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<?php
/*
* (c) Markus Lanthaler <mail@markus-lanthaler.com>
*
* For the full copyright and license information, please view the LICENSE
* file that was distributed with this source code.
*/
namespace ML\JsonLD;
use ML\JsonLD\Exception\InvalidQuadException;
use ML\IRI\IRI;
/**
* NQuads serializes quads to the NQuads format
*
* @author Markus Lanthaler <mail@markus-lanthaler.com>
*/
class NQuads implements QuadSerializerInterface, QuadParserInterface
{
/**
* {@inheritdoc}
*/
public function serialize(array $quads)
{
$result = '';
foreach ($quads as $quad) {
$result .= ('_' === $quad->getSubject()->getScheme())
? $quad->getSubject()
: '<' . $quad->getSubject() . '>';
$result .= ' ';
$result .= ('_' === $quad->getProperty()->getScheme())
? $quad->getProperty()
: '<' . $quad->getProperty() . '>';
$result .= ' ';
if ($quad->getObject() instanceof IRI) {
$result .= ('_' === $quad->getObject()->getScheme())
? $quad->getObject()
: '<' . $quad->getObject() . '>';
} else {
$result .= '"' . str_replace(
array("\n", '"'),
array('\n', '\"'),
$quad->getObject()->getValue()) . '"';
$result .= ($quad->getObject() instanceof TypedValue)
? (RdfConstants::XSD_STRING === $quad->getObject()->getType())
? ''
: '^^<' . $quad->getObject()->getType() . '>'
: '@' . $quad->getObject()->getLanguage();
}
$result .= ' ';
if ($quad->getGraph()) {
$result .= ('_' === $quad->getGraph()->getScheme())
? $quad->getGraph() :
'<' . $quad->getGraph() . '>';
$result .= ' ';
}
$result .= ".\n";
}
return $result;
}
/**
* {@inheritdoc}
*
* This method is heavily based on DigitalBazaar's implementation used
* in their {@link https://github.com/digitalbazaar/php-json-ld php-json-ld}.
*
* @throws InvalidQuadException If an invalid quad that can't be parsed is
* encountered.
*/
public function parse($input)
{
// define partial regexes
$iri = '(?:<([^>]*)>)';
// blank node labels based on https://www.w3.org/TR/n-quads/#BNodes
$bnode = '(_:(?:[A-Za-z0-9_]|[A-Za-z0-9_][A-Za-z0-9_\-.]*[A-Za-z0-9_\-]))';
$plain = '"([^"\\\\]*(?:\\\\.[^"\\\\]*)*)"';
$datatype = "\\^\\^$iri";
$language = '(?:@([a-z]+(?:-[a-z0-9]+)*))';
$literal = "(?:$plain(?:$datatype|$language)?)";
$ws = '[ \\t]';
$comment = "#.*";
$subject = "(?:$iri|$bnode)$ws+";
$property = "$iri$ws+";
$object = "(?:$iri|$bnode|$literal)";
$graph = "$ws+(?:$iri|$bnode)";
// full regexes
$eoln = '/(?:(\r\n)|[\n\r])/';
$quadRegex = "/^$ws*$subject$property$object$graph?$ws*.$ws*$/";
$ignoreRegex = "/^$ws*(?:$comment)?$/";
// build RDF statements
$statements = array();
// split N-Quad input into lines
$lines = preg_split($eoln, $input);
$line_number = 0;
foreach ($lines as $line) {
$line_number++;
// skip empty lines
if (preg_match($ignoreRegex, $line)) {
continue;
}
// parse quad
if (!preg_match($quadRegex, $line, $match)) {
throw new InvalidQuadException(
sprintf(
'Error while parsing N-Quads. Invalid quad in line %d: %s',
$line_number,
$line
),
$line
);
}
// get subject
if ($match[1] !== '') {
$subject = new IRI($match[1]);
} else {
$subject = new IRI($match[2]);
}
// get property
$property = new IRI($match[3]);
// get object
if ($match[4] !== '') {
$object = new IRI($match[4]); // IRI
} elseif ($match[5] !== '') {
$object = new IRI($match[5]); // bnode
} else {
$unescaped = str_replace(
array('\"', '\t', '\n', '\r', '\\\\'),
array('"', "\t", "\n", "\r", '\\'),
$match[6]
);
if (isset($match[7]) && $match[7] !== '') {
$object = new TypedValue($unescaped, $match[7]);
} elseif (isset($match[8]) && $match[8] !== '') {
$object = new LanguageTaggedString($unescaped, $match[8]);
} else {
$object = new TypedValue($unescaped, RdfConstants::XSD_STRING);
}
}
// get graph
$graph = null;
if (isset($match[9]) && $match[9] !== '') {
$graph = new IRI($match[9]);
} elseif (isset($match[10]) && $match[10] !== '') {
$graph = new IRI($match[10]);
}
$quad = new Quad($subject, $property, $object, $graph);
// TODO Make sure that quads are unique??
$statements[] = $quad;
}
return $statements;
}
}
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