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| using System;
using System.Collections.Generic;
using System.Linq.Expressions;
using System.Reflection;
namespace ConsoleApplication1
{
class User
{
public string Name { get; set; }
public string Mail { get; set; }
}
class Program
{
static T convert<T>(Expression<Func<T, bool>> e)
where T : class, new()
{
Expression body = Expression.MemberInit(
Expression.New(typeof(T)),
getBindings(e));
LambdaExpression ctor = Expression.Lambda(body);
Func<T> f = ( Func<T> )ctor.Compile();
return f();
}
static IEnumerable<MemberBinding> getBindings<T>(Expression<Func<T, bool>> e)
{
LambdaExpression lambda = ( LambdaExpression )e;
return explore(lambda.Body);
}
static IEnumerable<MemberBinding> explore(Expression e)
{
BinaryExpression b = ( BinaryExpression )e;
MemberInfo mi = null;
Expression value = null;
if ( b.NodeType == ExpressionType.Equal ) {
if ( b.Left.NodeType == ExpressionType.MemberAccess )
mi = (( MemberExpression )b.Left).Member;
else if ( b.Left.NodeType == ExpressionType.Constant )
value = b.Left;
if ( b.Right.NodeType == ExpressionType.MemberAccess )
mi = (( MemberExpression )b.Right).Member;
else if ( b.Right.NodeType == ExpressionType.Constant )
value = b.Right;
yield return Expression.Bind(mi, value);
} else {
foreach ( var m in explore(b.Left) )
yield return m;
foreach ( var m in explore(b.Right) )
yield return m;
}
}
static void Main(string [] args)
{
var user = convert((User u) => u.Name == "Toto" && u.Mail == "toto@gmail.com");
}
}
} |
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