[Rdfapi-php-interest] N3 parser bugfix: lone semicolons

[Richard C. <ri...@cy...>]

Hi,

The N3 parser has a bug that causes broken triples in cases like this:

    <foo>
       :bar "bar";
       :baz "baz";
       .

The last statement (<foo> :baz "baz") is terminated by a semicolon  
*and* a dot. This is legal in N3, and in fact quite common because  
that way you can't mix up the end-of-line punctuation.

RAP's parser doesn't recognize this, sees a third triple with a null  
predicate and object, and generates two notices.

Here's a test case for /test/unit/Syntax/n3Parser_test.php that  
catches the bug:

         function testLoneSemicolon() {
             $n3 = '<a> <b> <c> ; .';
             $parser = &new N3Parser();
             $model = &$parser->parse2model($n3, false);
             $this->assertEqual(1, $model->size());
             $this->assertNoErrors();
         }

Here's the fix for /api/syntax/N3Parser.php . I've added two lines to  
the getPovs method, it's the comment line and the one after.

   function getPovs($list) {
     $povs = array();
     while (in_array(';', $list)) {
       $r=$this->posns($list,';');
       $pos=array_slice($r,0,2);
       $r = $this->getSpan($list, $pos[0], $pos[1]);
       $pov=$r[0];
       $list=$r[1];

       // skip lone semicolons, e.g. "<a> <b> <c> ; ."
       if (count($pov) == 1) continue;

       $povs[]=array_slice($pov,1);
     }

Best,
Richard