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    1   /*
    2    * Licensed to the Apache Software Foundation (ASF) under one or more
    3    * contributor license agreements. See the NOTICE file distributed with
    4    * this work for additional information regarding copyright ownership.
    5    * The ASF licenses this file to You under the Apache License, Version 2.0
    6    * (the "License"); you may not use this file except in compliance with
    7    * the License. You may obtain a copy of the License at
    8    *
    9    *      http://www.apache.org/licenses/LICENSE-2.0
    10   *
    11   * Unless required by applicable law or agreed to in writing, software
    12   * distributed under the License is distributed on an "AS IS" BASIS,
    13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    14   * See the License for the specific language governing permissions and
    15   * limitations under the License.
    16   */
    17
    18  package org.apache.logging.log4j.core.config.plugins.visitors;
    19
    20  import java.lang.annotation.Annotation;
    21  import java.lang.reflect.Member;
    22  import java.util.Map;
    23
    24  import org.apache.logging.log4j.Logger;
    25  import org.apache.logging.log4j.core.config.plugins.convert.TypeConverters;
    26  import org.apache.logging.log4j.core.lookup.StrSubstitutor;
    27  import org.apache.logging.log4j.core.util.Assert;
    28  import org.apache.logging.log4j.status.StatusLogger;
    29  import org.apache.logging.log4j.util.Strings;
    30
    31  /**
    32   * Base class for PluginVisitor implementations. Provides convenience methods as well as all method implementations
    33   * other than the {@code visit} method.
    34   *
    35   * @param <A> the Plugin annotation type.
    36   */
    37  public abstract class AbstractPluginVisitor<A extends Annotation> implements PluginVisitor<A> {
    38
    39      protected static final Logger LOGGER = StatusLogger.getLogger();
    40
    41      protected final Class<A> clazz;
    42      protected A annotation;
    43      protected String[] aliases;
    44      protected Class<?> conversionType;
    45      protected StrSubstitutor substitutor;
    46      protected Member member;
    47
    48      /**
    49       * This constructor must be overridden by implementation classes as a no-arg constructor.
    50       *
    51       * @param clazz the annotation class this PluginVisitor is for.
    52       */
    53      protected AbstractPluginVisitor(final Class<A> clazz) {
    54          this.clazz = clazz;
    55      }
    56
    57      @SuppressWarnings("unchecked")
    58      @Override
    59      public PluginVisitor<A> setAnnotation(final Annotation annotation) {
    60          final Annotation a = Assert.requireNonNull(annotation, "No annotation was provided");
    61          if (this.clazz.isInstance(a)) {
    62              this.annotation = (A) a;
    63          }
    64          return this;
    65      }
    66
    67      @Override
    68      public PluginVisitor<A> setAliases(final String... aliases) {
    69          this.aliases = aliases;
    70          return this;
    71      }
    72
    73      @Override
    74      public PluginVisitor<A> setConversionType(final Class<?> conversionType) {
    75          this.conversionType = Assert.requireNonNull(conversionType, "No conversion type class was provided");
    76          return this;
    77      }
    78
    79      @Override
    80      public PluginVisitor<A> setStrSubstitutor(final StrSubstitutor substitutor) {
    81          this.substitutor = Assert.requireNonNull(substitutor, "No StrSubstitutor was provided");
    82          return this;
    83      }
    84
    85      @Override
    86      public PluginVisitor<A> setMember(final Member member) {
    87          this.member = member;
    88          return this;
    89      }
    90
    91      /**
    92       * Removes an Entry from a given Map using a key name and aliases for that key. Keys are case-insensitive.
    93       *
    94       * @param attributes the Map to remove an Entry from.
    95       * @param name       the key name to look up.
    96       * @param aliases    optional aliases of the key name to look up.
    97       * @return the value corresponding to the given key or {@code null} if nonexistent.
    98       */
    99      protected static String removeAttributeValue(final Map<String, String> attributes,
    100                                                  final String name,
    101                                                  final String... aliases) {
    102         for (final Map.Entry<String, String> entry : attributes.entrySet()) {
    103             final String key = entry.getKey();
    104             final String value = entry.getValue();
    105             if (key.equalsIgnoreCase(name)) {
    106                 attributes.remove(key);
    107                 return value;
    108             }
    109             if (aliases != null) {
    110                 for (final String alias : aliases) {
    111                     if (key.equalsIgnoreCase(alias)) {
    112                         attributes.remove(key);
    113                         return value;
    114                     }
    115                 }
    116             }
    117         }
    118         return null;
    119     }
    120
    121     /**
    122      * Converts the given value into the configured type falling back to the provided default value.
    123      *
    124      * @param value        the value to convert.
    125      * @param defaultValue the fallback value to use in case of no value or an error.
    126      * @return the converted value whether that be based on the given value or the default value.
    127      */
    128     protected Object convert(final String value, final Object defaultValue) {
    129         if (defaultValue instanceof String) {
    130             return TypeConverters.convert(value, this.conversionType, Strings.trimToNull((String) defaultValue));
    131         }
    132         return TypeConverters.convert(value, this.conversionType, defaultValue);
    133     }
    134 }