添加项目文件。

CoreCms.Net.Model/Entities/Expression/ParameterRebinder.cs

@@ -0,0 +1,38 @@
+/***********************************************************************
+ *            Project: CoreCms
+ *        ProjectName: 核心内容管理系统                                
+ *                Web: https://www.corecms.net                      
+ *             Author: 大灰灰                                          
+ *              Email: jianweie@163.com                                
+ *         CreateTime: 2021/1/31 21:45:10
+ *        Description: 暂无
+ ***********************************************************************/
+
+using System.Collections.Generic;
+using System.Linq.Expressions;
+
+namespace CoreCms.Net.Model.Entities.Expression
+{
+    public class ParameterRebinder : ExpressionVisitor
+    {
+        private readonly Dictionary<ParameterExpression, ParameterExpression> map;
+
+        public ParameterRebinder(Dictionary<ParameterExpression, ParameterExpression> map)
+        {
+            this.map = map ?? new Dictionary<ParameterExpression, ParameterExpression>();
+        }
+
+        public static System.Linq.Expressions.Expression ReplaceParameters(
+            Dictionary<ParameterExpression, ParameterExpression> map, System.Linq.Expressions.Expression exp)
+        {
+            return new ParameterRebinder(map).Visit(exp);
+        }
+
+        protected override System.Linq.Expressions.Expression VisitParameter(ParameterExpression p)
+        {
+            ParameterExpression replacement;
+            if (map.TryGetValue(p, out replacement)) p = replacement;
+            return base.VisitParameter(p);
+        }
+    }
+}

CoreCms.Net.Model/Entities/Expression/PredicateBuilder.cs

@@ -0,0 +1,63 @@
+/***********************************************************************
+ *            Project: CoreCms
+ *        ProjectName: 核心内容管理系统                                
+ *                Web: https://www.corecms.net                      
+ *             Author: 大灰灰                                          
+ *              Email: jianweie@163.com                                
+ *         CreateTime: 2021/1/31 21:45:10
+ *        Description: 暂无
+ ***********************************************************************/
+
+using System;
+using System.Linq;
+using System.Linq.Expressions;
+
+namespace CoreCms.Net.Model.Entities.Expression
+{
+    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<T> Compose<T>(this Expression<T> first, Expression<T> second,
+            Func<System.Linq.Expressions.Expression, System.Linq.Expressions.Expression,
+                System.Linq.Expressions.Expression> merge)
+        {
+            // build parameter map (from parameters of second to parameters of first)  
+            var map = first.Parameters.Select((f, i) => new {f, s = second.Parameters[i]})
+                .ToDictionary(p => p.s, p => p.f);
+
+            // replace parameters in the second lambda expression with parameters from the first  
+            var secondBody = ParameterRebinder.ReplaceParameters(map, second.Body);
+
+            // apply composition of lambda expression bodies to parameters from the first expression   
+            return System.Linq.Expressions.Expression.Lambda<T>(merge(first.Body, secondBody), first.Parameters);
+        }
+
+        /// <summary>
+        ///     扩展啦
+        /// </summary>
+        /// <typeparam name="T"></typeparam>
+        /// <param name="first"></param>
+        /// <param name="second"></param>
+        /// <returns></returns>
+        public static Expression<Func<T, bool>> And<T>(this Expression<Func<T, bool>> first,
+            Expression<Func<T, bool>> second)
+        {
+            return first.Compose(second, System.Linq.Expressions.Expression.AndAlso);
+        }
+
+        public static Expression<Func<T, bool>> Or<T>(this Expression<Func<T, bool>> first,
+            Expression<Func<T, bool>> second)
+        {
+            return first.Compose(second, System.Linq.Expressions.Expression.OrElse);
+        }
+    }
+}