(에센스) 2020년 6월 26일 C#라이브러리 Expression(확장 방법)

using LinqKit;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;

namespace Core.Util
{
    public static partial class Extention
    {
        #region   AndIf AndOr

        ///


        ///      And
        /// 
        ///     
        ///     
        ///       
        ///     
        /// 
        public static Expression<Func<T, bool>> AndIf<T>(this Expression<Func<T, bool>> left, bool need, Expression<Func<T, bool>> right)
        {
            if (need)
            {
                return left.And(right);
            }
            else
            {
                return left;
            }
        }

        ///


        ///      Or
        /// 
        ///     
        ///     
        ///       
        ///     
        /// 
        public static Expression<Func<T, bool>> OrIf<T>(this Expression<Func<T, bool>> left, bool need, Expression<Func<T, bool>> right)
        {
            if (need)
            {
                return left.Or(right);
            }
            else
            {
                return left;
            }
        }

        #endregion

        #region   BuildExtendSelectExpre  

        ///


        ///             ,     
        /// TResult   TBase     
        /// 
        ///      
        ///     
        ///      
        /// 
        public static Expression<Func<TBase, TResult>> BuildExtendSelectExpre<TBase, TResult>(this Expression<Func<TBase, TResult>> expression)
        {
            return GetExtendSelectExpre<TBase, TResult, Func<TBase, TResult>>(expression);
        }

        ///


        ///             ,1     
        /// TResult   TBase     
        /// 
        ///      
        ///     1
        ///     
        ///      
        /// 
        public static Expression<Func<TBase, T1, TResult>> BuildExtendSelectExpre<TBase, T1, TResult>(this Expression<Func<TBase, T1, TResult>> expression)
        {
            return GetExtendSelectExpre<TBase, TResult, Func<TBase, T1, TResult>>(expression);
        }

        ///


        ///             ,2     
        /// TResult   TBase     
        /// 
        ///      
        ///     1
        ///     2
        ///     
        ///      
        /// 
        public static Expression<Func<TBase, T1, T2, TResult>> BuildExtendSelectExpre<TBase, T1, T2, TResult>(this Expression<Func<TBase, T1, T2, TResult>> expression)
        {
            return GetExtendSelectExpre<TBase, TResult, Func<TBase, T1, T2, TResult>>(expression);
        }

        ///


        ///             ,3     
        /// TResult   TBase     
        /// 
        ///      
        ///     1
        ///     2
        ///     3
        ///     
        ///      
        /// 
        public static Expression<Func<TBase, T1, T2, T3, TResult>> BuildExtendSelectExpre<TBase, T1, T2, T3, TResult>(this Expression<Func<TBase, T1, T2, T3, TResult>> expression)
        {
            return GetExtendSelectExpre<TBase, TResult, Func<TBase, T1, T2, T3, TResult>>(expression);
        }

        ///


        ///             ,4     
        /// TResult   TBase     
        /// 
        ///      
        ///     1
        ///     2
        ///     3
        ///     4
        ///     
        ///      
        /// 
        public static Expression<Func<TBase, T1, T2, T3, T4, TResult>> BuildExtendSelectExpre<TBase, T1, T2, T3, T4, TResult>(this Expression<Func<TBase, T1, T2, T3, T4, TResult>> expression)
        {
            return GetExtendSelectExpre<TBase, TResult, Func<TBase, T1, T2, T3, T4, TResult>>(expression);
        }

        ///


        ///             ,5     
        /// TResult   TBase     
        /// 
        ///      
        ///     1
        ///     2
        ///     3
        ///     4
        ///     5
        ///     
        ///      
        /// 
        public static Expression<Func<TBase, T1, T2, T3, T4, T5, TResult>> BuildExtendSelectExpre<TBase, T1, T2, T3, T4, T5, TResult>(this Expression<Func<TBase, T1, T2, T3, T4, T5, TResult>> expression)
        {
            return GetExtendSelectExpre<TBase, TResult, Func<TBase, T1, T2, T3, T4, T5, TResult>>(expression);
        }

        /// 
        ///             ,6     
        /// TResult   TBase     
        /// 
        ///      
        ///     1
        ///     2
        ///     3
        ///     4
        ///     5
        ///     6
        ///     
        ///      
        /// 
        public static Expression<Func<TBase, T1, T2, T3, T4, T5, T6, TResult>> BuildExtendSelectExpre<TBase, T1, T2, T3, T4, T5, T6, TResult>(this Expression<Func<TBase, T1, T2, T3, T4, T5, T6, TResult>> expression)
        {
            return GetExtendSelectExpre<TBase, TResult, Func<TBase, T1, T2, T3, T4, T5, T6, TResult>>(expression);
        }

        /// 
        ///             ,7     
        /// TResult   TBase     
        /// 
        ///      
        ///     1
        ///     2
        ///     3
        ///     4
        ///     5
        ///     6
        ///     7
        ///     
        ///      
        /// 
        public static Expression<Func<TBase, T1, T2, T3, T4, T5, T6, T7, TResult>> BuildExtendSelectExpre<TBase, T1, T2, T3, T4, T5, T6, T7, TResult>(this Expression<Func<TBase, T1, T2, T3, T4, T5, T6, T7, TResult>> expression)
        {
            return GetExtendSelectExpre<TBase, TResult, Func<TBase, T1, T2, T3, T4, T5, T6, T7, TResult>>(expression);
        }

        /// 
        ///             ,8     
        /// TResult   TBase     
        /// 
        ///      
        ///     1
        ///     2
        ///     3
        ///     4
        ///     5
        ///     6
        ///     7
        ///     8
        ///     
        ///      
        /// 
        public static Expression<Func<TBase, T1, T2, T3, T4, T5, T6, T7, T8, TResult>> BuildExtendSelectExpre<TBase, T1, T2, T3, T4, T5, T6, T7, T8, TResult>(this Expression<Func<TBase, T1, T2, T3, T4, T5, T6, T7, T8, TResult>> expression)
        {
            return GetExtendSelectExpre<TBase, TResult, Func<TBase, T1, T2, T3, T4, T5, T6, T7, T8, TResult>>(expression);
        }

        /// 
        ///             ,9     
        /// TResult   TBase     
        /// 
        ///      
        ///     1
        ///     2
        ///     3
        ///     4
        ///     5
        ///     6
        ///     7
        ///     8
        ///     9
        ///     
        ///      
        /// 
        public static Expression<Func<TBase, T1, T2, T3, T4, T5, T6, T7, T8, T9, TResult>> BuildExtendSelectExpre<TBase, T1, T2, T3, T4, T5, T6, T7, T8, T9, TResult>(this Expression<Func<TBase, T1, T2, T3, T4, T5, T6, T7, T8, T9, TResult>> expression)
        {
            return GetExtendSelectExpre<TBase, TResult, Func<TBase, T1, T2, T3, T4, T5, T6, T7, T8, T9, TResult>>(expression);
        }

        #endregion

        #region     

        private static Expression<TDelegate> GetExtendSelectExpre<TBase, TResult, TDelegate>(Expression<TDelegate> expression)
        {
            NewExpression newBody = Expression.New(typeof(TResult));
            MemberInitExpression oldExpression = (MemberInitExpression)expression.Body;

            ParameterExpression[] oldParamters = expression.Parameters.ToArray();
            List<string> existsProperties = new List<string>();
            oldExpression.Bindings.ToList().ForEach(aBinding =>
            {
                existsProperties.Add(aBinding.Member.Name);
            });

            List<MemberBinding> newBindings = new List<MemberBinding>();
            typeof(TBase).GetProperties().Where(x => !existsProperties.Contains(x.Name)).ToList().ForEach(aProperty =>
            {
                if (typeof(TResult).GetMembers().Any(x => x.Name == aProperty.Name))
                {
                    MemberBinding newMemberBinding = null;
                    var valueExpre = Expression.Property(oldParamters[0], aProperty.Name);
                    if (typeof(TBase).IsAssignableFrom(typeof(TResult)))
                    {
                        newMemberBinding = Expression.Bind(aProperty, valueExpre);
                    }
                    else
                    {
                        newMemberBinding = Expression.Bind(typeof(TResult).GetProperty(aProperty.Name), valueExpre);
                    }
                    newBindings.Add(newMemberBinding);
                }
            });

            newBindings.AddRange(oldExpression.Bindings);

            var body = Expression.MemberInit(newBody, newBindings.ToArray());
            var resExpression = Expression.Lambda<TDelegate>(body, oldParamters);

            return resExpression;
        }

        #endregion
    }

    /// 
    ///   ExpressionVisitor ，        
    /// 
    internal class ParameterReplaceVisitor : System.Linq.Expressions.ExpressionVisitor
    {
        public ParameterReplaceVisitor(ParameterExpression paramExpr)
        {
            _parameter = paramExpr;
        }

        //       
        private readonly ParameterExpression _parameter;

        protected override Expression VisitParameter(ParameterExpression p)
        {
            if (p.Type == _parameter.Type)
            {
                return _parameter;
            }

            else
            {
                return p;
            }
        }
    }
}

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(에센스) 2020년 6월 26일 C#라이브러리 Expression(확장 방법)

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