gee/hashset.vala

   1 /* hashset.vala
   2  *
   3  * Copyright (C) 1995-1997  Peter Mattis, Spencer Kimball and Josh MacDonald
   4  * Copyright (C) 1997-2000  GLib Team and others
   5  * Copyright (C) 2007-2009  Jürg Billeter
   6  *
   7  * This library is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11
  12  * This library is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with this library; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301  USA
  20  *
  21  * Author:
  22  *      Jürg Billeter <j@bitron.ch>
  23  */
  24
  25 using GLib;
  26
  27 /**
  28  * Hashtable implementation of the Set interface.
  29  */
  30 public class Vala.HashSet<G> : Set<G> {
  31         public override int size {
  32                 get { return _nnodes; }
  33         }
  34
  35         public HashFunc<G> hash_func {
  36                 set { _hash_func = value; }
  37         }
  38
  39         public EqualFunc<G> equal_func {
  40                 set { _equal_func = value; }
  41         }
  42
  43         private int _array_size;
  44         private int _nnodes;
  45         private Node<G>[] _nodes;
  46
  47         // concurrent modification protection
  48         private int _stamp = 0;
  49
  50         private HashFunc<G> _hash_func;
  51         private EqualFunc<G> _equal_func;
  52
  53         private const int MIN_SIZE = 11;
  54         private const int MAX_SIZE = 13845163;
  55
  56         public HashSet (HashFunc<G> hash_func = GLib.direct_hash, EqualFunc<G> equal_func = GLib.direct_equal) {
  57                 this.hash_func = hash_func;
  58                 this.equal_func = equal_func;
  59                 _array_size = MIN_SIZE;
  60                 _nodes = new Node<G>[_array_size];
  61         }
  62
  63         private Node<G>** lookup_node (G key) {
  64                 uint hash_value = _hash_func (key);
  65                 Node<G>** node = &_nodes[hash_value % _array_size];
  66                 while ((*node) != null && (hash_value != (*node)->key_hash || !_equal_func ((*node)->key, key))) {
  67                         node = &((*node)->next);
  68                 }
  69                 return node;
  70         }
  71
  72         public override bool contains (G key) {
  73                 Node<G>** node = lookup_node (key);
  74                 return (*node != null);
  75         }
  76
  77         public override Type get_element_type () {
  78                 return typeof (G);
  79         }
  80
  81         public override Vala.Iterator<G> iterator () {
  82                 return new Iterator<G> (this);
  83         }
  84
  85         public override bool add (G key) {
  86                 Node<G>** node = lookup_node (key);
  87                 if (*node != null) {
  88                         return false;
  89                 } else {
  90                         uint hash_value = _hash_func (key);
  91                         *node = new Node<G> (key, hash_value);
  92                         _nnodes++;
  93                         resize ();
  94                         _stamp++;
  95                         return true;
  96                 }
  97         }
  98
  99         public override bool remove (G key) {
 100                 Node<G>** node = lookup_node (key);
 101                 if (*node != null) {
 102                         Node<G> next = (owned) (*node)->next;
 103
 104                         (*node)->key = null;
 105                         delete *node;
 106
 107                         *node = (owned) next;
 108
 109                         _nnodes--;
 110                         resize ();
 111                         _stamp++;
 112                         return true;
 113                 }
 114                 return false;
 115         }
 116
 117         public override void clear () {
 118                 for (int i = 0; i < _array_size; i++) {
 119                         Node<G> node = (owned) _nodes[i];
 120                         while (node != null) {
 121                                 Node next = (owned) node.next;
 122                                 node.key = null;
 123                                 node = (owned) next;
 124                         }
 125                 }
 126                 _nnodes = 0;
 127                 resize ();
 128         }
 129
 130         private void resize () {
 131                 if ((_array_size >= 3 * _nnodes && _array_size >= MIN_SIZE) ||
 132                     (3 * _array_size <= _nnodes && _array_size < MAX_SIZE)) {
 133                         int new_array_size = (int) SpacedPrimes.closest (_nnodes);
 134                         new_array_size = new_array_size.clamp (MIN_SIZE, MAX_SIZE);
 135
 136                         Node<G>[] new_nodes = new Node<G>[new_array_size];
 137
 138                         for (int i = 0; i < _array_size; i++) {
 139                                 Node<G> node;
 140                                 Node<G> next = null;
 141                                 for (node = (owned) _nodes[i]; node != null; node = (owned) next) {
 142                                         next = (owned) node.next;
 143                                         uint hash_val = node.key_hash % new_array_size;
 144                                         node.next = (owned) new_nodes[hash_val];
 145                                         new_nodes[hash_val] = (owned) node;
 146                                 }
 147                         }
 148                         _nodes = (owned) new_nodes;
 149                         _array_size = new_array_size;
 150                 }
 151         }
 152
 153         ~HashSet () {
 154                 clear ();
 155         }
 156
 157         [Compact]
 158         private class Node<G> {
 159                 public G key;
 160                 public Node<G> next;
 161                 public uint key_hash;
 162
 163                 public Node (owned G k, uint hash) {
 164                         key = (owned) k;
 165                         key_hash = hash;
 166                 }
 167         }
 168
 169         private class Iterator<G> : Vala.Iterator<G> {
 170                 public HashSet<G> set {
 171                         set {
 172                                 _set = value;
 173                                 _stamp = _set._stamp;
 174                         }
 175                 }
 176
 177                 private HashSet<G> _set;
 178                 private int _index = -1;
 179                 private weak Node<G> _node;
 180
 181                 // concurrent modification protection
 182                 private int _stamp = 0;
 183
 184                 public Iterator (HashSet set) {
 185                         this.set = set;
 186                 }
 187
 188                 public override bool next () {
 189                         if (_node != null) {
 190                                 _node = _node.next;
 191                         }
 192                         while (_node == null && _index + 1 < _set._array_size) {
 193                                 _index++;
 194                                 _node = _set._nodes[_index];
 195                         }
 196                         return (_node != null);
 197                 }
 198
 199                 public override G? get () {
 200                         assert (_stamp == _set._stamp);
 201                         assert (_node != null);
 202                         return _node.key;
 203                 }
 204         }
 205 }
 206