001// Copyright 2006, 2007 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.internal.services;
016
017import org.apache.tapestry5.ioc.services.MethodSignature;
018
019/**
020 * Used by {@link org.apache.tapestry5.ioc.internal.services.PipelineBuilderImpl} to analyze service interface methods
021 * against filter interface methods to find the position of the extra service parameter (in the filter method).
022 */
023public class FilterMethodAnalyzer
024{
025    private final Class serviceInterface;
026
027    FilterMethodAnalyzer(Class serviceInterface)
028    {
029        this.serviceInterface = serviceInterface;
030    }
031
032    public int findServiceInterfacePosition(MethodSignature ms, MethodSignature fms)
033    {
034        if (ms.getReturnType() != fms.getReturnType()) return -1;
035
036        if (!ms.getName().equals(fms.getName())) return -1;
037
038        Class[] filterParameters = fms.getParameterTypes();
039        int filterParameterCount = filterParameters.length;
040        Class[] serviceParameters = ms.getParameterTypes();
041
042        if (filterParameterCount != (serviceParameters.length + 1)) return -1;
043
044        // TODO: check compatible exceptions!
045
046        // This needs work; it assumes the first occurance of the service interface
047        // in the filter interface method signature is the right match. That will suit
048        // most of the time.
049
050        boolean found = false;
051        int result = -1;
052
053        for (int i = 0; i < filterParameterCount; i++)
054        {
055            if (filterParameters[i] == serviceInterface)
056            {
057                result = i;
058                found = true;
059                break;
060            }
061        }
062
063        if (!found) return -1;
064
065        // Check that all the parameters before and after the service interface still
066        // match.
067
068        for (int i = 0; i < result; i++)
069        {
070            if (filterParameters[i] != serviceParameters[i]) return -1;
071        }
072
073        for (int i = result + 1; i < filterParameterCount; i++)
074        {
075            if (filterParameters[i] != serviceParameters[i - 1]) return -1;
076        }
077
078        return result;
079    }
080
081}