001// Copyright 2006, 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.ioc;
016
017import org.apache.tapestry5.ioc.internal.util.InternalUtils;
018
019/**
020 * A wrapper that allows objects of a target type to be ordered. Each Orderable object is given a unique id and a set of
021 * pre-requisites (objects which should be ordered earlier) and post-requisites (objects which should be ordered
022 * later).
023 *
024 * @param <T>
025 */
026public class Orderable<T>
027{
028    private final String id;
029
030    private final T target;
031
032    private final String[] constraints;
033
034    /**
035     * @param id     unique identifier for the target object
036     * @param target the object to be ordered; this may also be null (in which case the id represents a placeholder)
037     */
038
039    public Orderable(String id, T target, String... constraints)
040    {
041        assert InternalUtils.isNonBlank(id);
042        this.id = id;
043        this.target = target;
044        this.constraints = constraints;
045    }
046
047    public String getId()
048    {
049        return id;
050    }
051
052    public T getTarget()
053    {
054        return target;
055    }
056
057    public String[] getConstraints()
058    {
059        return constraints;
060    }
061
062    @Override
063    public String toString()
064    {
065        StringBuilder buffer = new StringBuilder("Orderable[");
066
067        buffer.append(id);
068
069        for (String c : constraints)
070        {
071            buffer.append(" ");
072            buffer.append(c);
073        }
074
075        buffer.append(" ");
076        buffer.append(target.toString());
077        buffer.append("]");
078
079        return buffer.toString();
080    }
081}