/*
Kooboo is a content management system based on ASP.NET MVC framework. Copyright 2009 Yardi Technology Limited.
This program is free software: you can redistribute it and/or modify it under the terms of the
GNU General Public License version 3 as published by the Free Software Foundation.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with this program.
If not, see http://www.kooboo.com/gpl3/.
*/
//refer:http://www.albahari.com/nutshell/predicatebuilder.aspx
using System;
using System.Linq;
using System.Linq.Expressions;
using System.Collections.Generic;
namespace Everest.Library.LINQ{
public static class PredicateBuilder
{
public static Expression<Func<T, bool>> True<T>() { return f => true; }
public static Expression<Func<T, bool>> False<T>() { return f => false; }
public static Expression<Func<T, bool>> Or<T>(this Expression<Func<T, bool>> expr1,
Expression<Func<T, bool>> expr2)
{
var invokedExpr = Expression.Invoke(expr2, expr1.Parameters.Cast<Expression>());
return Expression.Lambda<Func<T, bool>>
(Expression.Or(expr1.Body, expr2), expr1.Parameters);
}
public static Expression<Func<T, bool>> And<T>(this Expression<Func<T, bool>> expr1,
Expression<Func<T, bool>> expr2)
{
var invokedExpr = Expression.Invoke(expr2, expr1.Parameters.Cast<Expression>());
return Expression.Lambda<Func<T, bool>>
(Expression.And(expr1.Body, invokedExpr), expr1.Parameters);
}
}
}
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