wmaker/WINGs/hashtable.c

#include <sys/types.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>

#include "WUtil.h"




#define INITIAL_CAPACITY	23


#if defined(__GNUC__) && !defined(__STRICT_ANSI__)
# define INLINE inline
#else
# define INLINE
#endif


typedef struct HashItem {
    const void *key;
    const void *data;

    struct HashItem *next;	       /* collided item list */
} HashItem;


typedef struct W_HashTable {
    WMHashTableCallbacks callbacks;

    unsigned itemCount;
    unsigned size;		       /* table size */

    HashItem **table;
} HashTable;




#define HASH(table, key)  (((table)->callbacks.hash ? \
    (*(table)->callbacks.hash)(key) : hashPtr(key)) % (table)->size)

#define DUPKEY(table, key) ((table)->callbacks.retainKey ? \
    (*(table)->callbacks.retainKey)(key) : (key))

#define RELKEY(table, key) if ((table)->callbacks.releaseKey) \
    (*(table)->callbacks.releaseKey)(key)




static INLINE unsigned
hashString(const char *key)
{
    unsigned ret = 0;
    unsigned ctr = 0;

    while (*key) {
        ret ^= *(char*)key++ << ctr;
        ctr = (ctr + 1) % sizeof (char *);
    }

    return ret;
}



static INLINE unsigned
hashPtr(const void *key)
{
    return ((size_t)key / sizeof(char*));
}




static void
rellocateItem(WMHashTable *table, HashItem *item)
{
    unsigned h;

    h = HASH(table, item->key);

    item->next = table->table[h];
    table->table[h] = item;
}


static void
rebuildTable(WMHashTable *table)
{
    HashItem *next;
    HashItem **oldArray;
    int i;
    int oldSize;
    int newSize;

    oldArray = table->table;
    oldSize = table->size;

    newSize = table->size*2;

    table->table = wmalloc(sizeof(char*)*newSize);
    memset(table->table, 0, sizeof(char*)*newSize);
    table->size = newSize;

    for (i = 0; i < oldSize; i++) {
        while (oldArray[i]!=NULL) {
            next = oldArray[i]->next;
            rellocateItem(table, oldArray[i]);
            oldArray[i] = next;
        }
    }
    wfree(oldArray);
}



WMHashTable*
WMCreateHashTable(WMHashTableCallbacks callbacks)
{
    HashTable *table;

    table = wmalloc(sizeof(HashTable));
    memset(table, 0, sizeof(HashTable));

    table->callbacks = callbacks;

    table->size = INITIAL_CAPACITY;

    table->table = wmalloc(sizeof(HashItem*)*table->size);
    memset(table->table, 0, sizeof(HashItem*)*table->size);

    return table;
}


void
WMResetHashTable(WMHashTable *table)
{
    HashItem *item, *tmp;
    int i;

    for (i = 0; i < table->size; i++) {
        item = table->table[i];
        while (item) {
            tmp = item->next;
            RELKEY(table, item->key);
            wfree(item);
            item = tmp;
        }
    }

    table->itemCount = 0;

    if (table->size > INITIAL_CAPACITY) {
        wfree(table->table);
        table->size = INITIAL_CAPACITY;
        table->table = wmalloc(sizeof(HashItem*)*table->size);
    }
    memset(table->table, 0, sizeof(HashItem*)*table->size);
}


void
WMFreeHashTable(WMHashTable *table)
{
    HashItem *item, *tmp;
    int i;

    for (i = 0; i < table->size; i++) {
        item = table->table[i];
        while (item) {
            tmp = item->next;
            RELKEY(table, item->key);
            wfree(item);
            item = tmp;
        }
    }
    wfree(table->table);
    wfree(table);
}


unsigned
WMCountHashTable(WMHashTable *table)
{
    return table->itemCount;
}


void*
WMHashGet(WMHashTable *table, const void *key)
{
    unsigned h;
    HashItem *item;

    h = HASH(table, key);
    item = table->table[h];

    if (table->callbacks.keyIsEqual) {
        while (item) {
            if ((*table->callbacks.keyIsEqual)(key, item->key)) {
                break;
            }
            item = item->next;
        }
    } else {
        while (item) {
            if (key == item->key) {
                break;
            }
            item = item->next;
        }
    }
    if (item)
        return (void*)item->data;
    else
        return NULL;
}


Bool
WMHashGetItemAndKey(WMHashTable *table, const void *key,
                    void **retItem, void **retKey)
{
    unsigned h;
    HashItem *item;

    h = HASH(table, key);
    item = table->table[h];

    if (table->callbacks.keyIsEqual) {
        while (item) {
            if ((*table->callbacks.keyIsEqual)(key, item->key)) {
                break;
            }
            item = item->next;
        }
    } else {
        while (item) {
            if (key == item->key) {
                break;
            }
            item = item->next;
        }
    }
    if (item) {
        if (retKey)
            *retKey = (void*)item->key;
        if (retItem)
            *retItem = (void*)item->data;
        return True;
    } else {
        return False;
    }
}



void*
WMHashInsert(WMHashTable *table, const void *key, const void *data)
{
    unsigned h;
    HashItem *item;
    int replacing = 0;

    h = HASH(table, key);
    /* look for the entry */
    item = table->table[h];
    if (table->callbacks.keyIsEqual) {
        while (item) {
            if ((*table->callbacks.keyIsEqual)(key, item->key)) {
                replacing = 1;
                break;
            }
            item = item->next;
        }
    } else {
        while (item) {
            if (key == item->key) {
                replacing = 1;
                break;
            }
            item = item->next;
        }
    }

    if (replacing) {
        const void *old;

        old = item->data;
        item->data = data;
        RELKEY(table, item->key);
        item->key = DUPKEY(table, key);

        return (void*)old;
    } else {
        HashItem *nitem;

        nitem = wmalloc(sizeof(HashItem));
        nitem->key = DUPKEY(table, key);
        nitem->data = data;
        nitem->next = table->table[h];
        table->table[h] = nitem;

        table->itemCount++;
    }

    /* OPTIMIZE: put this in an idle handler.*/
    if (table->itemCount > table->size) {
#ifdef DEBUG0
        printf("rebuilding hash table...\n");
#endif
        rebuildTable(table);
#ifdef DEBUG0
        printf("finished rebuild.\n");
#endif
    }

    return NULL;
}


static HashItem*
deleteFromList(HashTable *table, HashItem *item, const void *key)
{
    HashItem *next;

    if (item==NULL)
        return NULL;

    if ((table->callbacks.keyIsEqual
         && (*table->callbacks.keyIsEqual)(key, item->key))
        || (!table->callbacks.keyIsEqual && key==item->key)) {

        next = item->next;
        RELKEY(table, item->key);
        wfree(item);

        table->itemCount--;

        return next;
    }

    item->next = deleteFromList(table, item->next, key);

    return item;
}


void
WMHashRemove(WMHashTable *table, const void *key)
{
    unsigned h;

    h = HASH(table, key);

    table->table[h] = deleteFromList(table, table->table[h], key);
}


WMHashEnumerator
WMEnumerateHashTable(WMHashTable *table)
{
    WMHashEnumerator enumerator;

    enumerator.table = table;
    enumerator.index = 0;
    enumerator.nextItem = table->table[0];

    return enumerator;
}



void*
WMNextHashEnumeratorItem(WMHashEnumerator *enumerator)
{
    const void *data = NULL;

    /* this assumes the table doesn't change between
     * WMEnumerateHashTable() and WMNextHashEnumeratorItem() calls */

    if (enumerator->nextItem==NULL) {
        HashTable *table = enumerator->table;
        while (++enumerator->index < table->size) {
            if (table->table[enumerator->index]!=NULL) {
                enumerator->nextItem = table->table[enumerator->index];
                break;
            }
        }
    }

    if (enumerator->nextItem) {
        data = ((HashItem*)enumerator->nextItem)->data;
        enumerator->nextItem = ((HashItem*)enumerator->nextItem)->next;
    }

    return (void*)data;
}


void*
WMNextHashEnumeratorKey(WMHashEnumerator *enumerator)
{
    const void *key = NULL;

    /* this assumes the table doesn't change between
     * WMEnumerateHashTable() and WMNextHashEnumeratorKey() calls */

    if (enumerator->nextItem==NULL) {
        HashTable *table = enumerator->table;
        while (++enumerator->index < table->size) {
            if (table->table[enumerator->index]!=NULL) {
                enumerator->nextItem = table->table[enumerator->index];
                break;
            }
        }
    }

    if (enumerator->nextItem) {
        key = ((HashItem*)enumerator->nextItem)->key;
        enumerator->nextItem = ((HashItem*)enumerator->nextItem)->next;
    }

    return (void*)key;
}


Bool
WMNextHashEnumeratorItemAndKey(WMHashEnumerator *enumerator,
                               void **item, void **key)
{
    /* this assumes the table doesn't change between
     * WMEnumerateHashTable() and WMNextHashEnumeratorItemAndKey() calls */

    if (enumerator->nextItem==NULL) {
        HashTable *table = enumerator->table;
        while (++enumerator->index < table->size) {
            if (table->table[enumerator->index]!=NULL) {
                enumerator->nextItem = table->table[enumerator->index];
                break;
            }
        }
    }

    if (enumerator->nextItem) {
        if (item)
            *item = (void*)((HashItem*)enumerator->nextItem)->data;
        if (key)
            *key = (void*)((HashItem*)enumerator->nextItem)->key;
        enumerator->nextItem = ((HashItem*)enumerator->nextItem)->next;

        return True;
    }

    return False;
}


static Bool
compareStrings(const char *key1, const char *key2)
{
    return strcmp(key1, key2)==0;
}


typedef unsigned (*hashFunc)(const void*);
typedef Bool (*isEqualFunc)(const void*, const void*);
typedef void* (*retainFunc)(const void*);
typedef void (*releaseFunc)(const void*);


const WMHashTableCallbacks WMIntHashCallbacks = {
    NULL,
    NULL,
    NULL,
    NULL
};

const WMHashTableCallbacks WMStringHashCallbacks = {
    (hashFunc)hashString,
    (isEqualFunc)compareStrings,
    (retainFunc)wstrdup,
    (releaseFunc)wfree
};



const WMHashTableCallbacks WMStringPointerHashCallbacks = {
    (hashFunc)hashString,
    (isEqualFunc)compareStrings,
    NULL,
    NULL
};