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// Copyright (c) Microsoft Corporation. All rights reserved. See License.txt in the project root for license information.
using System.Collections.Generic;
using System.Diagnostics;
using System.Dynamic;
using System.Linq;
using System.Linq.Expressions;
using System.Reflection;
namespace System.Web.Helpers.Test
{
/// <summary>
/// Dynamic object implementation over a regualar CLR object. Getmember accesses members through reflection.
/// </summary>
public class DynamicWrapper : IDynamicMetaObjectProvider
{
private object _object;
public DynamicWrapper(object obj)
{
_object = obj;
}
public DynamicMetaObject GetMetaObject(Expression parameter)
{
return new DynamicWrapperMetaObject(parameter, this);
}
private class DynamicWrapperMetaObject : DynamicMetaObject
{
public DynamicWrapperMetaObject(Expression expression, object value)
: base(expression, BindingRestrictions.Empty, value)
{
}
private object WrappedObject
{
get { return ((DynamicWrapper)Value)._object; }
}
private Expression GetDynamicExpression()
{
return Expression.Convert(Expression, typeof(DynamicWrapper));
}
private Expression GetWrappedObjectExpression()
{
FieldInfo fieldInfo = typeof(DynamicWrapper).GetField("_object", BindingFlags.NonPublic | BindingFlags.Instance);
Debug.Assert(fieldInfo != null);
return Expression.Convert(
Expression.Field(GetDynamicExpression(), fieldInfo),
WrappedObject.GetType());
}
private Expression GetMemberAccessExpression(string memberName)
{
return Expression.Property(
GetWrappedObjectExpression(),
memberName);
}
public override DynamicMetaObject BindGetMember(GetMemberBinder binder)
{
var binderDefault = binder.FallbackGetMember(this);
var expression = Expression.Convert(GetMemberAccessExpression(binder.Name), typeof(object));
var dynamicSuggestion = new DynamicMetaObject(expression, BindingRestrictions.GetTypeRestriction(Expression, LimitType)
.Merge(binderDefault.Restrictions));
return binder.FallbackGetMember(this, dynamicSuggestion);
}
public override IEnumerable<string> GetDynamicMemberNames()
{
return (from p in WrappedObject.GetType().GetProperties()
orderby p.Name
select p.Name).ToArray();
}
}
}
}
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