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//
// ImmutableMap.cs
//
// Authors:
// Alexander Chebaturkin (chebaturkin@gmail.com)
//
// Copyright (C) 2011 Alexander Chebaturkin
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
using System;
using System.Collections.Generic;
using System.Linq;
namespace Mono.CodeContracts.Static.DataStructures {
class ImmutableMap<K, V> : IImmutableMap<K, V>
where K : IEquatable<K> {
public static readonly ImmutableMap<K, V> Empty = new ImmutableMap<K, V> (ImmutableIntMap<Sequence<Pair<K, V>>>.Empty, 0, null);
private readonly int count;
private readonly IImmutableIntMap<Sequence<Pair<K, V>>> immutable_int_map;
private readonly Sequence<K> keys;
private ImmutableMap (IImmutableIntMap<Sequence<Pair<K, V>>> map, int count, Sequence<K> keys)
{
this.keys = keys;
this.count = count;
this.immutable_int_map = map;
}
#region Implementation of IImmutableMap<K,V>
public V this [K key]
{
get
{
V value;
return TryGetValue (key, out value) ? value : default(V);
}
}
public bool TryGetValue (K key, out V value)
{
for (Sequence<Pair<K, V>> list = this.immutable_int_map[key.GetHashCode ()]; list != null; list = list.Tail)
{
K k = list.Head.Key;
if (key.Equals (k))
return true.With (list.Head.Value, out value);
}
return false.Without (out value);
}
public K AnyKey
{
get { return this.keys.Head; }
}
public IEnumerable<K> Keys
{
get { return this.keys.AsEnumerable (); }
}
public int Count
{
get { return this.immutable_int_map.Count; }
}
public IImmutableMap<K, V> EmptyMap
{
get { return Empty; }
}
public IImmutableMap<K, V> Add (K key, V value)
{
int hashCode = key.GetHashCode ();
Sequence<Pair<K, V>> cur = this.immutable_int_map [hashCode];
Sequence<Pair<K, V>> newList = Remove (cur, key).Cons (new Pair<K, V> (key, value));
int diff = newList.Length () - cur.Length ();
Sequence<K> newKeys = diff == 0 ? this.keys : this.keys.Cons (key);
return new ImmutableMap<K, V> (this.immutable_int_map.Add (hashCode, newList), this.count + diff, newKeys);
}
public IImmutableMap<K, V> Remove (K key)
{
int hashCode = key.GetHashCode ();
Sequence<Pair<K, V>> from = this.immutable_int_map [hashCode];
if (from == null)
return this;
Sequence<Pair<K, V>> newList = Remove (from, key);
if (newList == from)
return this;
Sequence<K> newKeys = RemoveKey (key, this.keys);
if (newList == null)
return new ImmutableMap<K, V> (this.immutable_int_map.Remove (hashCode), this.count - 1, newKeys);
return new ImmutableMap<K, V> (this.immutable_int_map.Add (hashCode, newList), this.count - 1, newKeys);
}
public bool ContainsKey (K key)
{
return this.immutable_int_map [key.GetHashCode ()].AsEnumerable ().Any (pair => key.Equals (pair.Key));
}
public void Visit (Func<K, V, VisitStatus> func)
{
this.immutable_int_map.Visit (list => {
foreach (var pair in list.AsEnumerable ())
func (pair.Key, pair.Value);
});
}
private Sequence<Pair<K, V>> Remove (Sequence<Pair<K, V>> from, K key)
{
if (from == null)
return null;
if (key.Equals (from.Head.Key))
return from.Tail;
Sequence<Pair<K, V>> tail = Remove (from.Tail, key);
return tail == from.Tail ? from : tail.Cons (from.Head);
}
private static Sequence<K> RemoveKey (K key, Sequence<K> keys)
{
if (keys == null)
throw new InvalidOperationException ();
if (key.Equals (keys.Head))
return keys.Tail;
return RemoveKey (key, keys.Tail).Cons (keys.Head);
}
#endregion
public IImmutableMapFactory<K, V> Factory ()
{
return new MapFactory ();
}
private class MapFactory : IImmutableMapFactory<K, V>
{
public IImmutableMap<K, V> Empty { get { return ImmutableMap<K,V>.Empty;}}
}
}
}
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