Pass relation type to LinkList to avoid subclassing

Author: Matthias Gessinger

src/Abstractions/src/Asp.Versioning.Abstractions/DeprecationPolicy.cs

@@ -14,7 +14,7 @@ public class DeprecationPolicy
     /// </summary>
     public DeprecationPolicy()
     {
-        links = new DeprecationLinkList();
+        links = new LinkList( "deprecation" );
     }
 
     /// <summary>
@@ -63,15 +63,4 @@ public DeprecationPolicy( LinkHeaderValue link )
     /// links might be provided for different languages or different formats such as a HTML page
     /// or a JSON file.</remarks>
     public IList<LinkHeaderValue> Links => links;
-
-    internal sealed class DeprecationLinkList : LinkList
-    {
-        protected override void EnsureRelationType( LinkHeaderValue item )
-        {
-            if ( !item.RelationType.Equals( "deprecation", StringComparison.OrdinalIgnoreCase ) )
-            {
-                throw new ArgumentException( SR.InvalidDeprecationRelationType, nameof( item ) );
-            }
-        }
-    }
 }

src/Abstractions/src/Asp.Versioning.Abstractions/Format.cs

@@ -11,8 +11,10 @@ internal static class Format
 #if NETSTANDARD
     internal static readonly string ApiVersionBadStatus = SR.ApiVersionBadStatus;
     internal static readonly string ApiVersionBadGroupVersion = SR.ApiVersionBadGroupVersion;
+    internal static readonly string InvalidRelationType = SR.InvalidRelationType;
 #else
     internal static readonly CompositeFormat ApiVersionBadStatus = CompositeFormat.Parse( SR.ApiVersionBadStatus );
     internal static readonly CompositeFormat ApiVersionBadGroupVersion = CompositeFormat.Parse( SR.ApiVersionBadGroupVersion );
+    internal static readonly CompositeFormat InvalidRelationType = CompositeFormat.Parse( SR.InvalidRelationType );
 #endif
 }

src/Abstractions/src/Asp.Versioning.Abstractions/LinkList.cs

@@ -3,10 +3,11 @@
 namespace Asp.Versioning;
 
 using System.Collections.ObjectModel;
+using System.Globalization;
 
-internal abstract class LinkList : Collection<LinkHeaderValue>
+internal sealed class LinkList( string relationType ) : Collection<LinkHeaderValue>
 {
-    public LinkList() { }
+    private readonly string relationType = relationType;
 
     protected override void InsertItem( int index, LinkHeaderValue item )
     {
@@ -20,5 +21,12 @@ protected override void SetItem( int index, LinkHeaderValue item )
         base.SetItem( index, item );
     }
 
-    protected abstract void EnsureRelationType( LinkHeaderValue item );
+    private void EnsureRelationType( LinkHeaderValue item )
+    {
+        if ( !item.RelationType.Equals( relationType, StringComparison.OrdinalIgnoreCase ) )
+        {
+            var message = string.Format( CultureInfo.CurrentCulture, Format.InvalidRelationType, relationType );
+            throw new ArgumentException( message, nameof( item ) );
+        }
+    }
 }

src/Abstractions/src/Asp.Versioning.Abstractions/SR.Designer.cs

@@ -141,10 +141,7 @@
   <data name="InvalidOrMalformedHeader" xml:space="preserve">
     <value>The header contains invalid or missing values.</value>
   </data>
-  <data name="InvalidSunsetRelationType" xml:space="preserve">
-    <value>The relation type for a sunset policy link must be "sunset".</value>
-  </data>
-  <data name="InvalidDeprecationRelationType" xml:space="preserve">
-    <value>The relation type for a deprecation policy link must be "deprecation".</value>
+  <data name="InvalidRelationType" xml:space="preserve">
+    <value>The relation type for a {0} policy link must be "{0}".</value>
   </data>
 </root>

src/Abstractions/src/Asp.Versioning.Abstractions/SR.resx

@@ -14,7 +14,7 @@ public class SunsetPolicy
     /// </summary>
     public SunsetPolicy()
     {
-        links = new SunsetLinkList();
+        links = new LinkList( "sunset" );
     }
 
     /// <summary>
@@ -63,15 +63,4 @@ public SunsetPolicy( LinkHeaderValue link )
     /// links might be provided for different languages or different formats such as a HTML page
     /// or a JSON file.</remarks>
     public IList<LinkHeaderValue> Links => links;
-
-    internal sealed class SunsetLinkList : LinkList
-    {
-        protected override void EnsureRelationType( LinkHeaderValue item )
-        {
-            if ( !item.RelationType.Equals( "sunset", StringComparison.OrdinalIgnoreCase ) )
-            {
-                throw new ArgumentException( SR.InvalidSunsetRelationType, nameof( item ) );
-            }
-        }
-    }
 }