001// --------------------------------------------------------------------------------
002// Copyright 2002-2024 Echo Three, LLC
003//
004// Licensed under the Apache License, Version 2.0 (the "License");
005// you may not use this file except in compliance with the License.
006// You may obtain a copy of the License at
007//
008//     http://www.apache.org/licenses/LICENSE-2.0
009//
010// Unless required by applicable law or agreed to in writing, software
011// distributed under the License is distributed on an "AS IS" BASIS,
012// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013// See the License for the specific language governing permissions and
014// limitations under the License.
015// --------------------------------------------------------------------------------
016
017package com.echothree.model.control.sequence.server.logic.checksum;
018
019import org.apache.commons.lang.StringUtils;
020
021public class NoneSequenceChecksum
022        implements SequenceChecksum {
023
024    private NoneSequenceChecksum() {
025        super();
026    }
027
028    private static class SequenceChecksumHolder {
029        static SequenceChecksum instance = new NoneSequenceChecksum();
030    }
031
032    public static SequenceChecksum getInstance() {
033        return SequenceChecksumHolder.instance;
034    }
035
036    @Override
037    public String calculate(String value) {
038        return StringUtils.EMPTY;
039    }
040
041    @Override
042    public String regexp() {
043        return StringUtils.EMPTY;
044    }
045
046    @Override
047    public boolean verify(String value) {
048        return true;
049    }
050
051}