#160 Unhandled expression type: 'Index' (#162)

* #160 Unhandled expression type: 'Index'

* #160 Unhandled expression type: 'Index'

Author: doboczyakos

src/LinqKit.Core/ExpressionVisitor.cs

@@ -84,6 +84,9 @@ public virtual Expression Visit(Expression exp)
                 case ExpressionType.ListInit:
                     return VisitListInit((ListInitExpression)exp);
 #if !NET35
+                case ExpressionType.Index:
+                    return VisitIndex((IndexExpression)exp);
+
                 case ExpressionType.Extension:
                     return VisitExtension(exp);
 #endif
@@ -400,6 +403,20 @@ protected virtual Expression VisitInvocation(InvocationExpression iv)
             Expression expr = Visit(iv.Expression);
             return args != iv.Arguments || expr != iv.Expression ? Expression.Invoke(expr, args) : iv;
         }
+
+#if !NET35
+        /// <summary> Visit index expression </summary>
+        protected virtual Expression VisitIndex(IndexExpression exp)
+        {
+            var obj = Visit(exp.Object);
+            var args = VisitExpressionList(exp.Arguments);
+            if (obj != exp.Object || args != exp.Arguments)
+            {
+                return Expression.MakeIndex(obj, exp.Indexer, args);
+            }
+            return exp;
+        }
+#endif
     }
 }
 #endif

tests/LinqKit.Tests.Net452/ExpressionExpanderTests.cs

@@ -1,4 +1,7 @@
-using System.Linq.Expressions;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Linq.Expressions;
 using Xunit;
 
 namespace LinqKit.Tests.Net452
@@ -28,5 +31,20 @@ public void ExpressionCombiner_Expression_UnaryPlus()
             var executed = exp.Expand().ToString();
             Assert.Equal(exp.ToString(), executed);
         }
+
+        [Fact]
+        public void ExpressionExpander_Expression_Index()
+        {
+            var listParameter = Expression.Parameter(typeof(List<string>), "l");
+            Expression<Func<List<string>, string>> expression1 = Expression.Lambda<Func<List<string>, string>>(Expression.MakeIndex(
+                    listParameter,
+                    typeof(List<string>).GetProperties().SingleOrDefault(p => p.GetIndexParameters().Length > 0),
+                    new[] { Expression.Constant(0) }),
+                listParameter);
+            Expression<Func<string, string>> expression2 = s => s;
+
+            var executed = Linq.Expr((List<string> l) => expression2.Invoke(expression1.Invoke(l))).Expand().ToString();
+            Assert.Equal(expression1.ToString(), executed);
+        }
     }
 }