IList.cs source code in C# .NET

                        
Code:
                         / 4.0 / 4.0 / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / clr / src / BCL / System / Collections / IList.cs / 1305376 / IList.cs
                        

                        
                            // ==++== 
//
//   Copyright (c) Microsoft Corporation.  All rights reserved.
//
// ==--== 
/*============================================================
** 
** Interface:  IList 
**
** [....] 
**
**
** Purpose: Base interface for all Lists.
** 
**
===========================================================*/ 
namespace System.Collections { 

    using System; 
    using System.Diagnostics.Contracts;

    // An IList is an ordered collection of objects.  The exact ordering
    // is up to the implementation of the list, ranging from a sorted 
    // order to insertion order.
    [ContractClass(typeof(IListContract))] 
    [System.Runtime.InteropServices.ComVisible(true)] 
    public interface IList : ICollection
    { 
        // The Item property provides methods to read and edit entries in the List.
        Object this[int index] {
            get;
            set; 
        }
 
        // Adds an item to the list.  The exact position in the list is 
        // implementation-dependent, so while ArrayList may always insert
        // in the last available location, a SortedList most likely would not. 
        // The return value is the position the new element was inserted in.
        int Add(Object value);

        // Returns whether the list contains a particular item. 
        bool Contains(Object value);
 
        // Removes all items from the list. 
        void Clear();
 
        bool IsReadOnly
        { get; }

 
        bool IsFixedSize
        { 
            get; 
        }
 

        // Returns the index of a particular item, if it is in the list.
        // Returns -1 if the item isn't in the list.
        int IndexOf(Object value); 

        // Inserts value into the list at position index. 
        // index must be non-negative and less than or equal to the 
        // number of elements in the list.  If index equals the number
        // of items in the list, then value is appended to the end. 
        void Insert(int index, Object value);

        // Removes an item from the list.
        void Remove(Object value); 

        // Removes the item at position index. 
        void RemoveAt(int index); 
    }
 
    [ContractClassFor(typeof(IList))]
    internal abstract class IListContract : IList
    {
        int IList.Add(Object value) 
        {
            //Contract.Ensures(((IList)this).Count == Contract.OldValue(((IList)this).Count) + 1);  // Not threadsafe 
            // This method should return the index in which an item was inserted, but we have 
            // some internal collections that don't always insert items into the list, as well
            // as an MSDN sample code showing us returning -1.  Allow -1 to mean "did not insert". 
            Contract.Ensures(Contract.Result() >= -1);

            Contract.Ensures(Contract.Result() < ((IList)this).Count);
            return default(int); 
        }
 
        Object IList.this[int index] { 
            get {
                //Contract.Requires(index >= 0); 
                //Contract.Requires(index < ((IList)this).Count);
                return default(int);
            }
            set { 
                //Contract.Requires(index >= 0);
                //Contract.Requires(index < ((IList)this).Count); 
            } 
        }
 
        bool IList.IsFixedSize {
            get { return default(bool); }
        }
 
        bool IList.IsReadOnly {
            get { return default(bool); } 
        } 

        bool ICollection.IsSynchronized { 
            get { return default(bool); }
        }

        void IList.Clear() 
        {
            //Contract.Ensures(((IList)this).Count == 0  || ((IList)this).IsFixedSize);  // not threadsafe 
        } 

        bool IList.Contains(Object value) 
        {
            return default(bool);
        }
 
        void ICollection.CopyTo(Array array, int startIndex)
        { 
            //Contract.Requires(array != null); 
            //Contract.Requires(startIndex >= 0);
            //Contract.Requires(startIndex + ((IList)this).Count <= array.Length); 
        }

        int ICollection.Count {
            get { 
                Contract.Ensures(Contract.Result() >= 0);
                return default(int); 
            } 
        }
 
        IEnumerator IEnumerable.GetEnumerator()
        {
            Contract.Ensures(Contract.Result() != null);
            return default(IEnumerator); 
        }
 
        [Pure] 
        int IList.IndexOf(Object value)
        { 
            Contract.Ensures(Contract.Result() >= -1);
            Contract.Ensures(Contract.Result() < ((IList)this).Count);
            return default(int);
        } 

        void IList.Insert(int index, Object value) 
        { 
            //Contract.Requires(index >= 0);
            //Contract.Requires(index <= ((IList)this).Count);  // For inserting immediately after the end. 
            //Contract.Ensures(((IList)this).Count == Contract.OldValue(((IList)this).Count) + 1);  // Not threadsafe
        }

        void IList.Remove(Object value) 
        {
            // No information if removal fails. 
        } 

        void IList.RemoveAt(int index) 
        {
            //Contract.Requires(index >= 0);
            //Contract.Requires(index < ((IList)this).Count);
            //Contract.Ensures(((IList)this).Count == Contract.OldValue(((IList)this).Count) - 1);  // Not threadsafe 
        }
 
        Object ICollection.SyncRoot { 
            get {
                Contract.Ensures(Contract.Result