impl/src/main/java/org/apache/myfaces/util/NavigationUtils.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.myfaces.util;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import javax.faces.application.NavigationCase;
import javax.faces.context.FacesContext;
import org.apache.myfaces.config.element.NavigationRule;

/**
 *
 * @author lu4242
 */
public final class NavigationUtils
{
    public static Set<NavigationCase> convertNavigationCasesToAPI(NavigationRule rule)
    {
        List<? extends org.apache.myfaces.config.element.NavigationCase> configCases = rule.getNavigationCases();
        
        Set<NavigationCase> apiCases = new HashSet<>(configCases.size());
        for (org.apache.myfaces.config.element.NavigationCase configCase : configCases)
        {   
            if (configCase.getRedirect() != null)
            {
                String includeViewParamsAttribute = configCase.getRedirect().getIncludeViewParams();
                boolean includeViewParams = false; // default value is false
                if (includeViewParamsAttribute != null)
                {
                    includeViewParams = Boolean.valueOf(includeViewParamsAttribute);
                }
                apiCases.add(new NavigationCase(rule.getFromViewId(),
                        configCase.getFromAction(),
                        configCase.getFromOutcome(),configCase.getIf(),
                        configCase.getToViewId(),
                        configCase.getRedirect().getViewParams()
                        ,true,
                        includeViewParams));
            }
            else
            {
                apiCases.add(new NavigationCase(rule.getFromViewId(),
                        configCase.getFromAction(),
                        configCase.getFromOutcome(),configCase.getIf(),
                        configCase.getToViewId(),
                        null,
                        false,
                        false));
            }
        }
        
        return apiCases;
    }
    
    
   /**
     * Evaluate all EL expressions found as parameters and return a map that can be used for 
     * redirect or render bookmark links
     * 
     * @param facesContext
     * @param parameters parameter map retrieved from NavigationCase.getParameters()
     * @return
     */
    public static Map<String, List<String> > getEvaluatedNavigationParameters(
            FacesContext facesContext, 
            Map<String, List<String>> parameters)
    {
        if (parameters != null && !parameters.isEmpty())
        {
            Map<String,List<String>> evaluatedParameters = new HashMap<>(parameters.size());
            for (Map.Entry<String, List<String>> pair : parameters.entrySet())
            {
                boolean containsEL = false;
                for (String value : pair.getValue())
                {
                    if (_isExpression(value))
                    {
                        containsEL = true;
                        break;
                    }
                }
                if (containsEL)
                {
                    evaluatedParameters.put(pair.getKey(), 
                            _evaluateValueExpressions(facesContext, pair.getValue()));
                }
                else
                {
                    evaluatedParameters.put(pair.getKey(), pair.getValue());
                }
            }
            
            return evaluatedParameters;
        }

        return parameters;
    }
    
    /**
     * Checks the Strings in the List for EL expressions and evaluates them.
     * Note that the returned List will be a copy of the given List, because
     * otherwise it will have unwanted side-effects.
     * @param values
     * @return
     */
    private static List<String> _evaluateValueExpressions(FacesContext context, List<String> values)
    {
        // note that we have to create a new List here, because if we
        // change any value on the given List, it will be changed in the
        // NavigationCase too and the EL expression won't be evaluated again
        List<String> target = new ArrayList<>(values.size());
        for (int i = 0; i < values.size(); i++)
        {
            String value = values.get(i);
            // evaluate the ValueExpression
            value = context.getApplication().evaluateExpressionGet(context, value, String.class);
            target.add(value);
        }
        return target;
    }
    
    private static boolean _isExpression(String text)
    {
        return text.contains("#{");
    }
}