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Text-Functions for ldpath

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/**
 * Copyright (C) 2013 Salzburg Research.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package at.newmedialab.ldpath.model.functions.text;


import at.newmedialab.ldpath.api.backend.RDFBackend;
import at.newmedialab.ldpath.api.functions.SelectorFunction;
import com.google.common.base.Preconditions;

import java.net.URI;
import java.util.Collection;
import java.util.LinkedList;

public class StrLenFunction extends SelectorFunction {

    private static final URI dataType = URI.create("http://www.w3.org/2001/XMLSchema#integer");

    @Override
    public Collection apply(RDFBackend backend, Node context, Collection... args) throws IllegalArgumentException {
        Preconditions.checkArgument(args.length == 1, "Check usage: " + getSignature());

        LinkedList result = new LinkedList();
        for (Node node : args[0]) {
            final String stringValue = backend.stringValue(node);
            final int c = stringValue.length();
            result.add(backend.createLiteral(String.valueOf(c), null, dataType));
        }

        return result;

    }

    @Override
    public String getSignature() {
        return "fn:strlen(text: Literal) : IntegerLiteralList";
    }

    @Override
    public String getDescription() {
        return "returns the length of the given StringLiterals";
    }

    @Override
    public String getLocalName() {
        return "strlen";
    }

}