001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018package org.apache.logging.log4j.core.config.plugins.visitors;
019
020import java.lang.reflect.Array;
021import java.util.ArrayList;
022import java.util.Arrays;
023import java.util.Collection;
024import java.util.List;
025
026import org.apache.logging.log4j.core.LogEvent;
027import org.apache.logging.log4j.core.config.Configuration;
028import org.apache.logging.log4j.core.config.Node;
029import org.apache.logging.log4j.core.config.plugins.PluginElement;
030import org.apache.logging.log4j.core.config.plugins.util.PluginType;
031
032/**
033 * PluginVisitor implementation for {@link PluginElement}. Supports arrays as well as singular values.
034 */
035public class PluginElementVisitor extends AbstractPluginVisitor<PluginElement> {
036    public PluginElementVisitor() {
037        super(PluginElement.class);
038    }
039
040    @Override
041    public Object visit(final Configuration configuration, final Node node, final LogEvent event,
042                        final StringBuilder log) {
043        final String name = this.annotation.value();
044        if (this.conversionType.isArray()) {
045            setConversionType(this.conversionType.getComponentType());
046            final List<Object> values = new ArrayList<Object>();
047            final Collection<Node> used = new ArrayList<Node>();
048            log.append("={");
049            boolean first = true;
050            for (final Node child : node.getChildren()) {
051                final PluginType<?> childType = child.getType();
052                if (name.equalsIgnoreCase(childType.getElementName()) ||
053                    this.conversionType.isAssignableFrom(childType.getPluginClass())) {
054                    if (!first) {
055                        log.append(", ");
056                    }
057                    first = false;
058                    used.add(child);
059                    final Object childObject = child.getObject();
060                    if (childObject == null) {
061                        LOGGER.error("Null object returned for {} in {}.", child.getName(), node.getName());
062                        continue;
063                    }
064                    if (childObject.getClass().isArray()) {
065                        log.append(Arrays.toString((Object[]) childObject)).append('}');
066                        return childObject;
067                    }
068                    log.append(child.toString());
069                    values.add(childObject);
070                }
071            }
072            log.append('}');
073            // note that we need to return an empty array instead of null if the types are correct
074            if (!values.isEmpty() && !this.conversionType.isAssignableFrom(values.get(0).getClass())) {
075                LOGGER.error("Attempted to assign attribute {} to list of type {} which is incompatible with {}.",
076                    name, values.get(0).getClass(), this.conversionType);
077                return null;
078            }
079            node.getChildren().removeAll(used);
080            // we need to use reflection here because values.toArray() will cause type errors at runtime
081            final Object[] array = (Object[]) Array.newInstance(this.conversionType, values.size());
082            for (int i = 0; i < array.length; i++) {
083                array[i] = values.get(i);
084            }
085            return array;
086        }
087        final Node namedNode = findNamedNode(name, node.getChildren());
088        if (namedNode == null) {
089            log.append("null");
090            return null;
091        }
092        log.append(namedNode.getName()).append('(').append(namedNode.toString()).append(')');
093        node.getChildren().remove(namedNode);
094        return namedNode.getObject();
095    }
096
097    private Node findNamedNode(final String name, final Iterable<Node> children) {
098        for (final Node child : children) {
099            final PluginType<?> childType = child.getType();
100            if (name.equalsIgnoreCase(childType.getElementName()) ||
101                this.conversionType.isAssignableFrom(childType.getPluginClass())) {
102                // FIXME: check child.getObject() for null?
103                // doing so would be more consistent with the array version
104                return child;
105            }
106        }
107        return null;
108    }
109}