red_black

Overview

Prerequisites
Build
Usage
Interface
Implementation
Internals

red_black is a pair of C libraries that provide a simple interface for implementing (ordered) sets and associative arrays. red_black containers house their data in binary tree structures which are height-balanced by adhering to a tried-and-true set of rules--the red-black properties. With proper preservation of these properties, the RedBlackTree and RedBlackHMap interfaces are able to provide the following operations:

insert
random access
delete
(ordered) traverse
shallow copy
various set operations

with competitive worst-case performance guarantees. The red-black system of balance was chosen to provide greater responsiveness to mutations than more rigid constructs, such as AVL balance factor, without compromising a guaranteed logarithmic height, as is often the case with simpler methods like treap priority or splaying.
red_black distinguishes itself from many other balanced tree/hash table-balanced tree hybrid implementations by preferring finer casewise granularity over heavier abstraction throughout container accesses.

Prerequisites

GNU Make
gcc >= 4.8.1 (C99 and C++11 support for benchmarking against std containers)
ruby >= 1.9 (for Unity test runner generator scripts)

Build

$ git clone https://github.com/wrpaape/red_black.git
$ cd red_black
$ make

Will build static and shared versions of the RedBlackTree and RedBlackHMap libraries in the static and shared directories, as well as unit tests and example executables in the bin directory.

$ make run_tests

will run all unit tests, and

$ make clean

will delete all generated files.

Usage

Build the red_black libraries
If key order is required or memory is constrained, use a RedBlackTree.
If key order is not required and memory can be spared for extra speed, use a RedBlackHMap.

RedBlackTree Usage

Add #include "red_black_tree.h" to the top of your source file.
The file must be included with no path prefix since it will be including other module headers by paths relative to the include directory.
Implement an ordered set, associative array, or poor man's priority queue with the provided interface.
Keys are completely opaque to the RedBlackTree implementation.
Accordingly, a RedBlackComparator must be provided at initialization to determine ordering.
Internally keys are stored as const void *.
As a consequence, keys requiring more than sizeof(void *) bytes of storage must be accessible by pointer, and their memory must be managed externally. The same goes for keys where a access via an update or get might be useful, as only a copy of the actual stored key will be provided.
For instance, if the sizeof(int) on my machine is 4 bytes, and the sizeof(void *) is at least 8 bytes, then I could store key-value pairs of ints directly in my RedBlackTree like so:
```
struct KeyValue {
        int index;
        int counter;
};
...
struct KeyValue mapping = {
        .index   = 9001,
        .counter = 0
};
...
int status = red_black_tree_insert(&tree,
                                   *((void **) &mapping));
assert(status >= 0);
```

and not have to worry about their memory management. However, if I wanted to update the counter of a certain member index, the following would have no effect on the stored key:

```
struct KeyValue mapping;
struct KeyValue fetched;
...
mapping.index = 9001;
...
if (red_black_tree_fetch(&tree,
                         *((void **) &mapping),
                         (void **) &fetched)) {
        /* key with 'index' of 9001 exists in 'tree' */

        ++(fetched.counter); /* tree mapping NOT updated!, operates on copy */
}
```

In order to properly update tree, I would have to follow up with a set and clobber the old value:

```
if (red_black_tree_fetch(&tree,
                         *((void **) &mapping),
                         (void **) &fetched)) {
        /* key with 'index' of 9001 exists in 'tree' */

        ++(fetched.counter); /* increment counter */

        /* overwrite old value */
        red_black_tree_set(&tree,
                           *((void **) &fetched));
}
```

Compile your source code and link to either static/libred_black_tree.{a,lib} or shared/libred_black_tree.{so,dylib,dll}.
Remember to add the include directory to your preprocessor's search path either via compiler flag (i.e. -Ipath/to/include) or environment variable (i.e. CPATH=path/to/include:$CPATH).

RedBlackHMap Usage

Add #include "red_black_hmap.h" to the top of your source file.
The file must be included with no path prefix since it will be including other module headers by paths relative to the include directory.
Implement an unordered set or associative array with the provided interface.
RedBlackHMap can be thought of as a hash table of RedBlackTrees.
Accesses are made by hashing input keys of arbitrary length to a fixed word, which is then used to locate the bucket tree where it should reside. Bucket trees are ordered by this hash word, falling back on an unsigned memory comparison in case of equal (colliding) values. This method of key organization imposes three restrictions on the application developer:
1. Keys must be input by their address and length.
2. Key addresses must reference valid memory if length is nonzero.
  Keys of zero length will emit identical hash values and will not be compared by memory. Accordingly, keys of all addresses are considered equivalent to RedBlackHMap if their length is zero, and only one zero-length key may reside in the container at any time.
3. Keys must be bytewise-distinguishable.
  Keys of all types are handled as byte strings by RedBlackHMap. As a result, care must be taken with struct keys with fields having different alignments. Such structs must be packed, be cleared before having their fields set, or be passed in such a way that for length bytes from the input address no padding will be encountered.
  The following snippet:
```
#define NAME_LENGTH_MAX 20
#define SPECIES_CAT 0
...
struct Pet {
        char name[NAME_LENGTH_MAX + 1];
        int species;
};
...
struct Pet *charley_ptr = malloc(sizeof(*charley_ptr));
assert(charley_ptr != NULL);

/* insert Charley into set of 'Pet's */
(void) strcpy(&charley_ptr->name[0],
              "Charley");
charley_ptr->species = SPECIES_CAT;

int status = red_black_hmap_insert(&my_pets,
                                   (void *) charley_ptr,
                                   sizeof(*charley_ptr));
assert(status >= 0);

/* check if Charley is a member of 'my_pets' */
struct Pet charly = {
        .name    = "Charley",
        .species = SPECIES_CAT
};

if (red_black_hmap_find(&my_pets,
                        (void *) &charley,
                        sizeof(charley))) {
     /* found Charley */
     ...
}
```
may exhibit unexpected behavior. The name field will not always be completely filled for each Pet entry, and even if all my pets had 20-character (plus one for '\0' terminator) names, unused padding will still be added after the name field to ensure that species begins on an address aligned to sizeof(int). As such, the find routine above may fail to retrieve "Charley" the cat from my_pets.
If there is no need to distinguish Pet entries by species, the simple solution is to pass the string length of entry names as their key length. But if I needed to track "Charley" the frog as well I would need to swap the order of my Pet fields and pass sizeof(pet.species) + strlen(pet.name) as key length to avoid padding bytes, or just memset(&pet, 0, sizeof(pet)) before setting fields and pass sizeof(pet) as key length.
Compile your source code and link to either static/libred_black_hmap.{a,lib} or shared/libred_black_hmap.{so,dylib,dll}.
Remember to add the include directory to your preprocessor's search path either via compiler flag (i.e. -Ipath/to/include) or environment variable (i.e. CPATH=path/to/include:$CPATH).

Creation

init

void
red_black_tree_init(RedBlackTree *const restrict tree,
                    const RedBlackComparator comparator);

bool
red_black_hmap_init(RedBlackHMap *const restrict map);

initialize an empty red_black container
red_black_tree_init requires a key comparator (see RedBlackComparator) to determine ordering and performs no heap allocations, so it need not be destroyed until the first successful insertion is made. red_black_hmap_init will need to allocate an array of empty buckets, and so has an opportunity to fail -- a return value of true indicates success, false indicates failure.

Destruction

destroy

void
red_black_tree_destroy(RedBlackTree *const restrict tree);

void
red_black_hmap_destroy(RedBlackHMap *const restrict map);

free all internal allocations
RedBlackTree can and RedBlackHMap must store its keys by address and not by copy in order to adequately handle data of all sizes. Hence, a solution to maintaining persistent keys might be to allocate them on the heap as they are inserted. If an application loses reference to such keys, their memory will be leaked when their container is destroyed unless a final traversal is made to free them beforehand.

Insertion

insert

int
red_black_tree_insert(RedBlackTree *const restrict tree,
                      const void *const key);

int
red_black_hmap_insert(RedBlackHMap *const restrict map,
                      const void *const key,
                      const size_t length);

insert key into the container
If key is not already present in the container, an insertion is attempted. If the insertion succeeds, 1 is returned.
If key is already present, the container is untouched and 0 is returned.
If a memory allocation failure occurs, -1 is returned.

add

bool
red_black_tree_add(RedBlackTree *const restrict tree
8000
,
                   const void *const key);

bool
red_black_hmap_add(RedBlackHMap *const restrict map,
                   const void *const key,
                   const size_t length);

insert GUARANTEED UNIQUE key into the container
Some assumptions can be made if key is unique that will slightly speed up insertion, useful for initial provisioning.
If the insertion succeeds, true is returned.
If a memory allocation failure occurs, false is returned.
This call will segfault or worse if key is already present in the container.

put

int
red_black_tree_put(RedBlackTree *const restrict tree,
                   const void *const key);

int
red_black_hmap_put(RedBlackHMap *const restrict map,
                   const void *const key,
                   const size_t length);

insert key into the container--if key is already present, overwrite the old value
If the insertion suceeds, 1 is returned.
If key overwrites a matching key, 0 is returned.
If a memory allocation failure occurs, -1 is returned.

update

int
red_black_tree_update_set(RedBlackTree *const restrict tree,
                          const void *const key,
                          void **const restrict old_ptr);
int
red_black_tree_update_get(RedBlackTree *const restrict tree,
                          const void *const key,
                          void **const restrict old_ptr);

int
red_black_hmap_update_set(RedBlackHMap *const restrict map,
                          const void *const key,
                          const size_t length,
                          void **const restrict old_ptr);
int
red_black_hmap_update_get(RedBlackHMap *const restrict map,
                          const void *const key,
                          const size_t length,
                          void **const restrict old_ptr);

insert key into the container--if key is already present, set old_ptr to the member key's value
update_set will overwrite a matching key in the container with key (like a put) before setting old_ptr, whereas update_get will leave the container key untouched.
If the insertion suceeds, 1 is returned, and old_ptr is not set.
If a key matching key is present, 0 is returned, and old_ptr is set to its value.
If a memory allocation failure occurs, -1 is returned.

Deletion

delete

int
red_black_tree_delete(RedBlackTree *const restrict tree,
                      const void *const key);
int
red_black_tree_delete_min(RedBlackTree *const restrict tree);
int
red_black_tree_delete_max(RedBlackTree *const restrict tree);

int
red_black_hmap_delete(RedBlackHMap *const restrict map,
                      const void *const key,
                      const size_t length);

delete key from the container
If key was present in the container, it will be removed and 1 is returned.
If key was not found, the container is untouched and 0 is returned.

drop

void
red_black_tree_drop(RedBlackTree *const restrict tree,
                    const void *const key);
void
red_black_tree_drop_min(RedBlackTree *const restrict tree);
void
red_black_tree_drop_max(RedBlackTree *const restrict tree);

void
red_black_hmap_drop(RedBlackHMap *const restrict map,
                    const void *const key,
                    const size_t length);

delete GUARANTEED PRESENT key from the container
Some assumptions can be made if key a known member of the container that will slightly speed up deletion.
This call will segfault or worse if key is not present in the container.

remove

int
red_black_tree_remove(RedBlackTree *const restrict tree,
                      const void *const key,
                      void **const restrict remove_ptr);
int
red_black_tree_remove_min(RedBlackTree *const restrict tree,
                          void **const restrict remove_ptr);
int
red_black_tree_remove_max(RedBlackTree *const restrict tree,
                          void **const restrict remove_ptr);

int
red_black_hmap_remove(RedBlackHMap *const restrict map,
                      const void *const key,
                      const size_t length,
                      void **const restrict remove_ptr);

delete key from the container--if key was found, set remove_ptr to its value
If key was deleted from the container, 1 is returned and remove_ptr is set.
If key was not found, the container is untouched, 0 is returned, and remove_ptr is not set.

pluck

void *
red_black_tree_pluck(RedBlackTree *const restrict tree,
                     const void *const key);
void *
red_black_tree_pluck_min(RedBlackTree *const restrict tree);
void *
red_black_tree_pluck_max(RedBlackTree *const restrict tree);

void *
red_black_hmap_pluck(RedBlackHMap *const restrict map,
                     const void *const key,
                     const size_t length);

delete GUARANTEED PRESENT key from the container and return its value
Some assumptions can be made if key a known member of the container that will slightly speed up deletion.
This call will segfault or worse is key is not present in the container.

Traversal

init

void
red_black_tree_asc_itor_init(RedBlackTreeItor *const restrict itor,
                             const RedBlackTree *const restrict tree);
void
red_black_tree_desc_itor_init(RedBlackTreeItor *const restrict itor,
                              const RedBlackTree *const restrict tree);

void
red_black_hmap_itor_init(RedBlackHMapItor *const restrict itor,
                         const RedBlackHMap *const restrict map);

initialize a traversal Itor object to vist all keys of the container
RedBlackTreeItors may be initialized to traverse in ascending (asc, from "smallest" key to "largest") or descending (desc, from "largest" key to "smallest") fashion.
Container mutations are not allowed throughout the useful lifespan of the Itor (see next).
Neither Itor makes internal allocations, so no destructor function need be called when finished.

next

bool
red_black_tree_itor_next(RedBlackTreeItor *const restrict itor,
                         void **const restrict key_ptr);

bool
red_black_hmap_itor_next(RedBlackHMapItor *const restrict itor,
                         void **const restrict key_ptr,
                         size_t *const restrict length_ptr);

visit the next key is the container if any remain
Following an init or reset, as long as keys remain, next will return true and fetch the next key in the container by setting key_ptr (and length_ptr). false is returned without setting the input pointer(s) once all member keys have been traversed.
Since a stack of unvisted keys its maintained internally, container insertions and deletions must be avoided throughout the useful lifespan of an Itor.

reset

void
red_black_tree_itor_reset(RedBlackTreeItor *const restrict itor,
                          const RedBlackTree *const restrict tree);

void
red_black_hmap_itor_reset(RedBlackHMapItor *const restrict itor,
                          const RedBlackHMap *const restrict map);

begin iteration on a new container
Itor must be initialized at least once prior to a reset. A reset does not change the direction of iteration for RedBlackTreeItors.

Random Access

find

bool
red_black_tree_find(const RedBlackTree *const restrict tree,
                    const void *const key);

bool
red_black_hmap_find(const RedBlackHMap *const restrict map,
                    const void *const key,
                    const size_t length);

check if key is a member of the container
find returns true if key was found, false if it was not.

fetch

bool
red_black_tree_fetch(const RedBlackTree *const restrict tree,
                     const void *const key,
                     void **const restrict fetch_ptr);
bool
red_black_tree_fetch_min(const RedBlackTree *const restrict tree,
                         void **const restrict fetch_ptr);
bool
red_black_tree_fetch_max(const RedBlackTree *const restrict tree,
                         void **const restrict fetch_ptr);

bool
red_black_hmap_fetch(const RedBlackHMap *const restrict map,
                     const void *const key,
                     const size_t length,
                     void **const restrict fetch_ptr);

attempt to retrieve member key from the container
If key is found, store it in fetch_ptr and return true.
If key is not present, leave fetch_ptr unset and return false. RedBlackTree provides fetch_min/fetch_max to retrieve the smallest/largest key in tree without comparisons.

get

void *
red_black_tree_get(const RedBlackTree *const restrict tree,
                   const void *const key);
void *
red_black_tree_get_min(const RedBlackTree *const restrict tree);
void *
red_black_tree_get_max(const RedBlackTree *const restrict tree);

void *
red_black_hmap_get(const RedBlackHMap *const restrict map,
                   const void *const key,
                   const size_t length);

retrieve GUARANTEED PRESENT key from the container
get returns member key comparing equal to input key (and length).
RedBlackTree provides get_min/get_max to retrieve the smallest/largest key in tree without comparisons.
This call will segfault or worse if key is not present in the container or if tree is empty in the case of get_min/get_max.

replace

bool
red_black_tree_replace(const RedBlackTree *const restrict tree,
                       const void *const key);
bool
red_black_tree_replace_min(const RedBlackTree *const restrict tree,
                           const void *const key);
bool
red_black_tree_replace_max(const RedBlackTree *const restrict tree,
                           const void *const key);

bool
red_black_hmap_replace(const RedBlackHMap *const restrict map,
                       const void *const key,
                       const size_t length);

attempt to set member key in the container
If a key is found that matches input key (and length), it is replaced by key and true is returned.
If no matching key is found, the container is untouched and false is returned. RedBlackTree provides replace_min/replace_max to set the smallest/largest key in tree without comparisons.

set

void
red_black_tree_set(const RedBlackTree *const restrict tree,
                   const void *const key);
void
red_black_tree_set_min(const RedBlackTree *const restrict tree,
                       const void *const key);
void
red_black_tree_set_max(const RedBlackTree *const restrict tree,
                       const void *const key);

void
red_black_hmap_set(const RedBlackHMap *const restrict map,
                   const void *const key,
                   const size_t length);

set GUARANTEED PRESENT key from the container
The key matching input key (and length) is replaced by key.
RedBlackTree provides set_min/set_max to set the smallest/largest key in tree without comparisons.
This call will segfault or worse if key is not present in the container or if tree is empty in the case of set_min/set_max.

exchange

bool
red_black_tree_exchange(const RedBlackTree *const restrict tree,
                        const void *const key,
                        void **const restrict old_ptr);
bool
red_black_tree_exchange_min(const RedBlackTree *const restrict tree,
                            const void *const key,
                            void **const restrict old_ptr);
bool
red_black_tree_exchange_max(const RedBlackTree *const restrict tree,
                            const void *const key,
                            void **const restrict old_ptr);

bool
red_black_hmap_exchange(const RedBlackHMap *const restrict map,
                        const void *const key,
                        const size_t length,
                        void **const restrict old_ptr);

attempt to swap member key in the container
if a key is found that matches input key (and length), it is replaced by key, old_ptr is set to its old value, and true is returned.
If no matching key is found, the container is untouched, old_ptr is not set, and false is returned.
RedBlackTree provides exchange_min/exchange_max to swap the smallest/largest key in tree without comparisons.

swap

void *
red_black_tree_swap(const RedBlackTree *const restrict tree,
                    const void *const key);
void *
red_black_tree_swap_min(const RedBlackTree *const restrict tree,
                        const void *const key);
void *
red_black_tree_swap_max(const RedBlackTree *const restrict tree,
                        const void *const key);

void *
red_black_hmap_swap(const RedBlackHMap *const restrict map,
                    const void *const key,
                    const size_t length);

swap GUARANTEED PRESENT key in the container swap will replace the key matching key (and length) with key and return the old value.
RedBlackTree provides swap_min/swap_max to swap the smallest/largest key in tree without comparisons. This call will segfault or worse if key is not present in the container.

Clone

clone

bool
red_black_tree_clone(RedBlackTree *const restrict dst_tree,
                     const RedBlackTree *const restrict src_tree);

bool
red_black_hmap_clone(RedBlackHMap *const restrict dst_map,
                     const RedBlackHMap *const restrict src_map);

allocate a shallow copy of dst container and store it in src
If adequate memory can be allocated, the call succeeds and returns true. If memory allocation fails, false is returned and dst container is either left untouched or is destroyed if any intermediate allocations have been made.
A successfully cloned container is guaranteed to compare similar and congruent (see Set Comparison) to the original copy.
dst container must be provided free of internal allocations (uninitialized for hmap and no insertion history for tree) to avoid memory leaks.

Inspection

empty

bool
red_black_tree_empty(const RedBlackTree *const restrict tree);

bool
red_black_hmap_empty(const RedBlackHMap *const restrict map);

check if a container is empty
If the input container contains no keys, true is returned.
If the input container contains at least one key, false is returned.

count

unsigned int
red_black_tree_count(const RedBlackTree *const restrict tree);

unsigned int
red_black_hmap_count(const RedBlackHMap *const restrict map);

query the count of all member keys in the container
RedBlackHMap must maintain its member count to properly manage its buckets, so hmap_count is an O(1) operation.
RedBlackTree does not keep track of its member count, so a full tree traversal is required for tree_count (an O(n) operation).

verify

bool
red_black_tree_verify(const RedBlackTree *const restrict tree);

bool
red_black_hmap_verify(const RedBlackHMap *const restrict map);

examine the validity of the container state
verify scans all member keys in O(n) operations, stopping if either a pair of keys is found out of (hashed) order or another one of the red-black properties has been violated.
If the container is in a valid state, true is returned.
If the container is not safe to query/modify, false is returned.

Set Comparison

similar

bool
red_black_tree_similar(const RedBlackTree *const tree1,
                       const RedBlackTree *const tree2);

bool
red_black_hmap_similar(const RedBlackHMap *const map1,
                       const RedBlackHMap *const map2);

check if two containers are equal
If both containers contain exactly the same keys, return true.
If the set of keys differ at all between the two containers, return false.

congruent

bool
red_black_tree_congruent(const RedBlackTree *const tree1,
                         const RedBlackTree *const tree2);

bool
red_black_hmap_congruent(const RedBlackHMap *const map1,
                         const RedBlackHMap *const map2);

check if two containers are identical
The congruent query checks for container similarity AND equivalent container shape. Two congruent containers will always be similar, but the converse is not necessarily true. For instance a container and its clone will always compare similar AND congruent, however, two similar containers may not be congruent if their sequence of key insertions/deletions are not perfectly aligned.
If both containers contain exactly the same keys and share the same underlying shape, return true.
If the containers are not similar or are shaped differently, return false.

intersect

bool
red_black_tree_intersect(const RedBlackTree *const tree1,
                         const RedBlackTree *const tree2);

bool
red_black_hmap_intersect(const RedBlackHMap *const map1,
                         const RedBlackHMap *const map2);

check if two containers have an overlap in their key set
If at least one key is found in both containers, return true.
If both containers have completely disjoint key sets, return false.

subset

bool
red_black_tree_subset(const RedBlackTree *const tree1,
                      const RedBlackTree *const tree2);

bool
red_black_hmap_subset(const RedBlackHMap *const map1,
                      const RedBlackHMap *const map2);

check if container2 is a subset of container1
If all of the keys of container2 are members of container1, return true.
If at least one key in container2 is not present in container1, return false.

Set Building Operations

insert_all

int
red_black_tree_insert_all(RedBlackTree *const restrict dst_tree,
                          const RedBlackTree *const restrict src_tree);

int
red_black_hmap_insert_all(RedBlackHMap *const restrict dst_map,
                          const RedBlackHMap *const restrict src_map);

insert all of the keys of src container into dst container
On success, insert_all returns the count of additional keys inserted.

If memory allocation fails, -1 is returned and dst is left in an indeterminate (but valid and destructible) state.

put_all

int
red_black_tree_put_all(RedBlackTree *const restrict dst_tree,
                       const RedBlackTree *const restrict src_tree);

int
red_black_hmap_put_all(RedBlackHMap *const restrict dst_map,
                       const RedBlackHMap *const restrict src_map);

insert all of the keys of src container into dst container -- matching keys will be overwritten with those from src
On success, put_all returns the count of additional keys inserted.
If memory allocation fails, -1 is returned and dst is left in an indeterminate (but valid and destructible) state.

add_all

bool
red_black_tree_add_all(RedBlackTree *const restrict dst_tree,
                       const RedBlackTree *const restrict src_tree);

bool
red_black_hmap_add_all(RedBlackHMap *const restrict dst_map,
                       const RedBlackHMap *const restrict src_map);

insert all GUARANTEED UNIQUE keys of src container into dst container
Some assumptions can be made if all keys of src are known to be unique (i.e. intersect(dst, src) == false) that will slightly speed up insertion.
If add_all succeeds, true is returned.
If a memory allocation failure occurs, false is returned.
This call will segfault or worse if any src keys are present in dst container.

delete_all

int
red_black_tree_delete_all(RedBlackTree *const restrict dst_tree,
                          const RedBlackTree *const restrict src_tree);

int
red_black_hmap_delete_all(RedBlackHMap *const restrict dst_map,
                          const RedBlackHMap *const restrict src_map);

delete all of the keys of src container from dst container
delete_all returns the count of overlapping keys deleted.

drop_all

void
red_black_tree_drop_all(RedBlackTree *const restrict dst_tree,
                        const RedBlackTree *const restrict src_tree);

void
red_black_hmap_drop_all(RedBlackHMap *const restrict dst_map,
                        const RedBlackHMap *const restrict src_map);

delete all GUARANTEED PRESENT keys of src container from dst container
Some assumptions can be made if all keys of src are present in dst (i.e. subset(dst, src) == true) that will slightly speed up deletion.
This call will segfault or worse if src contains any keys that are not present in dst.

union

int
red_black_tree_union(RedBlackTree *const restrict union_tree,
                     const RedBlackTree *const tree1,
                     const RedBlackTree *const tree2);

int
red_black_hmap_union(RedBlackHMap *const restrict union_map,
                     const RedBlackHMap *const map1,
                     const RedBlackHMap *const map2);

Build the union set of keys from containers 1 and 2
union constructs a union container from the set of all unique keys between other two provided containers.
If union succeeds, a non-negative count of keys in union container is returned.
If memory allocation fails, -1 is returned and union container is either left untouched or is destroyed if any intermediate allocations have been made.
union container must be provided free of internal allocations (uninitialized for hmap and no insertion history for tree) to avoid memory leaks.

intersection

int
red_black_tree_intersection(RedBlackTree *const restrict intersection_tree,
                            const RedBlackTree *const tree1,
                            const RedBlackTree *const tree2);

int
red_black_hmap_intersection(RedBlackHMap *const restrict intersection_map,
                            const RedBlackHMap *const map1,
                            const RedBlackHMap *const map2);

Build the intersection set of keys from containers 1 and 2
intersection constructs a intersection container from the set of all unique keys between other two provided containers.
If intersection succeeds, a non-negative count of keys in intersection container is returned.
If memory allocation fails, -1 is returned and intersection container is either left untouched or is destroyed if any intermediate allocations have been made.
intersection container must be provided free of internal allocations (uninitialized for hmap and no insertion history for tree) to avoid memory leaks.

difference

int
red_black_tree_difference(RedBlackTree *const restrict difference_tree,
                          const RedBlackTree *const tree1,
                          const RedBlackTree *const tree2);

int
red_black_hmap_difference(RedBlackHMap *const restrict difference_map,
                          const RedBlackHMap *const map1,
                          const RedBlackHMap *const map2);

Build the difference set of keys from containers 1 and 2
difference constructs a difference container from the set of all keys in container 1 that are not present in container 2
If difference succeeds, a non-negative count of keys in difference container is returned.
If memory allocation fails, -1 is returned and difference container is either left untouched or is destroyed if any intermediate allocations have been made.
difference container must be provided free of internal allocations (uninitialized for hmap and no insertion history for tree) to avoid memory leaks.

sym_difference

int
red_black_tree_sym_difference(RedBlackTree *const restrict sym_difference_tree,
                              const RedBlackTree *const tree1,
                              const RedBlackTree *const tree2);

int
red_black_hmap_sym_difference(RedBlackHMap *const restrict sym_difference_map,
                              const RedBlackHMap *const map1,
                              const RedBlackHMap *const map2);

Build the symmetric difference set of keys from containers 1 and 2
sym_difference constructs a sym_difference container from the set of all non-overlapping keys among containers 1 and 2
If sym_difference succeeds, a non-negative count of keys in sym_difference container is returned.
If memory allocation fails, -1 is returned and sym_difference container is either left untouched or is destroyed if any intermediate allocations have been made.
sym_difference container must be provided free of internal allocations (uninitialized for hmap and no insertion history for tree) to avoid memory leaks.

Types

RedBlackComparator

declaration

typedef int
(*RedBlackComparator)(const void *key1,
                      const void *key2);

responsibility
maintain proper sorted order of tree nodes

behaviour
should compare two keys according to the table:

`return`	`key1` __ `key2`
`< 0`	`<`
`0`	`==`
`> 0`	`>`

without altering their values

examples

/* for trees housing integer keys */
#include <stdint.h> /* intptr_t */
int
compare_integer_keys(const void *key1,
                     const void *key2)
{
        const int int_key1 = (int) (intptr_t) key1;
        const int int_key2 = (int) (intptr_t) key2;

#if 0 /* if domain of keys is known to be small */
        return int_key1 - int_key2;

#else /* if subtraction of keys may cause arithmetic overflow */
        if (int_key1 < int_key2)
                return -1;

        return (int_key1 > int_key2); /* 1, 0 */
#endif
}


/* for trees housing string keys */
int
compare_string_keys(const void *key1,
                    const void *key2)
{
        const unsigned char *string1;
        const unsigned char *string2;
        int token1;
        int token2;

        string1 = (const unsigned char *) key1;
        string2 = (const unsigned char *) key2;

        while (1) {
                token1 = (int) *string1;
                token2 = (int) *string2;

                if (token1 != token2)
                        return token1 - token2;

                if (token1 == 0)
                        return 0;

                ++string1;
                ++string2;
        }
}

Implementation

The "Parent" Pointer Compromise

TODO

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Name		Name	Last commit message	Last commit date
Latest commit History 290 Commits
benchmark		benchmark
bin		bin
examples		examples
include		include
key_accessors		key_accessors
obj		obj
shared		shared
src		src
static		static
test		test
Makefile		Makefile
README.md		README.md

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