package org.apache.lucene.analysis.util;
   
   /*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF 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
   *
   *     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.
   */
  
  import java.util.Arrays;
  import java.util.AbstractMap;
  import java.util.AbstractSet;
  import java.util.Iterator;
  import java.util.Map;
  import java.util.Set;
  
  import org.apache.lucene.analysis.util.CharacterUtils;
  
  /**
   * A simple class that stores key Strings as char[]'s in a
   * hash table. Note that this is not a general purpose
   * class.  For example, it cannot remove items from the
   * map, nor does it resize its hash table to be smaller,
   * etc.  It is designed to be quick to retrieve items
   * by char[] keys without the necessity of converting
   * to a String first.
   */
  public class CharArrayMap<V> extends AbstractMap<Object,V> {
    // private only because missing generics
    private static final CharArrayMap<?> EMPTY_MAP = new EmptyCharArrayMap<>();
  
    private final static int INIT_SIZE = 8;
    private final CharacterUtils charUtils;
    private boolean ignoreCase;  
    private int count;
    char[][] keys; // package private because used in CharArraySet's non Set-conform CharArraySetIterator
    V[] values; // package private because used in CharArraySet's non Set-conform CharArraySetIterator
  
    /**
     * Create map with enough capacity to hold startSize terms
     *
     * @param startSize
     *          the initial capacity
     * @param ignoreCase
     *          <code>false</code> if and only if the set should be case sensitive
     *          otherwise <code>true</code>.
     */
    @SuppressWarnings("unchecked")
    public CharArrayMap(int startSize, boolean ignoreCase) {
      this.ignoreCase = ignoreCase;
      int size = INIT_SIZE;
      while(startSize + (startSize>>2) > size)
        size <<= 1;
      keys = new char[size][];
      values = (V[]) new Object[size];
      this.charUtils = CharacterUtils.getInstance();
    }
  
    /**
     * Creates a map from the mappings in another map. 
     *
     * @param c
     *          a map whose mappings to be copied
     * @param ignoreCase
     *          <code>false</code> if and only if the set should be case sensitive
     *          otherwise <code>true</code>.
     */
    public CharArrayMap(Map<?,? extends V> c, boolean ignoreCase) {
      this(c.size(), ignoreCase);
      putAll(c);
    }
    
    /** Create set from the supplied map (used internally for readonly maps...) */
    private CharArrayMap(CharArrayMap<V> toCopy){
      this.keys = toCopy.keys;
      this.values = toCopy.values;
      this.ignoreCase = toCopy.ignoreCase;
      this.count = toCopy.count;
      this.charUtils = toCopy.charUtils;
    }
    
    /** Clears all entries in this map. This method is supported for reusing, but not {@link Map#remove}. */
    @Override
    public void clear() {
      count = 0;
      Arrays.fill(keys, null);
      Arrays.fill(values, null);
    }
  
   /** true if the <code>len</code> chars of <code>text</code> starting at <code>off</code>
    * are in the {@link #keySet()} */
   public boolean containsKey(char[] text, int off, int len) {
     return keys[getSlot(text, off, len)] != null;
   }
 
   /** true if the <code>CharSequence</code> is in the {@link #keySet()} */
   public boolean containsKey(CharSequence cs) {
     return keys[getSlot(cs)] != null;
   }
 
   @Override
   public boolean containsKey(Object o) {
     if (o instanceof char[]) {
       final char[] text = (char[])o;
       return containsKey(text, 0, text.length);
     } 
     return containsKey(o.toString());
   }
 
   /** returns the value of the mapping of <code>len</code> chars of <code>text</code>
    * starting at <code>off</code> */
   public V get(char[] text, int off, int len) {
     return values[getSlot(text, off, len)];
   }
 
   /** returns the value of the mapping of the chars inside this {@code CharSequence} */
   public V get(CharSequence cs) {
     return values[getSlot(cs)];
   }
 
   @Override
   public V get(Object o) {
     if (o instanceof char[]) {
       final char[] text = (char[])o;
       return get(text, 0, text.length);
     } 
     return get(o.toString());
   }
 
   private int getSlot(char[] text, int off, int len) {
     int code = getHashCode(text, off, len);
     int pos = code & (keys.length-1);
     char[] text2 = keys[pos];
     if (text2 != null && !equals(text, off, len, text2)) {
       final int inc = ((code>>8)+code)|1;
       do {
         code += inc;
         pos = code & (keys.length-1);
         text2 = keys[pos];
       } while (text2 != null && !equals(text, off, len, text2));
     }
     return pos;
   }
 
   /** Returns true if the String is in the set */  
   private int getSlot(CharSequence text) {
     int code = getHashCode(text);
     int pos = code & (keys.length-1);
     char[] text2 = keys[pos];
     if (text2 != null && !equals(text, text2)) {
       final int inc = ((code>>8)+code)|1;
       do {
         code += inc;
         pos = code & (keys.length-1);
         text2 = keys[pos];
       } while (text2 != null && !equals(text, text2));
     }
     return pos;
   }
 
   /** Add the given mapping. */
   public V put(CharSequence text, V value) {
     return put(text.toString(), value); // could be more efficient
   }
 
   @Override
   public V put(Object o, V value) {
     if (o instanceof char[]) {
       return put((char[])o, value);
     }
     return put(o.toString(), value);
   }
   
   /** Add the given mapping. */
   public V put(String text, V value) {
     return put(text.toCharArray(), value);
   }
 
   /** Add the given mapping.
    * If ignoreCase is true for this Set, the text array will be directly modified.
    * The user should never modify this text array after calling this method.
    */
   public V put(char[] text, V value) {
     if (ignoreCase) {
       charUtils.toLowerCase(text, 0, text.length);
     }
     int slot = getSlot(text, 0, text.length);
     if (keys[slot] != null) {
       final V oldValue = values[slot];
       values[slot] = value;
       return oldValue;
     }
     keys[slot] = text;
     values[slot] = value;
     count++;
 
     if (count + (count>>2) > keys.length) {
       rehash();
     }
 
     return null;
   }
 
   @SuppressWarnings("unchecked")
   private void rehash() {
     assert keys.length == values.length;
     final int newSize = 2*keys.length;
     final char[][] oldkeys = keys;
     final V[] oldvalues = values;
     keys = new char[newSize][];
     values = (V[]) new Object[newSize];
 
     for(int i=0; i<oldkeys.length; i++) {
       char[] text = oldkeys[i];
       if (text != null) {
         // todo: could be faster... no need to compare strings on collision
         final int slot = getSlot(text,0,text.length);
         keys[slot] = text;
         values[slot] = oldvalues[i];
       }
     }
   }
   
   private boolean equals(char[] text1, int off, int len, char[] text2) {
     if (len != text2.length)
       return false;
     final int limit = off+len;
     if (ignoreCase) {
       for(int i=0;i<len;) {
         final int codePointAt = charUtils.codePointAt(text1, off+i, limit);
         if (Character.toLowerCase(codePointAt) != charUtils.codePointAt(text2, i, text2.length))
           return false;
         i += Character.charCount(codePointAt); 
       }
     } else {
       for(int i=0;i<len;i++) {
         if (text1[off+i] != text2[i])
           return false;
       }
     }
     return true;
   }
 
   private boolean equals(CharSequence text1, char[] text2) {
     int len = text1.length();
     if (len != text2.length)
       return false;
     if (ignoreCase) {
       for(int i=0;i<len;) {
         final int codePointAt = charUtils.codePointAt(text1, i);
         if (Character.toLowerCase(codePointAt) != charUtils.codePointAt(text2, i, text2.length))
           return false;
         i += Character.charCount(codePointAt);
       }
     } else {
       for(int i=0;i<len;i++) {
         if (text1.charAt(i) != text2[i])
           return false;
       }
     }
     return true;
   }
   
   private int getHashCode(char[] text, int offset, int len) {
     if (text == null)
       throw new NullPointerException();
     int code = 0;
     final int stop = offset + len;
     if (ignoreCase) {
       for (int i=offset; i<stop;) {
         final int codePointAt = charUtils.codePointAt(text, i, stop);
         code = code*31 + Character.toLowerCase(codePointAt);
         i += Character.charCount(codePointAt);
       }
     } else {
       for (int i=offset; i<stop; i++) {
         code = code*31 + text[i];
       }
     }
     return code;
   }
 
   private int getHashCode(CharSequence text) {
     if (text == null)
       throw new NullPointerException();
     int code = 0;
     int len = text.length();
     if (ignoreCase) {
       for (int i=0; i<len;) {
         int codePointAt = charUtils.codePointAt(text, i);
         code = code*31 + Character.toLowerCase(codePointAt);
         i += Character.charCount(codePointAt);
       }
     } else {
       for (int i=0; i<len; i++) {
         code = code*31 + text.charAt(i);
       }
     }
     return code;
   }
 
   @Override
   public V remove(Object key) {
     throw new UnsupportedOperationException();
   }
 
   @Override
   public int size() {
     return count;
   }
 
   @Override
   public String toString() {
     final StringBuilder sb = new StringBuilder("{");
     for (Map.Entry<Object,V> entry : entrySet()) {
       if (sb.length()>1) sb.append(", ");
       sb.append(entry);
     }
     return sb.append('}').toString();
   }
 
   private EntrySet entrySet = null;
   private CharArraySet keySet = null;
   
   EntrySet createEntrySet() {
     return new EntrySet(true);
   }
   
   @Override
   public final EntrySet entrySet() {
     if (entrySet == null) {
       entrySet = createEntrySet();
     }
     return entrySet;
   }
   
   // helper for CharArraySet to not produce endless recursion
   final Set<Object> originalKeySet() {
     return super.keySet();
   }
 
   /** Returns an {@link CharArraySet} view on the map's keys.
    * The set will use the same {@code matchVersion} as this map. */
   @Override @SuppressWarnings({"unchecked","rawtypes"})
   public final CharArraySet keySet() {
     if (keySet == null) {
       // prevent adding of entries
       keySet = new CharArraySet((CharArrayMap) this) {
         @Override
         public boolean add(Object o) {
           throw new UnsupportedOperationException();
         }
         @Override
         public boolean add(CharSequence text) {
           throw new UnsupportedOperationException();
         }
         @Override
         public boolean add(String text) {
           throw new UnsupportedOperationException();
         }
         @Override
         public boolean add(char[] text) {
           throw new UnsupportedOperationException();
         }
       };
     }
     return keySet;
   }
 
   /** public iterator class so efficient methods are exposed to users */
   public class EntryIterator implements Iterator<Map.Entry<Object,V>> {
     private int pos=-1;
     private int lastPos;
     private final boolean allowModify;
     
     private EntryIterator(boolean allowModify) {
       this.allowModify = allowModify;
       goNext();
     }
 
     private void goNext() {
       lastPos = pos;
       pos++;
       while (pos < keys.length && keys[pos] == null) pos++;
     }
 
     @Override
     public boolean hasNext() {
       return pos < keys.length;
     }
 
     /** gets the next key... do not modify the returned char[] */
     public char[] nextKey() {
       goNext();
       return keys[lastPos];
     }
 
     /** gets the next key as a newly created String object */
     public String nextKeyString() {
       return new String(nextKey());
     }
 
     /** returns the value associated with the last key returned */
     public V currentValue() {
       return values[lastPos];
     }
 
     /** sets the value associated with the last key returned */    
     public V setValue(V value) {
       if (!allowModify)
         throw new UnsupportedOperationException();
       V old = values[lastPos];
       values[lastPos] = value;
       return old;      
     }
 
     /** use nextCharArray() + currentValue() for better efficiency. */
     @Override
     public Map.Entry<Object,V> next() {
       goNext();
       return new MapEntry(lastPos, allowModify);
     }
 
     @Override
     public void remove() {
       throw new UnsupportedOperationException();
     }
   }
 
   private final class MapEntry implements Map.Entry<Object,V> {
     private final int pos;
     private final boolean allowModify;
 
     private MapEntry(int pos, boolean allowModify) {
       this.pos = pos;
       this.allowModify = allowModify;
     }
 
     @Override
     public Object getKey() {
       // we must clone here, as putAll to another CharArrayMap
       // with other case sensitivity flag would corrupt the keys
       return keys[pos].clone();
     }
 
     @Override
     public V getValue() {
       return values[pos];
     }
 
     @Override
     public V setValue(V value) {
       if (!allowModify)
         throw new UnsupportedOperationException();
       final V old = values[pos];
       values[pos] = value;
       return old;
     }
 
     @Override
     public String toString() {
       return new StringBuilder().append(keys[pos]).append('=')
         .append((values[pos] == CharArrayMap.this) ? "(this Map)" : values[pos])
         .toString();
     }
   }
 
   /** public EntrySet class so efficient methods are exposed to users */
   public final class EntrySet extends AbstractSet<Map.Entry<Object,V>> {
     private final boolean allowModify;
     
     private EntrySet(boolean allowModify) {
       this.allowModify = allowModify;
     }
   
     @Override
     public EntryIterator iterator() {
       return new EntryIterator(allowModify);
     }
     
     @Override
     @SuppressWarnings("unchecked")
     public boolean contains(Object o) {
       if (!(o instanceof Map.Entry))
         return false;
       final Map.Entry<Object,V> e = (Map.Entry<Object,V>)o;
       final Object key = e.getKey();
       final Object val = e.getValue();
       final Object v = get(key);
       return v == null ? val == null : v.equals(val);
     }
     
     @Override
     public boolean remove(Object o) {
       throw new UnsupportedOperationException();
     }
     
     @Override
     public int size() {
       return count;
     }
     
     @Override
     public void clear() {
       if (!allowModify)
         throw new UnsupportedOperationException();
       CharArrayMap.this.clear();
     }
   }
   
   /**
    * Returns an unmodifiable {@link CharArrayMap}. This allows to provide
    * unmodifiable views of internal map for "read-only" use.
    * 
    * @param map
    *          a map for which the unmodifiable map is returned.
    * @return an new unmodifiable {@link CharArrayMap}.
    * @throws NullPointerException
    *           if the given map is <code>null</code>.
    */
   public static <V> CharArrayMap<V> unmodifiableMap(CharArrayMap<V> map) {
     if (map == null)
       throw new NullPointerException("Given map is null");
     if (map == emptyMap() || map.isEmpty())
       return emptyMap();
     if (map instanceof UnmodifiableCharArrayMap)
       return map;
     return new UnmodifiableCharArrayMap<>(map);
   }
 
   /**
    * Returns a copy of the given map as a {@link CharArrayMap}. If the given map
    * is a {@link CharArrayMap} the ignoreCase property will be preserved.
    * 
    * @param map
    *          a map to copy
    * @return a copy of the given map as a {@link CharArrayMap}. If the given map
    *         is a {@link CharArrayMap} the ignoreCase property as well as the
    *         matchVersion will be of the given map will be preserved.
    */
   @SuppressWarnings("unchecked")
   public static <V> CharArrayMap<V> copy(final Map<?,? extends V> map) {
     if(map == EMPTY_MAP)
       return emptyMap();
     if(map instanceof CharArrayMap) {
       CharArrayMap<V> m = (CharArrayMap<V>) map;
       // use fast path instead of iterating all values
       // this is even on very small sets ~10 times faster than iterating
       final char[][] keys = new char[m.keys.length][];
       System.arraycopy(m.keys, 0, keys, 0, keys.length);
       final V[] values = (V[]) new Object[m.values.length];
       System.arraycopy(m.values, 0, values, 0, values.length);
       m = new CharArrayMap<>(m);
       m.keys = keys;
       m.values = values;
       return m;
     }
     // In jdk-9b54 or later, a plain diamond causes compile error with "-source 1.7":
     return new CharArrayMap<V>(map, false);
   }
   
   /** Returns an empty, unmodifiable map. */
   @SuppressWarnings("unchecked")
   public static <V> CharArrayMap<V> emptyMap() {
     return (CharArrayMap<V>) EMPTY_MAP;
   }
   
   // package private CharArraySet instanceof check in CharArraySet
   static class UnmodifiableCharArrayMap<V> extends CharArrayMap<V> {
 
     UnmodifiableCharArrayMap(CharArrayMap<V> map) {
       super(map);
     }
 
     @Override
     public void clear() {
       throw new UnsupportedOperationException();
     }
 
     @Override
     public V put(Object o, V val){
       throw new UnsupportedOperationException();
     }
     
     @Override
     public V put(char[] text, V val) {
       throw new UnsupportedOperationException();
     }
 
     @Override
     public V put(CharSequence text, V val) {
       throw new UnsupportedOperationException();
     }
 
     @Override
     public V put(String text, V val) {
       throw new UnsupportedOperationException();
     }
     
     @Override
     public V remove(Object key) {
       throw new UnsupportedOperationException();
     }
   
     @Override
     EntrySet createEntrySet() {
       return new EntrySet(false);
     }
   }
   
   /**
    * Empty {@link org.apache.lucene.analysis.util.CharArrayMap.UnmodifiableCharArrayMap} optimized for speed.
    * Contains checks will always return <code>false</code> or throw
    * NPE if necessary.
    */
   private static final class EmptyCharArrayMap<V> extends UnmodifiableCharArrayMap<V> {
     EmptyCharArrayMap() {
       super(new CharArrayMap<V>(0, false));
     }
     
     @Override
     public boolean containsKey(char[] text, int off, int len) {
       if(text == null)
         throw new NullPointerException();
       return false;
     }
 
     @Override
     public boolean containsKey(CharSequence cs) {
       if(cs == null)
         throw new NullPointerException();
       return false;
     }
 
     @Override
     public boolean containsKey(Object o) {
       if(o == null)
         throw new NullPointerException();
       return false;
     }
     
     @Override
     public V get(char[] text, int off, int len) {
       if(text == null)
         throw new NullPointerException();
       return null;
     }
 
     @Override
     public V get(CharSequence cs) {
       if(cs == null)
         throw new NullPointerException();
       return null;
     }
 
     @Override
     public V get(Object o) {
       if(o == null)
         throw new NullPointerException();
       return null;
     }
   }
 }