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Incorrect handling for undefined, empty prefixes in N3 deserialization #312

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jsalonen opened this issue Jul 12, 2013 · 3 comments
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@jsalonen
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As mentioned in Stackoverflow.com question, RDFLib incorrectly handles undefined, empty prefixes when deserializing them from N3:

http://stackoverflow.com/questions/17616463/error-in-serializing-notation3-file-into-rdfxml-format-in-python

N3 specification defines the following:

The empty prefix "" is by default , bound to "#" -- the local namespace of the file. The parser behaves as though there were a
@prefix : <#>.

However, as a current behavior the parser raises an error:

rdflib.plugins.parsers.notation3.BadSyntax: at line 5 of <>:

Would you consider this something that could/should be fixed?

@gromgull
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hi sorry for the late reply. Where in the N3 spec is this defined? There is no mention of it here:

http://www.w3.org/DesignIssues/Notation3

Nor in the turtle spec?

We stole the n3 parser from cwm - I had hoped they would get the corner cases right :)

@gromgull
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Never mind, it was linked in the stack overflow post:

http://www.w3.org/TeamSubmission/n3/#namespaces

I guess this IS a bug, it's a shame it is not aligned in N3 and Turtle though.

@jsalonen
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Yeah this blows :(

Is there anything I can do that would help here?

mamash pushed a commit to TritonDataCenter/pkgsrc-wip that referenced this issue Feb 15, 2014
	2013/12/31 RELEASE 4.1
======================

This is a new minor version RDFLib, which includes a handful of new features:

* A TriG parser was added (we already had a serializer) - it is
  up-to-date wrt. to the newest spec from: http://www.w3.org/TR/trig/

* The Turtle parser was made up to date wrt. to the latest Turtle spec.

* Many more tests have been added - RDFLib now has over 2000
  (passing!) tests. This is mainly thanks to the NT, Turtle, TriG,
  NQuads and SPARQL test-suites from W3C. This also included many
  fixes to the nt and nquad parsers.

* ```ConjunctiveGraph``` and ```Dataset``` now support directly adding/removing
  quads with ```add/addN/remove``` methods.

* ```rdfpipe``` command now supports datasets, and reading/writing context
  sensitive formats.

* Optional graph-tracking was added to the Store interface, allowing
  empty graphs to be tracked for Datasets. The DataSet class also saw
  a general clean-up, see: RDFLib/rdflib#309

* After long deprecation, ```BackwardCompatibleGraph``` was removed.

Minor enhancements/bugs fixed:
------------------------------

* Many code samples in the documentation were fixed thanks to @PuckCh

* The new ```IOMemory``` store was optimised a bit

* ```SPARQL(Update)Store``` has been made more generic.

* MD5 sums were never reinitialized in ```rdflib.compare```

* Correct default value for empty prefix in N3
  [#312]RDFLib/rdflib#312

* Fixed tests when running in a non UTF-8 locale
  [#344]RDFLib/rdflib#344

* Prefix in the original turtle have an impact on SPARQL query
  resolution
  [#313]RDFLib/rdflib#313

* Duplicate BNode IDs from N3 Parser
  [#305]RDFLib/rdflib#305

* Use QNames for TriG graph names
  [#330]RDFLib/rdflib#330

* \uXXXX escapes in Turtle/N3 were fixed
  [#335]RDFLib/rdflib#335

* A way to limit the number of triples retrieved from the
  ```SPARQLStore``` was added
  [#346]RDFLib/rdflib#346

* Dots in localnames in Turtle
  [#345]RDFLib/rdflib#345
  [#336]RDFLib/rdflib#336

* ```BNode``` as Graph's public ID
  [#300]RDFLib/rdflib#300

* Introduced ordering of ```QuotedGraphs```
  [#291]RDFLib/rdflib#291

2013/05/22 RELEASE 4.0.1
========================

Following RDFLib tradition, some bugs snuck into the 4.0 release.
This is a bug-fixing release:

* the new URI validation caused lots of problems, but is
  nescessary to avoid ''RDF injection'' vulnerabilities. In the
  spirit of ''be liberal in what you accept, but conservative in
  what you produce", we moved validation to serialisation time.

* the   ```rdflib.tools```   package    was   missing   from   the
  ```setup.py```  script, and  was therefore  not included  in the
  PYPI tarballs.

* RDF parser choked on empty namespace URI
  [#288](RDFLib/rdflib#288)

* Parsing from ```sys.stdin``` was broken
  [#285](RDFLib/rdflib#285)

* The new IO store had problems with concurrent modifications if
  several graphs used the same store
  [#286](RDFLib/rdflib#286)

* Moved HTML5Lib dependency to the recently released 1.0b1 which
  support python3

2013/05/16 RELEASE 4.0
======================

This release includes several major changes:

* The new SPARQL 1.1 engine (rdflib-sparql) has been included in
  the core distribution. SPARQL 1.1 queries and updates should
  work out of the box.

  * SPARQL paths are exposed as operators on ```URIRefs```, these can
    then be be used with graph.triples and friends:

    ```py
    # List names of friends of Bob:
    g.triples(( bob, FOAF.knows/FOAF.name , None ))

    # All super-classes:
    g.triples(( cls, RDFS.subClassOf * '+', None ))
    ```

      * a new ```graph.update``` method will apply SPARQL update statements

* Several RDF 1.1 features are available:
  * A new ```DataSet``` class
  * ```XMLLiteral``` and ```HTMLLiterals```
  * ```BNode``` (de)skolemization is supported through ```BNode.skolemize```,
    ```URIRef.de_skolemize```, ```Graph.skolemize``` and ```Graph.de_skolemize```

* Handled of Literal equality was split into lexical comparison
  (for normal ```==``` operator) and value space (using new ```Node.eq```
  methods). This introduces some slight backwards incomaptible
  changes, but was necessary, as the old version had
  inconsisten hash and equality methods that could lead the
  literals not working correctly in dicts/sets.
  The new way is more in line with how SPARQL 1.1 works.
  For the full details, see:

  https://github.com/RDFLib/rdflib/wiki/Literal-reworking

* Iterating over ```QueryResults``` will generate ```ResultRow``` objects,
  these allow access to variable bindings as attributes or as a
  dict. I.e.

  ```py
  for row in graph.query('select ... ') :
     print row.age, row["name"]
  ```

* "Slicing" of Graphs and Resources as syntactic sugar:
  ([#271](RDFLib/rdflib#271))

  ```py
  graph[bob : FOAF.knows/FOAF.name]
            -> generator over the names of Bobs friends
  ```

* The ```SPARQLStore``` and ```SPARQLUpdateStore``` are now included
  in the RDFLib core

* The documentation has been given a major overhaul, and examples
  for most features have been added.


Minor Changes:
--------------

* String operations on URIRefs return new URIRefs: ([#258](RDFLib/rdflib#258))
  ```py
  >>> URIRef('http://example.org/')+'test
  rdflib.term.URIRef('http://example.org/test')
  ```

* Parser/Serializer plugins are also found by mime-type, not just
  by plugin name:  ([#277](RDFLib/rdflib#277))
* ```Namespace``` is no longer a subclass of ```URIRef```
* URIRefs and Literal language tags are validated on construction,
  avoiding some "RDF-injection" issues ([#266](RDFLib/rdflib#266))
* A new memory store needs much less memory when loading large
  graphs ([#268](RDFLib/rdflib#268))
* Turtle/N3 serializer now supports the base keyword correctly ([#248](RDFLib/rdflib#248))
* py2exe support was fixed ([#257](RDFLib/rdflib#257))
* Several bugs in the TriG serializer were fixed
* Several bugs in the NQuads parser were fixed
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