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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* version 2 for more details (a copy is included in the LICENSE file that
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*
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* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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#include "precompiled.hpp"
#include "libadt/dict.hpp"
#include "utilities/powerOfTwo.hpp"
// Dictionaries - An Abstract Data Type
// %%%%% includes not needed with AVM framework - Ungar
#include <assert.h>
//------------------------------data-----------------------------------------
// String hash tables
#define MAXID 20
static uint8_t initflag = 0; // True after 1st initialization
static const char shft[MAXID] = {1,2,3,4,5,6,7,1,2,3,4,5,6,7,1,2,3,4,5,6};
static short xsum[MAXID];
//------------------------------bucket---------------------------------------
class bucket : public ResourceObj {
public:
uint _cnt, _max; // Size of bucket
void **_keyvals; // Array of keys and values
};
//------------------------------Dict-----------------------------------------
// The dictionary is kept has a hash table. The hash table is a even power
// of two, for nice modulo operations. Each bucket in the hash table points
// to a linear list of key-value pairs; each key & value is just a (void *).
// The list starts with a count. A hash lookup finds the list head, then a
// simple linear scan finds the key. If the table gets too full, it's
// doubled in size; the total amount of EXTRA times all hash functions are
// computed for the doubling is no more than the current size - thus the
// doubling in size costs no more than a constant factor in speed.
Dict::Dict(CmpKey initcmp, Hash inithash) : _arena(Thread::current()->resource_area()),
_hash(inithash), _cmp(initcmp) {
int i;
// Precompute table of null character hashes
if( !initflag ) { // Not initializated yet?
xsum[0] = (1<<shft[0])+1; // Initialize
for(i=1; i<MAXID; i++) {
xsum[i] = (1<<shft[i])+1+xsum[i-1];
}
initflag = 1; // Never again
}
_size = 16; // Size is a power of 2
_cnt = 0; // Dictionary is empty
_bin = (bucket*)_arena->Amalloc_4(sizeof(bucket)*_size);
memset((void*)_bin,0,sizeof(bucket)*_size);
}
Dict::Dict(CmpKey initcmp, Hash inithash, Arena *arena, int size)
: _arena(arena), _hash(inithash), _cmp(initcmp) {
int i;
// Precompute table of null character hashes
if( !initflag ) { // Not initializated yet?
xsum[0] = (1<<shft[0])+1; // Initialize
for(i=1; i<MAXID; i++) {
xsum[i] = (1<<shft[i])+1+xsum[i-1];
}
initflag = 1; // Never again
}
i = MAX2(16, round_up_power_of_2(size));
_size = i; // Size is a power of 2
_cnt = 0; // Dictionary is empty
_bin = (bucket*)_arena->Amalloc_4(sizeof(bucket)*_size);
memset((void*)_bin,0,sizeof(bucket)*_size);
}
//------------------------------~Dict------------------------------------------
// Delete an existing dictionary.
Dict::~Dict() {
/*
tty->print("~Dict %d/%d: ",_cnt,_size);
for( uint i=0; i < _size; i++) // For complete new table do
tty->print("%d ",_bin[i]._cnt);
tty->print("\n");*/
/*for( uint i=0; i<_size; i++ ) {
FREE_FAST( _bin[i]._keyvals );
} */
}
//------------------------------Clear----------------------------------------
// Zap to empty; ready for re-use
void Dict::Clear() {
_cnt = 0; // Empty contents
for( uint i=0; i<_size; i++ )
_bin[i]._cnt = 0; // Empty buckets, but leave allocated
// Leave _size & _bin alone, under the assumption that dictionary will
// grow to this size again.
}
//------------------------------doubhash---------------------------------------
// Double hash table size. If can't do so, just suffer. If can, then run
// thru old hash table, moving things to new table. Note that since hash
// table doubled, exactly 1 new bit is exposed in the mask - so everything
// in the old table ends up on 1 of two lists in the new table; a hi and a
// lo list depending on the value of the bit.
void Dict::doubhash(void) {
uint oldsize = _size;
_size <<= 1; // Double in size
_bin = (bucket*)_arena->Arealloc(_bin, sizeof(bucket) * oldsize, sizeof(bucket) * _size);
memset((void*)(&_bin[oldsize]), 0, oldsize * sizeof(bucket));
// Rehash things to spread into new table
for (uint i = 0; i < oldsize; i++) { // For complete OLD table do
bucket *b = &_bin[i]; // Handy shortcut for _bin[i]
if (!b->_keyvals) continue; // Skip empties fast
bucket *nb = &_bin[i+oldsize]; // New bucket shortcut
uint j = b->_max; // Trim new bucket to nearest power of 2
while (j > b->_cnt) { j >>= 1; } // above old bucket _cnt
if (!j) { j = 1; } // Handle zero-sized buckets
nb->_max = j << 1;
// Allocate worst case space for key-value pairs
nb->_keyvals = (void**)_arena->Amalloc_4(sizeof(void *) * nb->_max * 2);
uint nbcnt = 0;
for (j = 0; j < b->_cnt; ) { // Rehash all keys in this bucket
void *key = b->_keyvals[j + j];
if ((_hash(key) & (_size-1)) != i) { // Moving to hi bucket?
nb->_keyvals[nbcnt + nbcnt] = key;
nb->_keyvals[nbcnt + nbcnt + 1] = b->_keyvals[j + j + 1];
nb->_cnt = nbcnt = nbcnt + 1;
b->_cnt--; // Remove key/value from lo bucket
b->_keyvals[j + j] = b->_keyvals[b->_cnt + b->_cnt];
b->_keyvals[j + j + 1] = b->_keyvals[b->_cnt + b->_cnt + 1];
// Don't increment j, hash compacted element also.
} else {
j++; // Iterate.
}
} // End of for all key-value pairs in bucket
} // End of for all buckets
}
//------------------------------Dict-----------------------------------------
// Deep copy a dictionary.
Dict::Dict( const Dict &d ) : ResourceObj(d), _arena(d._arena), _size(d._size), _cnt(d._cnt), _hash(d._hash), _cmp(d._cmp) {
_bin = (bucket*)_arena->Amalloc_4(sizeof(bucket)*_size);
memcpy( (void*)_bin, (void*)d._bin, sizeof(bucket)*_size );
for( uint i=0; i<_size; i++ ) {
if( !_bin[i]._keyvals ) continue;
_bin[i]._keyvals=(void**)_arena->Amalloc_4( sizeof(void *)*_bin[i]._max*2);
memcpy( _bin[i]._keyvals, d._bin[i]._keyvals,_bin[i]._cnt*2*sizeof(void*));
}
}
//------------------------------Dict-----------------------------------------
// Deep copy a dictionary.
Dict &Dict::operator =( const Dict &d ) {
if( _size < d._size ) { // If must have more buckets
_arena = d._arena;
_bin = (bucket*)_arena->Arealloc( _bin, sizeof(bucket)*_size, sizeof(bucket)*d._size );
memset( (void*)(&_bin[_size]), 0, (d._size-_size)*sizeof(bucket) );
_size = d._size;
}
uint i;
for( i=0; i<_size; i++ ) // All buckets are empty
_bin[i]._cnt = 0; // But leave bucket allocations alone
_cnt = d._cnt;
*(Hash*)(&_hash) = d._hash;
*(CmpKey*)(&_cmp) = d._cmp;
for( i=0; i<_size; i++ ) {
bucket *b = &d._bin[i]; // Shortcut to source bucket
for( uint j=0; j<b->_cnt; j++ )
Insert( b->_keyvals[j+j], b->_keyvals[j+j+1] );
}
return *this;
}
//------------------------------Insert----------------------------------------
// Insert or replace a key/value pair in the given dictionary. If the
// dictionary is too full, it's size is doubled. The prior value being
// replaced is returned (NULL if this is a 1st insertion of that key). If
// an old value is found, it's swapped with the prior key-value pair on the
// list. This moves a commonly searched-for value towards the list head.
void *Dict::Insert(void *key, void *val, bool replace) {
uint hash = _hash( key ); // Get hash key
uint i = hash & (_size-1); // Get hash key, corrected for size
bucket *b = &_bin[i]; // Handy shortcut
for( uint j=0; j<b->_cnt; j++ ) {
if( !_cmp(key,b->_keyvals[j+j]) ) {
if (!replace) {
return b->_keyvals[j+j+1];
} else {
void *prior = b->_keyvals[j+j+1];
b->_keyvals[j+j ] = key; // Insert current key-value
b->_keyvals[j+j+1] = val;
return prior; // Return prior
}
}
}
if( ++_cnt > _size ) { // Hash table is full
doubhash(); // Grow whole table if too full
i = hash & (_size-1); // Rehash
b = &_bin[i]; // Handy shortcut
}
if( b->_cnt == b->_max ) { // Must grow bucket?
if( !b->_keyvals ) {
b->_max = 2; // Initial bucket size
b->_keyvals = (void**)_arena->Amalloc_4(sizeof(void*) * b->_max * 2);
} else {
b->_keyvals = (void**)_arena->Arealloc(b->_keyvals, sizeof(void*) * b->_max * 2, sizeof(void*) * b->_max * 4);
b->_max <<= 1; // Double bucket
}
}
b->_keyvals[b->_cnt+b->_cnt ] = key;
b->_keyvals[b->_cnt+b->_cnt+1] = val;
b->_cnt++;
return NULL; // Nothing found prior
}
//------------------------------Delete---------------------------------------
// Find & remove a value from dictionary. Return old value.
void *Dict::Delete(void *key) {
uint i = _hash( key ) & (_size-1); // Get hash key, corrected for size
bucket *b = &_bin[i]; // Handy shortcut
for( uint j=0; j<b->_cnt; j++ )
if( !_cmp(key,b->_keyvals[j+j]) ) {
void *prior = b->_keyvals[j+j+1];
b->_cnt--; // Remove key/value from lo bucket
b->_keyvals[j+j ] = b->_keyvals[b->_cnt+b->_cnt ];
b->_keyvals[j+j+1] = b->_keyvals[b->_cnt+b->_cnt+1];
_cnt--; // One less thing in table
return prior;
}
return NULL;
}
//------------------------------FindDict-------------------------------------
// Find a key-value pair in the given dictionary. If not found, return NULL.
// If found, move key-value pair towards head of list.
void *Dict::operator [](const void *key) const {
uint i = _hash( key ) & (_size-1); // Get hash key, corrected for size
bucket *b = &_bin[i]; // Handy shortcut
for( uint j=0; j<b->_cnt; j++ )
if( !_cmp(key,b->_keyvals[j+j]) )
return b->_keyvals[j+j+1];
return NULL;
}
//------------------------------CmpDict--------------------------------------
// CmpDict compares two dictionaries; they must have the same keys (their
// keys must match using CmpKey) and they must have the same values (pointer
// comparison). If so 1 is returned, if not 0 is returned.
int32_t Dict::operator ==(const Dict &d2) const {
if( _cnt != d2._cnt ) return 0;
if( _hash != d2._hash ) return 0;
if( _cmp != d2._cmp ) return 0;
for( uint i=0; i < _size; i++) { // For complete hash table do
bucket *b = &_bin[i]; // Handy shortcut
if( b->_cnt != d2._bin[i]._cnt ) return 0;
if( memcmp(b->_keyvals, d2._bin[i]._keyvals, b->_cnt*2*sizeof(void*) ) )
return 0; // Key-value pairs must match
}
return 1; // All match, is OK
}
//------------------------------print------------------------------------------
// Handier print routine
void Dict::print() {
DictI i(this); // Moved definition in iterator here because of g++.
tty->print("Dict@" INTPTR_FORMAT "[%d] = {", p2i(this), _cnt);
for( ; i.test(); ++i ) {
tty->print("(" INTPTR_FORMAT "," INTPTR_FORMAT "),", p2i(i._key), p2i(i._value));
}
tty->print_cr("}");
}
//------------------------------Hashing Functions----------------------------
// Convert string to hash key. This algorithm implements a universal hash
// function with the multipliers frozen (ok, so it's not universal). The
// multipliers (and allowable characters) are all odd, so the resultant sum
// is odd - guaranteed not divisible by any power of two, so the hash tables
// can be any power of two with good results. Also, I choose multipliers
// that have only 2 bits set (the low is always set to be odd) so
// multiplication requires only shifts and adds. Characters are required to
// be in the range 0-127 (I double & add 1 to force oddness). Keys are
// limited to MAXID characters in length. Experimental evidence on 150K of
// C text shows excellent spreading of values for any size hash table.
int hashstr(const void *t) {
char c, k = 0;
int32_t sum = 0;
const char *s = (const char *)t;
while( ((c = *s++) != '\0') && (k < MAXID-1) ) { // Get characters till null or MAXID-1
c = (c<<1)+1; // Characters are always odd!
sum += c + (c<<shft[k++]); // Universal hash function
}
return (int)((sum+xsum[k]) >> 1); // Hash key, un-modulo'd table size
}
//------------------------------hashptr--------------------------------------
// Slimey cheap hash function; no guaranteed performance. Better than the
// default for pointers, especially on MS-DOS machines.
int hashptr(const void *key) {
return ((intptr_t)key >> 2);
}
// Slimey cheap hash function; no guaranteed performance.
int hashkey(const void *key) {
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