/**
* librdf_storage_find_statements_in_context - search the storage for matching statements in a given context
* @storage: &librdf_storage object
* @statement: &librdf_statement partial statement to find
* @context_node: context &librdf_node (or NULL)
*
* Searches the storage for a (partial) statement as described in
* librdf_statement_match() in the given context and returns a
* &librdf_stream of matching &librdf_statement objects. If
* context is NULL, this is equivalent to librdf_storage_find_statements.
*
* Return value: &librdf_stream of matching statements (may be empty) or NULL on failure
**/
librdf_stream*
librdf_storage_find_statements_in_context(librdf_storage* storage, librdf_statement* statement, librdf_node* context_node)
{
librdf_stream *stream;
LIBRDF_ASSERT_OBJECT_POINTER_RETURN_VALUE(storage, librdf_storage, NULL);
LIBRDF_ASSERT_OBJECT_POINTER_RETURN_VALUE(statement, librdf_statement, NULL);
if(storage->factory->find_statements_in_context)
return storage->factory->find_statements_in_context(storage, statement, context_node);
stream=librdf_storage_context_as_stream(storage, context_node);
if(!stream)
return NULL;
librdf_stream_add_map(stream,
&librdf_stream_statement_find_map,
(librdf_stream_map_free_context_handler)&librdf_free_statement, (void*)statement);
return stream;
}
static librdf_stream*
librdf_storage_trees_serialise_range(librdf_storage* storage, librdf_statement* range)
{
librdf_storage_trees_instance* context=(librdf_storage_trees_instance*)storage->instance;
librdf_storage_trees_serialise_stream_context* scontext;
librdf_stream* stream;
int filter = 0;
scontext=(librdf_storage_trees_serialise_stream_context*)LIBRDF_CALLOC(librdf_storage_trees_serialise_stream_context, 1, sizeof(librdf_storage_trees_serialise_stream_context));
if(!scontext)
return NULL;
scontext->iterator = NULL;
/* ?s ?p ?o */
if (!range || (!range->subject && !range->predicate && !range->object)) {
scontext->iterator=librdf_avltree_get_iterator_start(storage->world, context->graph->spo_tree,
NULL, NULL);
if (range) {
librdf_free_statement(range);
range=NULL;
}
/* s ?p o */
} else if (range->subject && !range->predicate && range->object) {
if (context->index_sop)
scontext->iterator=librdf_avltree_get_iterator_start(storage->world, context->graph->sop_tree,
range, librdf_storage_trees_avl_free);
else
filter=1;
/* s _ _ */
} else if (range->subject) {
scontext->iterator=librdf_avltree_get_iterator_start(storage->world, context->graph->spo_tree,
range, librdf_storage_trees_avl_free);
/* ?s _ o */
} else if (range->object) {
if (context->index_ops)
scontext->iterator=librdf_avltree_get_iterator_start(storage->world, context->graph->ops_tree,
range, librdf_storage_trees_avl_free);
else
filter=1;
/* ?s p ?o */
} else { /* range->predicate != NULL */
if (context->index_pso)
scontext->iterator=librdf_avltree_get_iterator_start(storage->world, context->graph->pso_tree,
range, librdf_storage_trees_avl_free);
else
filter=1;
}
/* If filter is set, we're missing the required index.
* Iterate over the entire model and filter the stream.
* (With a fully indexed store, this will never happen) */
if (filter) {
scontext->iterator=librdf_avltree_get_iterator_start(storage->world, context->graph->spo_tree,
range, librdf_storage_trees_avl_free);
}
#ifdef RDF_STORAGE_TREES_WITH_CONTEXTS
scontext->context_node=NULL;
#endif
if(!scontext->iterator) {
LIBRDF_FREE(librdf_storage_trees_serialise_stream_context, scontext);
return librdf_new_empty_stream(storage->world);
}
scontext->storage=storage;
librdf_storage_add_reference(scontext->storage);
stream=librdf_new_stream(storage->world,
(void*)scontext,
&librdf_storage_trees_serialise_end_of_stream,
&librdf_storage_trees_serialise_next_statement,
&librdf_storage_trees_serialise_get_statement,
&librdf_storage_trees_serialise_finished);
if(!stream) {
librdf_storage_trees_serialise_finished((void*)scontext);
return NULL;
}
if(filter) {
if(librdf_stream_add_map(stream, &librdf_stream_statement_find_map, NULL, (void*)range)) {
/* error - stream_add_map failed */
librdf_free_stream(stream);
stream=NULL;
}
}
return stream;
}
