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Editing File: /usr/share/doc/python-pycparser-2.14/examples/c_files/hash.c

/*
** C implementation of a hash table ADT
*/
typedef enum tagReturnCode {SUCCESS, FAIL} ReturnCode;

typedef struct tagEntry
{
    char* key;
    char* value;
} Entry;

typedef struct tagNode
{
    Entry* entry;

struct tagNode* next;
} Node;

typedef struct tagHash
{
    unsigned int table_size;

Node** heads;

} Hash;

static unsigned int hash_func(const char* str, unsigned int table_size)
{
    unsigned int hash_value;
    unsigned int a = 127;

for (hash_value = 0; *str != 0; ++str)
        hash_value = (a*hash_value + *str) % table_size;

return hash_value;
}

ReturnCode HashCreate(Hash** hash, unsigned int table_size)
{
    unsigned int i;

if (table_size < 1)
        return FAIL;

//
    // Allocate space for the Hash
    //
    if (((*hash) = malloc(sizeof(**hash))) == NULL)
        return FAIL;

//
    // Allocate space for the array of list heads
    //
    if (((*hash)->heads = malloc(table_size*sizeof(*((*hash)->heads)))) == NULL)
        return FAIL;

//
    // Initialize Hash info
    //
    for (i = 0; i < table_size; ++i)
    {
        (*hash)->heads[i] = NULL;
    }

(*hash)->table_size = table_size;

return SUCCESS;
}

ReturnCode HashInsert(Hash* hash, const Entry* entry)
{
    unsigned int index = hash_func(entry->key, hash->table_size);
    Node* temp = hash->heads[index];

HashRemove(hash, entry->key);

if ((hash->heads[index] = malloc(sizeof(Node))) == NULL)
        return FAIL;

hash->heads[index]->entry = malloc(sizeof(Entry));
    hash->heads[index]->entry->key = malloc(strlen(entry->key)+1);
    hash->heads[index]->entry->value = malloc(strlen(entry->value)+1);
    strcpy(hash->heads[index]->entry->key, entry->key);
    strcpy(hash->heads[index]->entry->value, entry->value);

hash->heads[index]->next = temp;

return SUCCESS;
}

const Entry* HashFind(const Hash* hash, const char* key)
{
    unsigned int index = hash_func(key, hash->table_size);
    Node* temp = hash->heads[index];

while (temp != NULL)
    {
        if (!strcmp(key, temp->entry->key))
            return temp->entry;

temp = temp->next;
    }

return NULL;
}

ReturnCode HashRemove(Hash* hash, const char* key)
{
    unsigned int index = hash_func(key, hash->table_size);
    Node* temp1 = hash->heads[index];
    Node* temp2 = temp1;

while (temp1 != NULL)
    {
        if (!strcmp(key, temp1->entry->key))
        {
            if (temp1 == hash->heads[index])
                hash->heads[index] = hash->heads[index]->next;
            else
                temp2->next = temp1->next;

free(temp1->entry->key);
            free(temp1->entry->value);
            free(temp1->entry);
            free(temp1);
            temp1 = NULL;

return SUCCESS;
        }
        
        temp2 = temp1;
        temp1 = temp1->next;
    }

return FAIL;
}

void HashPrint(Hash* hash, void (*PrintFunc)(char*, char*))
{
    unsigned int i;

if (hash == NULL || hash->heads == NULL)
        return;

for (i = 0; i < hash->table_size; ++i)
    {
        Node* temp = hash->heads[i];

while (temp != NULL)
        {
            PrintFunc(temp->entry->key, temp->entry->value);
            temp = temp->next;
        }
    }
}

void HashDestroy(Hash* hash)
{
    unsigned int i;

if (hash == NULL)
        return;

for (i = 0; i < hash->table_size; ++i)
    {
        Node* temp = hash->heads[i];

while (temp != NULL)
        {
            Node* temp2 = temp;

free(temp->entry->key);
            free(temp->entry->value);
            free(temp->entry);

temp = temp->next;
            
            free(temp2);
        }
    }

free(hash->heads);
    hash->heads = NULL;

free(hash);
}

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