libdict 1.0.7
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pr_tree.h File Reference

Path-reduction tree [Gonnet 1983]. More...

#include "dict.h"
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Typedefs

typedef struct pr_tree pr_tree
 A path-reduction tree.
 
typedef struct pr_itor pr_itor
 An iterator over a path-reduction tree.
 

Functions

pr_tree * pr_tree_new (dict_compare_func cmp_func)
 Create an empty tree that orders keys with |cmp_func| (must not be NULL).
 
dict * pr_dict_new (dict_compare_func cmp_func)
 Like pr_tree_new(), but wrapped in a generic dict for use with the dict_* macros.
 
size_t pr_tree_free (pr_tree *tree, dict_delete_func delete_func)
 Remove every element, calling |delete_func|(key, datum) for each unless |delete_func| is NULL, and free the tree.
 
dict_insert_result pr_tree_insert (pr_tree *tree, void *key)
 Insert |key| unless an equal key is present.
 
void ** pr_tree_search (pr_tree *tree, const void *key)
 Return the address of the datum stored for |key|, or NULL if |key| is not present.
 
void ** pr_tree_search_le (pr_tree *tree, const void *key)
 Return the address of the datum of the greatest key less than or equal to |key|, or NULL if there is none.
 
void ** pr_tree_search_lt (pr_tree *tree, const void *key)
 Return the address of the datum of the greatest key less than |key|, or NULL if there is none.
 
void ** pr_tree_search_ge (pr_tree *tree, const void *key)
 Return the address of the datum of the least key greater than or equal to |key|, or NULL if there is none.
 
void ** pr_tree_search_gt (pr_tree *tree, const void *key)
 Return the address of the datum of the least key greater than |key|, or NULL if there is none.
 
dict_remove_result pr_tree_remove (pr_tree *tree, const void *key)
 Remove the element with key |key|.
 
size_t pr_tree_clear (pr_tree *tree, dict_delete_func delete_func)
 Remove every element, calling |delete_func|(key, datum) for each unless |delete_func| is NULL.
 
size_t pr_tree_traverse (pr_tree *tree, dict_visit_func visit, void *user_data)
 Call |visit|(key, datum, |user_data|) for each element in key order, stopping early if |visit| returns false.
 
bool pr_tree_select (pr_tree *tree, size_t n, const void **key, void **datum)
 Store the key and datum of the |n|th element in key order (0-based) through |key| and |datum| and return true, or store NULL through them and return false if |n| is out of range.
 
size_t pr_tree_count (const pr_tree *tree)
 Return the number of elements.
 
size_t pr_tree_min_path_length (const pr_tree *tree)
 Return the shallowest depth at which a child link is absent, the root being at depth 1, or 0 for an empty tree.
 
size_t pr_tree_max_path_length (const pr_tree *tree)
 Return the greatest depth of any node, the root being at depth 1, or 0 for an empty tree: the height of the tree.
 
size_t pr_tree_total_path_length (const pr_tree *tree)
 Return the sum of the depths of all nodes, the root being at depth 1, or 0 for an empty tree.
 
bool pr_tree_verify (const pr_tree *tree)
 Check the internal invariants of the tree and return true if they hold, or print the first failed check to stderr and return false.
 
pr_itor * pr_itor_new (pr_tree *tree)
 Create an iterator over |tree| that is not positioned on any element yet.
 
dict_itor * pr_dict_itor_new (pr_tree *tree)
 Like pr_itor_new(), but wrapped in a generic dict_itor for use with the dict_itor_* macros.
 
void pr_itor_free (pr_itor *itor)
 Free an iterator.
 
bool pr_itor_valid (const pr_itor *itor)
 Return whether |itor| is positioned on an element.
 
void pr_itor_invalidate (pr_itor *itor)
 Unposition |itor|, so that it is not positioned on any element.
 
bool pr_itor_next (pr_itor *itor)
 Move |itor| to the next element in key order and return true, or unposition it and return false if there is none.
 
bool pr_itor_prev (pr_itor *itor)
 Move |itor| to the previous element in key order and return true, or unposition it and return false if there is none.
 
bool pr_itor_nextn (pr_itor *itor, size_t count)
 Move |itor| |count| elements forward and return whether it is still positioned.
 
bool pr_itor_prevn (pr_itor *itor, size_t count)
 Move |itor| |count| elements back and return whether it is still positioned.
 
bool pr_itor_first (pr_itor *itor)
 Position |itor| on the first element in key order and return true, or unposition it and return false if the tree is empty.
 
bool pr_itor_last (pr_itor *itor)
 Position |itor| on the last element in key order and return true, or unposition it and return false if the tree is empty.
 
bool pr_itor_search (pr_itor *itor, const void *key)
 Position |itor| on |key| and return true, or unposition it and return false if |key| is not present.
 
bool pr_itor_search_le (pr_itor *itor, const void *key)
 Position |itor| on the greatest key less than or equal to |key| and return true, or unposition it and return false if there is none.
 
bool pr_itor_search_lt (pr_itor *itor, const void *key)
 Position |itor| on the greatest key less than |key| and return true, or unposition it and return false if there is none.
 
bool pr_itor_search_ge (pr_itor *itor, const void *key)
 Position |itor| on the least key greater than or equal to |key| and return true, or unposition it and return false if there is none.
 
bool pr_itor_search_gt (pr_itor *itor, const void *key)
 Position |itor| on the least key greater than |key| and return true, or unposition it and return false if there is none.
 
const void * pr_itor_key (const pr_itor *itor)
 Return the key |itor| is positioned on, or NULL if it is not positioned.
 
void ** pr_itor_datum (pr_itor *itor)
 Return the address of the datum |itor| is positioned on, through which it can be read or replaced, or NULL if it is not positioned.
 
int pr_itor_compare (const pr_itor *i1, const pr_itor *i2)
 Compare the positions of two iterators over the same tree: return a negative value, zero, or a positive value as |i1| is before, at, or after |i2| in key order.
 
bool pr_itor_remove (pr_itor *itor)
 Remove the element |itor| is positioned on and unposition |itor|; return false if it was not positioned.
 

Detailed Description

Path-reduction tree [Gonnet 1983].

Each node stores the size of its subtree, and the tree rotates whenever a rotation reduces the total path length, which keeps it balanced: insert, search and remove take O(log n) time, and selecting the nth element also takes only O(log n).

Definition in file pr_tree.h.

Typedef Documentation

◆ pr_itor

typedef struct pr_itor pr_itor

An iterator over a path-reduction tree.

Opaque: create one with pr_itor_new().

Definition at line 121 of file pr_tree.h.

◆ pr_tree

typedef struct pr_tree pr_tree

A path-reduction tree.

Opaque: create one with pr_tree_new().

Definition at line 45 of file pr_tree.h.

Function Documentation

◆ pr_dict_itor_new()

dict_itor * pr_dict_itor_new ( pr_tree * tree)

Like pr_itor_new(), but wrapped in a generic dict_itor for use with the dict_itor_* macros.

Free it with dict_itor_free().

Definition at line 522 of file pr_tree.c.

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◆ pr_dict_new()

dict * pr_dict_new ( dict_compare_func cmp_func)

Like pr_tree_new(), but wrapped in a generic dict for use with the dict_* macros.

Free it with dict_free(). Returns NULL if memory cannot be allocated.

Definition at line 125 of file pr_tree.c.

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◆ pr_itor_compare()

int pr_itor_compare ( const pr_itor * i1,
const pr_itor * i2 )

Compare the positions of two iterators over the same tree: return a negative value, zero, or a positive value as |i1| is before, at, or after |i2| in key order.

An unpositioned iterator compares before every positioned one.

Definition at line 551 of file pr_tree.c.

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◆ pr_itor_datum()

void ** pr_itor_datum ( pr_itor * itor)

Return the address of the datum |itor| is positioned on, through which it can be read or replaced, or NULL if it is not positioned.

Definition at line 550 of file pr_tree.c.

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◆ pr_itor_first()

bool pr_itor_first ( pr_itor * itor)

Position |itor| on the first element in key order and return true, or unposition it and return false if the tree is empty.

Definition at line 542 of file pr_tree.c.

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◆ pr_itor_free()

void pr_itor_free ( pr_itor * itor)

Free an iterator.

Definition at line 535 of file pr_tree.c.

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◆ pr_itor_invalidate()

void pr_itor_invalidate ( pr_itor * itor)

Unposition |itor|, so that it is not positioned on any element.

Definition at line 537 of file pr_tree.c.

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◆ pr_itor_key()

const void * pr_itor_key ( const pr_itor * itor)

Return the key |itor| is positioned on, or NULL if it is not positioned.

The key belongs to the container and must not be modified in a way that changes how it compares.

Definition at line 549 of file pr_tree.c.

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◆ pr_itor_last()

bool pr_itor_last ( pr_itor * itor)

Position |itor| on the last element in key order and return true, or unposition it and return false if the tree is empty.

Definition at line 543 of file pr_tree.c.

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◆ pr_itor_new()

pr_itor * pr_itor_new ( pr_tree * tree)

Create an iterator over |tree| that is not positioned on any element yet.

Returns NULL if memory cannot be allocated.

Definition at line 511 of file pr_tree.c.

◆ pr_itor_next()

bool pr_itor_next ( pr_itor * itor)

Move |itor| to the next element in key order and return true, or unposition it and return false if there is none.

An unpositioned iterator stays unpositioned and returns false.

Definition at line 538 of file pr_tree.c.

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◆ pr_itor_nextn()

bool pr_itor_nextn ( pr_itor * itor,
size_t count )

Move |itor| |count| elements forward and return whether it is still positioned.

It becomes unpositioned if it runs past the last element.

Definition at line 540 of file pr_tree.c.

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◆ pr_itor_prev()

bool pr_itor_prev ( pr_itor * itor)

Move |itor| to the previous element in key order and return true, or unposition it and return false if there is none.

An unpositioned iterator stays unpositioned and returns false.

Definition at line 539 of file pr_tree.c.

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◆ pr_itor_prevn()

bool pr_itor_prevn ( pr_itor * itor,
size_t count )

Move |itor| |count| elements back and return whether it is still positioned.

It becomes unpositioned if it runs past the first element.

Definition at line 541 of file pr_tree.c.

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◆ pr_itor_remove()

bool pr_itor_remove ( pr_itor * itor)

Remove the element |itor| is positioned on and unposition |itor|; return false if it was not positioned.

No delete function is called, so fetch the key and datum first if they need freeing. See Iterator invalidation for which iterators this invalidates.

Definition at line 554 of file pr_tree.c.

◆ pr_itor_search()

bool pr_itor_search ( pr_itor * itor,
const void * key )

Position |itor| on |key| and return true, or unposition it and return false if |key| is not present.

Definition at line 544 of file pr_tree.c.

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◆ pr_itor_search_ge()

bool pr_itor_search_ge ( pr_itor * itor,
const void * key )

Position |itor| on the least key greater than or equal to |key| and return true, or unposition it and return false if there is none.

Definition at line 547 of file pr_tree.c.

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◆ pr_itor_search_gt()

bool pr_itor_search_gt ( pr_itor * itor,
const void * key )

Position |itor| on the least key greater than |key| and return true, or unposition it and return false if there is none.

Definition at line 548 of file pr_tree.c.

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◆ pr_itor_search_le()

bool pr_itor_search_le ( pr_itor * itor,
const void * key )

Position |itor| on the greatest key less than or equal to |key| and return true, or unposition it and return false if there is none.

Definition at line 545 of file pr_tree.c.

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◆ pr_itor_search_lt()

bool pr_itor_search_lt ( pr_itor * itor,
const void * key )

Position |itor| on the greatest key less than |key| and return true, or unposition it and return false if there is none.

Definition at line 546 of file pr_tree.c.

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◆ pr_itor_valid()

bool pr_itor_valid ( const pr_itor * itor)

Return whether |itor| is positioned on an element.

Definition at line 536 of file pr_tree.c.

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◆ pr_tree_clear()

size_t pr_tree_clear ( pr_tree * tree,
dict_delete_func delete_func )

Remove every element, calling |delete_func|(key, datum) for each unless |delete_func| is NULL.

Returns the number of elements removed. The tree stays usable. See Iterator invalidation for which iterators this invalidates.

Definition at line 351 of file pr_tree.c.

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◆ pr_tree_count()

size_t pr_tree_count ( const pr_tree * tree)

Return the number of elements.

Takes O(1) time.

Definition at line 388 of file pr_tree.c.

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◆ pr_tree_free()

size_t pr_tree_free ( pr_tree * tree,
dict_delete_func delete_func )

Remove every element, calling |delete_func|(key, datum) for each unless |delete_func| is NULL, and free the tree.

Returns the number of elements removed. Iterators over the tree may afterwards only be freed.

Definition at line 138 of file pr_tree.c.

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◆ pr_tree_insert()

dict_insert_result pr_tree_insert ( pr_tree * tree,
void * key )

Insert |key| unless an equal key is present.

Returns {&datum, true} for a new key, whose datum starts as NULL; the tree stores the |key| pointer itself, it does not copy the key. If an equal key is present, returns {&datum, false} with that key's datum, and |key| is not stored and still belongs to the caller. Returns {NULL, false} if memory cannot be allocated.

Definition at line 265 of file pr_tree.c.

◆ pr_tree_max_path_length()

size_t pr_tree_max_path_length ( const pr_tree * tree)

Return the greatest depth of any node, the root being at depth 1, or 0 for an empty tree: the height of the tree.

A statistic for testing and benchmarking.

Definition at line 389 of file pr_tree.c.

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◆ pr_tree_min_path_length()

size_t pr_tree_min_path_length ( const pr_tree * tree)

Return the shallowest depth at which a child link is absent, the root being at depth 1, or 0 for an empty tree.

A statistic for testing and benchmarking.

Definition at line 390 of file pr_tree.c.

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◆ pr_tree_new()

pr_tree * pr_tree_new ( dict_compare_func cmp_func)

Create an empty tree that orders keys with |cmp_func| (must not be NULL).

Returns NULL if memory cannot be allocated.

Definition at line 110 of file pr_tree.c.

◆ pr_tree_remove()

dict_remove_result pr_tree_remove ( pr_tree * tree,
const void * key )

Remove the element with key |key|.

Returns {key, datum, true}, handing the stored key and datum back to the caller (no delete function is called), or {NULL, NULL, false} if |key| is not present. See Iterator invalidation for which iterators this invalidates.

Definition at line 341 of file pr_tree.c.

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◆ pr_tree_search()

void ** pr_tree_search ( pr_tree * tree,
const void * key )

Return the address of the datum stored for |key|, or NULL if |key| is not present.

Definition at line 139 of file pr_tree.c.

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◆ pr_tree_search_ge()

void ** pr_tree_search_ge ( pr_tree * tree,
const void * key )

Return the address of the datum of the least key greater than or equal to |key|, or NULL if there is none.

Definition at line 142 of file pr_tree.c.

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◆ pr_tree_search_gt()

void ** pr_tree_search_gt ( pr_tree * tree,
const void * key )

Return the address of the datum of the least key greater than |key|, or NULL if there is none.

Definition at line 143 of file pr_tree.c.

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◆ pr_tree_search_le()

void ** pr_tree_search_le ( pr_tree * tree,
const void * key )

Return the address of the datum of the greatest key less than or equal to |key|, or NULL if there is none.

Definition at line 140 of file pr_tree.c.

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◆ pr_tree_search_lt()

void ** pr_tree_search_lt ( pr_tree * tree,
const void * key )

Return the address of the datum of the greatest key less than |key|, or NULL if there is none.

Definition at line 141 of file pr_tree.c.

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◆ pr_tree_select()

bool pr_tree_select ( pr_tree * tree,
size_t n,
const void ** key,
void ** datum )

Store the key and datum of the |n|th element in key order (0-based) through |key| and |datum| and return true, or store NULL through them and return false if |n| is out of range.

Either may be NULL. Takes O(log n) time.

Definition at line 360 of file pr_tree.c.

◆ pr_tree_total_path_length()

size_t pr_tree_total_path_length ( const pr_tree * tree)

Return the sum of the depths of all nodes, the root being at depth 1, or 0 for an empty tree.

A statistic for testing and benchmarking.

Definition at line 391 of file pr_tree.c.

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◆ pr_tree_traverse()

size_t pr_tree_traverse ( pr_tree * tree,
dict_visit_func visit,
void * user_data )

Call |visit|(key, datum, |user_data|) for each element in key order, stopping early if |visit| returns false.

Returns the number of calls made.

Definition at line 354 of file pr_tree.c.

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◆ pr_tree_verify()

bool pr_tree_verify ( const pr_tree * tree)

Check the internal invariants of the tree and return true if they hold, or print the first failed check to stderr and return false.

Meant for testing and debugging; takes O(n) time.

Definition at line 496 of file pr_tree.c.