#define V int // list value data type #define PFX intl // list function’s prefix #define SNAME int_list // list struct name (struct int_list) #define CMC_EXT_STR // Enables an extra functionality (STR) of the list #include “cmc/list.h”
// This header file includes a lot of functions that can be used as methods to // basic data types. In this case, cmc_i32_str is used
Features
The C Macro Collections library is organized into many other sub-libraries. The following table is a quick overview.
Library | Name | Description |
---|---|---|
CMC | Macro Collections | The main library with dynamically-sized collections |
COR | Core | Core functionalities used by more than one collection, usually from different sub-libraries |
EXT | Extensions | Extension to collections |
SAC | Statically Allocated Collections | Collections with a fixed sized array that don’t use any heap allocation |
TSC | Thread-Safe Collections | Collections that allow multiple operations from multiple threads |
UTL | Utilities | General utilities |
Project Structure
- benchmarks - Where all benchmarks are hosted
- docs - A folder hosting the generated documentation by mdBook
- documentation - The markdowns used by mdBook to generate the website
- examples - Examples using the C Macro Collections Library
- src - All headers part of the C Macro Collections Library
- tests - Where all tests are hosted
Available Collections
The following table is an overview of all the currently available or upcoming data structures:
Collection |
Abstract Data Type |
Data Structure |
Details |
---|---|---|---|
BitSet bitset.h |
Set | Dynamic Array | A set of bits that can be individually modified and queried, each identified by a bit index |
Deque deque.h |
Double-Ended Queue | Dynamic Circular Array | A circular array that allows push and pop on both ends (only) at constant time |
HashBidiMap hashbidimap.h |
Bidirectional Map | Two Hashtables | A bijection between two sets of unique keys and unique values K <-> V using two hashtables |
HashMap hashmap.h |
Map | Flat Hashtable | A unique set of keys associated with a value K -> V with constant time look up using a hashtable with open addressing and robin hood hashing |
HashMultiMap hashmultimap.h |
Multimap | Hashtable | A mapping of multiple keys with one node per key using a hashtable with separate chaining |
HashMultiSet hashmultiset.h |
Multiset | Flat Hashtable | A mapping of a value and its multiplicity using a hashtable with open addressing and robin hood hashing |
HashSet hashset.h |
Set | Flat Hashtable | A unique set of values with constant time look up using a hashtable with open addressing and robin hood hashing |
Heap heap.h |
Priority Queue | Dynamic Array | A binary heap as a dynamic array as an implicit data structure |
IntervalHeap intervalheap.h |
Double-Ended Priority Queue | Custom Dynamic Array | A dynamic array of nodes, each hosting one value from the MinHeap and one from the MaxHeap |
LinkedList linkedlist.h |
List | Doubly-Linked List | A default doubly-linked list |
List list.h |
List | Dynamic Array | A dynamic array with push and pop anywhere on the array |
Queue queue.h |
FIFO | Dynamic Circular Array | A queue using a circular array with enqueue at the back index and dequeue at the front index |
SkipList WIP |
Sorted List | Skip List | A sorted Linked List with average O(log n) search, insertion and deletion complexity |
SortedList sortedlist.h |
Sorted List | Sorted Dynamic Array | A lazily sorted dynamic array that is sorted only when necessary |
Stack stack.h |
FILO | Dynamic Array | A stack with push and pop at the end of a dynamic array |
TreeBidiMap WIP |
Sorted Bidirectional Map | Two AVL Trees | A sorted bijection between two sets of unique keys and unique values K <-> V using two AVL trees |
TreeMap treemap.h |
Sorted Map | AVL Tree | A unique set of keys associated with a value K -> V using an AVL tree with log(n) look up and sorted iteration |
TreeMultiMap WIP |
Sorted Multimap | AVL Tree | A sorted mapping of multiple keys with one node per key using an AVL Tree of linked-lists |
TreeMultiSet WIP |
Sorted Multiset | AVL Tree | A sorted mapping of a value and its multiplicity using an AVL tree |
TreeSet treeset.h |
Sorted Set | AVL Tree | A unique set of keys using an AVL tree with log(n) look up and sorted iteration |
Other Features
These are some features within the library that are implemented by all collections.
Two-way iterators
All collections come with a two-way iterator. You can go back and forwards in constant time and access elements in constant time.
Custom Allocation
All collections have a cmc_alloc_node
which provides pointers to the four dynamic memory allocation functions in C: malloc
, calloc
, realloc
and free
. These pointers can be customized for each individual collection created or a default can be used, as specified in cmc_alloc_node_default
.
Callbacks
Every function that operates on a collection can be separated in 5 different types. Create, Read, Update, Delete and (an extra one besides CRUD) Resize. You can define one callback function for each operation. Check out the documentation to see when each callback function is called.
Functions Table
Functions table is a struct
of function pointers containing ‘methods’ for a custom data type. Some methods are optional and others are needed in order for a collection to operate. They are:
CMP
A comparator function is used in sorted collections or when an equality is being checked like when trying to find a certain element in a list. It is responsible for taking two arguments of the same data type and comparing them. The return value is an int
with the following definitions:
- Return
1
if the first argument is greater than the second; - Return
0
if the first argument equals the second; - Return
-1
if the first argument is less than the second.
CPY
A copy function is used when a collection is being copied. It can be used to make a deep copy of of your custom data type. It must take a single parameter and return a new copy of that same data type. If this function is absent (NULL
) the data type will be copied by assignment (for pointers this is a shallow copy).
STR
A string function is responsible for taking a FILE
pointer and a custom data type and outputting the string representation of that data returning a bool
indication success or failure. It is useful for debugging.
FREE
The free function is called when a collection is cleared (all elements removed) or freed (all elements removed and freed from memory) and it is responsible for completely freeing all resources that are usually acquired by your data type.
HASH
This function receives a custom data type as parameter and returns a size_t
hash of that data. Used in hashtables.
PRI
A priority function works much like the comparator function except that it compares the priority between two elements. It is used in collections whose structure is based on the priority of elements and not in their general comparison.
- Return
1
if the first argument has a greater priority than the second; - Return
0
if the first argument has the same priority as second; - Return
-1
if the first argument has a lower priority than the second.
The following table shows which functions are required, optional or never used for each Collection:
Collection | CMP | CPY | STR | FREE | HASH | PRI |
---|---|---|---|---|---|---|
BitSet | ||||||
Deque | ||||||
HashMap | ||||||
HashBidiMap | ||||||
HashMultiMap | ||||||
HashMultiSet | ||||||
HashSet | ||||||
Heap | ||||||
IntervalHeap | ||||||
List | ||||||
LinkedList | ||||||
Queue | ||||||
SortedList | ||||||
Stack | ||||||
TreeMap | ||||||
TreeSet |
Color | Label |
---|---|
Required for basic functionality. | |
Required for specific functions. | |
Required for non-core specific functions. | |
Optional. | |
Not Used. |
Design Decisions
Stack vs Heap Allocation
Currently all collections need to be allocated on the heap. Iterators have both options but it is encouraged to allocate them on the stack since they don’t require dynamic memory.
Some collections overlap others in terms of functionality
Yes, you can use a Deque as a Queue or a List as a Stack without any major cost, but the idea is to have the least amount of code to fulfill the needs of a collection.
Take for example the Stack. It is simple, small and doesn’t have many functions. If you generate a List to be used (only) as a Stack (which is one of the bulkiest collections) you’ll end up with a lot of code generated and compiled for nothing.
The Deque versus Queue situation is a little less problematic, but again, you need to be careful when generating a lot of code as compilation times might go up to 15 seconds even with modern ultra-fast compilers.
Another example is using a HashMap/TreeMap as a HashSet/TreeSet (with a dummy value that is never used), but I just think that this is a bad thing to do and you would be wasting some memory. Also, the sets generate a lot of code related to set theory, whereas maps don’t.
But what about the LinkedList ?
You can use them as Stacks, Queues and Deques, but with modern memory hierarchy models, array-based data structures have a significantly faster runtime due to caching, so I didn’t bother to have specific implementations of those aforementioned collections.
You can’t structurally modify a collection when iterating over it
Modifying a collection will possibly invalidate all iterators currently initialized by it. Currently, the only collection that allows this is the LinkedList (using the node-based functions, not the iterator).
Special Macros
CMC_NO_ALLOC
- disables"cor/alloc.h"
, useful for statically allocated collections (SAC)CMC_NO_IMPORTS
- disables all imports from the standard library at"cor/core.h"