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   /*
    * Copyright 2013 The Netty Project
    *
    * The Netty Project 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:
    *
    *   https://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 io.netty.channel.group;
  
  import io.netty.channel.Channel;
  import io.netty.channel.ServerChannel;
  
  /**
   * Helper class which provides often used {@link ChannelMatcher} implementations.
   */
  public final class ChannelMatchers {
  
      private static final ChannelMatcher ALL_MATCHER = new ChannelMatcher() {
          @Override
          public boolean matches(Channel channel) {
              return true;
          }
      };
  
      private static final ChannelMatcher SERVER_CHANNEL_MATCHER = isInstanceOf(ServerChannel.class);
      private static final ChannelMatcher NON_SERVER_CHANNEL_MATCHER = isNotInstanceOf(ServerChannel.class);
  
      private ChannelMatchers() {
          // static methods only
      }
  
      /**
       * Returns a {@link ChannelMatcher} that matches all {@link Channel}s.
       */
      public static ChannelMatcher all() {
          return ALL_MATCHER;
      }
  
      /**
       * Returns a {@link ChannelMatcher} that matches all {@link Channel}s except the given.
       */
      public static ChannelMatcher isNot(Channel channel) {
          return invert(is(channel));
      }
  
      /**
       * Returns a {@link ChannelMatcher} that matches the given {@link Channel}.
       */
      public static ChannelMatcher is(Channel channel) {
          return new InstanceMatcher(channel);
      }
  
      /**
       * Returns a {@link ChannelMatcher} that matches all {@link Channel}s that are an instance of sub-type of
       * the given class.
       */
      public static ChannelMatcher isInstanceOf(Class<? extends Channel> clazz) {
          return new ClassMatcher(clazz);
      }
  
      /**
       * Returns a {@link ChannelMatcher} that matches all {@link Channel}s that are <strong>not</strong> an
       * instance of sub-type of the given class.
       */
      public static ChannelMatcher isNotInstanceOf(Class<? extends Channel> clazz) {
          return invert(isInstanceOf(clazz));
      }
  
      /**
       * Returns a {@link ChannelMatcher} that matches all {@link Channel}s that are of type {@link ServerChannel}.
       */
      public static ChannelMatcher isServerChannel() {
           return SERVER_CHANNEL_MATCHER;
      }
  
      /**
       * Returns a {@link ChannelMatcher} that matches all {@link Channel}s that are <strong>not</strong> of type
       * {@link ServerChannel}.
       */
      public static ChannelMatcher isNonServerChannel() {
          return NON_SERVER_CHANNEL_MATCHER;
      }
  
      /**
       * Invert the given {@link ChannelMatcher}.
       */
      public static ChannelMatcher invert(ChannelMatcher matcher) {
          return new InvertMatcher(matcher);
      }
  
      /**
      * Return a composite of the given {@link ChannelMatcher}s. This means all {@link ChannelMatcher} must
      * return {@code true} to match.
      */
     public static ChannelMatcher compose(ChannelMatcher... matchers) {
         if (matchers.length < 1) {
             throw new IllegalArgumentException("matchers must at least contain one element");
         }
         if (matchers.length == 1) {
             return matchers[0];
         }
         return new CompositeMatcher(matchers);
     }
 
     private static final class CompositeMatcher implements ChannelMatcher {
         private final ChannelMatcher[] matchers;
 
         CompositeMatcher(ChannelMatcher... matchers) {
             this.matchers = matchers;
         }
 
         @Override
         public boolean matches(Channel channel) {
             for (ChannelMatcher m: matchers) {
                 if (!m.matches(channel)) {
                     return false;
                 }
             }
             return true;
         }
     }
 
     private static final class InvertMatcher implements ChannelMatcher {
         private final ChannelMatcher matcher;
 
         InvertMatcher(ChannelMatcher matcher) {
             this.matcher = matcher;
         }
 
         @Override
         public boolean matches(Channel channel) {
             return !matcher.matches(channel);
         }
     }
 
     private static final class InstanceMatcher implements ChannelMatcher {
         private final Channel channel;
 
         InstanceMatcher(Channel channel) {
             this.channel = channel;
         }
 
         @Override
         public boolean matches(Channel ch) {
             return channel == ch;
         }
     }
 
     private static final class ClassMatcher implements ChannelMatcher {
         private final Class<? extends Channel> clazz;
 
         ClassMatcher(Class<? extends Channel> clazz) {
             this.clazz = clazz;
         }
 
         @Override
         public boolean matches(Channel ch) {
             return clazz.isInstance(ch);
         }
     }
 }