com.day.cq.commons.inherit.ComponentInheritanceValueMap Maven / Gradle / Ivy

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package com.day.cq.commons.inherit;

import org.apache.sling.api.resource.Resource;
import org.apache.sling.api.resource.ResourceUtil;
import org.apache.sling.api.resource.ValueMap;

import com.day.cq.commons.ValueMapWrapper;
import com.day.cq.commons.jcr.JcrConstants;

/**
 * An {@link InheritanceValueMap} for a given {@link Resource} that will inherit values from
 * ancestors up to its ancestral component, but no higher.
 *
 * 
 *     For example, given: /content/parent/page/jcr:content/footer/image/@width,
 *     the ComponentInheritanceValueMap will search for a width property in:
 *     

 *         /content/parent/page/jcr:content/footer/image/@width
 *         /content/parent/page/jcr:content/footer/@width
 *         /content/parent/page/jcr:content/@width
 *     
 *     Having not found it in any of those locations, it will then return null.
 *
 * 
 *     Note that ComponentInheritanceValueMap searches only the component
 *     hierarchy.  It will not (for instance), look in:
 *     

 *         /content/parent/jcr:content/footer/image/@width
 *     
 *     See {@link com.day.cq.commons.inherit.HierarchyNodeInheritanceValueMap} for that
 *     functionality.
 */
public class ComponentInheritanceValueMap extends ValueMapWrapper implements InheritanceValueMap {

    protected Resource resource;

    /**
     * Will wrap the {@link ValueMap} returned by
     * resource.adaptTo(ValueMap.class), or use an empty map if
     * resource is null or if it doesn't adapt to a ValueMap. The
     * inheritance is internally resolved by fetching the parent resource and
     * wrapping it into an {@link ComponentInheritanceValueMap} as well.
     *
     * @param resource
     *            the resource to start from
     */
    public ComponentInheritanceValueMap(Resource resource) {
        super(ResourceUtil.getValueMap(resource));
        this.resource = resource;
    }

    /**
     * Use this if the underlying {@link Resource} for a {@link ValueMap} is not
     * available and no inheritance is needed. Using the inheritance-enabled
     * {@link #getInherited(String, Class) getter}
     * {@link #getInherited(String, Object) methods} will behave exactly like
     * the normal ValueMap getters.
     *
     * @param map
     *            a ValueMap to wrap
     */
    public ComponentInheritanceValueMap(ValueMap map) {
        super(map);
        this.resource = null;
    }

    @SuppressWarnings("unchecked")
    public  T get(String name, Class type) {
        // overwritten to fix NPE
        if (type == null) {
            return (T) get(name);
        }
        return super.get(name, type);
    }

    public  T getInherited(String name, Class type) {
        T value = get(name, type);
        if (value == null) {
            value = getParentComponentValue(name, type);
        }
        return value;
    }

    @SuppressWarnings("unchecked")
    public  T getInherited(String name, T defaultValue) {
        Class type;
        if (defaultValue == null) {
            type = null;
        } else {
            // special handling in case the default value implements one
            // of the interface types supported by the convertToType method
            type = (Class) defaultValue.getClass();
        }

        T value = getInherited(name, type);
        if (value == null) {
            value = defaultValue;
        }

        return value;
    }

    protected  T getParentComponentValue(final String name, final Class type) {
        // stop inheritance in case resource is null or a page's content resource
        if (resource == null || resource.getName().equals(JcrConstants.JCR_CONTENT)) {
            return null;
        }

        Resource parent = resource.getParent();
        if(parent == null) {
            return null;
        }

        return new ComponentInheritanceValueMap(parent).getInherited(name, type);
    }
}