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/* ****************************************************************************
*
* Copyright (c) Microsoft Corporation.
*
* This source code is subject to terms and conditions of the Apache License, Version 2.0. A
* copy of the license can be found in the License.html file at the root of this distribution. If
* you cannot locate the Apache License, Version 2.0, please send an email to
* dlr@microsoft.com. By using this source code in any fashion, you are agreeing to be bound
* by the terms of the Apache License, Version 2.0.
*
* You must not remove this notice, or any other, from this software.
*
*
* ***************************************************************************/
using System;
using System.Collections.Generic;
using System.Text;
using System.Dynamic.Utils;
#if CLR2
namespace Microsoft.Scripting.Ast {
#else
namespace System.Linq.Expressions {
#endif
/// <summary>
/// Provides a wrapper around an IArgumentProvider which exposes the argument providers
/// members out as an IList of Expression. This is used to avoid allocating an array
/// which needs to be stored inside of a ReadOnlyCollection. Instead this type has
/// the same amount of overhead as an array without duplicating the storage of the
/// elements. This ensures that internally we can avoid creating and copying arrays
/// while users of the Expression trees also don't pay a size penalty for this internal
/// optimization. See IArgumentProvider for more general information on the Expression
/// tree optimizations being used here.
/// </summary>
class ListArgumentProvider : IList<Expression> {
private readonly IArgumentProvider _provider;
private readonly Expression _arg0;
internal ListArgumentProvider(IArgumentProvider provider, Expression arg0) {
_provider = provider;
_arg0 = arg0;
}
#region IList<Expression> Members
public int IndexOf(Expression item) {
if (_arg0 == item) {
return 0;
}
for (int i = 1; i < _provider.ArgumentCount; i++) {
if (_provider.GetArgument(i) == item) {
return i;
}
}
return -1;
}
public void Insert(int index, Expression item) {
throw ContractUtils.Unreachable;
}
public void RemoveAt(int index) {
throw ContractUtils.Unreachable;
}
public Expression this[int index] {
get {
if (index == 0) {
return _arg0;
}
return _provider.GetArgument(index);
}
set {
throw ContractUtils.Unreachable;
}
}
#endregion
#region ICollection<Expression> Members
public void Add(Expression item) {
throw ContractUtils.Unreachable;
}
public void Clear() {
throw ContractUtils.Unreachable;
}
public bool Contains(Expression item) {
return IndexOf(item) != -1;
}
public void CopyTo(Expression[] array, int arrayIndex) {
array[arrayIndex++] = _arg0;
for (int i = 1; i < _provider.ArgumentCount; i++) {
array[arrayIndex++] = _provider.GetArgument(i);
}
}
public int Count {
get { return _provider.ArgumentCount; }
}
public bool IsReadOnly {
get { return true; }
}
public bool Remove(Expression item) {
throw ContractUtils.Unreachable;
}
#endregion
#region IEnumerable<Expression> Members
public IEnumerator<Expression> GetEnumerator() {
yield return _arg0;
for (int i = 1; i < _provider.ArgumentCount; i++) {
yield return _provider.GetArgument(i);
}
}
#endregion
#region IEnumerable Members
System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator() {
yield return _arg0;
for (int i = 1; i < _provider.ArgumentCount; i++) {
yield return _provider.GetArgument(i);
}
}
#endregion
}
}
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