LiteralImpl.php

<?php

/*
 * This file is part of Saft.
 *
 * (c) Konrad Abicht <hi@inspirito.de>
 * (c) Natanael Arndt <arndt@informatik.uni-leipzig.de>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace Saft\Rdf;

class LiteralImpl extends AbstractLiteral
{
    /**
     * @var string
     */
    protected static $xsdString = 'http://www.w3.org/2001/XMLSchema#string';

    /**
     * @var string
     */
    protected static $rdfLangString = 'http://www.w3.org/1999/02/22-rdf-syntax-ns#langString';

    /**
     * @var string
     */
    protected $value;

    /**
     * @var Node
     */
    protected $datatype = null;

    /**
     * @var string
     */
    protected $lang = null;

    /**
     * @param string    $value    The Literal value
     * @param NamedNode $datatype The datatype of the Literal (respectively defaults to xsd:string or rdf:langString)
     * @param string    $lang     The language tag of the Literal (optional)
     */
    public function __construct($value, NamedNode $datatype = null, $lang = null)
    {
        if ($value === null) {
            throw new \Exception('Literal value can\'t be null. Please use AnyPattern if you need a variable.');
        } elseif (!is_string($value)) {
            throw new \Exception('The literal value has to be of type string');
        }

        $this->value = $value;

        if ($lang !== null) {
            $this->lang = (string) $lang;
        }

        if (
            $lang !== null &&
            $lang !== '' &&
            $datatype !== null &&
            $datatype->isNamed() &&
            $datatype->getUri() !== self::$rdfLangString
        ) {
            throw new \Exception('Language tagged Literals must have <'.self::$rdfLangString.'> datatype.');
        }

        if (
            ($lang === null || $lang == '') &&
            $datatype !== null &&
            $datatype->isNamed() &&
            $datatype->getUri() === self::$rdfLangString
        ) {
            throw new \Exception('No or empty Language Tag for Literals with <'.self::$rdfLangString.'> datatype.');
        }

        if ($datatype !== null) {
            $this->datatype = $datatype;
        } elseif ($lang !== null) {
            $this->datatype = new NamedNodeImpl(self::$rdfLangString);
        } else {
            $this->datatype = new NamedNodeImpl(self::$xsdString);
        }
    }

    /**
     * @return string
     */
    public function getValue()
    {
        return $this->value;
    }

    /**
     * Get the datatype of the Literal. It can be one of the XML Schema datatypes (XSD) or anything else. If the URI is
     * needed it can be retrieved by calling ->getDatatype()->getUri().
     *
     * An overview about all XML Schema datatypes: {@url http://www.w3.org/TR/xmlschema-2/#built-in-datatypes}
     *
     * @return Node the datatype of the Literal as named node
     */
    public function getDatatype()
    {
        return $this->datatype;
    }

    /**
     * @return string|null
     */
    public function getLanguage()
    {
        return $this->lang;
    }
}