Combining multiple expressions 合并多个System.Linq.Expressions.Expression

using System;

using System.Collections.Generic;

using System.Linq;



namespace System.Linq.Expressions

{

    public static class ExpressionExtensions

    {

        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, invokedExpr), 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);

        }



        public static Expression<Func<T, bool>> WhereAnd<T>(this IEnumerable<Expression<Func<T, bool>>> exprs)

        {

            Expression<Func<T, bool>> FinalQuery = t => true;

            foreach (var expr in exprs)

            {

                FinalQuery = FinalQuery.And(expr);

            }

            return FinalQuery;

        }



        public static Expression<Func<T, bool>> WhereOr<T>(this IEnumerable<Expression<Func<T, bool>>> exprs)

        {

            Expression<Func<T, bool>> FinalQuery = t => false;

            foreach (var expr in exprs)

            {

                FinalQuery = FinalQuery.Or(expr);

            }

            return FinalQuery;

        }

    }

}