001    // Copyright 2005 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    
015    package org.apache.tapestry.util;
016    
017    import org.apache.hivemind.Location;
018    import org.apache.hivemind.Resource;
019    import org.apache.hivemind.util.Defense;
020    
021    /**
022     * Implementation of {@link org.apache.hivemind.Location} that is used to describe a location within
023     * a resource. This is used when the location within the resource can't be expressed as a line and
024     * column. One example is for setting the location of an annotation. This is useful for line-precise
025     * exception reporting of errors related to annotations.
026     * 
027     * @author Howard Lewis Ship
028     * @since 4.0
029     */
030    public class DescribedLocation implements Location
031    {
032        private final Resource _resource;
033    
034        private final String _description;
035    
036        public DescribedLocation(Resource resource, String description)
037        {
038            Defense.notNull(resource, "resource");
039            Defense.notNull(description, "description");
040    
041            _resource = resource;
042            _description = description;
043        }
044    
045        /**
046         * Returns the description provided in the constructor.
047         */
048    
049        public String toString()
050        {
051            return _description;
052        }
053    
054        /**
055         * Returns the resource provided in the constructor.
056         */
057    
058        public Resource getResource()
059        {
060            return _resource;
061        }
062    
063        /**
064         * Always returns 0.
065         */
066    
067        public int getLineNumber()
068        {
069            return 0;
070        }
071    
072        /**
073         * Always returns 0.
074         */
075    
076        public int getColumnNumber()
077        {
078            return 0;
079        }
080    
081        /**
082         * A DescribedLocation is equal to another only if their resources are equal, and their
083         * descriptions are equal.
084         */
085        public boolean equals(Object other)
086        {
087            if (other instanceof DescribedLocation)
088            {
089                DescribedLocation otherLocation = (DescribedLocation) other;
090    
091                return _resource.equals(otherLocation._resource)
092                        && _description.equals(otherLocation._description);
093            }
094    
095            return false;
096        }
097    }