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using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Signum.Utilities.ExpressionTrees;
using System.Linq.Expressions;
using System.Diagnostics;
using Signum.Engine.Maps;
using Signum.Entities;
using System.Reflection;
using Signum.Utilities.Reflection;
namespace Signum.Engine.Linq
{
public class QueryFilterer : SimpleExpressionVisitor
{
static GenericInvoker<Func<Schema, IQueryable, IQueryable>> miFilter = new GenericInvoker<Func<Schema, IQueryable, IQueryable>>((s,q) => s.OnFilterQuery<TypeDN>((IQueryable<TypeDN>)q));
protected override Expression VisitConstant(ConstantExpression c)
{
if (typeof(IQueryable).IsAssignableFrom(c.Type))
{
IQueryable query = (IQueryable)c.Value;
if (query.IsBase() && typeof(IdentifiableEntity).IsAssignableFrom(query.ElementType))
{
IQueryable newQuery = miFilter.GetInvoker(c.Type.GetGenericArguments())(Schema.Current, query);
if (newQuery != query)
return newQuery.Expression;
return c;
}
else
{
/// <summary>
/// Replaces every expression like ConstantExpression{ Type = IQueryable, Value = complexExpr } by complexExpr
/// </summary>
return DbQueryProvider.Clean(query.Expression);
}
}
return base.VisitConstant(c);
}
internal static Expression Filter(Expression expression)
{
return new QueryFilterer().Visit(expression);
}
}
}
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I'm Computer Scientist, one of the founders of Signum Software, and the lead developer behind Signum Framework.
www.signumframework.com
I love programming in C#, Linq, Compilers, Algorithms, Functional Programming, Computer Graphics, Maths...