /** "pointer" to an AVL tree - this is a reference
     56     counted object - use grpc_avl_ref to add a reference,
     57     grpc_avl_unref when done with a reference */
     58 typedef struct grpc_avl {
     59   const grpc_avl_vtable* vtable;
     60   grpc_avl_node* root;
     61 } grpc_avl;
     62 
     63 /** Create an immutable AVL tree. */
     64 grpc_avl grpc_avl_create(const grpc_avl_vtable* vtable);
     65 /** Add a reference to an existing tree - returns
     66     the tree as a convenience. The optional user_data will be passed to vtable
     67     functions. */
     68 grpc_avl grpc_avl_ref(grpc_avl avl, void* user_data);
     69 /** Remove a reference to a tree - destroying it if there
     70     are no references left. The optional user_data will be passed to vtable
     71     functions. */
     72 void grpc_avl_unref(grpc_avl avl, void* user_data);
     73 /** Return a new tree with (key, value) added to avl.
     74     implicitly unrefs avl to allow easy chaining.
     75     if key exists in avl, the new tree's key entry updated
     76     (i.e. a duplicate is not created). The optional user_data will be passed to
     77     vtable functions. */
     78 grpc_avl grpc_avl_add(grpc_avl avl, void* key, void* value, void* user_data);
     79 /** Return a new tree with key deleted
     80     implicitly unrefs avl to allow easy chaining. The optional user_data will be
     81     passed to vtable functions. */
     82 grpc_avl grpc_avl_remove(grpc_avl avl, void* key, void* user_data);
     83 /** Lookup key, and return the associated value.
     84     Does not mutate avl.
     85     Returns NULL if key is not found. The optional user_data will be passed to
     86     vtable functions.*/
     87 void* grpc_avl_get(grpc_avl avl, void* key, void* user_data);
     88 /** Return 1 if avl contains key, 0 otherwise; if it has the key, sets *value to
     89     its value. The optional user_data will be passed to vtable functions. */
     90 int grpc_avl_maybe_get(grpc_avl avl, void* key, void** value, void* user_data);
     91 /** Return 1 if avl is empty, 0 otherwise */
     92 int grpc_avl_is_empty(grpc_avl avl);
     93 
     94 #endif /* GRPC_CORE_LIB_AVL_AVL_H */
     95