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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.Dynamic;
using System.Linq.Expressions;
using System.Reflection;
namespace System.Web.Helpers.Test
{
/// <summary>
/// Dynamic object implementation over a dictionary that doesn't implement anything but the interface.
/// Used for testing our types that consume dynamic objects to make sure they don't make any assumptions on the implementation.
/// </summary>
public class DynamicDictionary : IDynamicMetaObjectProvider
{
private readonly Dictionary<string, object> _values = new Dictionary<string, object>();
public object this[string name]
{
get
{
object result;
_values.TryGetValue(name, out result);
return result;
}
set { _values[name] = value; }
}
public DynamicMetaObject GetMetaObject(Expression parameter)
{
return new DynamicDictionaryMetaObject(parameter, this);
}
private class DynamicDictionaryMetaObject : DynamicMetaObject
{
private static readonly PropertyInfo ItemPropery = typeof(DynamicDictionary).GetProperty("Item");
public DynamicDictionaryMetaObject(Expression expression, object value)
: base(expression, BindingRestrictions.Empty, value)
{
}
private IDictionary<string, object> WrappedDictionary
{
get { return ((DynamicDictionary)Value)._values; }
}
private Expression GetDynamicExpression()
{
return Expression.Convert(Expression, typeof(DynamicDictionary));
}
private Expression GetIndexExpression(string key)
{
return Expression.MakeIndex(
GetDynamicExpression(),
ItemPropery,
new[]
{
Expression.Constant(key)
}
);
}
private Expression GetSetValueExpression(string key, object value)
{
return Expression.Assign(
GetIndexExpression(key),
Expression.Convert(Expression.Constant(value),
typeof(object))
);
}
public override DynamicMetaObject BindGetMember(GetMemberBinder binder)
{
var binderDefault = binder.FallbackGetMember(this);
var expression = Expression.Convert(GetIndexExpression(binder.Name),
typeof(object));
var dynamicSuggestion = new DynamicMetaObject(expression, BindingRestrictions.GetTypeRestriction(Expression, LimitType)
.Merge(binderDefault.Restrictions));
return binder.FallbackGetMember(this, dynamicSuggestion);
}
public override DynamicMetaObject BindSetMember(SetMemberBinder binder, DynamicMetaObject value)
{
var binderDefault = binder.FallbackSetMember(this, value);
Expression expression = GetSetValueExpression(binder.Name, value.Value);
var dynamicSuggestion = new DynamicMetaObject(expression, BindingRestrictions.GetTypeRestriction(Expression, LimitType)
.Merge(binderDefault.Restrictions));
return binder.FallbackSetMember(this, value, dynamicSuggestion);
}
public override IEnumerable<string> GetDynamicMemberNames()
{
return WrappedDictionary.Keys;
}
}
}
}
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