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root/gclib/gclib/GHash.hh
Revision: 16
Committed: Mon Jul 18 20:56:02 2011 UTC (8 years ago) by gpertea
File size: 16767 byte(s)
Log Message:
sync with local source

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