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Functions | Variables

Low-complexity tree container. More...

Functions

struct AVTreeNodeav_tree_node_alloc (void)
 Allocate an AVTreeNode. More...
 
voidav_tree_find (const struct AVTreeNode *root, void *key, int(*cmp)(const void *key, const void *b), void *next[2])
 Find an element. More...
 
voidav_tree_insert (struct AVTreeNode **rootp, void *key, int(*cmp)(const void *key, const void *b), struct AVTreeNode **next)
 Insert or remove an element. More...
 
void av_tree_destroy (struct AVTreeNode *t)
 
void av_tree_enumerate (struct AVTreeNode *t, void *opaque, int(*cmp)(void *opaque, void *elem), int(*enu)(void *opaque, void *elem))
 Apply enu(opaque, &elem) to all the elements in the tree in a given range. More...
 

Variables

const int av_tree_node_size
 

Detailed Description

Low-complexity tree container.

Insertion, removal, finding equal, largest which is smaller than and smallest which is larger than, all have O(log n) worst-case complexity.

Function Documentation

struct AVTreeNode* av_tree_node_alloc ( void  )

Allocate an AVTreeNode.

Definition at line 34 of file tree.c.

Referenced by add_entry(), ff_nut_add_sp(), and load_glyph().

void* av_tree_find ( const struct AVTreeNode root,
void key,
int(*)(const void *key, const void *b cmp,
void next[2] 
)

Find an element.

Parameters
roota pointer to the root node of the tree
nextIf next is not NULL, then next[0] will contain the previous element and next[1] the next element. If either does not exist, then the corresponding entry in next is unchanged.
cmpcompare function used to compare elements in the tree, API identical to that of Standard C's qsort It is guranteed that the first and only the first argument to cmp() will be the key parameter to av_tree_find(), thus it could if the user wants, be a different type (like an opaque context).
Returns
An element with cmp(key, elem) == 0 or NULL if no such element exists in the tree.
void* av_tree_insert ( struct AVTreeNode **  rootp,
void key,
int(*)(const void *key, const void *b cmp,
struct AVTreeNode **  next 
)

Insert or remove an element.

If *next is NULL, then the supplied element will be removed if it exists. If *next is non-NULL, then the supplied element will be inserted, unless it already exists in the tree.

Parameters
rootpA pointer to a pointer to the root node of the tree; note that the root node can change during insertions, this is required to keep the tree balanced.
keypointer to the element key to insert in the tree
nextUsed to allocate and free AVTreeNodes. For insertion the user must set it to an allocated and zeroed object of at least av_tree_node_size bytes size. av_tree_insert() will set it to NULL if it has been consumed. For deleting elements *next is set to NULL by the user and av_tree_insert() will set it to the AVTreeNode which was used for the removed element. This allows the use of flat arrays, which have lower overhead compared to many malloced elements. You might want to define a function like:
void *tree_insert(struct AVTreeNode **rootp, void *key,
int (*cmp)(void *key, const void *b),
AVTreeNode **next)
{
if (!*next)
return av_tree_insert(rootp, key, cmp, next);
}
void *tree_remove(struct AVTreeNode **rootp, void *key,
int (*cmp)(void *key, const void *b, AVTreeNode **next))
{
av_freep(next);
return av_tree_insert(rootp, key, cmp, next);
}
cmpcompare function used to compare elements in the tree, API identical to that of Standard C's qsort
Returns
If no insertion happened, the found element; if an insertion or removal happened, then either key or NULL will be returned. Which one it is depends on the tree state and the implementation. You should make no assumptions that it's one or the other in the code.

Definition at line 59 of file tree.c.

Referenced by add_entry(), av_tree_insert(), ff_nut_add_sp(), and load_glyph().

void av_tree_destroy ( struct AVTreeNode t)

Definition at line 146 of file tree.c.

Referenced by av_tree_destroy(), cache_close(), ff_nut_free_sp(), and uninit().

void av_tree_enumerate ( struct AVTreeNode t,
void opaque,
int(*)(void *opaque, void *elem)  cmp,
int(*)(void *opaque, void *elem)  enu 
)

Apply enu(opaque, &elem) to all the elements in the tree in a given range.

Parameters
cmpa comparison function that returns < 0 for an element below the range, > 0 for an element above the range and == 0 for an element inside the range
Note
The cmp function should use the same ordering used to construct the tree.

Definition at line 155 of file tree.c.

Referenced by av_tree_enumerate(), cache_close(), ff_nut_free_sp(), and uninit().

Variable Documentation

const int av_tree_node_size

Definition at line 32 of file tree.c.