source: trunk/docx4j/src/main/java/org/docx4j/utils/AbstractTraversalUtilVisitorCallback.java @ 1479

package org.docx4j.utils;

import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.lang.reflect.TypeVariable;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.docx4j.TraversalUtil;
import org.docx4j.XmlUtils;

/** @author alberto */
public abstract class AbstractTraversalUtilVisitorCallback extends TraversalUtil.CallbackImpl {
        
        /**
         * Get the actual type arguments a child class has used to extend a generic base class.
         * based on http://www.artima.com/weblogs/viewpost.jsp?thread=208860
         */
        protected Class findClassParameter(Class childClass) {
    Map<Type, Type> resolvedTypes = new HashMap<Type, Type>();
    Type type = childClass;
            // start walking up the inheritance hierarchy until we hit baseClass
            while (! getTypeClass(type).equals(TraversalUtilVisitor.class)) {
                if (type instanceof Class) {
                        // there is no useful information for us in raw types, so just keep going.
                        type = ((Class) type).getGenericSuperclass();
                }
                else {
                        ParameterizedType parameterizedType = (ParameterizedType) type;
                        Class<?> rawType = (Class)parameterizedType.getRawType();
                        Type[] actualTypeArguments = parameterizedType.getActualTypeArguments();
                        TypeVariable<?>[] typeParameters = rawType.getTypeParameters();
                        for (int i = 0; i < actualTypeArguments.length; i++) {
                          resolvedTypes.put(typeParameters[i], actualTypeArguments[i]);
                        }
                  
                        if (!rawType.equals(TraversalUtilVisitor.class)) {
                          type = rawType.getGenericSuperclass();
                        }
                }
            }
            
            // finally, for each actual type argument provided to baseClass, determine (if possible)
            // the raw class for that type argument.
            Type baseType =
                (type instanceof Class ?
                        ((Class)type).getTypeParameters()[0] :
                        ((ParameterizedType)type).getActualTypeArguments()[0]);
            
            // resolve types by chasing down type variables.
            while (resolvedTypes.containsKey(baseType)) {
                baseType = resolvedTypes.get(baseType);
            }
            return getTypeClass(baseType);
        }

    
        protected Class getTypeClass(Type type) {
        return (type instanceof Class ?
                        (Class)type :
                        (type instanceof ParameterizedType ?
                         getTypeClass(((ParameterizedType) type).getRawType()) : null));
        }  

        // Depth first
        @Override
        public void walkJAXBElements(Object parent) {
        List children = getChildren(parent);
                if (children != null) {
                        for (Object o : children) {
                                // if its wrapped in javax.xml.bind.JAXBElement, get its
                                // value; this is ok, provided the results of the Callback
                                // won't be marshalled
                                o = XmlUtils.unwrap(o);
                                this.apply(o, parent, children);
                                if (this.shouldTraverse(o)) {
                                        walkJAXBElements(o);
                                }
                        }
                }
        }

        @Override
        public final List<Object> apply(Object o) {
                throw new UnsupportedOperationException("Invalid apply method - Abstract traversal util should use apply(Object child, Object parent, List siblings)");
        }
        
        protected abstract List<Object> apply(Object child, Object parent, List children);

}