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```
Cheesemap
====
Cheesemap is a swiss-table like HashMap implementation in C. It's designed to be fast but also easy to understand and improve.
The HashMap might be a little memory efficient especially right after resizes and doesn't yet provide a shrink method. The HashMap
is not yet production tested but fully working.
* Example
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "cheesemap.h"
_Noreturn void panic_impl(const char* file, cm_u32 line, const char* fmt,
...) {
fprintf(stderr, "Panic at %s:%u: ", file, line);
va_list args;
va_start(args, fmt);
vfprintf(stderr, fmt, args);
va_end(args);
fprintf(stderr, "\n");
abort();
}
// Convenience macro for array length
#define countof(arr) (sizeof(arr) / sizeof(*(arr)))
// Simple hash function for string keys
cm_u64 hash_string(const cm_u8* key, cm_u8* user) {
(void)user;
const char* str = *(const char**)key;
cm_u64 hash = 5381;
int c;
while ((c = *str++)) hash = ((hash << 5) + hash) + c; // hash * 33 + c
return hash;
}
// Compare function for string keys
bool compare_string(const cm_u8* key1, const cm_u8* key2, cm_u8* user) {
(void)user;
return strcmp(*(const char**)key1, *(const char**)key2) == 0;
}
// Default allocator (uses malloc)
void* default_alloc(cm_usize size, cm_u8* user) {
(void)user;
return malloc(size);
}
// Default deallocator (uses free)
void default_dealloc(void* ptr, cm_u8* user) {
(void)user;
free(ptr);
}
int main(void) {
// Create a map: string -> int (word frequency counter)
struct cheesemap map;
cm_new_(&map, const char*, int, NULL, hash_string, compare_string,
default_alloc, default_dealloc);
// Count word frequencies
const char* words[] = {"hello", "world", "hello",
"cheesemap", "world", "hello"};
for (size_t i = 0; i < countof(words); i++) {
int* count;
if (cm_lookup_(&map, words[i], &count)) {
(*count)++; // Word exists, increment
} else {
int initial = 1;
cm_insert_(&map, words[i], initial);
}
}
// Iterate and print all word counts
printf("Word frequencies:\n");
struct cheesemap_iter iter;
cm_iter_init(&iter, &map);
const char** word;
int* count;
while (cm_iter_next_(&iter, &map, &word, &count)) {
printf(" %s: %d\n", *word, *count);
}
// Lookup a specific word
const char* search = "hello";
if (cm_lookup_(&map, search, &count)) {
printf("\n'%s' appears %d times\n", search, *count);
}
// Remove a word
const char* remove = "world";
cm_remove_(&map, remove, NULL);
printf("Removed '%s'\n", remove);
// Verify removal
if (!cm_lookup_(&map, remove, &count)) {
printf("'%s' no longer in map\n", remove);
}
cm_drop(&map);
return 0;
}
Copyright © 2026 Fabrice
```
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