/**
* librdf_storage_find_statements - search the storage for matching statements
* @storage: &librdf_storage object
* @statement: &librdf_statement partial statement to find
*
* Searches the storage for a (partial) statement as described in
* librdf_statement_match() and returns a &librdf_stream of
* matching &librdf_statement objects.
*
* Return value: &librdf_stream of matching statements (may be empty) or NULL on failure
**/
librdf_stream*
librdf_storage_find_statements(librdf_storage* storage,
librdf_statement* statement)
{
librdf_node *subject, *predicate, *object;
librdf_iterator *iterator;
LIBRDF_ASSERT_OBJECT_POINTER_RETURN_VALUE(storage, librdf_storage, NULL);
LIBRDF_ASSERT_OBJECT_POINTER_RETURN_VALUE(statement, librdf_statement, NULL);
subject=librdf_statement_get_subject(statement);
predicate=librdf_statement_get_predicate(statement);
object=librdf_statement_get_object(statement);
/* try to pick the most efficient storage back end */
/* only subject/source field blank -> use find_sources */
if(!subject && predicate && object &&
storage->factory->find_sources) {
iterator=storage->factory->find_sources(storage, predicate, object);
if(iterator)
return librdf_new_stream_from_node_iterator(iterator, statement,
LIBRDF_STATEMENT_SUBJECT);
return NULL;
}
/* only predicate/arc field blank -> use find_arcs */
if(subject && !predicate && object &&
storage->factory->find_arcs) {
iterator=storage->factory->find_arcs(storage, subject, object);
if(iterator)
return librdf_new_stream_from_node_iterator(iterator, statement,
LIBRDF_STATEMENT_PREDICATE);
return NULL;
}
/* only object/target field blank -> use find_targets */
if(subject && predicate && !object &&
storage->factory->find_targets) {
iterator=storage->factory->find_targets(storage, subject, predicate);
if(iterator)
return librdf_new_stream_from_node_iterator(iterator, statement,
LIBRDF_STATEMENT_OBJECT);
return NULL;
}
return storage->factory->find_statements(storage, statement);
}
int
main(int argc, char *argv[])
{
librdf_statement *statement;
librdf_stream* stream;
const char *program=librdf_basename((const char*)argv[0]);
librdf_world *world;
librdf_uri* prefix_uri;
librdf_node* nodes[STREAM_NODES_COUNT];
int i;
librdf_iterator* iterator;
int count;
world=librdf_new_world();
librdf_world_open(world);
prefix_uri=librdf_new_uri(world, (const unsigned char*)NODE_URI_PREFIX);
if(!prefix_uri) {
fprintf(stderr, "%s: Failed to create prefix URI\n", program);
return(1);
}
for(i=0; i < STREAM_NODES_COUNT; i++) {
unsigned char buf[2];
buf[0]='a'+i;
buf[1]='\0';
nodes[i]=librdf_new_node_from_uri_local_name(world, prefix_uri, buf);
if(!nodes[i]) {
fprintf(stderr, "%s: Failed to create node %i (%s)\n", program, i, buf);
return(1);
}
}
fprintf(stdout, "%s: Creating static node iterator\n", program);
iterator = librdf_node_new_static_node_iterator(world, nodes, STREAM_NODES_COUNT);
if(!iterator) {
fprintf(stderr, "%s: Failed to create static node iterator\n", program);
return(1);
}
statement=librdf_new_statement_from_nodes(world,
librdf_new_node_from_uri_string(world, (const unsigned char*)"http://example.org/resource"),
librdf_new_node_from_uri_string(world, (const unsigned char*)"http://example.org/property"),
NULL);
if(!statement) {
fprintf(stderr, "%s: Failed to create statement\n", program);
return(1);
}
fprintf(stdout, "%s: Creating stream from node iterator\n", program);
stream=librdf_new_stream_from_node_iterator(iterator, statement, LIBRDF_STATEMENT_OBJECT);
if(!stream) {
fprintf(stderr, "%s: Failed to createstatic node stream\n", program);
return(1);
}
/* This is to check that the stream_from_node_iterator code
* *really* takes a copy of what it needs from statement
*/
fprintf(stdout, "%s: Freeing statement\n", program);
librdf_free_statement(statement);
fprintf(stdout, "%s: Listing static node stream\n", program);
count=0;
while(!librdf_stream_end(stream)) {
librdf_statement* s_statement=librdf_stream_get_object(stream);
if(!s_statement) {
fprintf(stderr, "%s: librdf_stream_current returned NULL when not end of stream\n", program);
return(1);
}
fprintf(stdout, "%s: statement %d is: ", program, count);
librdf_statement_print(s_statement, stdout);
fputc('\n', stdout);
librdf_stream_next(stream);
count++;
}
if(count != STREAM_NODES_COUNT) {
fprintf(stderr, "%s: Stream returned %d statements, expected %d\n", program,
count, STREAM_NODES_COUNT);
return(1);
}
fprintf(stdout, "%s: stream from node iterator worked ok\n", program);
fprintf(stdout, "%s: Freeing stream\n", program);
librdf_free_stream(stream);
fprintf(stdout, "%s: Freeing nodes\n", program);
for (i=0; i<STREAM_NODES_COUNT; i++) {
librdf_free_node(nodes[i]);
}
librdf_free_uri(prefix_uri);
librdf_free_world(world);
/* keep gcc -Wall happy */
return(0);
}
