/mcs/class/System.Data.Linq/src/DbLinq/Data/Linq/Identity/IdentityKey.cs

#region MIT license

// 

// MIT license

//

// Copyright (c) 2007-2008 Jiri Moudry, Pascal Craponne

// 

// 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.

// 

#endregion



using System;

using System.Collections.Generic;



namespace DbLinq.Data.Linq.Identity

{

    /// <summary>

    /// Identifies an object in a unique way (think Primay Keys in a database table)

    /// Identity is:

    /// - A type

    /// - A collection 

    /// 

    /// Example: to store Product with ProductID=1, we use the following IdentityKey:

    ///  IdentityKey{Type=Product, Keys={1}}

    /// </summary>

#if !MONO_STRICT

    public

#endif

    sealed class IdentityKey

    {

        /// <summary>

        /// Entity type

        /// </summary>

        public Type Type { get; private set; }

        /// <summary>

        /// Entity keys

        /// </summary>

        public IList<object> Keys { get; private set; }



        private readonly int hashCode;



        /// <summary>

        /// Determines equality between two refs

        /// </summary>

        /// <param name="obj"></param>

        /// <returns></returns>

        public override bool Equals(object obj)

        {

            var other = (IdentityKey)obj;

            if (Type != other.Type)

                return false;

            if (Keys.Count != other.Keys.Count)

                return false;

            for (int keyIndex = 0; keyIndex < Keys.Count; keyIndex++)

            {

                if (!Equals(Keys[keyIndex], other.Keys[keyIndex]))

                    return false;

            }

            return true;

        }



        /// <summary>

        /// Computes hash code

        /// </summary>

        /// <returns></returns>

        public override int GetHashCode()

        {

            return hashCode;

        }



        /// <summary>

        /// Initializes a new instance of the <see cref="IdentityKey"/> class.

        /// </summary>

        /// <param name="type">The type.</param>

        /// <param name="keys">The keys.</param>

        public IdentityKey(Type type, IEnumerable<object> keys)

        {

            Type = type;

            Keys = new List<object>(keys);



            // Done here becouse IdentityKeys exists to be keys in dictionaries...

            hashCode = type.GetHashCode();

            foreach (object key in keys)

            {

                hashCode ^= key.GetHashCode();

            }

        }



        /// <summary>

        /// Initializes a new instance of the <see cref="IdentityKey"/> class.

        /// </summary>

        /// <param name="type">The type.</param>

        /// <param name="keys">The keys.</param>

        public IdentityKey(Type type, params object[] keys)

        {

            Type = type;

            Keys = new List<object>(keys);



            // Done here becouse IdentityKeys exists to be keys in dictionaries...

            hashCode = Type.GetHashCode();

            foreach (object key in Keys)

            {

                hashCode ^= key.GetHashCode();

            }

        }

    }

}