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/*

 * Copyright Aduna (http://www.aduna-software.com/) (c) 2011.

 *

 * Licensed under the Aduna BSD-style license.

 */

package org.openrdf.query.algebra.evaluation.function.string;

import org.openrdf.model.Literal;

import org.openrdf.model.Value;

import org.openrdf.model.ValueFactory;

import org.openrdf.model.vocabulary.FN;

import org.openrdf.model.vocabulary.XMLSchema;

import org.openrdf.query.algebra.evaluation.ValueExprEvaluationException;

import org.openrdf.query.algebra.evaluation.function.Function;

import org.openrdf.query.algebra.evaluation.util.QueryEvaluationUtil;

/**

 * The SPARQL built-in {@link Function} STRLEN, as defined in <a

 * href="http://www.w3.org/TR/sparql11-query/#func-strlen">SPARQL Query Language

 * for RDF</a>

 *

 * @author Jeen Broekstra

 */

public class StrLen implements Function {

    public String getURI() {

        return FN.STRING_LENGTH.toString();

    }

    public Literal evaluate(ValueFactory valueFactory, Value... args)

        throws ValueExprEvaluationException

    {

        if (args.length != 1) {

            throw new ValueExprEvaluationException("STRLEN requires 1 argument, got " + args.length);

        }

        Value argValue = args[0];

        if (argValue instanceof Literal) {

            Literal literal = (Literal)argValue;

            // strlen function accepts only string literals

            if (QueryEvaluationUtil.isStringLiteral(literal)) {

                // TODO we jump through some hoops here to get an xsd:integer

                // literal. Shouldn't createLiteral(int) return an xsd:integer

                // rather than an xsd:int?

                Integer length = literal.getLabel().length();

                return valueFactory.createLiteral(length.toString(), XMLSchema.INTEGER);

            }

            else {

                throw new ValueExprEvaluationException("unexpected input value for strlen function: " + argValue);

            }

        }

        else {

            throw new ValueExprEvaluationException("unexpected input value for strlen function: " + argValue);

        }

    }

}