gclib/gclib/GHash.hh

/********************************************************************************
*                  Hash table class template (char* based)                               *
*********************************************************************************/

#ifndef GHash_HH
#define GHash_HH
#include "GBase.h"
/**
* This class maintains a fast-access hash table of entities
* indexed by a character string.
* It is typically used to map strings to pointers; however, overloading
* the createData() and deleteData() members allows any type of data to
* be indexed by strings.
*/
typedef struct {
     char*   key;              // Key string
     bool    keyalloc;         //shared key flag (to not free the key chars)
     int     hash;             // Hash value of key
     pointer data;              // Data
     bool    mark;             // Entry is marked
     } GHashEntry;

template <class OBJ> class  GHash {
 protected:
  GHashEntry* hash;         // Hash
  int         fCapacity;     // table size
  int         fCount;        // number of valid entries
  int  fCurrentEntry;
  char* lastkeyptr; //pointer to last key string added
    //---------- Raw data retrieval (including empty entries
  // Return key at position pos.
  const char* Key(uint pos) const { return hash[pos].key; }
  // return data OBJ* at given position
  OBJ* Data(uint pos) const { return (OBJ*) hash[pos].data; }
  // Return mark flag of entry at position pos.
  bool Mark(uint pos) const { return hash[pos].mark; }
  // Return position of first filled slot, or >= fCapacity
  int First() const;
  // Return position of last filled slot or -1
  int Last() const;
  // Return position of next filled slot in hash table
  // or a value greater than or equal to fCapacity if no filled
  // slot was found
  int Next(int pos) const;
  //Return position of previous filled slot in hash table
  //or a -1 if no filled slot was found
  int Prev(int pos) const;

private:
  GHash(const GHash&);
  GHash &operator=(const GHash&);
  GFreeProc* fFreeProc; //procedure to free item data
protected:
public:
  static void DefaultFreeProc(pointer item) {
      delete (OBJ*)item;
      item=NULL;
      }
public:
  GHash(GFreeProc* freeProc); // constructs of an empty hash
  GHash(bool doFree=true); // constructs of an empty hash (free the item objects)
  void setFreeItem(GFreeProc *freeProc) { fFreeProc=freeProc; }
  void setFreeItem(bool doFree) { fFreeProc=(doFree)? &DefaultFreeProc : NULL; }
  int Capacity() const { return fCapacity; } // table's size, including the empty slots.
  void Resize(int m);  // Resize the table to the given size.
  int Count() const { return fCount; }// the total number of entries in the table.
  // Insert a new entry into the table given key and mark.
  // If there is already an entry with that key, leave it unchanged,
  const OBJ* Add(const char* ky, const OBJ* ptr=NULL, bool mrk=false);
  //same as Add, but the key pointer is stored directly, no string duplicate
  //is made (shared-key-Add)
  const OBJ* shkAdd(const char* ky, const OBJ* ptr, bool mrk=false);

  // Replace data at key, if the entry's mark is less than
  // or equal to the given mark.  If there was no existing entry,
  // a new entry is inserted with the given mark.
  OBJ* Replace(const char* ky, const OBJ* ptr, bool mrk=false);
  // Remove a given key and its data
  OBJ* Remove(const char* ky);
  // Find data OBJ* given key.
  OBJ* Find(const char* ky, char** keyptr=NULL);
  bool hasKey(const char* ky);
  char* getLastKey() { return lastkeyptr; }
  OBJ* operator[](const char* ky) { return Find(ky); }
  void startIterate(); //iterator-like initialization
  char* NextKey(); //returns next valid key in the table (NULL if no more)
  OBJ* NextData(); //returns next valid hash[].data
  OBJ* NextData(char*& nextkey); //returns next valid hash[].data
                                //or NULL if no more
                                //nextkey is SET to the corresponding key
  GHashEntry* NextEntry(); //returns a pointer to a GHashEntry

  /// Clear all entries
  void Clear();

  /// Destructor
  virtual ~GHash();
  };
//
//======================== method definitions ========================
//
/*
  Notes:
  - The hash algorithm should yield a fCount in the range [0...GHash::EMPTY)
     GHash::EMPTY and GHash::UNUSED are needed for flag purposes.
  - Since the algorithm doubles the table size when exceeding MAX_LOAD,
    it would be prudent to keep MIN_LOAD less than 1/2 MAX_LOAD;
    otherwise, the algorithm might hip-hop between halving and doubling,
    which would be quite expensive!!
  - Not many people seem to know that hash tables don't have to be prime
    numbers; in fact, a table size of 2**n and odd probe distance are very
    easy to arrange, and this works just as well!
  - We store the hash key, so that 99.999% of the time we can compare hash numbers;
    only when hash numbers match do we need to compare keys.
    Thus, with a good hash function, the fCount of calls to strcmp() should be
    roughly the same as the fCount of successful lookups.
  - The hash table should NEVER get full, or stuff will loop forever!!
*/

// Initial table size (MUST be power of 2)
#define DEF_HASH_SIZE      32
// Maximum hash table load factor (%)
#define MAX_LOAD           80
// Minimum hash table load factor (%)
#define MIN_LOAD           10
// Probe Position [0..n-1]
#define HASH1(x,n) (((unsigned int)(x)*13)%(n))
// Probe Distance [1..n-1]
#define HASH2(x,n) (1|(((unsigned int)(x)*17)%((n)-1)))

#define FREEDATA (fFreeProc!=NULL)

/*******************************************************************************/
// Construct empty hash
template <class OBJ> GHash<OBJ>::GHash(GFreeProc* freeProc) {
  GMALLOC(hash, sizeof(GHashEntry)*DEF_HASH_SIZE);
  fFreeProc=freeProc;
  for (uint i=0; i<DEF_HASH_SIZE; i++)
         hash[i].hash=-1; //this will be an indicator for 'empty' entries
  fCapacity=DEF_HASH_SIZE;
  fCount=0;
  }

template <class OBJ> GHash<OBJ>::GHash(bool doFree) {
  GMALLOC(hash, sizeof(GHashEntry)*DEF_HASH_SIZE);
  fFreeProc = (doFree)?&DefaultFreeProc : NULL;
  for (uint i=0; i<DEF_HASH_SIZE; i++)
         hash[i].hash=-1; //this will be an indicator for 'empty' entries
  fCapacity=DEF_HASH_SIZE;
  fCount=0;
  }


// Resize table
template <class OBJ> void GHash<OBJ>::Resize(int m){
  register int i,n,p,x,h;
  GHashEntry *k;
  GASSERT(fCount<=fCapacity);
  if(m<DEF_HASH_SIZE) m=DEF_HASH_SIZE;
  n=fCapacity;
  while((n>>2)>m) n>>=1;            // Shrink until n/4 <= m
  while((n>>1)<m) n<<=1;            // Grow until m <= n/2
  GASSERT(m<=(n>>1));
  GASSERT(DEF_HASH_SIZE<=n);
  if(n!=fCapacity){
    GASSERT(m<=n);
    GMALLOC(k, sizeof(GHashEntry)*n);
    for(i=0; i<n; i++) k[i].hash=-1;
    for(i=0; i<fCapacity; i++){
      h=hash[i].hash;
      if(0<=h){
        p=HASH1(h,n);
        GASSERT(0<=p && p<n);
        x=HASH2(h,n);
        GASSERT(1<=x && x<n);
        while(k[p].hash!=-1) p=(p+x)%n;
        GASSERT(k[p].hash<0);
        k[p]=hash[i];
        }
      }
    GFREE(hash);
    hash=k;
    fCapacity=n;
    }
  }

// add a new entry, leave it alone if already existing
template <class OBJ> const OBJ* GHash<OBJ>::Add(const char* ky,
                      const OBJ* pdata,bool mrk){
  register int p,i,x,h,n;
  if(!ky) GError("GHash::insert: NULL key argument.\n");
  GASSERT(fCount<fCapacity);
  h=strhash(ky);
  GASSERT(0<=h);
  p=HASH1(h,fCapacity);
  GASSERT(0<=p && p<fCapacity);
  x=HASH2(h,fCapacity);
  GASSERT(1<=x && x<fCapacity);
  i=-1;
  n=fCapacity;
  while(n && hash[p].hash!=-1){
    if ((i==-1)&&(hash[p].hash==-2)) i=p;
    if (hash[p].hash==h && strcmp(hash[p].key,ky)==0) {
      //replace hash data for this key!
      lastkeyptr=hash[p].key;
      hash[p].data = (void*) pdata;
      return (OBJ*)hash[p].data;
      }
    p=(p+x)%fCapacity;
    n--;
    }
  if(i==-1) i=p;
  GTRACE(("GHash::insert: key=\"%s\"\n",ky));
  //GMessage("GHash::insert: key=\"%s\"\n",ky);
  GASSERT(0<=i && i<fCapacity);
  GASSERT(hash[i].hash<0);
  hash[i].hash=h;
  hash[i].mark=mrk;
  hash[i].key=Gstrdup(ky);
  hash[i].keyalloc=true;
  lastkeyptr=hash[i].key;
  hash[i].data= (void*) pdata;
  fCount++;
  if((100*fCount)>=(MAX_LOAD*fCapacity)) Resize(fCount);
  GASSERT(fCount<fCapacity);
  return pdata;
  }

template <class OBJ> const OBJ* GHash<OBJ>::shkAdd(const char* ky,
                      const OBJ* pdata,bool mrk){
  register int p,i,x,h,n;
  if(!ky) GError("GHash::insert: NULL key argument.\n");
  GASSERT(fCount<fCapacity);
  h=strhash(ky);
  GASSERT(0<=h);
  p=HASH1(h,fCapacity);
  GASSERT(0<=p && p<fCapacity);
  x=HASH2(h,fCapacity);
  GASSERT(1<=x && x<fCapacity);
  i=-1;
  n=fCapacity;
  while(n && hash[p].hash!=-1){
    if((i==-1)&&(hash[p].hash==-2)) i=p;
    if(hash[p].hash==h && strcmp(hash[p].key,ky)==0){
      //replace hash data for this key!
      lastkeyptr=hash[p].key;
      hash[p].data = (void*) pdata;
      return (OBJ*)hash[p].data;
      }
    p=(p+x)%fCapacity;
    n--;
    }
  if(i==-1) i=p;
  GTRACE(("GHash::insert: key=\"%s\"\n",ky));
  //GMessage("GHash::insert: key=\"%s\"\n",ky);
  GASSERT(0<=i && i<fCapacity);
  GASSERT(hash[i].hash<0);
  hash[i].hash=h;
  hash[i].mark=mrk;
  hash[i].key=(char *)ky;
  lastkeyptr=hash[i].key;
  hash[i].keyalloc=false;
  hash[i].data= (void*) pdata;
  fCount++;
  if((100*fCount)>=(MAX_LOAD*fCapacity)) Resize(fCount);
  GASSERT(fCount<fCapacity);
  return pdata;
  }


// Add or replace entry
template <class OBJ>  OBJ* GHash<OBJ>::Replace(const char* ky,const OBJ* pdata, bool mrk){
  register int p,i,x,h,n;
  if(!ky){ GError("GHash::replace: NULL key argument.\n"); }
  GASSERT(fCount<fCapacity);
  h=strhash(ky);
  GASSERT(0<=h);
  p=HASH1(h,fCapacity);
  GASSERT(0<=p && p<fCapacity);
  x=HASH2(h,fCapacity);
  GASSERT(1<=x && x<fCapacity);
  i=-1;
  n=fCapacity;
  while(n && hash[p].hash!=-1){
    if((i==-1)&&(hash[p].hash==-2)) i=p;
    if(hash[p].hash==h && strcmp(hash[p].key,ky)==0){
      if(hash[p].mark<=mrk){
        GTRACE(("GHash::replace: %08x: replacing: \"%s\"\n",this,ky));
        if (FREEDATA) (*fFreeProc)(hash[p].data);
        hash[p].mark=mrk;
        hash[p].data=pdata;
        }
      return hash[p].data;
      }
    p=(p+x)%fCapacity;
    n--;
    }
  if(i==-1) i=p;
  GTRACE(("GHash::replace: %08x: inserting: \"%s\"\n",this,ky));
  GASSERT(0<=i && i<fCapacity);
  GASSERT(hash[i].hash<0);
  hash[i].hash=h;
  hash[i].mark=mrk;
  hash[i].key=Gstrdup(ky);
  hash[i].data=pdata;
  fCount++;
  if((100*fCount)>=(MAX_LOAD*fCapacity)) Resize(fCount);
  GASSERT(fCount<fCapacity);
  return pdata;
  }


// Remove entry
template <class OBJ> OBJ* GHash<OBJ>::Remove(const char* ky){
  register int p,x,h,n;
  if(!ky){ GError("GHash::remove: NULL key argument.\n"); }
  if(0<fCount){
    h=strhash(ky);
    GASSERT(0<=h);
    p=HASH1(h,fCapacity);
    GASSERT(0<=p && p<fCapacity);
    x=HASH2(h,fCapacity);
    GASSERT(1<=x && x<fCapacity);
    GASSERT(fCount<fCapacity);
    n=fCapacity;
    while(n && hash[p].hash!=-1){
      if(hash[p].hash==h && strcmp(hash[p].key,ky)==0){
        GTRACE(("GHash::remove: %08x removing: \"%s\"\n",this,ky));
        hash[p].hash=-2;
        hash[p].mark=false;
        if (hash[p].keyalloc) GFREE((hash[p].key));
        if (FREEDATA) (*fFreeProc)(hash[p].data);
        hash[p].key=NULL;
        hash[p].data=NULL;
        fCount--;
        if((100*fCount)<=(MIN_LOAD*fCapacity)) Resize(fCount);
        GASSERT(fCount<fCapacity);
        return NULL;
        }
      p=(p+x)%fCapacity;
      n--;
      }
    }
  return NULL;
  }


// Find entry
template <class OBJ> bool GHash<OBJ>::hasKey(const char* ky) {
  register int p,x,h,n;
  if(!ky){ GError("GHash::find: NULL key argument.\n"); }
  if(0<fCount){
    h=strhash(ky);
    GASSERT(0<=h);
    p=HASH1(h,fCapacity);
    GASSERT(0<=p && p<fCapacity);
    x=HASH2(h,fCapacity);
    GASSERT(1<=x && x<fCapacity);
    GASSERT(fCount<fCapacity);
    n=fCapacity;
    while(n && hash[p].hash!=-1){
      if(hash[p].hash==h && strcmp(hash[p].key,ky)==0){
        return true;
        }
      p=(p+x)%fCapacity;
      n--;
      }
    }
  return false;
}

template <class OBJ> OBJ* GHash<OBJ>::Find(const char* ky, char** keyptr){
  register int p,x,h,n;
  if(!ky){ GError("GHash::find: NULL key argument.\n"); }
  if(0<fCount){
    h=strhash(ky);
    GASSERT(0<=h);
    p=HASH1(h,fCapacity);
    GASSERT(0<=p && p<fCapacity);
    x=HASH2(h,fCapacity);
    GASSERT(1<=x && x<fCapacity);
    GASSERT(fCount<fCapacity);
    n=fCapacity;
    while(n && hash[p].hash!=-1){
      if(hash[p].hash==h && strcmp(hash[p].key,ky)==0){
        if (keyptr!=NULL) *keyptr = hash[p].key;
        return (OBJ*)hash[p].data;
        }
      p=(p+x)%fCapacity;
      n--;
      }
    }
  return NULL;
  }


template <class OBJ> void GHash<OBJ>::startIterate() {// initialize a key iterator; call
 fCurrentEntry=0;
}

template <class OBJ> char* GHash<OBJ>::NextKey() {
 register int pos=fCurrentEntry;
 while (pos<fCapacity && hash[pos].hash<0) pos++;
 if (pos==fCapacity) {
                 fCurrentEntry=fCapacity;
                 return NULL;
                 }
              else {
                 fCurrentEntry=pos+1;
                 return hash[pos].key;
                 }
}

template <class OBJ> OBJ* GHash<OBJ>::NextData() {
 register int pos=fCurrentEntry;
 while (pos<fCapacity && hash[pos].hash<0) pos++;
 if (pos==fCapacity) {
                 fCurrentEntry=fCapacity;
                 return NULL;
                 }
              else {
                 fCurrentEntry=pos+1;
                 return (OBJ*)hash[pos].data;
                 }

}

template <class OBJ> OBJ* GHash<OBJ>::NextData(char* &nextkey) {
 register int pos=fCurrentEntry;
 while (pos<fCapacity && hash[pos].hash<0) pos++;
 if (pos==fCapacity) {
                 fCurrentEntry=fCapacity;
                 nextkey=NULL;
                 return NULL;
                 }
              else {
                 fCurrentEntry=pos+1;
                 nextkey=hash[pos].key;
                 return (OBJ*)hash[pos].data;
                 }

}

template <class OBJ> GHashEntry* GHash<OBJ>::NextEntry() {
 register int pos=fCurrentEntry;
 while (pos<fCapacity && hash[pos].hash<0) pos++;
 if (pos==fCapacity) {
                 fCurrentEntry=fCapacity;
                 return NULL;
                 }
              else {
                 fCurrentEntry=pos+1;
                 return &hash[pos];
                 }
}


// Get first non-empty entry
template <class OBJ> int GHash<OBJ>::First() const {
  register int pos=0;
  while(pos<fCapacity){ if(0<=hash[pos].hash) break; pos++; }
  GASSERT(fCapacity<=pos || 0<=hash[pos].hash);
  return pos;
  }

// Get last non-empty entry
template <class OBJ> int GHash<OBJ>::Last() const {
  register int pos=fCapacity-1;
  while(0<=pos){ if(0<=hash[pos].hash) break; pos--; }
  GASSERT(pos<0 || 0<=hash[pos].hash);
  return pos;
  }


// Find next valid entry
template <class OBJ> int GHash<OBJ>::Next(int pos) const {
  GASSERT(0<=pos && pos<fCapacity);
  while(++pos <= fCapacity-1){ if(0<=hash[pos].hash) break; }
  GASSERT(fCapacity<=pos || 0<=hash[pos].hash);
  return pos;
  }


// Find previous valid entry
template <class OBJ> int GHash<OBJ>::Prev(int pos) const {
  GASSERT(0<=pos && pos<fCapacity);
  while(--pos >= 0){ if(0<=hash[pos].hash) break; }
  GASSERT(pos<0 || 0<=hash[pos].hash);
  return pos;
  }


// Remove all
template <class OBJ> void GHash<OBJ>::Clear(){
  register int i;
  for(i=0; i<fCapacity; i++){
    if(hash[i].hash>=0){
      if (hash[i].keyalloc) GFREE((hash[i].key));
      if (FREEDATA)
            (*fFreeProc)(hash[i].data);
      }
    }
  GFREE(hash);
  GMALLOC(hash, sizeof(GHashEntry)*DEF_HASH_SIZE);
  //reinitialize it
  for (i=0; i<DEF_HASH_SIZE; i++)
         hash[i].hash=-1; //this will be an indicator for 'empty' entries
  fCapacity=DEF_HASH_SIZE;
  fCount=0;
  }


// Save data
/*
void GHash::Save(Stream& store) const {
  Object::save(store);
  store << fCapacity;
  store << fCount;
  for(int i=0; i<fCapacity; i++){
    store << hash[i].hash;
    if(hash[i].hash>=0){
      uint len=strlen(hash[i].key);
      store << len;
      store << hash[i].mark;
      store.save(hash[i].key,len);
      }
    }
  }


// Load data
void GHash::Load(Stream& store){
  Object::load(store);
  store >> fCapacity;
  store >> fCount;
  for(int i=0; i<fCapacity; i++){
    store >> hash[i].hash;
    if(hash[i].hash>=0){
      uint len;
      store >> len;
      store >> hash[i].mark;
      GMALLOC(hash[i].key,len+1);
      store.load(hash[i].key,len);
      hash[i].key[len]='\0';
      }
    }
  }
*/

// Destroy table
template <class OBJ> GHash<OBJ>::~GHash(){
  register int i;
  for(i=0; i<fCapacity; i++){
    if(hash[i].hash>=0){
      if (hash[i].keyalloc) GFREE((hash[i].key));
      if (FREEDATA) (*fFreeProc)(hash[i].data);
      }
    }
  GFREE(hash);
  }

#endif
Revision:	2
Committed:	Mon Mar 22 22:03:27 2010 UTC (12 years, 4 months ago) by gpertea
File size:	16896 byte(s)
Log Message:	added my gclib source files
Line	File contents
1	/********************************************************************************
2	* Hash table class template (char* based) *
3	*********************************************************************************/
4
5	#ifndef GHash_HH
6	#define GHash_HH
7	#include "GBase.h"
8	/**
9	* This class maintains a fast-access hash table of entities
10	* indexed by a character string.
11	* It is typically used to map strings to pointers; however, overloading
12	* the createData() and deleteData() members allows any type of data to
13	* be indexed by strings.
14	*/
15	typedef struct {
16	char* key; // Key string
17	bool keyalloc; //shared key flag (to not free the key chars)
18	int hash; // Hash value of key
19	pointer data; // Data
20	bool mark; // Entry is marked
21	} GHashEntry;
22
23	template <class OBJ> class GHash {
24	protected:
25	GHashEntry* hash; // Hash
26	int fCapacity; // table size
27	int fCount; // number of valid entries
28	int fCurrentEntry;
29	char* lastkeyptr; //pointer to last key string added
30	//---------- Raw data retrieval (including empty entries
31	// Return key at position pos.
32	const char* Key(uint pos) const { return hash[pos].key; }
33	// return data OBJ* at given position
34	OBJ* Data(uint pos) const { return (OBJ*) hash[pos].data; }
35	// Return mark flag of entry at position pos.
36	bool Mark(uint pos) const { return hash[pos].mark; }
37	// Return position of first filled slot, or >= fCapacity
38	int First() const;
39	// Return position of last filled slot or -1
40	int Last() const;
41	// Return position of next filled slot in hash table
42	// or a value greater than or equal to fCapacity if no filled
43	// slot was found
44	int Next(int pos) const;
45	//Return position of previous filled slot in hash table
46	//or a -1 if no filled slot was found
47	int Prev(int pos) const;
48
49	private:
50	GHash(const GHash&);
51	GHash &operator=(const GHash&);
52	GFreeProc* fFreeProc; //procedure to free item data
53	protected:
54	public:
55	static void DefaultFreeProc(pointer item) {
56	delete (OBJ*)item;
57	item=NULL;
58	}
59	public:
60	GHash(GFreeProc* freeProc); // constructs of an empty hash
61	GHash(bool doFree=true); // constructs of an empty hash (free the item objects)
62	void setFreeItem(GFreeProc *freeProc) { fFreeProc=freeProc; }
63	void setFreeItem(bool doFree) { fFreeProc=(doFree)? &DefaultFreeProc : NULL; }
64	int Capacity() const { return fCapacity; } // table's size, including the empty slots.
65	void Resize(int m); // Resize the table to the given size.
66	int Count() const { return fCount; }// the total number of entries in the table.
67	// Insert a new entry into the table given key and mark.
68	// If there is already an entry with that key, leave it unchanged,
69	const OBJ* Add(const char* ky, const OBJ* ptr=NULL, bool mrk=false);
70	//same as Add, but the key pointer is stored directly, no string duplicate
71	//is made (shared-key-Add)
72	const OBJ* shkAdd(const char* ky, const OBJ* ptr, bool mrk=false);
73
74	// Replace data at key, if the entry's mark is less than
75	// or equal to the given mark. If there was no existing entry,
76	// a new entry is inserted with the given mark.
77	OBJ* Replace(const char* ky, const OBJ* ptr, bool mrk=false);
78	// Remove a given key and its data
79	OBJ* Remove(const char* ky);
80	// Find data OBJ* given key.
81	OBJ* Find(const char* ky, char** keyptr=NULL);
82	bool hasKey(const char* ky);
83	char* getLastKey() { return lastkeyptr; }
84	OBJ* operator[](const char* ky) { return Find(ky); }
85	void startIterate(); //iterator-like initialization
86	char* NextKey(); //returns next valid key in the table (NULL if no more)
87	OBJ* NextData(); //returns next valid hash[].data
88	OBJ* NextData(char*& nextkey); //returns next valid hash[].data
89	//or NULL if no more
90	//nextkey is SET to the corresponding key
91	GHashEntry* NextEntry(); //returns a pointer to a GHashEntry
92
93	/// Clear all entries
94	void Clear();
95
96	/// Destructor
97	virtual ~GHash();
98	};
99	//
100	//======================== method definitions ========================
101	//
102	/*
103	Notes:
104	- The hash algorithm should yield a fCount in the range [0...GHash::EMPTY)
105	GHash::EMPTY and GHash::UNUSED are needed for flag purposes.
106	- Since the algorithm doubles the table size when exceeding MAX_LOAD,
107	it would be prudent to keep MIN_LOAD less than 1/2 MAX_LOAD;
108	otherwise, the algorithm might hip-hop between halving and doubling,
109	which would be quite expensive!!
110	- Not many people seem to know that hash tables don't have to be prime
111	numbers; in fact, a table size of 2**n and odd probe distance are very
112	easy to arrange, and this works just as well!
113	- We store the hash key, so that 99.999% of the time we can compare hash numbers;
114	only when hash numbers match do we need to compare keys.
115	Thus, with a good hash function, the fCount of calls to strcmp() should be
116	roughly the same as the fCount of successful lookups.
117	- The hash table should NEVER get full, or stuff will loop forever!!
118	*/
119
120	// Initial table size (MUST be power of 2)
121	#define DEF_HASH_SIZE 32
122	// Maximum hash table load factor (%)
123	#define MAX_LOAD 80
124	// Minimum hash table load factor (%)
125	#define MIN_LOAD 10
126	// Probe Position [0..n-1]
127	#define HASH1(x,n) (((unsigned int)(x)*13)%(n))
128	// Probe Distance [1..n-1]
129	#define HASH2(x,n) (1\|(((unsigned int)(x)*17)%((n)-1)))
130
131	#define FREEDATA (fFreeProc!=NULL)
132
133	/*******************************************************************************/
134	// Construct empty hash
135	template <class OBJ> GHash<OBJ>::GHash(GFreeProc* freeProc) {
136	GMALLOC(hash, sizeof(GHashEntry)*DEF_HASH_SIZE);
137	fFreeProc=freeProc;
138	for (uint i=0; i<DEF_HASH_SIZE; i++)
139	hash[i].hash=-1; //this will be an indicator for 'empty' entries
140	fCapacity=DEF_HASH_SIZE;
141	fCount=0;
142	}
143
144	template <class OBJ> GHash<OBJ>::GHash(bool doFree) {
145	GMALLOC(hash, sizeof(GHashEntry)*DEF_HASH_SIZE);
146	fFreeProc = (doFree)?&DefaultFreeProc : NULL;
147	for (uint i=0; i<DEF_HASH_SIZE; i++)
148	hash[i].hash=-1; //this will be an indicator for 'empty' entries
149	fCapacity=DEF_HASH_SIZE;
150	fCount=0;
151	}
152
153
154	// Resize table
155	template <class OBJ> void GHash<OBJ>::Resize(int m){
156	register int i,n,p,x,h;
157	GHashEntry *k;
158	GASSERT(fCount<=fCapacity);
159	if(m<DEF_HASH_SIZE) m=DEF_HASH_SIZE;
160	n=fCapacity;
161	while((n>>2)>m) n>>=1; // Shrink until n/4 <= m
162	while((n>>1)<m) n<<=1; // Grow until m <= n/2
163	GASSERT(m<=(n>>1));
164	GASSERT(DEF_HASH_SIZE<=n);
165	if(n!=fCapacity){
166	GASSERT(m<=n);
167	GMALLOC(k, sizeof(GHashEntry)*n);
168	for(i=0; i<n; i++) k[i].hash=-1;
169	for(i=0; i<fCapacity; i++){
170	h=hash[i].hash;
171	if(0<=h){
172	p=HASH1(h,n);
173	GASSERT(0<=p && p<n);
174	x=HASH2(h,n);
175	GASSERT(1<=x && x<n);
176	while(k[p].hash!=-1) p=(p+x)%n;
177	GASSERT(k[p].hash<0);
178	k[p]=hash[i];
179	}
180	}
181	GFREE(hash);
182	hash=k;
183	fCapacity=n;
184	}
185	}
186
187	// add a new entry, leave it alone if already existing
188	template <class OBJ> const OBJ* GHash<OBJ>::Add(const char* ky,
189	const OBJ* pdata,bool mrk){
190	register int p,i,x,h,n;
191	if(!ky) GError("GHash::insert: NULL key argument.\n");
192	GASSERT(fCount<fCapacity);
193	h=strhash(ky);
194	GASSERT(0<=h);
195	p=HASH1(h,fCapacity);
196	GASSERT(0<=p && p<fCapacity);
197	x=HASH2(h,fCapacity);
198	GASSERT(1<=x && x<fCapacity);
199	i=-1;
200	n=fCapacity;
201	while(n && hash[p].hash!=-1){
202	if ((i==-1)&&(hash[p].hash==-2)) i=p;
203	if (hash[p].hash==h && strcmp(hash[p].key,ky)==0) {
204	//replace hash data for this key!
205	lastkeyptr=hash[p].key;
206	hash[p].data = (void*) pdata;
207	return (OBJ*)hash[p].data;
208	}
209	p=(p+x)%fCapacity;
210	n--;
211	}
212	if(i==-1) i=p;
213	GTRACE(("GHash::insert: key=\"%s\"\n",ky));
214	//GMessage("GHash::insert: key=\"%s\"\n",ky);
215	GASSERT(0<=i && i<fCapacity);
216	GASSERT(hash[i].hash<0);
217	hash[i].hash=h;
218	hash[i].mark=mrk;
219	hash[i].key=Gstrdup(ky);
220	hash[i].keyalloc=true;
221	lastkeyptr=hash[i].key;
222	hash[i].data= (void*) pdata;
223	fCount++;
224	if((100fCount)>=(MAX_LOADfCapacity)) Resize(fCount);
225	GASSERT(fCount<fCapacity);
226	return pdata;
227	}
228
229	template <class OBJ> const OBJ* GHash<OBJ>::shkAdd(const char* ky,
230	const OBJ* pdata,bool mrk){
231	register int p,i,x,h,n;
232	if(!ky) GError("GHash::insert: NULL key argument.\n");
233	GASSERT(fCount<fCapacity);
234	h=strhash(ky);
235	GASSERT(0<=h);
236	p=HASH1(h,fCapacity);
237	GASSERT(0<=p && p<fCapacity);
238	x=HASH2(h,fCapacity);
239	GASSERT(1<=x && x<fCapacity);
240	i=-1;
241	n=fCapacity;
242	while(n && hash[p].hash!=-1){
243	if((i==-1)&&(hash[p].hash==-2)) i=p;
244	if(hash[p].hash==h && strcmp(hash[p].key,ky)==0){
245	//replace hash data for this key!
246	lastkeyptr=hash[p].key;
247	hash[p].data = (void*) pdata;
248	return (OBJ*)hash[p].data;
249	}
250	p=(p+x)%fCapacity;
251	n--;
252	}
253	if(i==-1) i=p;
254	GTRACE(("GHash::insert: key=\"%s\"\n",ky));
255	//GMessage("GHash::insert: key=\"%s\"\n",ky);
256	GASSERT(0<=i && i<fCapacity);
257	GASSERT(hash[i].hash<0);
258	hash[i].hash=h;
259	hash[i].mark=mrk;
260	hash[i].key=(char *)ky;
261	lastkeyptr=hash[i].key;
262	hash[i].keyalloc=false;
263	hash[i].data= (void*) pdata;
264	fCount++;
265	if((100fCount)>=(MAX_LOADfCapacity)) Resize(fCount);
266	GASSERT(fCount<fCapacity);
267	return pdata;
268	}
269
270
271	// Add or replace entry
272	template <class OBJ> OBJ* GHash<OBJ>::Replace(const char* ky,const OBJ* pdata, bool mrk){
273	register int p,i,x,h,n;
274	if(!ky){ GError("GHash::replace: NULL key argument.\n"); }
275	GASSERT(fCount<fCapacity);
276	h=strhash(ky);
277	GASSERT(0<=h);
278	p=HASH1(h,fCapacity);
279	GASSERT(0<=p && p<fCapacity);
280	x=HASH2(h,fCapacity);
281	GASSERT(1<=x && x<fCapacity);
282	i=-1;
283	n=fCapacity;
284	while(n && hash[p].hash!=-1){
285	if((i==-1)&&(hash[p].hash==-2)) i=p;
286	if(hash[p].hash==h && strcmp(hash[p].key,ky)==0){
287	if(hash[p].mark<=mrk){
288	GTRACE(("GHash::replace: %08x: replacing: \"%s\"\n",this,ky));
289	if (FREEDATA) (*fFreeProc)(hash[p].data);
290	hash[p].mark=mrk;
291	hash[p].data=pdata;
292	}
293	return hash[p].data;
294	}
295	p=(p+x)%fCapacity;
296	n--;
297	}
298	if(i==-1) i=p;
299	GTRACE(("GHash::replace: %08x: inserting: \"%s\"\n",this,ky));
300	GASSERT(0<=i && i<fCapacity);
301	GASSERT(hash[i].hash<0);
302	hash[i].hash=h;
303	hash[i].mark=mrk;
304	hash[i].key=Gstrdup(ky);
305	hash[i].data=pdata;
306	fCount++;
307	if((100fCount)>=(MAX_LOADfCapacity)) Resize(fCount);
308	GASSERT(fCount<fCapacity);
309	return pdata;
310	}
311
312
313	// Remove entry
314	template <class OBJ> OBJ* GHash<OBJ>::Remove(const char* ky){
315	register int p,x,h,n;
316	if(!ky){ GError("GHash::remove: NULL key argument.\n"); }
317	if(0<fCount){
318	h=strhash(ky);
319	GASSERT(0<=h);
320	p=HASH1(h,fCapacity);
321	GASSERT(0<=p && p<fCapacity);
322	x=HASH2(h,fCapacity);
323	GASSERT(1<=x && x<fCapacity);
324	GASSERT(fCount<fCapacity);
325	n=fCapacity;
326	while(n && hash[p].hash!=-1){
327	if(hash[p].hash==h && strcmp(hash[p].key,ky)==0){
328	GTRACE(("GHash::remove: %08x removing: \"%s\"\n",this,ky));
329	hash[p].hash=-2;
330	hash[p].mark=false;
331	if (hash[p].keyalloc) GFREE((hash[p].key));
332	if (FREEDATA) (*fFreeProc)(hash[p].data);
333	hash[p].key=NULL;
334	hash[p].data=NULL;
335	fCount--;
336	if((100fCount)<=(MIN_LOADfCapacity)) Resize(fCount);
337	GASSERT(fCount<fCapacity);
338	return NULL;
339	}
340	p=(p+x)%fCapacity;
341	n--;
342	}
343	}
344	return NULL;
345	}
346
347
348	// Find entry
349	template <class OBJ> bool GHash<OBJ>::hasKey(const char* ky) {
350	register int p,x,h,n;
351	if(!ky){ GError("GHash::find: NULL key argument.\n"); }
352	if(0<fCount){
353	h=strhash(ky);
354	GASSERT(0<=h);
355	p=HASH1(h,fCapacity);
356	GASSERT(0<=p && p<fCapacity);
357	x=HASH2(h,fCapacity);
358	GASSERT(1<=x && x<fCapacity);
359	GASSERT(fCount<fCapacity);
360	n=fCapacity;
361	while(n && hash[p].hash!=-1){
362	if(hash[p].hash==h && strcmp(hash[p].key,ky)==0){
363	return true;
364	}
365	p=(p+x)%fCapacity;
366	n--;
367	}
368	}
369	return false;
370	}
371
372	template <class OBJ> OBJ* GHash<OBJ>::Find(const char* ky, char** keyptr){
373	register int p,x,h,n;
374	if(!ky){ GError("GHash::find: NULL key argument.\n"); }
375	if(0<fCount){
376	h=strhash(ky);
377	GASSERT(0<=h);
378	p=HASH1(h,fCapacity);
379	GASSERT(0<=p && p<fCapacity);
380	x=HASH2(h,fCapacity);
381	GASSERT(1<=x && x<fCapacity);
382	GASSERT(fCount<fCapacity);
383	n=fCapacity;
384	while(n && hash[p].hash!=-1){
385	if(hash[p].hash==h && strcmp(hash[p].key,ky)==0){
386	if (keyptr!=NULL) *keyptr = hash[p].key;
387	return (OBJ*)hash[p].data;
388	}
389	p=(p+x)%fCapacity;
390	n--;
391	}
392	}
393	return NULL;
394	}
395
396
397	template <class OBJ> void GHash<OBJ>::startIterate() {// initialize a key iterator; call
398	fCurrentEntry=0;
399	}
400
401	template <class OBJ> char* GHash<OBJ>::NextKey() {
402	register int pos=fCurrentEntry;
403	while (pos<fCapacity && hash[pos].hash<0) pos++;
404	if (pos==fCapacity) {
405	fCurrentEntry=fCapacity;
406	return NULL;
407	}
408	else {
409	fCurrentEntry=pos+1;
410	return hash[pos].key;
411	}
412	}
413
414	template <class OBJ> OBJ* GHash<OBJ>::NextData() {
415	register int pos=fCurrentEntry;
416	while (pos<fCapacity && hash[pos].hash<0) pos++;
417	if (pos==fCapacity) {
418	fCurrentEntry=fCapacity;
419	return NULL;
420	}
421	else {
422	fCurrentEntry=pos+1;
423	return (OBJ*)hash[pos].data;
424	}
425
426	}
427
428	template <class OBJ> OBJ* GHash<OBJ>::NextData(char* &nextkey) {
429	register int pos=fCurrentEntry;
430	while (pos<fCapacity && hash[pos].hash<0) pos++;
431	if (pos==fCapacity) {
432	fCurrentEntry=fCapacity;
433	nextkey=NULL;
434	return NULL;
435	}
436	else {
437	fCurrentEntry=pos+1;
438	nextkey=hash[pos].key;
439	return (OBJ*)hash[pos].data;
440	}
441
442	}
443
444	template <class OBJ> GHashEntry* GHash<OBJ>::NextEntry() {
445	register int pos=fCurrentEntry;
446	while (pos<fCapacity && hash[pos].hash<0) pos++;
447	if (pos==fCapacity) {
448	fCurrentEntry=fCapacity;
449	return NULL;
450	}
451	else {
452	fCurrentEntry=pos+1;
453	return &hash[pos];
454	}
455	}
456
457
458	// Get first non-empty entry
459	template <class OBJ> int GHash<OBJ>::First() const {
460	register int pos=0;
461	while(pos<fCapacity){ if(0<=hash[pos].hash) break; pos++; }
462	GASSERT(fCapacity<=pos \|\| 0<=hash[pos].hash);
463	return pos;
464	}
465
466	// Get last non-empty entry
467	template <class OBJ> int GHash<OBJ>::Last() const {
468	register int pos=fCapacity-1;
469	while(0<=pos){ if(0<=hash[pos].hash) break; pos--; }
470	GASSERT(pos<0 \|\| 0<=hash[pos].hash);
471	return pos;
472	}
473
474
475	// Find next valid entry
476	template <class OBJ> int GHash<OBJ>::Next(int pos) const {
477	GASSERT(0<=pos && pos<fCapacity);
478	while(++pos <= fCapacity-1){ if(0<=hash[pos].hash) break; }
479	GASSERT(fCapacity<=pos \|\| 0<=hash[pos].hash);
480	return pos;
481	}
482
483
484	// Find previous valid entry
485	template <class OBJ> int GHash<OBJ>::Prev(int pos) const {
486	GASSERT(0<=pos && pos<fCapacity);
487	while(--pos >= 0){ if(0<=hash[pos].hash) break; }
488	GASSERT(pos<0 \|\| 0<=hash[pos].hash);
489	return pos;
490	}
491
492
493	// Remove all
494	template <class OBJ> void GHash<OBJ>::Clear(){
495	register int i;
496	for(i=0; i<fCapacity; i++){
497	if(hash[i].hash>=0){
498	if (hash[i].keyalloc) GFREE((hash[i].key));
499	if (FREEDATA)
500	(*fFreeProc)(hash[i].data);
501	}
502	}
503	GFREE(hash);
504	GMALLOC(hash, sizeof(GHashEntry)*DEF_HASH_SIZE);
505	//reinitialize it
506	for (i=0; i<DEF_HASH_SIZE; i++)
507	hash[i].hash=-1; //this will be an indicator for 'empty' entries
508	fCapacity=DEF_HASH_SIZE;
509	fCount=0;
510	}
511
512
513	// Save data
514	/*
515	void GHash::Save(Stream& store) const {
516	Object::save(store);
517	store << fCapacity;
518	store << fCount;
519	for(int i=0; i<fCapacity; i++){
520	store << hash[i].hash;
521	if(hash[i].hash>=0){
522	uint len=strlen(hash[i].key);
523	store << len;
524	store << hash[i].mark;
525	store.save(hash[i].key,len);
526	}
527	}
528	}
529
530
531	// Load data
532	void GHash::Load(Stream& store){
533	Object::load(store);
534	store >> fCapacity;
535	store >> fCount;
536	for(int i=0; i<fCapacity; i++){
537	store >> hash[i].hash;
538	if(hash[i].hash>=0){
539	uint len;
540	store >> len;
541	store >> hash[i].mark;
542	GMALLOC(hash[i].key,len+1);
543	store.load(hash[i].key,len);
544	hash[i].key[len]='\0';
545	}
546	}
547	}
548	*/
549
550	// Destroy table
551	template <class OBJ> GHash<OBJ>::~GHash(){
552	register int i;
553	for(i=0; i<fCapacity; i++){
554	if(hash[i].hash>=0){
555	if (hash[i].keyalloc) GFREE((hash[i].key));
556	if (FREEDATA) (*fFreeProc)(hash[i].data);
557	}
558	}
559	GFREE(hash);
560	}
561
562	#endif