default implementation now does not throw an error, it just concatena…

…tes it in regular style with "&" as separator. in already implemented languages, it returns the language specific translation for "and". #392

src/Humanizer/Configuration/CollectionFormatterRegistry.cs

@@ -5,16 +5,16 @@ namespace Humanizer.Configuration
     internal class CollectionFormatterRegistry : LocaliserRegistry<ICollectionFormatter>
     {
         public CollectionFormatterRegistry()
-            : base(new DefaultCollectionFormatter())
+            : base(new DefaultCollectionFormatter("&"))
         {
             Register("en", new OxfordStyleCollectionFormatter("and"));
-            Register("it", new RegularStyleCollectionFormatter("e"));
-            Register("de", new RegularStyleCollectionFormatter("und"));
-            Register("dk", new RegularStyleCollectionFormatter("og"));
-            Register("nl", new RegularStyleCollectionFormatter("en"));
-            Register("pt", new RegularStyleCollectionFormatter("e"));
-            Register("nn", new RegularStyleCollectionFormatter("og"));
-            Register("nb", new RegularStyleCollectionFormatter("og"));
+            Register("it", new DefaultCollectionFormatter("e"));
+            Register("de", new DefaultCollectionFormatter("und"));
+            Register("dk", new DefaultCollectionFormatter("og"));
+            Register("nl", new DefaultCollectionFormatter("en"));
+            Register("pt", new DefaultCollectionFormatter("e"));
+            Register("nn", new DefaultCollectionFormatter("og"));
+            Register("nb", new DefaultCollectionFormatter("og"));
         }
     }
 }

src/Humanizer/Humanizer.csproj

@@ -58,7 +58,6 @@
     <Compile Include="DateTimeHumanizeStrategy\IDateTimeOffsetHumanizeStrategy.cs" />
     <Compile Include="DateTimeHumanizeStrategy\PrecisionDateTimeOffsetHumanizeStrategy.cs" />
     <Compile Include="Localisation\CollectionFormatters\DefaultCollectionFormatter.cs" />
-    <Compile Include="Localisation\CollectionFormatters\RegularStyleCollectionFormatter.cs" />
     <Compile Include="Localisation\CollectionFormatters\ICollectionFormatter.cs" />
     <Compile Include="Localisation\CollectionFormatters\OxfordStyleCollectionFormatter.cs" />
     <Compile Include="Localisation\Formatters\SerbianFormatter.cs" />

src/Humanizer/Localisation/CollectionFormatters/DefaultCollectionFormatter.cs

@@ -1,12 +1,18 @@
 using System;
 using System.Collections.Generic;
+using System.Linq;
 
 namespace Humanizer.Localisation.CollectionFormatters
 {
     class DefaultCollectionFormatter : ICollectionFormatter
     {
         protected String DefaultSeparator = "";
 
+        public DefaultCollectionFormatter(string defaultSeparator)
+        {
+            DefaultSeparator = defaultSeparator;
+        }
+
         public virtual string Humanize<T>(IEnumerable<T> collection)
         {
             return Humanize(collection, o => o.ToString(), DefaultSeparator);
@@ -24,7 +30,26 @@ public virtual string Humanize<T>(IEnumerable<T> collection, String separator)
 
         public virtual string Humanize<T>(IEnumerable<T> collection, Func<T, String> objectFormatter, String separator)
         {
-            throw new NotImplementedException("A collection formatter for the current culture has not been implemented yet.");
+            if (collection == null)
+                throw new ArgumentException("collection");
+
+            T[] itemsArray = collection as T[] ?? collection.ToArray();
+
+            int count = itemsArray.Length;
+
+            if (count == 0)
+                return "";
+
+            if (count == 1)
+                return objectFormatter(itemsArray[0]);
+
+            IEnumerable<T> itemsBeforeLast = itemsArray.Take(count - 1);
+            T lastItem = itemsArray.Skip(count - 1).First();
+
+            return String.Format("{0} {1} {2}",
+                String.Join(", ", itemsBeforeLast.Select(objectFormatter)),
+                separator,
+                objectFormatter(lastItem));
         }
     }
 }

src/Humanizer/Localisation/CollectionFormatters/OxfordStyleCollectionFormatter.cs

@@ -7,8 +7,8 @@ namespace Humanizer.Localisation.CollectionFormatters
     internal class OxfordStyleCollectionFormatter : DefaultCollectionFormatter
     {
         public OxfordStyleCollectionFormatter(string defaultSeparator)
+            : base(defaultSeparator ?? "and")
         {
-            DefaultSeparator = defaultSeparator ?? "and";
         }
 
         public override string Humanize<T>(IEnumerable<T> collection, Func<T, string> objectFormatter, String separator)