Lambda表达式公共拼接函数（原创）

#region Lambda公共拼接函数
/// <summary>
/// LambdaWhere(枚举)
/// </summary>
public enum LambdaWhere : int
{
And = ,
Or =
}
/// <summary>
/// Lambda公共拼接函数(来自：http://www.cnblogs.com/CielWater)
/// </summary>
/// <param name="BodyLeft">要拼接的Lambda表达式</param>
/// <param name="BodyRight">要拼接的Lambda表达式</param>
/// <param name="LambdaWhere">拼接方式，And或者Or</param>
/// <returns></returns>
public Expression<Func<T, bool>> Lambda<T>(Expression<Func<T, bool>> BodyLeft, Expression<Func<T, bool>> BodyRight, LambdaWhere LambdaWhere)
{
if (BodyLeft != null && BodyRight != null)
{
ParameterExpression pe = BodyLeft.Parameters.Single();
switch (LambdaWhere)
{
case LambdaWhere.And:
BodyLeft = Expression.Lambda<Func<T, bool>>(
Expression.And(BodyLeft.Body, Expression.Invoke(BodyRight, pe)), pe);
break;
default:
BodyLeft = Expression.Lambda<Func<T, bool>>(
Expression.Or(BodyLeft.Body, Expression.Invoke(BodyRight, pe)), pe);
break;
}
}
else if (BodyLeft != null)
{
return BodyLeft;
}
else
{
return BodyRight;
}
return BodyLeft;
}
#endregion