On 27/05/11 10:38, Andy Seaborne wrote:
On 26/05/11 15:37, Laurent Pellegrino wrote:
Hi all,
I am using FmtUtils.stringForNode(...) from ARQ to encode a Node to a
String. Now, I have to perform the reverse operation: from the String
I want to create the Node. Is there a class and method to do that from
the ARQ library?
It seems that NodecLib.decode(...) do the trick but it is in the TDB
library and I am not sure that it works with any output from
FmtUtils.stringForNode(...)?
Kind Regards,
Laurent
There are ways to reverse the process - too many in fact.
Simple: SSE.parseNode: String -> Node
It uses a javacc parser so the overall efficiency isn't ideal.
But RIOT is in the process of reworking I/O for efficiency; the input
side is the area that is most finished. The tokenizer will do what you
want.
What's missing in RIOT is Node to stream writing without using FmtUtils
-- this is OutputLangUtils which is unfinished. FmtUtils creates
intermediate strings, when the output could be straight to a stream,
avoiding a copy and the temporary object allocation.
The Tokenizer is:
interface Tokenizer extends Iterator<Token>
and see org.openjena.riot.tokens.TokenizerFactory
especially if you have a sequence of them to parse ... like a TSV file.
But you will have to manage newlines as to the tokenizer they are
whitespace like anything else.
This does not stop Tokenizer being used as-is because you can check the
line number with Tokenizer.getLine() When it changes, you're on a new
line of the TSV file.
Andy
There is some stuff in my scratch area for streams of tuples of RDF
terms and variables:
https://svn.apache.org/repos/asf/incubator/jena/Scratch/AFS/trunk/src/riot/io/
TokenInputStream and TokenOutputStream might be useful.
Until TSV, a tuple of terms is a number of RDF terms, terminated by a
DOT (not newline).
This could be useful to JENA-44, JENA-45 and JENA-69
I'm keen that we create a single solid I/O layer so it can teste and
optimized then shared amongst all the code doing I/O related things.
Nodec is an interface specializes attempt to ByteBuffers for file, not
stream I/O. File I/O can be random access.
Andy
