Synopsis

CN_Map (Clara Nguyen's Map) is a generic associative data structure that gives C programmers a way to store data in key/value pairs. It is an implementation of the self-balancing Red-Black Tree.

In CN_Maps, users are able to store any type they wish for both keys and values. Key values are sorted and must be unique.

What to include

Include the following files in your project:

#include "cn_cmp.h"
#include "cn_map.h"

Unlike other CNDS libraries, this one recommends the inclusion of 2 files:

• cn_map.h has the definitions for the CN_Map.
• cn_cmp.h includes comparison utility functions that can be used to sort keys.

Datatypes added

CN_Map is a library. It adds structs, typedefs, and functions that users are able to use. Here are what it contains:

Typedefs

• CNM_UINT = unsigned int
• CNM_U64 = unsigned long long
• CNM_BYTE = unsigned char
• CNC_COMP = int

Structs

• CN_MAP = The actual CN_Map itself. This is a pointer type to struct cn_map, so all functions pass pointers rather than copies.
• CNM_ITERATOR = CN_Map iterator used to traverse the map.
• CNM_NODE = Node that holds a key/value pair in the CN_Map

Enums

• CNM_COLOUR = Colour of a node. Defined as [ CNM_RED, CNM_BLACK, CNM_DOUBLE_BLACK ]

Besides constructors, All "cn_map" functions take a "CN_MAP" data type in front of it. This may be misleading at first, since CN_MAP is actually a pointer type. So function calls do not copy the data structure. Do note this if you decide to expand on this library.

Why the typedefs? If I need to make a hotfix on types in this library, it'd be a single line of code changed.

Container Properties

• Associative - Elements are accessed by their key, which can be any type defined by the user.
• Sorted - Elements in CN_Maps are sorted based on a user-given comparison function. When iterated through, keys will always be in order.
• Dynamic - Users can specify custom destructor and sorting functions which are called at various times during the CN_Map's lifetime.
• Generic - Despite C lacking templates, CN_Map allows the user to specify the data types for both the key and value.

Download

Grab it from GitHub, here: https://github.com/iDestyKK/CN_Map

Example Usage

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "cn_cmp.h"
#include "cn_map.h"

main() {
	CN_MAP map = cn_map_init(char, int, cn_cmp_char);

	char key;
	int  value;

	//Put in a-z with 0-25 in as key/value pairs.
	for (key = 'a', value = 0; key <= 'z'; key++, value++) {
		cn_map_insert(map, &key, &value);
	}

	//Iterate through
	CNM_ITERATOR it;

	for (cn_map_begin(map, &it); !cn_map_at_end(map, &it); cn_map_next(map, &it)) {
		printf(
			"%c -> %d\n",
			cn_map_iterator_key  (&it, char),
			cn_map_iterator_value(&it, int)
		);
	}
}