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#include <string.h>
#include <stdlib.h>
#include <lyn/lookup.h>
struct lookup lookup_create(size_t s)
{
return (struct lookup){.ns = s, .root = NULL};
}
unsigned long djb2(const unsigned char *str)
{
unsigned long hash = 5381;
int c;
while ((c = *str++))
hash = ((hash << 5) + hash) + c; /* hash * 33 + c */
return hash;
}
static size_t lookup_size(struct lookup *l, size_t key_len)
{
return sizeof(struct lookup_node) + l->ns + key_len + 1;
}
static struct lookup_node *create_node(struct lookup *l, unsigned long hash, const char *key, const void *n)
{
size_t key_len = strlen(key);
struct lookup_node *new = malloc(lookup_size(l, key_len));
if (!new)
return NULL;
memcpy(new->data, n, l->ns);
strcpy(new->data + l->ns, key);
new->hash = hash;
new->left = NULL;
new->right = NULL;
return new;
}
void *lookup_insert(struct lookup *l, const char *key, const void *n)
{
enum {INSERT_LEFT, INSERT_RIGHT} side = INSERT_LEFT;
unsigned long hash = djb2((const unsigned char *)key);
if (!l->root) {
struct lookup_node *new = create_node(l, hash, key, n);
if (!new)
return NULL;
l->root = new;
return &new->data;
}
struct lookup_node *cmp = l->root;
while (cmp) {
if (cmp->hash == hash) {
if (strcmp(cmp->data + l->ns, key) == 0)
return NULL;
if (cmp->left) {
cmp = cmp->left;
continue;
}
side = INSERT_LEFT;
break;
}
else if (cmp->hash < hash) {
if (cmp->left) {
cmp = cmp->left;
continue;
}
side = INSERT_LEFT;
break;
}
else if (cmp->hash > hash) {
if (cmp->right) {
cmp = cmp->right;
continue;
}
side = INSERT_RIGHT;
break;
}
}
struct lookup_node *new = create_node(l, hash, key, n);
if (!new)
return NULL;
if (side == INSERT_LEFT)
cmp->left = new;
else if (side == INSERT_RIGHT)
cmp->right = new;
else
abort();
return &new->data;
}
void *lookup_at(struct lookup *l, const char *key)
{
unsigned long hash = djb2((const unsigned char *)key);
struct lookup_node *n = l->root;
while (n) {
if (n->hash == hash) {
if (strcmp(n->data + l->ns, key) == 0)
return &n->data;
n = n->left;
}
else if (n->hash < hash) {
n = n->left;
}
else if (n->hash > hash) {
n = n->right;
}
}
return NULL;
}
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