* Fixed a multiselect bug in the mailbox view. Ctrl-click was selecting a message...

[citadel.git] / libcitadel / lib / hash.c

#include <stdint.h>
#include <stdlib.h>
#include <string.h>
//dbg
#include <stdio.h>
#include "libcitadel.h"
#include "lookup3.h"

typedef struct Payload Payload;

struct Payload {
        /**
         * \brief Hash Payload storage Structure; filled in linear.
         */
        void *Data; /**< the Data belonging to this storage */
        DeleteHashDataFunc Destructor; /**< if we want to destroy Data, do it with this function. */
};

struct HashKey {
        /**
         * \brief Hash key element; sorted by key
         */
        long Key;         /**< Numeric Hashkey comperator for hash sorting */
        long Position;    /**< Pointer to a Payload struct in the Payload Aray */
        char *HashKey;    /**< the Plaintext Hashkey */
        long HKLen;       /**< length of the Plaintext Hashkey */
        Payload *PL;      /**< pointer to our payload for sorting */
};

struct HashList {
        /**
         * \brief Hash structure; holds arrays of Hashkey and Payload. 
         */
        Payload **Members;     /**< Our Payload members. This fills up linear */
        HashKey **LookupTable; /**< Hash Lookup table. Elements point to members, and are sorted by their hashvalue */
        char **MyKeys;         /**< this keeps the members for a call of GetHashKeys */
        HashFunc Algorithm;    /**< should we use an alternating algorithm to calc the hash values? */
        long nMembersUsed;     /**< how many pointers inside of the array are used? */
        long MemberSize;       /**< how big is Members and LookupTable? */
        long tainted;          /**< if 0, we're hashed, else s.b. else sorted us in his own way. */
        long uniq;             /**< are the keys going to be uniq? */
};

struct HashPos {
        /**
         * \brief Anonymous Hash Iterator Object. used for traversing the whole array from outside 
         */
        long Position;
        int StepWidth;
};


/**
 * \brief Iterate over the hash and call PrintEntry. 
 * \param Hash your Hashlist structure
 * \param Trans is called so you could for example print 'A:' if the next entries are like that.
 *        Must be aware to receive NULL in both pointers.
 * \param PrintEntry print entry one by one
 * \returns the number of items printed
 */
int PrintHash(HashList *Hash, TransitionFunc Trans, PrintHashDataFunc PrintEntry)
{
        int i;
        void *Previous;
        void *Next;
        const char* KeyStr;

        if (Hash == NULL)
                return 0;

        for (i=0; i < Hash->nMembersUsed; i++) {
                if (i==0) {
                        Previous = NULL;
                }
                else {
                        if (Hash->LookupTable[i - 1] == NULL)
                                Previous = NULL;
                        else
                                Previous = Hash->Members[Hash->LookupTable[i-1]->Position]->Data;
                }
                if (Hash->LookupTable[i] == NULL) {
                        KeyStr = "";
                        Next = NULL;
                }
                else {
                        Next = Hash->Members[Hash->LookupTable[i]->Position]->Data;
                        KeyStr = Hash->LookupTable[i]->HashKey;
                }

                Trans(Previous, Next, i % 2);
                PrintEntry(KeyStr, Next, i % 2);
        }
        return i;
}


/**
 * \brief verify the contents of a hash list; here for debugging purposes.
 * \param Hash your Hashlist structure
 * \param First Functionpointer to allow you to print your payload
 * \param Second Functionpointer to allow you to print your payload
 * \returns 0
 */
int dbg_PrintHash(HashList *Hash, PrintHashContent First, PrintHashContent Second)
{
        const char *foo;
        const char *bar;
        const char *bla = "";
        long key;
        long i;

        if (Hash == NULL)
                return 0;

        if (Hash->MyKeys != NULL)
                free (Hash->MyKeys);

        Hash->MyKeys = (char**) malloc(sizeof(char*) * Hash->nMembersUsed);
#ifdef DEBUG
        printf("----------------------------------\n");
#endif
        for (i=0; i < Hash->nMembersUsed; i++) {
                
                if (Hash->LookupTable[i] == NULL)
                {
                        foo = "";
                        bar = "";
                        key = 0;
                }
                else 
                {
                        key = Hash->LookupTable[i]->Key;
                        foo = Hash->LookupTable[i]->HashKey;
                        if (First != NULL)
                                bar = First(Hash->Members[Hash->LookupTable[i]->Position]->Data);
                        else 
                                bar = "";
                        if (Second != NULL)
                                bla = Second(Hash->Members[Hash->LookupTable[i]->Position]->Data);
                        else
                                bla = "";
                }
#ifdef DEBUG
                printf (" ---- Hashkey[%ld][%ld]: '%s' Value: '%s' ; %s\n", i, key, foo, bar, bla);
#endif
        }
#ifdef DEBUG
        printf("----------------------------------\n");
#endif
        return 0;
}


/**
 * \brief instanciate a new hashlist
 * \returns the newly allocated list. 
 */
HashList *NewHash(int Uniq, HashFunc F)
{
        HashList *NewList;
        NewList = malloc (sizeof(HashList));
        memset(NewList, 0, sizeof(HashList));

        NewList->Members = malloc(sizeof(Payload*) * 100);
        memset(NewList->Members, 0, sizeof(Payload*) * 100);

        NewList->LookupTable = malloc(sizeof(HashKey*) * 100);
        memset(NewList->LookupTable, 0, sizeof(HashKey*) * 100);

        NewList->MemberSize = 100;
        NewList->tainted = 0;
        NewList->uniq = Uniq;
        NewList->Algorithm = F;

        return NewList;
}

int GetCount(HashList *Hash)
{
        if(Hash==NULL) return 0;
        return Hash->nMembersUsed;
}


/**
 * \brief private destructor for one hash element.
 * Crashing? go one frame up and do 'print *FreeMe->LookupTable[i]'
 * \param Data an element to free using the user provided destructor, or just plain free
 */
static void DeleteHashPayload (Payload *Data)
{
        /** do we have a destructor for our payload? */
        if (Data->Destructor)
                Data->Destructor(Data->Data);
        else
                free(Data->Data);
}

/**
 * \brief Destructor for nested hashes
 */
void HDeleteHash(void *vHash)
{
        HashList *FreeMe = (HashList*)vHash;
        DeleteHash(&FreeMe);
}

/**
 * \brief destroy a hashlist and all of its members
 * Crashing? do 'print *FreeMe->LookupTable[i]'
 * \param Hash Hash to destroy. Is NULL'ed so you are shure its done.
 */
void DeleteHash(HashList **Hash)
{
        int i;
        HashList *FreeMe;

        FreeMe = *Hash;
        if (FreeMe == NULL)
                return;
        for (i=0; i < FreeMe->nMembersUsed; i++)
        {
                /** get rid of our payload */
                if (FreeMe->Members[i] != NULL)
                {
                        DeleteHashPayload(FreeMe->Members[i]);
                        free(FreeMe->Members[i]);
                }
                /** delete our hashing data */
                if (FreeMe->LookupTable[i] != NULL)
                {
                        free(FreeMe->LookupTable[i]->HashKey);
                        free(FreeMe->LookupTable[i]);
                }
        }
        /** now, free our arrays... */
        free(FreeMe->LookupTable);
        free(FreeMe->Members);
        /** did s.b. want an array of our keys? free them. */
        if (FreeMe->MyKeys != NULL)
                free(FreeMe->MyKeys);
        /** buye bye cruel world. */    
        free (FreeMe);
        *Hash = NULL;
}

/**
 * \brief Private function to increase the hash size.
 * \param Hash the Hasharray to increase
 */
static void IncreaseHashSize(HashList *Hash)
{
        /* Ok, Our space is used up. Double the available space. */
        Payload **NewPayloadArea;
        HashKey **NewTable;
        
        if (Hash == NULL)
                return ;

        /** double our payload area */
        NewPayloadArea = (Payload**) malloc(sizeof(Payload*) * Hash->MemberSize * 2);
        memset(&NewPayloadArea[Hash->MemberSize], 0, sizeof(Payload*) * Hash->MemberSize);
        memcpy(NewPayloadArea, Hash->Members, sizeof(Payload*) * Hash->MemberSize);
        free(Hash->Members);
        Hash->Members = NewPayloadArea;
        
        /** double our hashtable area */
        NewTable = malloc(sizeof(HashKey*) * Hash->MemberSize * 2);
        memset(&NewTable[Hash->MemberSize], 0, sizeof(HashKey*) * Hash->MemberSize);
        memcpy(NewTable, Hash->LookupTable, sizeof(HashKey*) * Hash->MemberSize);
        free(Hash->LookupTable);
        Hash->LookupTable = NewTable;
        
        Hash->MemberSize *= 2;
}


/**
 * \brief private function to add a new item to / replace an existing in -  the hashlist
 * if the hash list is full, its re-alloced with double size.
 * \parame Hash our hashlist to manipulate
 * \param HashPos where should we insert / replace?
 * \param HashKeyStr the Hash-String
 * \param HKLen length of HashKeyStr
 * \param Data your Payload to add
 * \param Destructor Functionpointer to free Data. if NULL, default free() is used.
 */
static void InsertHashItem(HashList *Hash, 
                           long HashPos, 
                           long HashBinKey, 
                           const char *HashKeyStr, 
                           long HKLen, 
                           void *Data,
                           DeleteHashDataFunc Destructor)
{
        Payload *NewPayloadItem;
        HashKey *NewHashKey;

        if (Hash == NULL)
                return;

        if (Hash->nMembersUsed >= Hash->MemberSize)
                IncreaseHashSize (Hash);

        /** Arrange the payload */
        NewPayloadItem = (Payload*) malloc (sizeof(Payload));
        NewPayloadItem->Data = Data;
        NewPayloadItem->Destructor = Destructor;
        /** Arrange the hashkey */
        NewHashKey = (HashKey*) malloc (sizeof(HashKey));
        NewHashKey->HashKey = (char *) malloc (HKLen + 1);
        NewHashKey->HKLen = HKLen;
        memcpy (NewHashKey->HashKey, HashKeyStr, HKLen + 1);
        NewHashKey->Key = HashBinKey;
        NewHashKey->PL = NewPayloadItem;
        /** our payload is queued at the end... */
        NewHashKey->Position = Hash->nMembersUsed;
        /** but if we should be sorted into a specific place... */
        if ((Hash->nMembersUsed != 0) && 
            (HashPos != Hash->nMembersUsed) ) {
                long ItemsAfter;

                ItemsAfter = Hash->nMembersUsed - HashPos;
                /** make space were we can fill us in */
                if (ItemsAfter > 0)
                {
                        memmove(&Hash->LookupTable[HashPos + 1],
                                &Hash->LookupTable[HashPos],
                                ItemsAfter * sizeof(HashKey*));
                } 
        }
        
        Hash->Members[Hash->nMembersUsed] = NewPayloadItem;
        Hash->LookupTable[HashPos] = NewHashKey;
        Hash->nMembersUsed++;
}

/**
 * \brief if the user has tainted the hash, but wants to insert / search items by their key
 *  we need to search linear through the array. You have been warned that this will take more time!
 * \param Hash Our Hash to manipulate
 * \param HashBinKey the Hash-Number to lookup. 
 * \returns the position (most closely) matching HashBinKey (-> Caller needs to compare! )
 */
static long FindInTaintedHash(HashList *Hash, long HashBinKey)
{
        long SearchPos;

        if (Hash == NULL)
                return 0;

        for (SearchPos = 0; SearchPos < Hash->nMembersUsed; SearchPos ++) {
                if (Hash->LookupTable[SearchPos]->Key == HashBinKey){
                        return SearchPos;
                }
        }
        return SearchPos;
}

/**
 * \brief Private function to lookup the Item / the closest position to put it in
 * \param Hash Our Hash to manipulate
 * \param HashBinKey the Hash-Number to lookup. 
 * \returns the position (most closely) matching HashBinKey (-> Caller needs to compare! )
 */
static long FindInHash(HashList *Hash, long HashBinKey)
{
        long SearchPos;
        long StepWidth;

        if (Hash == NULL)
                return 0;

        if (Hash->tainted)
                return FindInTaintedHash(Hash, HashBinKey);

        SearchPos = Hash->nMembersUsed / 2;
        StepWidth = SearchPos / 2;
        while ((SearchPos > 0) && 
               (SearchPos < Hash->nMembersUsed)) 
        {
                /** Did we find it? */
                if (Hash->LookupTable[SearchPos]->Key == HashBinKey){
                        return SearchPos;
                }
                /** are we Aproximating in big steps? */
                if (StepWidth > 1){
                        if (Hash->LookupTable[SearchPos]->Key > HashBinKey)
                                SearchPos -= StepWidth;
                        else
                                SearchPos += StepWidth;
                        StepWidth /= 2;                 
                }
                else { /** We are right next to our target, within 4 positions */
                        if (Hash->LookupTable[SearchPos]->Key > HashBinKey) {
                                if ((SearchPos > 0) && 
                                    (Hash->LookupTable[SearchPos - 1]->Key < HashBinKey))
                                        return SearchPos;
                                SearchPos --;
                        }
                        else {
                                if ((SearchPos + 1 < Hash->nMembersUsed) && 
                                    (Hash->LookupTable[SearchPos + 1]->Key > HashBinKey))
                                        return SearchPos;
                                SearchPos ++;
                        }
                        StepWidth--;
                }
        }
        return SearchPos;
}


/**
 * \brief another hashing algorithm; treat it as just a pointer to long.
 * \param str Our pointer to the long value
 * \param len the length of the data pointed to; needs to be sizeof int, else we won't use it!
 * \returns the calculated hash value
 */
int Flathash(const char *str, long len)
{
        if (len != sizeof (int))
                return 0;
        else return *(int*)str;
}

/**
 * \brief private abstract wrapper around the hashing algorithm
 * \param HKey the hash string
 * \param HKLen length of HKey
 * \returns the calculated hash value
 */
inline static long CalcHashKey (HashList *Hash, const char *HKey, long HKLen)
{
        if (Hash == NULL)
                return 0;

        if (Hash->Algorithm == NULL)
                return hashlittle(HKey, HKLen, 9283457);
        else
                return Hash->Algorithm(HKey, HKLen);
}


/**
 * \brief Add a new / Replace an existing item in the Hash
 * \param HashList the list to manipulate
 * \param HKey the hash-string to store Data under
 * \param HKeyLen Length of HKey
 * \param Data the payload you want to associate with HKey
 * \param DeleteIt if not free() should be used to delete Data set to NULL, else DeleteIt is used.
 */
void Put(HashList *Hash, const char *HKey, long HKLen, void *Data, DeleteHashDataFunc DeleteIt)
{
        long HashBinKey;
        long HashAt;

        if (Hash == NULL)
                return;

        /** first, find out were we could fit in... */
        HashBinKey = CalcHashKey(Hash, HKey, HKLen);
        HashAt = FindInHash(Hash, HashBinKey);

        if (HashAt >= Hash->MemberSize)
                IncreaseHashSize (Hash);

        /** oh, we're brand new... */
        if (Hash->LookupTable[HashAt] == NULL) {
                InsertHashItem(Hash, HashAt, HashBinKey, HKey, HKLen, Data, DeleteIt);
        }/** Insert After? */
        else if (Hash->LookupTable[HashAt]->Key > HashBinKey) {
                InsertHashItem(Hash, HashAt, HashBinKey, HKey, HKLen, Data, DeleteIt);
        }/** Insert before? */
        else if (Hash->LookupTable[HashAt]->Key < HashBinKey) {
                InsertHashItem(Hash, HashAt + 1, HashBinKey, HKey, HKLen, Data, DeleteIt);
        }
        else { /** Ok, we have a colision. replace it. */
                if (Hash->uniq) {
                        long PayloadPos;
                        
                        PayloadPos = Hash->LookupTable[HashAt]->Position;
                        DeleteHashPayload(Hash->Members[PayloadPos]);
                        Hash->Members[PayloadPos]->Data = Data;
                        Hash->Members[PayloadPos]->Destructor = DeleteIt;
                }
                else {
                        InsertHashItem(Hash, HashAt + 1, HashBinKey, HKey, HKLen, Data, DeleteIt);
                }
        }
}

/**
 * \brief Lookup the Data associated with HKey
 * \param Hash the Hashlist to search in
 * \param HKey the hashkey to look up
 * \param HKLen length of HKey
 * \param Data returns the Data associated with HKey
 * \returns 0 if not found, 1 if.
 */
int GetHash(HashList *Hash, const char *HKey, long HKLen, void **Data)
{
        long HashBinKey;
        long HashAt;

        if (Hash == NULL)
                return 0;

        if (HKLen <= 0) {
                *Data = NULL;
                return  0;
        }
        /** first, find out were we could be... */
        HashBinKey = CalcHashKey(Hash, HKey, HKLen);
        HashAt = FindInHash(Hash, HashBinKey);
        if ((HashAt < 0) || /**< Not found at the lower edge? */
            (HashAt >= Hash->nMembersUsed) || /**< Not found at the upper edge? */
            (Hash->LookupTable[HashAt]->Key != HashBinKey)) { /**< somewhere inbetween but no match? */
                *Data = NULL;
                return 0;
        }
        else { /** GOTCHA! */
                long MemberPosition;

                MemberPosition = Hash->LookupTable[HashAt]->Position;
                *Data = Hash->Members[MemberPosition]->Data;
                return 1;
        }
}

/* TODO? */
int GetKey(HashList *Hash, char *HKey, long HKLen, void **Payload)
{
        return 0;
}

/**
 * \brief get the Keys present in this hash, simila to array_keys() in PHP
 *  Attention: List remains to Hash! don't modify or free it!
 * \param Hash Your Hashlist to extract the keys from
 * \param List returns the list of hashkeys stored in Hash
 */
int GetHashKeys(HashList *Hash, char ***List)
{
        long i;
        if (Hash == NULL)
                return 0;
        if (Hash->MyKeys != NULL)
                free (Hash->MyKeys);

        Hash->MyKeys = (char**) malloc(sizeof(char*) * Hash->nMembersUsed);
        for (i=0; i < Hash->nMembersUsed; i++) {
        
                Hash->MyKeys[i] = Hash->LookupTable[i]->HashKey;
        }
        *List = (char**)Hash->MyKeys;
        return Hash->nMembersUsed;
}

/**
 * \brief creates a hash-linear iterator object
 * \param Hash the list we reference
 * \param in which step width should we iterate?
 *  If negative, the last position matching the 
 *  step-raster is provided.
 * \returns the hash iterator
 */
HashPos *GetNewHashPos(HashList *Hash, int StepWidth)
{
        HashPos *Ret;
        
        Ret = (HashPos*)malloc(sizeof(HashPos));
        if (StepWidth != 0)
                Ret->StepWidth = StepWidth;
        else
                Ret->StepWidth = 1;
        if (Ret->StepWidth <  0) {
                Ret->Position = Hash->nMembersUsed - 1;
        }
        else {
                Ret->Position = 0;
        }
        return Ret;
}

/**
 * \brief retrieve the counter from the itteratoor
 * \param the Iterator to analyze
 * \returns the n'th hashposition we point at
 */
int GetHashPosCounter(HashPos *At)
{
        return At->Position;
}

/**
 * \brief frees a linear hash iterator
 */
void DeleteHashPos(HashPos **DelMe)
{
        if (*DelMe != NULL)
        {
                free(*DelMe);
                *DelMe = NULL;
        }
}


/**
 * \brief Get the data located where HashPos Iterator points at, and Move HashPos one forward
 * \param Hash your Hashlist to follow
 * \param HKLen returns Length of Hashkey Returned
 * \param HashKey returns the Hashkey corrosponding to HashPos
 * \param Data returns the Data found at HashPos
 * \returns whether the item was found or not.
 */
int GetNextHashPos(HashList *Hash, HashPos *At, long *HKLen, const char **HashKey, void **Data)
{
        long PayloadPos;
        long offset = 0;

        if ((Hash == NULL) || (At->Position >= Hash->nMembersUsed) || (At->Position < 0))
                return 0;
        *HKLen = Hash->LookupTable[At->Position]->HKLen;
        *HashKey = Hash->LookupTable[At->Position]->HashKey;
        PayloadPos = Hash->LookupTable[At->Position]->Position;
        *Data = Hash->Members[PayloadPos]->Data;
        /* Position is NULL-Based, while Stepwidth is not... */
        if (At->StepWidth < 0)
                offset = 1;
        if ((At->Position % abs(At->StepWidth)) == 0)
                At->Position += At->StepWidth;
        else 
                At->Position += ((At->Position) % abs(At->StepWidth)) * 
                        (At->StepWidth / abs(At->StepWidth));

        if (At->Position > Hash->nMembersUsed) {
                At->Position = Hash->nMembersUsed - 1;
                return 0;
        } else if (At->Position <= 0) {
                At->Position = 0;
                return 0;
        }
        return 1;
}

/**
 * \brief Get the data located where At points to
 * note: you should prefer iterator operations instead of using me.
 * \param Hash your Hashlist peek from
 * \param HKLen returns Length of Hashkey Returned
 * \param HashKey returns the Hashkey corrosponding to HashPos
 * \param Data returns the Data found at HashPos
 * \returns whether the item was found or not.
 */
int GetHashAt(HashList *Hash,long At, long *HKLen, const char **HashKey, void **Data)
{
        long PayloadPos;

        if ((Hash == NULL) || (At >= Hash->nMembersUsed))
                return 0;
        *HKLen = Hash->LookupTable[At]->HKLen;
        *HashKey = Hash->LookupTable[At]->HashKey;
        PayloadPos = Hash->LookupTable[At]->Position;
        *Data = Hash->Members[PayloadPos]->Data;
        return 1;
}

/**
 * \brief sorting function for sorting the Hash alphabeticaly by their strings
 * \param Key1 first item
 * \param Key2 second item
 */
static int SortByKeys(const void *Key1, const void* Key2)
{
        HashKey *HKey1, *HKey2;
        HKey1 = *(HashKey**) Key1;
        HKey2 = *(HashKey**) Key2;

        return strcasecmp(HKey1->HashKey, HKey2->HashKey);
}

/**
 * \brief sorting function for sorting the Hash alphabeticaly reverse by their strings
 * \param Key1 first item
 * \param Key2 second item
 */
static int SortByKeysRev(const void *Key1, const void* Key2)
{
        HashKey *HKey1, *HKey2;
        HKey1 = *(HashKey**) Key1;
        HKey2 = *(HashKey**) Key2;

        return strcasecmp(HKey2->HashKey, HKey1->HashKey);
}

/**
 * \brief sorting function to regain hash-sequence and revert tainted status
 * \param Key1 first item
 * \param Key2 second item
 */
static int SortByHashKeys(const void *Key1, const void* Key2)
{
        HashKey *HKey1, *HKey2;
        HKey1 = *(HashKey**) Key1;
        HKey2 = *(HashKey**) Key2;

        return HKey1->Key > HKey2->Key;
}


/**
 * \brief sort the hash alphabeticaly by their keys.
 * Caution: This taints the hashlist, so accessing it later 
 * will be significantly slower! You can un-taint it by SortByHashKeyStr
 * \param Hash the list to sort
 * \param Order 0/1 Forward/Backward
 */
void SortByHashKey(HashList *Hash, int Order)
{
        if (Hash->nMembersUsed < 2)
                return;
        qsort(Hash->LookupTable, Hash->nMembersUsed, sizeof(HashKey*), 
              (Order)?SortByKeys:SortByKeysRev);
        Hash->tainted = 1;
}

/**
 * \brief sort the hash by their keys (so it regains untainted state).
 * this will result in the sequence the hashing allgorithm produces it by default.
 * \param Hash the list to sort
 */
void SortByHashKeyStr(HashList *Hash)
{
        Hash->tainted = 0;
        if (Hash->nMembersUsed < 2)
                return;
        qsort(Hash->LookupTable, Hash->nMembersUsed, sizeof(HashKey*), SortByHashKeys);
}


/**
 * \brief gives user sort routines access to the hash payload
 * \param Searchentry to retrieve Data to
 * \returns Data belonging to HashVoid
 */
const void *GetSearchPayload(const void *HashVoid)
{
        return (*(HashKey**)HashVoid)->PL->Data;
}

/**
 * \brief sort the hash by your sort function. see the following sample.
 * this will result in the sequence the hashing allgorithm produces it by default.
 * \param Hash the list to sort
 * \param SortBy Sortfunction; see below how to implement this
 */
void SortByPayload(HashList *Hash, CompareFunc SortBy)
{
        if (Hash->nMembersUsed < 2)
                return;
        qsort(Hash->LookupTable, Hash->nMembersUsed, sizeof(HashKey*), SortBy);
        Hash->tainted = 1;
}




/**
 * given you've put char * into your hash as a payload, a sort function might
 * look like this:
 * int SortByChar(const void* First, const void* Second)
 * {
 *      char *a, *b;
 *      a = (char*) GetSearchPayload(First);
 *      b = (char*) GetSearchPayload(Second);
 *      return strcmp (a, b);
 * }
 */


/*
 * Generic function to free a pointer.  This can be used as a callback with the
 * hash table, even on systems where free() is defined as a macro or has had other
 * horrible things done to it.
 */
void generic_free_handler(void *ptr) {
        free(ptr);
}

/*
 * Generic function to free a reference.  
 * since a reference actualy isn't needed to be freed, do nothing.
 */
void reference_free_handler(void *ptr) 
{
        return;
}