content: /*
   * Copyright 2010 Roger Kapsi
   *
   *   Licensed 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
   *
   *       http://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 org.apache.cassandra.index.sasi.utils.trie;
  
  import java.util.Comparator;
  
  /**
   * This class is taken from https://github.com/rkapsi/patricia-trie (v0.6), and slightly modified
   * to correspond to Cassandra code style, as the only Patricia Trie implementation,
   * which supports pluggable key comparators (e.g. commons-collections PatriciaTrie (which is based
   * on rkapsi/patricia-trie project) only supports String keys)
   * but unfortunately is not deployed to the maven central as a downloadable artifact.
   */
  
  /**
   * The {@link KeyAnalyzer} provides bit-level access to keys
   * for the {@link PatriciaTrie}.
   */
  public interface KeyAnalyzer<K> extends Comparator<K>
  {
      /**
       * Returned by {@link #bitIndex(Object, Object)} if a key's
       * bits were all zero (0).
       */
      int NULL_BIT_KEY = -1;
  
      /**
       * Returned by {@link #bitIndex(Object, Object)} if a the
       * bits of two keys were all equal.
       */
      int EQUAL_BIT_KEY = -2;
  
      /**
       * Returned by {@link #bitIndex(Object, Object)} if a keys
       * indices are out of bounds.
       */
      int OUT_OF_BOUNDS_BIT_KEY = -3;
  
      /**
       * Returns the key's length in bits.
       */
      int lengthInBits(K key);
  
      /**
       * Returns {@code true} if a key's bit it set at the given index.
       */
      boolean isBitSet(K key, int bitIndex);
  
      /**
       * Returns the index of the first bit that is different in the two keys.
       */
      int bitIndex(K key, K otherKey);
  
      /**
       * Returns {@code true} if the second argument is a
       * prefix of the first argument.
       */
      boolean isPrefix(K key, K prefix);
  }
  