    001// Copyright 2006, 2007, 2012 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
    017/**
    018 * Used by {@link org.apache.tapestry5.ioc.internal.services.PipelineBuilderImpl} to analyze service interface methods
    019 * against filter interface methods to find the position of the extra service parameter (in the filter method).
    020 */
    021public class FilterMethodAnalyzer
    022{
    023    private final Class serviceInterface;
    024
    025    FilterMethodAnalyzer(Class serviceInterface)
    026    {
    027        this.serviceInterface = serviceInterface;
    028    }
    029
    030    public int findServiceInterfacePosition(MethodSignature ms, MethodSignature fms)
    031    {
    032        if (ms.getReturnType() != fms.getReturnType()) return -1;
    033
    034        if (!ms.getName().equals(fms.getName())) return -1;
    035
    036        Class[] filterParameters = fms.getParameterTypes();
    037        int filterParameterCount = filterParameters.length;
    038        Class[] serviceParameters = ms.getParameterTypes();
    039
    040        if (filterParameterCount != (serviceParameters.length + 1)) return -1;
    041
    042        // TODO: check compatible exceptions!
    043
    044        // This needs work; it assumes the first occurance of the service interface
    045        // in the filter interface method signature is the right match. That will suit
    046        // most of the time.
    047
    048        boolean found = false;
    049        int result = -1;
    050
    051        for (int i = 0; i < filterParameterCount; i++)
    052        {
    053            if (filterParameters[i] == serviceInterface)
    054            {
    055                result = i;
    056                found = true;
    057                break;
    058            }
    059        }
    060
    061        if (!found) return -1;
    062
    063        // Check that all the parameters before and after the service interface still
    064        // match.
    065
    066        for (int i = 0; i < result; i++)
    067        {
    068            if (filterParameters[i] != serviceParameters[i]) return -1;
    069        }
    070
    071        for (int i = result + 1; i < filterParameterCount; i++)
    072        {
    073            if (filterParameters[i] != serviceParameters[i - 1]) return -1;
    074        }
    075
    076        return result;
    077    }
    078
    079}