Sicherung

FSI.Lib/NLogViewer/Helper/PredicateBuilder.cs

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+using System;
+using System.Linq;
+using System.Linq.Expressions;
+
+namespace DJ.Helper
+{
+    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<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.OrElse (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.AndAlso (expr1.Body, invokedExpr), expr1.Parameters);
+        }
+    }
+}