5 Relation *relation_create(TupleSchema *schema) {
6 Relation *r = (Relation *) malloc( sizeof( Relation ) );
8 .content = (HashVector) {
10 .variant = Nibble_index_levels,
14 .fill = 0, .holes = 0, .type = (ItemKeyFun*) schema
16 .constraints = (Vector) {
17 .variant = single_index_level,
25 #define COPYA(T,P,N) (T*) memcpy( malloc( N * sizeof(T) ), P, N * sizeof( T ) )
26 #define COPY(T,P) COPYA(T,P,1)
28 // Add an indexing HashVector to the Relation using the given column
29 // flags with 1 indicating key column and 0 indicating value column.
30 int relation_add_constraint(Relation *r,...) {
32 TupleSchema *ts = (TupleSchema *) r->content.type;
33 tuple *columns = (tuple*) calloc( ts->arity, sizeof( void* ) );
36 for ( ; i < ts->arity; i++ ) {
37 if ( va_arg( ap, int ) ) {
38 (*columns)[i] = ts->columns[i];
42 ts = TupleSchema_create( ts->arity, columns );
43 i = (int) r->constraints.size;
46 HashVector_create( Nibble_index_levels, (ItemKeyFun*) ts ) );
50 //============== Adding an item =============
51 // Iteration context for adding or querying a Relation
58 // Determine matches to ((Knockout*)data)->key in
59 // (HashVector*)item, optionally using ((Knockout*)data)->columns
60 // for ignoring full matches to the key tuple.
61 static int knockout_check(VectorIndex index,void *item,void *data) {
62 Knockout *kod = (Knockout*) data;
64 for ( ; i < ((HashVector*) item)->table.size; i++ ) {
65 void *old = HashVector_next( (HashVector*) item, &i, kod->item );
67 HashVector_add( &kod->knockouts, old );
73 // delete the (tuple*)item from the (HashVector*)data
74 static int knockout_delete(VectorIndex index,void *item,void *data) {
75 HashVector_delete( (HashVector*) item, data );
79 // add the (tuple*)data to the (HashVector*)item
80 static int knockout_add(VectorIndex index,void *item,void *data) {
81 HashVector_add( (HashVector*)item, data );
85 // Find and remove all collisions for a query, unless "add" is
86 // non-zero in which case the function aborts if there is any match in
88 static int knockout_clear(Knockout *this,Relation *r,tuple *item,int add) {
89 (*this) = (Knockout) {
93 .variant = Nibble_index_levels, .size = 16, .entries = 0
95 .fill = 0, .holes = 0, .type = r->content.type,
99 knockout_check( 0, &r->content, this );
101 if ( this->knockouts.fill > 0 ) {
104 // Find all constraint knockouts for addition
105 Vector_iterate( &r->constraints, 0, knockout_check, this );
107 if ( this->knockouts.fill > 0 ) {
108 // Delete them from all tables
110 for ( i = 0; i < this->knockouts.table.size; i++ ) {
111 void *t = HashVector_next( &this->knockouts, &i, 0 );
113 HashVector_delete( &r->content, t );
114 Vector_iterate( &r->constraints, 0, knockout_delete, t );
121 // add a tuple to a Relation and return a Vector of knocked out
122 // tuples, if any, or 0 otherwise.
123 Vector *relation_add(Relation *r,tuple *item) {
125 if ( knockout_clear( &data, r, item, 1 ) ) {
127 HashVector_add( &r->content, item );
128 Vector_iterate( &r->constraints, 0, knockout_add, item );
129 return HashVector_contents( &data.knockouts, single_index_level, 0 );
134 Vector *relation_delete(Relation *r,tuple *item) {
136 (void) knockout_clear( &data, r, item, 0 );
137 return HashVector_contents( &data.knockouts, single_index_level, 0 );
140 void *relation_next(Relation *r,VectorIndex *index,tuple *query) {
141 return HashVector_next( &r->content, index, query );