connLAN / C-Macro-Collections

Easy to use, header only, macro generated, generic and type-safe Data Structures in C

C Macro Collections

Easy to use, header only, macro generated, generic and type-safe Data Structures in C.

Table of Contents

• Project Structure
• Available Collections
• Features
• Overall To-Do
• Design Decisions
• What to use
• How to use

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
  • cmc - The main C Macro Collections Library
  • cor - Core includes in the C Macro Collections Library
  • dev - The main C Macro Collections Library for development (containing logging)
  • sac - Statically Allocated Collections
  • utl - Utility like ForEach macros, logging, etc
  • macro_collections.h - Master header containing all collections and utilities
• tests - Where all tests are hosted

Available Collections

• Linear Collections
  • List, LinkedList, Deque, Stack, Queue, SortedList
• Sets
  • HashSet, TreeSet, HashMultiSet
• Maps
  • HashMap, TreeMap, HashMultiMap
• Bidirectional Maps
  • HashBidiMap
• Heaps
  • Heap, IntervalHeap
• WIP
  • BitSet, Matrix, TreeBidiMap, TreeMultiMap, TreeMultiSet

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
Matrix WIP	Regular Matrix	Dynamic Array of Dynamic Arrays	A regular matrix with arbitrary rows and columns
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
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

Features

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 to 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
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.

Overall To-Do

In the long term, these are the steps left for the completion of this library:

• Complete the implementation of all the functions in the scope of the TODO file for the main collections;
• Reorganize and complete all tests for the cmc collections;
• Make an exact copy of all collections to dev with many logging utility, for them to be used under development;
• Port all of these collections to be statically allocated and be part of the sac library;
• Complete all tests for sac.

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).

What to use

The following table shows how each collection is implemented and how well they do when using as common abstract data types.

• Ideal - The collection implements correctly the abstract data type;
• Not Ideal - The implementation is fulfilled but some functionalities are either not part of the ADT or not present;
• Bad - It can be done, but its a bad idea.

How to use

To generate the collection, all you need to do is to include the necessary header files. You can include the containers you want to use individually or you can include the master header, macro_collections.h, that comes with the entire C-Macro-Collections library.

Macros

Note here that SNAME represents the uppercase name of the collection.

Every collection is separated by two parts:

• HEADER - Contains all struct definitions and function definitions.
• SOURCE - Contains all function implementations.

All collections have three main macros:

• CMC_GENERATE_SNAME - Generates CMC_GENERATE_SNAME_HEADER and CMC_GENERATE_SNAME_SOURCE.

Or you can generate each part individually:

• CMC_GENERATE_SNAME_HEADER - Generates all struct definitions and function definitions.
• CMC_GENERATE_SNAME_SOURCE - Generates all function implementations.

Parameters

When including macro_collections.h in your source code you gain access to a macro called CMC_COLLECTION_GENERATE with the following parameters:

• C - Container name in uppercase (BIDIMAP, DEQUE, HASHMAP, HASHSET, HEAP, INTERVALHEAP, LINKEDLIST, LIST, MULTIMAP, MULTISET, QUEUE, SORTEDLIST, STACK, TREEMAP, TREESET).
• PFX - Functions prefix or namespace.
• SNAME - Structure name (struct SNAME).
• K - Key type. Only used in HASHMAP, TREEMAP, MULTIMAP and BIDIMAP; ignored by others.
• V - Value type. Primary type for most collections, or value to be mapped by HASHMAP, TREEMAP, MULTIMAP and BIDIMAP.

In fact, all macros follow this pattern. So whenever you see a macro with a bunch of parameters and you don't know what they are, you can check out the above list.

For Each

There are 2 for-each macros:

• CMC_FOREACH - Starts at the start of the collection towards the end.

• CMC_FOREACH_REV - Starts at the end of the collection towards the start.

• PFX - Functions prefix or namespace.

• SNAME - Structure name.

• TARGET - The variable name of the collection you wish to iterate over.

• ITERNAME - Iterator variable name.

For CMC_FOREACH and CMC_FOREACH_REV you will be able to name the iterator variable through the ITERNAME parameter.

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Check out some code reviews that covers some parts the project:

About	Link
Unit Test ./utl/test.h
Interval Heap ./cmc/intervalheap.h
Hash Set ./cmc/hashset.h
Linked List ./cmc/linkedlist.h
Others