6 #define COLUMN def->columns
9 * This callback function returns the hashcode of a key.
11 * \param this is a pointer to the itemkeyfun record from where this
12 * callback got invoked
14 * \param key is the key to produce a hascode for
16 * \returns the hashcode which is a vector_index (i.e. unsigned long)
18 * The hashcode is used for indexing into the backing vector for
19 * finding the an item via its key. The same key must map consistently
20 * to the same hashcode while the hashtable contains an item with that
21 * key. Different keys map map to the same hashcode, in which case the
22 * vector placement is made at the first empty or hole slot following
25 static unsigned long tupleitem_hashcode(void *this,void *key) {
26 tupleschema *def = (tupleschema *) this;
27 tuple *kp = (tuple*) key;
29 unsigned long value = 5381;
30 for ( ; i < def->arity; i++ ) {
34 value += COLUMN[i]->hashcode( COLUMN[i], (*kp)[i] );
44 * This callback function determines whether an item has a
47 static int tupleitem_haskey(void *this,void *item,void *key) {
48 tupleschema *def = (tupleschema *) this;
49 tuple *kp = (tuple*) key;
50 tuple *tp = (tuple*) item;
52 for ( ; i < def->arity; i++ ) {
53 if ( COLUMN[i] && (*kp)[i] ) {
54 if ( COLUMN[i]->haskey( COLUMN[i], (*tp)[i], (*kp)[i] ) == 0 ) {
64 * This callback function returns the key of an item by considering
67 static void *tupleitem_itemkey(void *this,void *item) {
68 tupleschema *def = (tupleschema *) this;
69 tuple *tp = (tuple*) item;
72 for ( i = 0 ; i < def->arity; i++ ) {
77 void **parts = calloc( keylen, sizeof( void* ) );
78 for ( i = 0, j = 0; i < def->arity; i++ ) {
80 parts[j++] = COLUMN[i]->itemkey( COLUMN[i], (*tp)[i] );
87 * This callback function handles a key obtained from the itemkey
88 * callback function to reclaim temporary allocation.
90 static void tupleitem_releasekey(void *this,void *key) {
91 tupleschema *def = (tupleschema *) this;
92 tuple *kp = (tuple*) key;
94 for ( i = 0, j = 0; i < def->arity; i++ ) {
96 COLUMN[i]->releasekey( COLUMN[i], (*kp)[j++] );
102 #define OUT(X) a = X; if ( a > limit ) return 0; buffer += a; limit -= a
105 * This callback function writes a representation of an item into
106 * a character buffer.
108 static int tupleitem_tostring(void *this,void *item,char *buffer,int limit) {
109 tupleschema *def = (tupleschema *) this;
110 tuple *t = (tuple*) item;
113 for ( i = 0; i < def->arity; i++ ) {
114 OUT( snprintf( buffer, limit, x ) );
116 OUT( def->columns[i]->tostring(
117 def->columns[i], (*t)[i], buffer, limit ) );
119 OUT( snprintf( buffer, limit, ">" ) );
125 tuple *tuple_create(int arity,...) {
128 tuple *t = (tuple *)malloc( arity * sizeof( void* ) );
129 va_start( ap, arity );
130 for ( i = 0; i < arity; i++ ) {
131 (*t)[i] = va_arg( ap, void* );
137 itemkeyfun tupleschema_callbacks = {
138 .hashcode = tupleitem_hashcode,
139 .haskey = tupleitem_haskey,
140 .itemkey = tupleitem_itemkey,
141 .releasekey = tupleitem_releasekey,
142 .tostring = tupleitem_tostring
145 tupleschema *tupleschema_create(int arity,tuple *columns) {
146 tupleschema *ts = (tupleschema*) malloc( sizeof( tupleschema ) );
147 (*ts) = (tupleschema) {
148 .base = tupleschema_callbacks,
150 .columns = (itemkeyfun**) columns
155 #define COPYA(T,P,N) (T*) memcpy( malloc( N * sizeof(T) ), P, N * sizeof( T ) )
156 #define COPY(T,P) COPYA(T,P,1)
158 // Duplicate a tupleschema with optionally some columns reset.
159 tupleschema *tupleschema_mask(tupleschema *schema,...) {
160 tupleschema *masked = COPY(tupleschema,schema);
161 masked->columns = COPYA( itemkeyfun*, schema->columns, schema->arity );
164 va_start( ap, schema );
166 i = va_arg( ap, int );
167 if ( i < 0 || i >= schema->arity ) {
170 masked->columns[i] = 0;
176 unsigned long tuple_mask(int arity,tuple *t) {
177 unsigned long mask = 0;
178 while ( arity-- > 0 ) {
180 if ( (*t)[ arity ] ) {