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Infrastructure/Hncore.Infrastructure/EntitiesExtension/ExpressionBuilder.cs

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+using System;
+using System.Linq;
+using System.Linq.Expressions;
+
+namespace Hncore.Infrastructure.EntitiesExtension
+{
+    /// <summary>
+    /// Extension methods for add And and Or with parameters rebinder
+    /// </summary>
+    public static class ExpressionBuilder
+    {
+        /// <summary>
+        /// Compose two expression and merge all in a new expression
+        /// </summary>
+        /// <typeparam name="T">Type of params in expression</typeparam>
+        /// <param name="first">Expression instance</param>
+        /// <param name="second">Expression to merge</param>
+        /// <param name="merge">Function to merge</param>
+        /// <returns>New merged expressions</returns>
+        public static Expression<T> Compose<T>(this Expression<T> first, Expression<T> second, Func<Expression, Expression, 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 Expression.Lambda<T>(merge(first.Body, secondBody), first.Parameters);
+        }
+        /// <summary>
+        /// And operator
+        /// </summary>
+        /// <typeparam name="T">Type of params in expression</typeparam>
+        /// <param name="first">Right Expression in AND operation</param>
+        /// <param name="second">Left Expression in And operation</param>
+        /// <returns>New AND expression</returns>
+        public static Expression<Func<T, bool>> And<T>(this Expression<Func<T, bool>> first, Expression<Func<T, bool>> second)
+        {
+            return first.Compose(second, Expression.AndAlso);
+        }
+        /// <summary>
+        /// Or operator
+        /// </summary>
+        /// <typeparam name="T">Type of param in expression</typeparam>
+        /// <param name="first">Right expression in OR operation</param>
+        /// <param name="second">Left expression in OR operation</param>
+        /// <returns>New Or expressions</returns>
+        public static Expression<Func<T, bool>> Or<T>(this Expression<Func<T, bool>> first, Expression<Func<T, bool>> second)
+        {
+            return first.Compose(second, Expression.Or);
+        }
+    }
+}