Fixes #313 (#314)

ListFormatter:
In v1.6.1 a Selector was tested for having the name "index", even if data was not an IList, and returned the CollectionIndex. This is now implemented again in the ListFormatter.TryEvaluateSelector(...)

src/SmartFormat.Tests/Extensions/ListFormatterTests.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections;
 using System.Collections.Generic;
 using System.Globalization;
 using System.Linq;
@@ -66,6 +67,22 @@ public void Null_List()
         Assert.AreEqual(string.Empty, result);
     }
 
+    [Test]
+    public void Enumerable_With_SelectorName_Index_Is_Recognized()
+    {
+        var smart = Smart.CreateDefaultSmartFormat();
+        var objects = new object[]
+        {
+            new { Content = "Content A" },
+            new { Content = "Content B" }
+        };
+
+        // Linq Select returns an IEnumerable.
+        // "Index" selector should be recognized even when the argument is not an IList
+        var result = smart.Format("{0:{Content} with Index {Index}|, }", objects.Select(x => x));
+        Assert.That(result, Is.EqualTo("Content A with Index 0, Content B with Index 1"));
+    }
+
     [Test]
     public void List_of_anonymous_types_and_enumerables()
     {
@@ -292,4 +309,4 @@ public void Null_IList_Not_Nullable_Should_Throw()
             Throws.Exception.TypeOf<FormattingException>().And.Message
                 .Contains("{Numbers[0]}"));
     }
-}
+}

src/SmartFormat/Extensions/ListFormatter.cs

@@ -6,6 +6,7 @@
 using System.Collections;
 using System.Threading;
 using SmartFormat.Core.Extensions;
+using SmartFormat.Core.Formatting;
 using SmartFormat.Core.Parsing;
 using SmartFormat.Core.Settings;
 using SmartFormat.Pooling.SmartPools;
@@ -76,8 +77,16 @@ public bool TryEvaluateSelector(ISelectorInfo selectorInfo)
         var current = selectorInfo.CurrentValue;
         var selector = selectorInfo.SelectorText;
 
-        if (current is not IList currentList) return false;
+        // Check whether the selector is named "Index"
+        var selectorIsIndex = current is IEnumerable && selector.Equals("index", StringComparison.OrdinalIgnoreCase);
+        if (selectorIsIndex && selectorInfo.SelectorIndex == 0)
+        {
+            selectorInfo.Result = CollectionIndex;
+            return true;
+        }
 
+        if (current is not IList currentList) return false;
+
         // See if we're trying to access a specific index:
         var isAbsolute = selectorInfo.SelectorIndex == 0 && selectorInfo.SelectorOperator.Length == 0;
         if (!isAbsolute && int.TryParse(selector, out var itemIndex) &&
@@ -91,22 +100,11 @@ public bool TryEvaluateSelector(ISelectorInfo selectorInfo)
             return true;
         }
 
-        // We want to see if there is an "Index" property that was supplied.
-        if (selector.Equals("index", StringComparison.OrdinalIgnoreCase))
+        // Looking for 2 lists to sync: "{List1: {List2[Index]}}"
+        if (selectorIsIndex && 0 <= CollectionIndex && CollectionIndex < currentList.Count)
         {
-            // Looking for "{Index}"
-            if (selectorInfo.SelectorIndex == 0)
-            {
-                selectorInfo.Result = CollectionIndex;
-                return true;
-            }
-
-            // Looking for 2 lists to sync: "{List1: {List2[Index]} }"
-            if (0 <= CollectionIndex && CollectionIndex < currentList.Count)
-            {
-                selectorInfo.Result = currentList[CollectionIndex];
-                return true;
-            }
+            selectorInfo.Result = currentList[CollectionIndex];
+            return true;
         }
 
         return false;

src/SmartFormat/Extensions/ReflectionSource.cs

@@ -44,7 +44,6 @@ public class ReflectionSource : Source
     /// <inheritdoc />
     public override bool TryEvaluateSelector(ISelectorInfo selectorInfo)
     {
-
         var current = selectorInfo.CurrentValue;
 
         if (TrySetResultForNullableOperator(selectorInfo)) return true;
@@ -95,7 +94,7 @@ private bool EvaluateMembers(ISelectorInfo selectorInfo, string selector, object
             switch (member.MemberType)
             {
                 case MemberTypes.Field:
-                    //  Selector is a Field; retrieve the value:
+                    // Selector is a Field; retrieve the value:
                     var field = member as FieldInfo;
                     selectorInfo.Result = field?.GetValue(current);
                     if (IsTypeCacheEnabled) TypeCache[(sourceType, selector)] = (field, null);
@@ -104,17 +103,17 @@ private bool EvaluateMembers(ISelectorInfo selectorInfo, string selector, object
                 case MemberTypes.Method:
                     if (!TryGetMethodInfo(member, out var method)) continue;
 
-                    //  Check that this method is valid -- it needs to return a value and has to be parameter-less:
-                    //  We are only looking for a parameter-less Function/Property:
+                    // Check that this method is valid -- it needs to return a value and has to be parameter-less:
+                    // We are only looking for a parameter-less Function/Property:
                     if (method?.GetParameters().Length > 0) continue;
 
-                    //  Make sure that this method is not void! It has to be a Function!
+                    // Make sure that this method is not void! It has to be a Function!
                     if (method?.ReturnType == typeof(void)) continue;
 
                     // Add to cache
                     if (IsTypeCacheEnabled) TypeCache[(sourceType, selector)] = (null, method);
 
-                    //  Retrieve the Selectors/ParseFormat value:
+                    // Retrieve the Selectors/ParseFormat value:
                     selectorInfo.Result = method?.Invoke(current, Array.Empty<object>());
                     return true;
             }
@@ -141,4 +140,4 @@ private static bool TryGetMethodInfo(MemberInfo member, out MethodInfo? method)
         method = member as MethodInfo;
         return true;
     }
-}
+}