Raptor Parser (RDF)

It provides a RDF parser using rapper command line tool from Raptor RDF parsing and serializing utility. The generated internal PHP-representations (quads, ...) are compatible to https://github.com/sweetrdf/rdfInterface and can be used together with other rdfInterface implementations, such as quickRdfIo to serialize RDF in another format, for instance.

Installation

Requirements

• PHP 8.0+
• Raptor RDF parser utility is installed (we need its rapper command line tool); its usually not part of the default installation
  • on Debian/Ubuntu: run apt-get install raptor2-utils
  • Package might be namend differently in other Linux distributions

Composer

Install it using Composer: composer require sweetrdf/quick-rdf-io-raptor.

You need an implementation of rdfInterfaces, such as quickRdf. For starters, just use composer require sweetrdf/quick-rdf

Usage

Note: We are using rdfInterface implementations from https://github.com/sweetrdf/quickRdf in the following. Make sure you installed the package before running the code.

Parsing

Parse a file:

use \quickrdf\DataFactory;
use \quickRdfIo\Raptor\Parser;

// create a file handle for a n-quads/n-triple file
$fileHandle = fopen('/path/to/n-quads-file.nq', 'r');

// init a parser instance and read file handle
$parser = new Parser(new DataFactory());
$quadsIterator = $parser->parseStream($fileHandle);

// iterate through the quads
// note: the file isn't read before, only as you iterating $quadIterator
foreach ($quadsIterator as $quad ) {
    var_dump($quad);
}

// free file handle
fclose($fileHandle);

Parse a string:

use \quickrdf\DataFactory;
use \quickRdfIo\Raptor\Parser;

$str = '_:foo <http://foo> <http://bar> .';

// init a parser instance and read RDF string
$parser = new Parser(new DataFactory());
$quadsIterator = $parser->parse($str);

// iterate through the quads
foreach ($quadsIterator as $quad ) {
    var_dump($quad);
}

Caveats and known issues

When using this class keep the following in mind:

• The Parser class is basically a wrapper around the rapper command, which means input must be prepared for further processing (may impact performance). A readable local file as source is needed as well as a local file for generated N-Quads output, which is used for the internal NQuads parser later on.

License

MIT