Collection.cs

using System.Collections.Generic;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Threading;

namespace System.Collections.ObjectModel
{
    [Serializable]
    [ComVisible(false)]
    [DebuggerTypeProxy(typeof(Mscorlib_CollectionDebugView<>))]
    [DebuggerDisplay("Count = {Count}")]
    [__DynamicallyInvokable]
    public class Collection<T> : IList<T>, ICollection<T>, IEnumerable<T>, IEnumerable, IList, ICollection, IReadOnlyList<T>, IReadOnlyCollection<T>
    {
        private IList<T> items;

        [NonSerialized]
        private object _syncRoot;

        [__DynamicallyInvokable]
        public int Count
        {
            [__DynamicallyInvokable]
            get
            {
                return items.Count;
            }
        }

        [__DynamicallyInvokable]
        protected IList<T> Items
        {
            [__DynamicallyInvokable]
            get
            {
                return items;
            }
        }

        [__DynamicallyInvokable]
        public T this[int index]
        {
            [__DynamicallyInvokable]
            get
            {
                return items[index];
            }
            [__DynamicallyInvokable]
            set
            {
                if (items.IsReadOnly)
                {
                    ThrowHelper.ThrowNotSupportedException(ExceptionResource.NotSupported_ReadOnlyCollection);
                }
                if (index < 0 || index >= items.Count)
                {
                    ThrowHelper.ThrowArgumentOutOfRangeException();
                }
                SetItem(index, value);
            }
        }

        [__DynamicallyInvokable]
        bool ICollection<T>.IsReadOnly
        {
            [__DynamicallyInvokable]
            get
            {
                return items.IsReadOnly;
            }
        }

        [__DynamicallyInvokable]
        bool ICollection.IsSynchronized
        {
            [__DynamicallyInvokable]
            get
            {
                return false;
            }
        }

        [__DynamicallyInvokable]
        object ICollection.SyncRoot
        {
            [__DynamicallyInvokable]
            get
            {
                if (_syncRoot == null)
                {
                    ICollection collection = items as ICollection;
                    if (collection != null)
                    {
                        _syncRoot = collection.SyncRoot;
                    }
                    else
                    {
                        Interlocked.CompareExchange<object>(ref _syncRoot, new object(), (object)null);
                    }
                }
                return _syncRoot;
            }
        }

        [__DynamicallyInvokable]
        object IList.this[int index]
        {
            [__DynamicallyInvokable]
            get
            {
                return items[index];
            }
            [__DynamicallyInvokable]
            set
            {
                ThrowHelper.IfNullAndNullsAreIllegalThenThrow<T>(value, ExceptionArgument.value);
                try
                {
                    this[index] = (T)value;
                }
                catch (InvalidCastException)
                {
                    ThrowHelper.ThrowWrongValueTypeArgumentException(value, typeof(T));
                }
            }
        }

        [__DynamicallyInvokable]
        bool IList.IsReadOnly
        {
            [__DynamicallyInvokable]
            get
            {
                return items.IsReadOnly;
            }
        }

        [__DynamicallyInvokable]
        bool IList.IsFixedSize
        {
            [__DynamicallyInvokable]
            get
            {
                return (items as IList)?.IsFixedSize ?? items.IsReadOnly;
            }
        }

        [__DynamicallyInvokable]
        public Collection()
        {
            items = new List<T>();
        }

        [__DynamicallyInvokable]
        public Collection(IList<T> list)
        {
            if (list == null)
            {
                ThrowHelper.ThrowArgumentNullException(ExceptionArgument.list);
            }
            items = list;
        }

        [__DynamicallyInvokable]
        public void Add(T item)
        {
            if (items.IsReadOnly)
            {
                ThrowHelper.ThrowNotSupportedException(ExceptionResource.NotSupported_ReadOnlyCollection);
            }
            int count = items.Count;
            InsertItem(count, item);
        }

        [__DynamicallyInvokable]
        public void Clear()
        {
            if (items.IsReadOnly)
            {
                ThrowHelper.ThrowNotSupportedException(ExceptionResource.NotSupported_ReadOnlyCollection);
            }
            ClearItems();
        }

        [__DynamicallyInvokable]
        public void CopyTo(T[] array, int index)
        {
            items.CopyTo(array, index);
        }

        [__DynamicallyInvokable]
        public bool Contains(T item)
        {
            return items.Contains(item);
        }

        [__DynamicallyInvokable]
        public IEnumerator<T> GetEnumerator()
        {
            return items.GetEnumerator();
        }

        [__DynamicallyInvokable]
        public int IndexOf(T item)
        {
            return items.IndexOf(item);
        }

        [__DynamicallyInvokable]
        public void Insert(int index, T item)
        {
            if (items.IsReadOnly)
            {
                ThrowHelper.ThrowNotSupportedException(ExceptionResource.NotSupported_ReadOnlyCollection);
            }
            if (index < 0 || index > items.Count)
            {
                ThrowHelper.ThrowArgumentOutOfRangeException(ExceptionArgument.index, ExceptionResource.ArgumentOutOfRange_ListInsert);
            }
            InsertItem(index, item);
        }

        [__DynamicallyInvokable]
        public bool Remove(T item)
        {
            if (items.IsReadOnly)
            {
                ThrowHelper.ThrowNotSupportedException(ExceptionResource.NotSupported_ReadOnlyCollection);
            }
            int num = items.IndexOf(item);
            if (num < 0)
            {
                return false;
            }
            RemoveItem(num);
            return true;
        }

        [__DynamicallyInvokable]
        public void RemoveAt(int index)
        {
            if (items.IsReadOnly)
            {
                ThrowHelper.ThrowNotSupportedException(ExceptionResource.NotSupported_ReadOnlyCollection);
            }
            if (index < 0 || index >= items.Count)
            {
                ThrowHelper.ThrowArgumentOutOfRangeException();
            }
            RemoveItem(index);
        }

        [__DynamicallyInvokable]
        protected virtual void ClearItems()
        {
            items.Clear();
        }

        [__DynamicallyInvokable]
        protected virtual void InsertItem(int index, T item)
        {
            items.Insert(index, item);
        }

        [__DynamicallyInvokable]
        protected virtual void RemoveItem(int index)
        {
            items.RemoveAt(index);
        }

        [__DynamicallyInvokable]
        protected virtual void SetItem(int index, T item)
        {
            items[index] = item;
        }

        [__DynamicallyInvokable]
        IEnumerator IEnumerable.GetEnumerator()
        {
            return ((IEnumerable)items).GetEnumerator();
        }

        [__DynamicallyInvokable]
        void ICollection.CopyTo(Array array, int index)
        {
            if (array == null)
            {
                ThrowHelper.ThrowArgumentNullException(ExceptionArgument.array);
            }
            if (array.Rank != 1)
            {
                ThrowHelper.ThrowArgumentException(ExceptionResource.Arg_RankMultiDimNotSupported);
            }
            if (array.GetLowerBound(0) != 0)
            {
                ThrowHelper.ThrowArgumentException(ExceptionResource.Arg_NonZeroLowerBound);
            }
            if (index < 0)
            {
                ThrowHelper.ThrowArgumentOutOfRangeException(ExceptionArgument.index, ExceptionResource.ArgumentOutOfRange_NeedNonNegNum);
            }
            if (array.Length - index < Count)
            {
                ThrowHelper.ThrowArgumentException(ExceptionResource.Arg_ArrayPlusOffTooSmall);
            }
            T[] array2 = array as T[];
            if (array2 != null)
            {
                items.CopyTo(array2, index);
                return;
            }
            Type elementType = array.GetType().GetElementType();
            Type typeFromHandle = typeof(T);
            if (!elementType.IsAssignableFrom(typeFromHandle) && !typeFromHandle.IsAssignableFrom(elementType))
            {
                ThrowHelper.ThrowArgumentException(ExceptionResource.Argument_InvalidArrayType);
            }
            object[] array3 = array as object[];
            if (array3 == null)
            {
                ThrowHelper.ThrowArgumentException(ExceptionResource.Argument_InvalidArrayType);
            }
            int count = items.Count;
            try
            {
                for (int i = 0; i < count; i++)
                {
                    array3[index++] = items[i];
                }
            }
            catch (ArrayTypeMismatchException)
            {
                ThrowHelper.ThrowArgumentException(ExceptionResource.Argument_InvalidArrayType);
            }
        }

        [__DynamicallyInvokable]
        int IList.Add(object value)
        {
            if (items.IsReadOnly)
            {
                ThrowHelper.ThrowNotSupportedException(ExceptionResource.NotSupported_ReadOnlyCollection);
            }
            ThrowHelper.IfNullAndNullsAreIllegalThenThrow<T>(value, ExceptionArgument.value);
            try
            {
                Add((T)value);
            }
            catch (InvalidCastException)
            {
                ThrowHelper.ThrowWrongValueTypeArgumentException(value, typeof(T));
            }
            return Count - 1;
        }

        [__DynamicallyInvokable]
        bool IList.Contains(object value)
        {
            if (IsCompatibleObject(value))
            {
                return Contains((T)value);
            }
            return false;
        }

        [__DynamicallyInvokable]
        int IList.IndexOf(object value)
        {
            if (IsCompatibleObject(value))
            {
                return IndexOf((T)value);
            }
            return -1;
        }

        [__DynamicallyInvokable]
        void IList.Insert(int index, object value)
        {
            if (items.IsReadOnly)
            {
                ThrowHelper.ThrowNotSupportedException(ExceptionResource.NotSupported_ReadOnlyCollection);
            }
            ThrowHelper.IfNullAndNullsAreIllegalThenThrow<T>(value, ExceptionArgument.value);
            try
            {
                Insert(index, (T)value);
            }
            catch (InvalidCastException)
            {
                ThrowHelper.ThrowWrongValueTypeArgumentException(value, typeof(T));
            }
        }

        [__DynamicallyInvokable]
        void IList.Remove(object value)
        {
            if (items.IsReadOnly)
            {
                ThrowHelper.ThrowNotSupportedException(ExceptionResource.NotSupported_ReadOnlyCollection);
            }
            if (IsCompatibleObject(value))
            {
                Remove((T)value);
            }
        }

        private static bool IsCompatibleObject(object value)
        {
            if (!(value is T))
            {
                if (value == null)
                {
                    return default(T) == null;
                }
                return false;
            }
            return true;
        }
    }
}