// ==++==
// 
//   Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// ==--==
//
// <OWNER>Microsoft</OWNER>
// <OWNER>Microsoft</OWNER>
 
using System;
using System.Collections.Generic;
using System.Diagnostics.Contracts;
 
namespace System.Runtime.InteropServices.WindowsRuntime
{
    // Provides access to a System.Collections.Generic.KeyValuePair<K, V> via the IKeyValuePair<K, V> WinRT interface.
    internal sealed class CLRIKeyValuePairImpl<K, V> : IKeyValuePair<K, V>
    {
        private readonly KeyValuePair<K, V> _pair;
 
        public CLRIKeyValuePairImpl([In] ref KeyValuePair<K, V> pair)
        {
            _pair = pair;
        }
 
        // IKeyValuePair<K, V> implementation
        [Pure]
        public K Key
        {
            get { return _pair.Key; }
        }
 
        [Pure]
        public V Value
        {
            get { return _pair.Value; }
        }
 
        // Called from the VM to wrap a boxed KeyValuePair with a CLRIKeyValuePairImpl.
        internal static object BoxHelper(object pair)
        {
            Contract.Requires(pair != null);
 
            KeyValuePair<K, V> unboxedPair = (KeyValuePair<K, V>)pair;
            return new CLRIKeyValuePairImpl<K, V>(ref unboxedPair);
        }
 
        // Called from the VM to get a boxed KeyValuePair out of a CLRIKeyValuePairImpl.
        internal static object UnboxHelper(object wrapper)
        {
            Contract.Requires(wrapper != null);
            
            CLRIKeyValuePairImpl<K, V> reference = (CLRIKeyValuePairImpl<K, V>)wrapper;
            return reference._pair;
        }
 
        public override string ToString()
        {
            return _pair.ToString();
        }
    }
}