* Allow hashiterator to do bigger steps than 1 and to go reverse

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

diff --git a/libcitadel/lib/hash.c b/libcitadel/lib/hash.c
index 9ab2aa6e3db5440ef412c170dbb12c676edc46a7..fd8916f1757988627045b9dca75f7088e5b6025f 100644 (file)
--- a/libcitadel/lib/hash.c
+++ b/libcitadel/lib/hash.c
@@ -46,6 +46,7 @@ struct HashPos {
         * \brief Anonymous Hash Iterator Object. used for traversing the whole array from outside 
         */
        long Position;
+       int StepWidth;
 };
 
 
@@ -195,6 +196,15 @@ static void DeleteHashPayload (Payload *Data)
                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]'
@@ -400,6 +410,20 @@ static long FindInHash(HashList *Hash, long HashBinKey)
        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
@@ -535,17 +559,41 @@ int GetHashKeys(HashList *Hash, char ***List)
 
 /**
  * \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(void)
+HashPos *GetNewHashPos(HashList *Hash, int StepWidth)
 {
        HashPos *Ret;
        
        Ret = (HashPos*)malloc(sizeof(HashPos));
-       Ret->Position = 0;
+       if (StepWidth != 0)
+               Ret->StepWidth = StepWidth;
+       else
+               Ret->StepWidth = 1;
+       if (Ret->StepWidth <  0) {
+               Ret->Position = (Hash->nMembersUsed % (-Ret->StepWidth)) 
+                       * (-Ret->StepWidth);
+       }
+       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
  */
@@ -571,13 +619,18 @@ int GetNextHashPos(HashList *Hash, HashPos *At, long *HKLen, const char **HashKe
 {
        long PayloadPos;
 
-       if ((Hash == NULL) || (Hash->nMembersUsed <= At->Position))
+       if ((Hash == NULL) || (At->Position >= Hash->nMembersUsed))
                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;
-       At->Position++;
+
+       At->Position += At->StepWidth;
+       if (At->Position > Hash->nMembersUsed) {
+               At->Position = Hash->nMembersUsed;
+               return 0;
+       }
        return 1;
 }
 
@@ -703,5 +756,14 @@ 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;
+}
+