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  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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  24 
  25 // Dictionaries - An Abstract Data Type
  26 
  27 #include "adlc.hpp"
  28 
  29 // #include "dict.hpp"
  30 
  31 
  32 //------------------------------data-----------------------------------------
  33 // String hash tables
  34 #define MAXID 20
  35 static char initflag = 0;       // True after 1st initialization
  36 static char shft[MAXID + 1] = {1,2,3,4,5,6,7,1,2,3,4,5,6,7,1,2,3,4,5,6,7};
  37 static short xsum[MAXID];
  38 
  39 //------------------------------bucket---------------------------------------
  40 class bucket {
  41 public:
  42   int          _cnt, _max;      // Size of bucket
  43   const void **_keyvals;        // Array of keys and values
  44 };
  45 
  46 //------------------------------Dict-----------------------------------------
  47 // The dictionary is kept has a hash table.  The hash table is a even power
  48 // of two, for nice modulo operations.  Each bucket in the hash table points
  49 // to a linear list of key-value pairs; each key & value is just a (void *).
  50 // The list starts with a count.  A hash lookup finds the list head, then a
  51 // simple linear scan finds the key.  If the table gets too full, it's
  52 // doubled in size; the total amount of EXTRA times all hash functions are
  53 // computed for the doubling is no more than the current size - thus the
  54 // doubling in size costs no more than a constant factor in speed.
  55 Dict::Dict(CmpKey initcmp, Hash inithash) : _hash(inithash), _cmp(initcmp), _arena(NULL) {
  56   init();
  57 }
  58 
  59 Dict::Dict(CmpKey initcmp, Hash inithash, Arena *arena) : _hash(inithash), _cmp(initcmp), _arena(arena) {
  60   init();
  61 }
  62 
  63 void Dict::init() {
  64   int i;
  65 
  66   // Precompute table of null character hashes
  67   if (!initflag) {              // Not initializated yet?
  68     xsum[0] = (short) ((1 << shft[0]) + 1);  // Initialize
  69     for( i = 1; i < MAXID; i++) {
  70       xsum[i] = (short) ((1 << shft[i]) + 1 + xsum[i-1]);
  71     }
  72     initflag = 1;               // Never again
  73   }
  74 
  75   _size = 16;                   // Size is a power of 2
  76   _cnt = 0;                     // Dictionary is empty
  77   _bin = (bucket*)_arena->Amalloc_4(sizeof(bucket) * _size);
  78   memset(_bin, 0, sizeof(bucket) * _size);
  79 }
  80 
  81 //------------------------------~Dict------------------------------------------
  82 // Delete an existing dictionary.
  83 Dict::~Dict() {
  84 }
  85 
  86 //------------------------------Clear----------------------------------------
  87 // Zap to empty; ready for re-use
  88 void Dict::Clear() {
  89   _cnt = 0;                     // Empty contents
  90   for( int i=0; i<_size; i++ )
  91     _bin[i]._cnt = 0;           // Empty buckets, but leave allocated
  92   // Leave _size & _bin alone, under the assumption that dictionary will
  93   // grow to this size again.
  94 }
  95 
  96 //------------------------------doubhash---------------------------------------
  97 // Double hash table size.  If can't do so, just suffer.  If can, then run
  98 // thru old hash table, moving things to new table.  Note that since hash
  99 // table doubled, exactly 1 new bit is exposed in the mask - so everything
 100 // in the old table ends up on 1 of two lists in the new table; a hi and a
 101 // lo list depending on the value of the bit.
 102 void Dict::doubhash(void) {
 103   int oldsize = _size;
 104   _size <<= 1;                  // Double in size
 105   _bin = (bucket*)_arena->Arealloc( _bin, sizeof(bucket)*oldsize, sizeof(bucket)*_size );
 106   memset( &_bin[oldsize], 0, oldsize*sizeof(bucket) );
 107   // Rehash things to spread into new table
 108   for( int i=0; i < oldsize; i++) { // For complete OLD table do
 109     bucket *b = &_bin[i];       // Handy shortcut for _bin[i]
 110     if( !b->_keyvals ) continue;        // Skip empties fast
 111 
 112     bucket *nb = &_bin[i+oldsize];  // New bucket shortcut
 113     int j = b->_max;                // Trim new bucket to nearest power of 2
 114     while( j > b->_cnt ) j >>= 1;   // above old bucket _cnt
 115     if( !j ) j = 1;             // Handle zero-sized buckets
 116     nb->_max = j<<1;
 117     // Allocate worst case space for key-value pairs
 118     nb->_keyvals = (const void**)_arena->Amalloc_4( sizeof(void *)*nb->_max*2 );
 119     int nbcnt = 0;
 120 
 121     for( j=0; j<b->_cnt; j++ ) {  // Rehash all keys in this bucket
 122       const void *key = b->_keyvals[j+j];
 123       if( (_hash( key ) & (_size-1)) != i ) { // Moving to hi bucket?
 124         nb->_keyvals[nbcnt+nbcnt] = key;
 125         nb->_keyvals[nbcnt+nbcnt+1] = b->_keyvals[j+j+1];
 126         nb->_cnt = nbcnt = nbcnt+1;
 127         b->_cnt--;              // Remove key/value from lo bucket
 128         b->_keyvals[j+j  ] = b->_keyvals[b->_cnt+b->_cnt  ];
 129         b->_keyvals[j+j+1] = b->_keyvals[b->_cnt+b->_cnt+1];
 130         j--;                    // Hash compacted element also
 131       }
 132     } // End of for all key-value pairs in bucket
 133   } // End of for all buckets
 134 
 135 
 136 }
 137 
 138 //------------------------------Dict-----------------------------------------
 139 // Deep copy a dictionary.
 140 Dict::Dict( const Dict &d ) : _size(d._size), _cnt(d._cnt), _hash(d._hash),_cmp(d._cmp), _arena(d._arena) {
 141   _bin = (bucket*)_arena->Amalloc_4(sizeof(bucket)*_size);
 142   memcpy( _bin, d._bin, sizeof(bucket)*_size );
 143   for( int i=0; i<_size; i++ ) {
 144     if( !_bin[i]._keyvals ) continue;
 145     _bin[i]._keyvals=(const void**)_arena->Amalloc_4( sizeof(void *)*_bin[i]._max*2);
 146     memcpy( _bin[i]._keyvals, d._bin[i]._keyvals,_bin[i]._cnt*2*sizeof(void*));
 147   }
 148 }
 149 
 150 //------------------------------Dict-----------------------------------------
 151 // Deep copy a dictionary.
 152 Dict &Dict::operator =( const Dict &d ) {
 153   if( _size < d._size ) {       // If must have more buckets
 154     _arena = d._arena;
 155     _bin = (bucket*)_arena->Arealloc( _bin, sizeof(bucket)*_size, sizeof(bucket)*d._size );
 156     memset( &_bin[_size], 0, (d._size-_size)*sizeof(bucket) );
 157     _size = d._size;
 158   }
 159   for( int i=0; i<_size; i++ ) // All buckets are empty
 160     _bin[i]._cnt = 0;           // But leave bucket allocations alone
 161   _cnt = d._cnt;
 162   *(Hash*)(&_hash) = d._hash;
 163   *(CmpKey*)(&_cmp) = d._cmp;
 164   for(int k=0; k<_size; k++ ) {
 165     bucket *b = &d._bin[k];     // Shortcut to source bucket
 166     for( int j=0; j<b->_cnt; j++ )
 167       Insert( b->_keyvals[j+j], b->_keyvals[j+j+1] );
 168   }
 169   return *this;
 170 }
 171 
 172 //------------------------------Insert---------------------------------------
 173 // Insert or replace a key/value pair in the given dictionary.  If the
 174 // dictionary is too full, it's size is doubled.  The prior value being
 175 // replaced is returned (NULL if this is a 1st insertion of that key).  If
 176 // an old value is found, it's swapped with the prior key-value pair on the
 177 // list.  This moves a commonly searched-for value towards the list head.
 178 const void *Dict::Insert(const void *key, const void *val) {
 179   int hash = _hash( key );      // Get hash key
 180   int i = hash & (_size-1);     // Get hash key, corrected for size
 181   bucket *b = &_bin[i];         // Handy shortcut
 182   for( int j=0; j<b->_cnt; j++ )
 183     if( !_cmp(key,b->_keyvals[j+j]) ) {
 184       const void *prior = b->_keyvals[j+j+1];
 185       b->_keyvals[j+j  ] = key; // Insert current key-value
 186       b->_keyvals[j+j+1] = val;
 187       return prior;             // Return prior
 188     }
 189 
 190   if( ++_cnt > _size ) {        // Hash table is full
 191     doubhash();                 // Grow whole table if too full
 192     i = hash & (_size-1);       // Rehash
 193     b = &_bin[i];               // Handy shortcut
 194   }
 195   if( b->_cnt == b->_max ) {    // Must grow bucket?
 196     if( !b->_keyvals ) {
 197       b->_max = 2;              // Initial bucket size
 198       b->_keyvals = (const void**)_arena->Amalloc_4( sizeof(void *)*b->_max*2 );
 199     } else {
 200       b->_keyvals = (const void**)_arena->Arealloc( b->_keyvals, sizeof(void *)*b->_max*2, sizeof(void *)*b->_max*4 );
 201       b->_max <<= 1;            // Double bucket
 202     }
 203   }
 204   b->_keyvals[b->_cnt+b->_cnt  ] = key;
 205   b->_keyvals[b->_cnt+b->_cnt+1] = val;
 206   b->_cnt++;
 207   return NULL;                  // Nothing found prior
 208 }
 209 
 210 //------------------------------Delete---------------------------------------
 211 // Find & remove a value from dictionary. Return old value.
 212 const void *Dict::Delete(void *key) {
 213   int i = _hash( key ) & (_size-1);     // Get hash key, corrected for size
 214   bucket *b = &_bin[i];         // Handy shortcut
 215   for( int j=0; j<b->_cnt; j++ )
 216     if( !_cmp(key,b->_keyvals[j+j]) ) {
 217       const void *prior = b->_keyvals[j+j+1];
 218       b->_cnt--;                // Remove key/value from lo bucket
 219       b->_keyvals[j+j  ] = b->_keyvals[b->_cnt+b->_cnt  ];
 220       b->_keyvals[j+j+1] = b->_keyvals[b->_cnt+b->_cnt+1];
 221       _cnt--;                   // One less thing in table
 222       return prior;
 223     }
 224   return NULL;
 225 }
 226 
 227 //------------------------------FindDict-------------------------------------
 228 // Find a key-value pair in the given dictionary.  If not found, return NULL.
 229 // If found, move key-value pair towards head of list.
 230 const void *Dict::operator [](const void *key) const {
 231   int i = _hash( key ) & (_size-1);     // Get hash key, corrected for size
 232   bucket *b = &_bin[i];         // Handy shortcut
 233   for( int j=0; j<b->_cnt; j++ )
 234     if( !_cmp(key,b->_keyvals[j+j]) )
 235       return b->_keyvals[j+j+1];
 236   return NULL;
 237 }
 238 
 239 //------------------------------CmpDict--------------------------------------
 240 // CmpDict compares two dictionaries; they must have the same keys (their
 241 // keys must match using CmpKey) and they must have the same values (pointer
 242 // comparison).  If so 1 is returned, if not 0 is returned.
 243 int Dict::operator ==(const Dict &d2) const {
 244   if( _cnt != d2._cnt ) return 0;
 245   if( _hash != d2._hash ) return 0;
 246   if( _cmp != d2._cmp ) return 0;
 247   for( int i=0; i < _size; i++) {       // For complete hash table do
 248     bucket *b = &_bin[i];       // Handy shortcut
 249     if( b->_cnt != d2._bin[i]._cnt ) return 0;
 250     if( memcmp(b->_keyvals, d2._bin[i]._keyvals, b->_cnt*2*sizeof(void*) ) )
 251       return 0;                 // Key-value pairs must match
 252   }
 253   return 1;                     // All match, is OK
 254 }
 255 
 256 
 257 //------------------------------print----------------------------------------
 258 static void printvoid(const void* x) { printf("%p", x);  }
 259 void Dict::print() {
 260   print(printvoid, printvoid);
 261 }
 262 void Dict::print(PrintKeyOrValue print_key, PrintKeyOrValue print_value) {
 263   for( int i=0; i < _size; i++) {       // For complete hash table do
 264     bucket *b = &_bin[i];       // Handy shortcut
 265     for( int j=0; j<b->_cnt; j++ ) {
 266       print_key(  b->_keyvals[j+j  ]);
 267       printf(" -> ");
 268       print_value(b->_keyvals[j+j+1]);
 269       printf("\n");
 270     }
 271   }
 272 }
 273 
 274 //------------------------------Hashing Functions----------------------------
 275 // Convert string to hash key.  This algorithm implements a universal hash
 276 // function with the multipliers frozen (ok, so it's not universal).  The
 277 // multipliers (and allowable characters) are all odd, so the resultant sum
 278 // is odd - guaranteed not divisible by any power of two, so the hash tables
 279 // can be any power of two with good results.  Also, I choose multipliers
 280 // that have only 2 bits set (the low is always set to be odd) so
 281 // multiplication requires only shifts and adds.  Characters are required to
 282 // be in the range 0-127 (I double & add 1 to force oddness).  Keys are
 283 // limited to MAXID characters in length.  Experimental evidence on 150K of
 284 // C text shows excellent spreading of values for any size hash table.
 285 int hashstr(const void *t) {
 286   register char c, k = 0;
 287   register int sum = 0;
 288   register const char *s = (const char *)t;
 289 
 290   while (((c = s[k]) != '\0') && (k < MAXID-1)) { // Get characters till nul
 291     c = (char) ((c << 1) + 1);    // Characters are always odd!
 292     sum += c + (c << shft[k++]);  // Universal hash function
 293   }
 294   assert(k < (MAXID), "Exceeded maximum name length");
 295   return (int)((sum+xsum[k]) >> 1); // Hash key, un-modulo'd table size
 296 }
 297 
 298 //------------------------------hashptr--------------------------------------
 299 // Slimey cheap hash function; no guaranteed performance.  Better than the
 300 // default for pointers, especially on MS-DOS machines.
 301 int hashptr(const void *key) {
 302 #ifdef __TURBOC__
 303     return (int)((intptr_t)key >> 16);
 304 #else  // __TURBOC__
 305     return (int)((intptr_t)key >> 2);
 306 #endif
 307 }
 308 
 309 // Slimey cheap hash function; no guaranteed performance.
 310 int hashkey(const void *key) {
 311   return (int)((intptr_t)key);
 312 }
 313 
 314 //------------------------------Key Comparator Functions---------------------
 315 int cmpstr(const void *k1, const void *k2) {
 316   return strcmp((const char *)k1,(const char *)k2);
 317 }
 318 
 319 // Cheap key comparator.
 320 int cmpkey(const void *key1, const void *key2) {
 321   if (key1 == key2) return 0;
 322   intptr_t delta = (intptr_t)key1 - (intptr_t)key2;
 323   if (delta > 0) return 1;
 324   return -1;
 325 }
 326 
 327 //=============================================================================
 328 //------------------------------reset------------------------------------------
 329 // Create an iterator and initialize the first variables.
 330 void DictI::reset( const Dict *dict ) {
 331   _d = dict;                    // The dictionary
 332   _i = (int)-1;         // Before the first bin
 333   _j = 0;                       // Nothing left in the current bin
 334   ++(*this);                    // Step to first real value
 335 }
 336 
 337 //------------------------------next-------------------------------------------
 338 // Find the next key-value pair in the dictionary, or return a NULL key and
 339 // value.
 340 void DictI::operator ++(void) {
 341   if( _j-- ) {                  // Still working in current bin?
 342     _key   = _d->_bin[_i]._keyvals[_j+_j];
 343     _value = _d->_bin[_i]._keyvals[_j+_j+1];
 344     return;
 345   }
 346 
 347   while( ++_i < _d->_size ) {   // Else scan for non-zero bucket
 348     _j = _d->_bin[_i]._cnt;
 349     if( !_j ) continue;
 350     _j--;
 351     _key   = _d->_bin[_i]._keyvals[_j+_j];
 352     _value = _d->_bin[_i]._keyvals[_j+_j+1];
 353     return;
 354   }
 355   _key = _value = NULL;
 356 }