linux-packaging-mono/mcs/class/Mono.CodeContracts/Mono.CodeContracts.Static.DataStructures.Patricia/EmptyNode.cs

// 
// EmptyNode.cs
// 
// Authors:
//	Alexander Chebaturkin (chebaturkin@gmail.com)
// 
// Copyright (C) 2012 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.IO;
using System.Text;

namespace Mono.CodeContracts.Static.DataStructures.Patricia
{
        public class EmptyNode<T> : PatriciaTrieNode<T>
    {
        public static readonly EmptyNode<T> Instance = new EmptyNode<T>();

        public override bool Contains(int key)
        {
            return false;
        }

        public override int Key { get { throw new NotSupportedException("No key for empty node");} }

        public override int Count
        {
            get { return 0; }
        }

        public override IImmutableIntMap<T> Add(int key, T value)
        {
            return new LeafNode<T>(key, value);
        }

        public override IImmutableIntMap<T> Remove(int key)
        {
            return this;
        }

        public override void Visit(Action<T> action)
        {
        }

        public override void Visit(Action<int, T> action)
        {
        }

        protected internal override void FillKeysTo(List<int> list)
        {
        }

        protected internal override void FillValuesTo(List<T> list)
        {
        }

        protected internal override void AppendToBuilder(StringBuilder sb)
        {
            sb.Append("*");
        }

        protected internal override void Dump(TextWriter tw, string prefix)
        {
            tw.WriteLine(prefix + "<empty/>");
        }

        public override T Lookup(int key)
        {
            return default(T);
        }
    }
}