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(vector_index 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(vector_index 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(vector_index 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,vector_index *index,tuple *query) {
141 return hashvector_next( &r->content, index, query );