feat:furion rbac搭建

Yi.Furion.Rbac/Yi.Framework.Infrastructure/Helper/ExpressionHelper.cs

@@ -0,0 +1,98 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Linq.Expressions;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Yi.Framework.Infrastructure.Helper
+{
+    public static class ExpressionHelper
+    {
+
+
+        /// <summary>
+        /// Expression表达式树lambda参数拼接组合
+        /// </summary>
+        /// <typeparam name="T"></typeparam>
+        /// <param name="first"></param>
+        /// <param name="second"></param>
+        /// <param name="merge"></param>
+        /// <returns></returns>
+        public static Expression<T> Compose<T>(this Expression<T> first, Expression<T> second, Func<Expression, Expression, Expression> merge)
+        {
+            var parameterMap = first.Parameters.Select((f, i) => new { f, s = second.Parameters[i] }).ToDictionary(p => p.s, p => p.f);
+            var secondBody = LambdaParameteRebinder.ReplaceParameter(parameterMap, second.Body);
+            return Expression.Lambda<T>(merge(first.Body, secondBody), first.Parameters);
+        }
+
+        /// <summary>
+        /// Expression表达式树lambda参数拼接--false
+        /// </summary>
+        /// <typeparam name="T"></typeparam>
+        /// <returns></returns>
+        public static Expression<Func<T, bool>> False<T>() => f => false;
+
+        /// <summary>
+        /// Expression表达式树lambda参数拼接-true
+        /// </summary>
+        /// <typeparam name="T"></typeparam>
+        /// <returns></returns>
+        public static Expression<Func<T, bool>> True<T>() => f => true;
+
+        /// <summary>
+        /// Expression表达式树lambda参数拼接--and
+        /// </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) => first.Compose(second, Expression.And);
+
+        /// <summary>
+        /// Expression表达式树lambda参数拼接--or
+        /// </summary>
+        /// <typeparam name="T"></typeparam>
+        /// <param name="first"></param>
+        /// <param name="second"></param>
+        /// <returns></returns>
+        public static Expression<Func<T, bool>> Or<T>(this Expression<Func<T, bool>> first, Expression<Func<T, bool>> second) => first.Compose(second, Expression.Or);
+    }
+
+    public class LambdaParameteRebinder : ExpressionVisitor
+    {
+        /// <summary>
+        /// 存放表达式树的参数的字典
+        /// </summary>
+        private readonly Dictionary<ParameterExpression, ParameterExpression> map;
+
+        /// <summary>
+        /// 构造函数
+        /// </summary>
+        /// <param name="map"></param>
+        public LambdaParameteRebinder(Dictionary<ParameterExpression, ParameterExpression> map)
+        {
+            this.map = map ?? new Dictionary<ParameterExpression, ParameterExpression>();
+        }
+
+        /// <summary>
+        /// 重载参数访问的方法，访问表达式树参数，如果字典中包含，则取出
+        /// </summary>
+        /// <param name="node">表达式树参数</param>
+        /// <returns></returns>
+        protected override Expression VisitParameter(ParameterExpression node)
+        {
+            if (map.TryGetValue(node, out ParameterExpression expression))
+            {
+                node = expression;
+            }
+            return base.VisitParameter(node);
+        }
+
+        public static Expression ReplaceParameter(Dictionary<ParameterExpression, ParameterExpression> map, Expression exp)
+        {
+            return new LambdaParameteRebinder(map).Visit(exp);
+        }
+    }
+
+}