/usr/include/GHash.hh is in libgff-dev 1.0-1.
This file is owned by root:root, with mode 0o644.
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* 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 (essentially, maps strings to pointers)
*/
template <class OBJ> class GHash {
protected:
struct GHashEntry {
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* 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;
}
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
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];
}
}
/// 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);
fCurrentEntry=-1;
fFreeProc=freeProc;
lastkeyptr=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;
}
template <class OBJ> GHash<OBJ>::GHash(bool doFree) {
GMALLOC(hash, sizeof(GHashEntry)*DEF_HASH_SIZE);
fCurrentEntry=-1;
lastkeyptr=NULL;
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, or update it if it already exists
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;
}
}
// 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
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