//FindStatements creates a channel used to iterate the set of statements in the model that matched the given partial statement
// bufferSize indicates how many statements can be on the channel at one time
func (model *Model) FindStatements(partialStatement *Statement, bufferSize int) chan *Statement {
chanStatement := make(chan *Statement, bufferSize)
go func() {
stream := C.librdf_model_find_statements(model.librdf_model, partialStatement.librdf_statement)
var librdfStatement *C.librdf_statement
var statement *Statement
var err error
var endOfStream C.int
if stream == nil {
panic(errors.New("librdf returned null stream"))
} else {
endOfStream = C.librdf_stream_end(stream)
for endOfStream == 0 {
if librdfStatement = C.librdf_stream_get_object(stream); librdfStatement == nil {
panic(errors.New("librdf returned null statement"))
}
if statement, err = NewStatement(model.world); err != nil {
panic(errors.New("Unable to create statement"))
}
statement.librdf_statement = librdfStatement
chanStatement <- statement
C.librdf_stream_next(stream)
endOfStream = C.librdf_stream_end(stream)
}
C.librdf_free_stream(stream)
}
close(chanStatement)
}()
return chanStatement
}
//ExecuteQueryToFormattedString executes a query and serializes the results to a string in the format provided
func (model *Model) ExecuteQueryToFormattedString(query *Query, format string) (string, error) {
var librdf_query *C.librdf_query
cQueryString := C.CString(query.queryString)
if cQueryString != nil {
defer C.free(unsafe.Pointer(cQueryString))
}
cName := C.CString(query.name)
if cName != nil {
defer C.free(unsafe.Pointer(cName))
}
cFormat := C.CString(format)
if cFormat != nil {
defer C.free(unsafe.Pointer(cFormat))
}
librdf_query = C.librdf_new_query(query.world.librdf_world, (*C.char)(unsafe.Pointer(cName)), nil, (*C.uchar)(unsafe.Pointer(cQueryString)), nil)
if librdf_query == nil {
return "", errors.New("Unable to create query for execution")
}
results := C.librdf_model_query_execute(model.librdf_model, librdf_query)
if results == nil {
return "", errors.New("Failed to execute query")
}
var cFormattedString *C.uchar
isBindings := C.librdf_query_results_is_bindings(results)
isBoolean := C.librdf_query_results_is_boolean(results)
if isBindings == 0 || isBoolean == 0 {
cFormattedString = C.librdf_query_results_to_string2(results, (*C.char)(unsafe.Pointer(cFormat)), nil, nil, nil)
} else {
var serializer *C.librdf_serializer
if serializer = C.librdf_new_serializer(query.world.librdf_world, (*C.char)(unsafe.Pointer(cFormat)), nil, nil); serializer == nil {
return "", errors.New("Failed to build serializer")
}
defer C.librdf_free_serializer(serializer)
var stream *C.librdf_stream
if stream = C.librdf_query_results_as_stream(results); stream == nil {
return "", errors.New("Failed to build stream from results")
}
defer C.librdf_free_stream(stream)
cFormattedString = C.librdf_serializer_serialize_stream_to_string(serializer, nil, stream)
}
if cFormattedString == nil {
return "", errors.New("Failed to build formatted string from results")
}
defer C.free(unsafe.Pointer(cFormattedString))
formattedString := C.GoString((*C.char)(unsafe.Pointer(cFormattedString)))
return formattedString, nil
}