MergedValueMap.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.sling.resourcemerger.impl;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

import org.apache.sling.api.resource.ValueMap;
import org.apache.sling.api.wrappers.ValueMapDecorator;

/**
 * A <code>MergedValueMap</code> is a {@link ValueMap} aggregated from the
 * different resources mapped to a {@link MergedResource}.
 */
public class MergedValueMap extends ValueMapDecorator {

    /**
     * Set of properties to exclude from override
     */
    private static final Set<String> EXCLUDED_PROPERTIES = new HashSet<String>();

    static {
        EXCLUDED_PROPERTIES.add(MergedResourceConstants.PN_HIDE_PROPERTIES);
        EXCLUDED_PROPERTIES.add(MergedResourceConstants.PN_HIDE_RESOURCE);
        EXCLUDED_PROPERTIES.add(MergedResourceConstants.PN_HIDE_CHILDREN);
        EXCLUDED_PROPERTIES.add(MergedResourceConstants.PN_ORDER_BEFORE);
    }

    /**
     * Constructor
     *
     * @param valueMaps a list of value maps to be aggregated into <i>this</i> value map
     */
    public MergedValueMap(final List<ValueMap> valueMaps) {
        super(new HashMap<String, Object>());
        
        List<String> propertyNamesToHide = new ArrayList<String>(EXCLUDED_PROPERTIES);
        
        // Iterate over value maps
        for (final ValueMap vm : valueMaps) {
            // Get properties to hide from local or underlying value maps
            final String[] propertiesToHide = vm.get(MergedResourceConstants.PN_HIDE_PROPERTIES, String[].class);
            if ( propertiesToHide != null ) {
                for (final String propName : propertiesToHide) {
                    if (propName.equals("*")) {
                        // hiding by wildcard only hides the underlying properties (not the local ones)
                        this.clear();
                        break;
                    } else {
                        propertyNamesToHide.add(propName);
                    }
                }
            }
            
            // Add all local properties
            this.putAll(vm);
        }

        // Hide excluded properties
        for (final String propertyNameToHide : propertyNamesToHide) {
            this.remove(propertyNameToHide);
        }
    }
}