001// Copyright 2008, 2010 The Apache Software Foundation
002//
003// Licensed under the Apache License, Version 2.0 (the "License");
004// you may not use this file except in compliance with the License.
005// You may obtain a copy of the License at
006//
007// http://www.apache.org/licenses/LICENSE-2.0
008//
009// Unless required by applicable law or agreed to in writing, software
010// distributed under the License is distributed on an "AS IS" BASIS,
011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012// See the License for the specific language governing permissions and
013// limitations under the License.
014
015package org.apache.tapestry5.internal;
016
017import java.util.Optional;
018
019import org.apache.tapestry5.EventContext;
020import org.apache.tapestry5.commons.util.CommonsUtils;
021
022/**
023 * Placeholder used when no context is available.
024 */
025public class EmptyEventContext implements EventContext
026{
027    /**
028     * Always returns zero.
029     */
030    public int getCount()
031    {
032        return 0;
033    }
034
035    /**
036     * This should never be called because the count is always zero.
037     */
038    public <T> T get(Class<T> desiredType, int index)
039    {
040        return null;
041    }
042
043    public String[] toStrings()
044    {
045        return CommonsUtils.EMPTY_STRING_ARRAY;
046    }
047
048    @Override
049    public boolean isEmpty()
050    {
051        return true;
052    }
053
054    @Override
055    public <T> Optional<T> tryGet(Class<T> desiredType, int index)
056    {
057        return Optional.empty();
058    }
059}