rxi/map

A type-safe hash map implementation for C

map

A type-safe generic hashmap implementation for C.

Installation

The map.c and map.h files can be dropped into an existing C project and compiled along with it.

Usage

Before using a map it should first be initialised using the map_init() function.

map_int_t m;
map_init(&m);

Values can added to a map using the map_set() function.

map_set(&m, "testkey", 123);

To retrieve a value from a map, the map_get() function can be used. map_get() will return a pointer to the key's value, or NULL if no mapping for that key exists.

int *val = map_get(&m, "testkey");
if (val) {
  printf("value: %d\n", *val);
} else {
  printf("value not found\n");
}

When you are done with a map the map_deinit() function should be called on it. This will free any memory the map allocated during use.

map_deinit(&m);

Types

map.h provides the following predefined map types:

Contained Type	Type name
void*	map_void_t
char*	map_str_t
int	map_int_t
char	map_char_t
float	map_float_t
double	map_double_t

To define a new map type the map_t() macro should be used:

/* Creates the type uint_map_t for storing unsigned ints */
typedef map_t(unsigned int) uint_map_t;

Functions

All map functions are macro functions. The parameter m in each function should be a pointer to the map struct which the operation is to be performed on. The key parameter should always be a string value.

map_t(T)

Creates a map struct for containing values of type T.

/* Typedefs the struct `fp_map_t` as a container for type FILE* */
typedef map_t(FILE*) fp_map_t;

map_init(m)

Initialises the map, this must be called before the map can be used.

map_deinit(m)

Deinitialises the map, freeing the memory the map allocated during use; this should be called when we're finished with a map.

map_get(m, key)

Returns a pointer to the value of the given key. If no mapping for the key exists then NULL will be returned.

map_set(m, key, value)

Sets the given key to the given value. Returns 0 on success, otherwise -1 is returned and the map remains unchanged.

map_remove(m, key)

Removes the mapping of the given key from the map. If the key does not exist in the map then the function has no effect.

map_iter(m)

Returns a map_iter_t which can be used with map_next() to iterate all the keys in the map.

map_next(m, iter)

Uses the map_iter_t returned by map_iter() to iterate all the keys in the map. map_next() returns a key with each call and returns NULL when there are no more keys.

const char *key;
map_iter_t iter = map_iter(&m);

while ((key = map_next(&m, &iter))) {
  printf("%s -> %d", key, *map_get(&m, key));
}

License

This library is free software; you can redistribute it and/or modify it under the terms of the MIT license. See LICENSE for details.

map's Issues

Custom type data

Hello, I learned your map code，After applying for space on the heap, calling map ﹣ deinit ﹣ will not release the empty space applied by the user. It is not very clear about this. If you want to request, email: [email protected], QQ: 8101309. If you can, can you direct me.

中文：您好，我学习了你的map代码，请问自定数据类型在堆上申请空间后，调用map_deinit_后不会释放用户自己申请的空吧，对这块不是很清楚，想请求下， 邮箱：[email protected],qq:8101309 如果可以的话能否直接指点下。

Valgrind predicts memory loss

Hello!

I am using many of your awesome libraries on several projects! Thank you for the awesome libs you write! I am also a love2d user so let's chat once you join the IRC room!

Anyway, currently, I am using map for a computational graph library: https://github.com/praisethemoon/cgraph

Note that this may be a false alarm, for my own code might be the source of this issues, but I would like to hear your own opinion on this one: as I profile my code with valgrind, I get this (among other problems related to my own code):

==3822== 8 bytes in 1 blocks are definitely lost in loss record 1 of 2
==3822==    at 0x4C2DB8F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==3822==    by 0x4C2FDEF: realloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==3822==    by 0x407541: map_resize (map.c:75)
==3822==    by 0x407808: map_set_ (map.c:147)
==3822==    by 0x4425DA: graphSetVar (cg_factory.c:114)
==3822==    by 0x4461E8: runGraphExample (main.c:792)
==3822==    by 0x446379: main (main.c:855)

What do you think?

Cheers!

maybe should test map_str_t

in map_set_(&(m)->base, key, &(m)->tmp, sizeof((m)->tmp)) ) , sizeof((m)->tmp)) is sizeof(ptr),the return value is always 4 or 8. I think there are some other bugs.

support sort

if it's passible to support sort?

Anything refer to the code explain?

Hi,
This is very strong code in practical.But i want to understand code through,could anyone give me some links refer to the code,
Thanks in advance.

map_void_t + map_get build error: Can not convert void* to void**

Any unit test ?

map_deinit crash after map_init without add any values

map_init(&m);
map_deinit(&m);  // crash

Simple showcase

Hello, you library look very nice at first glance. However in order to check for usability, i would have to write a main and test your features. Maybe you could provide a small main function showcasing the use and correct behaviour of your library ? Also it could give a few benchmark data maybe, but i'd rather have a simple showcase than a complex messy benchmark first.

undefined refence to « map_get_ »

Hello,

I try to compile this code but I get an error, do you know what's wrong because it works when I put it in the main of the map.c file.

Thanks

gcc test.c

#include <stdio.h>
#include "map.h"

int main (int argc, char *argv[])
{
	map_int_t m;
	map_init(&m);  
	int tt = map_set(&m, "testkey", 123);
	printf("%d", tt);
	int *val = map_get(&m, "testkey");
	if (val) {
		printf("value: %d\n", *val);
	} else {
		printf("value not found\n");
	}
	map_deinit(&m);
	return 0;
}