Make wrapper

src/SystemWebAdapters/src/Internal/FormCollectionReadOnlyDictionary.cs

@@ -0,0 +1,45 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Collections;
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+using Microsoft.AspNetCore.Http;
+using Microsoft.Extensions.Primitives;
+
+namespace System.Web.Internal;
+
+internal class FormCollectionReadOnlyDictionary : IReadOnlyDictionary<string, StringValues>
+{
+    private readonly IFormCollection _form;
+
+    public FormCollectionReadOnlyDictionary(IFormCollection form)
+    {
+        _form = form;
+    }
+
+    public StringValues this[string key] => _form[key];
+
+    public IEnumerable<string> Keys => _form.Keys;
+
+    public IEnumerable<StringValues> Values
+    {
+        get
+        {
+            foreach (var item in _form)
+            {
+                yield return item.Value;
+            }
+        }
+    }
+
+    public int Count => _form.Count;
+
+    public bool ContainsKey(string key) => _form.ContainsKey(key);
+
+    public IEnumerator<KeyValuePair<string, StringValues>> GetEnumerator() => _form.GetEnumerator();
+
+    public bool TryGetValue(string key, [MaybeNullWhen(false)] out StringValues value) => _form.TryGetValue(key, out value);
+
+    IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
+}

src/SystemWebAdapters/src/Internal/NameValueCollectionExtensions.cs

@@ -1,8 +1,10 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.Collections;
 using System.Collections.Generic;
 using System.Collections.Specialized;
+using System.Diagnostics.CodeAnalysis;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Http.Features;
 using Microsoft.Extensions.Primitives;
@@ -11,21 +13,27 @@ namespace System.Web.Internal;
 
 internal static class NameValueCollectionExtensions
 {
-    public static NameValueCollection ToNameValueCollection(this IQueryCollection query) => ToReadOnlyNameValueCollection(query.Count, query);
-
-    public static NameValueCollection ToNameValueCollection(this IFormCollection form) => ToReadOnlyNameValueCollection(form.Count, form);
-
-    public static NameValueCollection ToNameValueCollection(this IHeaderDictionary headers) => new StringValuesDictionaryNameValueCollection(headers);
+    public static NameValueCollection ToNameValueCollection(this IQueryCollection query)
+    {
+        if (query.Count == 0)
+        {
+            return StringValuesReadOnlyDictionaryNameValueCollection.Empty;
+        }
 
-    public static NameValueCollection ToNameValueCollection(this IServerVariablesFeature serverVariables) => new ServerVariablesNameValueCollection(serverVariables);
+        return new StringValuesReadOnlyDictionaryNameValueCollection(new QueryCollectionReadOnlyDictionary(query));
+    }
 
-    private static NameValueCollection ToReadOnlyNameValueCollection(int count, IEnumerable<KeyValuePair<string, StringValues>> items)
+    public static NameValueCollection ToNameValueCollection(this IFormCollection form)
     {
-        if (count == 0)
+        if (form.Count == 0)
         {
-            return StringValuesNameValueCollection.Empty;
+            return StringValuesReadOnlyDictionaryNameValueCollection.Empty;
         }
 
-        return new StringValuesNameValueCollection(items);
+        return new StringValuesReadOnlyDictionaryNameValueCollection(new FormCollectionReadOnlyDictionary(form));
     }
+
+    public static NameValueCollection ToNameValueCollection(this IHeaderDictionary headers) => new StringValuesDictionaryNameValueCollection(headers);
+
+    public static NameValueCollection ToNameValueCollection(this IServerVariablesFeature serverVariables) => new ServerVariablesNameValueCollection(serverVariables);
 }

src/SystemWebAdapters/src/Internal/QueryCollectionReadOnlyDictionary.cs

@@ -0,0 +1,45 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Collections;
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+using Microsoft.AspNetCore.Http;
+using Microsoft.Extensions.Primitives;
+
+namespace System.Web.Internal;
+
+internal class QueryCollectionReadOnlyDictionary : IReadOnlyDictionary<string, StringValues>
+{
+    private readonly IQueryCollection _query;
+
+    public QueryCollectionReadOnlyDictionary(IQueryCollection query)
+    {
+        _query = query;
+    }
+
+    public StringValues this[string key] => _query[key];
+
+    public IEnumerable<string> Keys => _query.Keys;
+
+    public IEnumerable<StringValues> Values
+    {
+        get
+        {
+            foreach (var item in _query)
+            {
+                yield return item.Value;
+            }
+        }
+    }
+
+    public int Count => _query.Count;
+
+    public bool ContainsKey(string key) => _query.ContainsKey(key);
+
+    public IEnumerator<KeyValuePair<string, StringValues>> GetEnumerator() => _query.GetEnumerator();
+
+    public bool TryGetValue(string key, [MaybeNullWhen(false)] out StringValues value) => _query.TryGetValue(key, out value);
+
+    IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
+}

src/SystemWebAdapters/src/Internal/ServerVariablesNameValueCollection.cs

@@ -1,14 +1,13 @@
-using System.Collections;
+using System.Collections;
 using System.Collections.Specialized;
 using System.Runtime.Serialization;
 using Microsoft.AspNetCore.Http.Features;
 
 namespace System.Web.Internal
 {
-    internal class ServerVariablesNameValueCollection : NameValueCollection
+    internal class ServerVariablesNameValueCollection : WrappingNameValueCollection
     {
         private const string EnumerationErrorMessage = "ASP.NET Core doesn't support enumerating server variables.";
-        private const string IndexErrorMessage = "ASP.NET Core doesn't support accessing server variables by index.";
         private const string SerializationErrorMessage = "ASP.NET Core doesn't suppor serialization of server variables.";
 
         private readonly IServerVariablesFeature _serverVariables;
@@ -33,14 +32,6 @@ public override void Add(string? name, string? value)
             _serverVariables[name] = value;
         }
 
-        public override KeysCollection Keys => throw new PlatformNotSupportedException("KeysCollection is not supported as Get(int) is not available.");
-
-        public override string? Get(int index) => throw new PlatformNotSupportedException(IndexErrorMessage);
-
-        public override string? GetKey(int index) => throw new PlatformNotSupportedException(IndexErrorMessage);
-
-        public override string[]? GetValues(int index) => throw new PlatformNotSupportedException(IndexErrorMessage);
-
         public override string[]? GetValues(string? name)
         {
             if (name is not null && _serverVariables[name] is string result)
@@ -87,6 +78,6 @@ public override void Set(string? name, string? value)
 
         public override void GetObjectData(SerializationInfo info, StreamingContext context) => throw new PlatformNotSupportedException(SerializationErrorMessage);
 
-        public override void OnDeserialization(object? sender)=> throw new PlatformNotSupportedException(SerializationErrorMessage);
+        public override void OnDeserialization(object? sender) => throw new PlatformNotSupportedException(SerializationErrorMessage);
     }
 }

src/SystemWebAdapters/src/Internal/StringValuesDictionaryNameValueCollection.cs

@@ -1,25 +1,22 @@
 using System.Collections;
 using System.Collections.Generic;
-using System.Collections.Specialized;
 using System.Linq;
 using Microsoft.Extensions.Primitives;
 
 namespace System.Web.Internal
 {
-    internal class StringValuesDictionaryNameValueCollection : NameValueCollection
+    internal class StringValuesDictionaryNameValueCollection : WrappingNameValueCollection
     {
-        private const string GetByIntNotSupported = "Get by index is not available on this platform";
-
-        private readonly IDictionary<string, StringValues> _headers;
+        private readonly IDictionary<string, StringValues> _values;
 
         public StringValuesDictionaryNameValueCollection(IDictionary<string, StringValues> headers)
         {
-            _headers = headers;
+            _values = headers;
         }
 
-        public override string?[] AllKeys => _headers.Keys.ToArray();
+        public override string?[] AllKeys => _values.Keys.ToArray();
 
-        public override int Count => _headers.Count;
+        public override int Count => _values.Count;
 
         public override void Add(string? name, string? value)
         {
@@ -28,39 +25,24 @@ public override void Add(string? name, string? value)
                 return;
             }
 
-            if (_headers.TryGetValue(name, out var existing))
+            if (_values.TryGetValue(name, out var existing))
             {
-                _headers[name] = StringValues.Concat(existing, value);
+                _values[name] = StringValues.Concat(existing, value);
             }
             else
             {
-                _headers.Add(name, value);
+                _values.Add(name, value);
             }
         }
 
-        public override KeysCollection Keys => throw new PlatformNotSupportedException("KeysCollection is not supported as Get(int) is not available.");
-
-        public override string? Get(int index) => throw new PlatformNotSupportedException(GetByIntNotSupported);
-
-        public override string? GetKey(int index) => throw new PlatformNotSupportedException(GetByIntNotSupported);
-
-        public override string[]? GetValues(int index) => throw new PlatformNotSupportedException(GetByIntNotSupported);
-
         public override string[]? GetValues(string? name)
-        {
-            if (name is not null && _headers.TryGetValue(name, out var values))
-            {
-                return values;
-            }
-
-            return null;
-        }
+            => name is not null && _values.TryGetValue(name, out var values) ? values : default;
 
         public override void Remove(string? name)
         {
             if (name is not null)
             {
-                _headers.Remove(name);
+                _values.Remove(name);
             }
         }
 
@@ -71,21 +53,14 @@ public override void Set(string? name, string? value)
                 return;
             }
 
-            _headers[name] = value;
+            _values[name] = value;
         }
 
         public override string? Get(string? name)
-        {
-            if (name is not null && _headers.TryGetValue(name, out var value))
-            {
-                return value;
-            }
-
-            return null;
-        }
+            => name is not null && _values.TryGetValue(name, out var values) ? values : default;
 
-        public override void Clear() => _headers.Clear();
+        public override void Clear() => _values.Clear();
 
-        public override IEnumerator GetEnumerator() => _headers.Keys.GetEnumerator();
+        public override IEnumerator GetEnumerator() => _values.Keys.GetEnumerator();
     }
 }

src/SystemWebAdapters/src/Internal/StringValuesReadOnlyDictionaryNameValueCollection.cs

@@ -0,0 +1,38 @@
+using System.Collections;
+using System.Collections.Generic;
+using System.Collections.Specialized;
+using System.Linq;
+using Microsoft.Extensions.Primitives;
+
+namespace System.Web.Internal
+{
+    internal class StringValuesReadOnlyDictionaryNameValueCollection : WrappingNameValueCollection
+    {
+        private readonly IReadOnlyDictionary<string, StringValues> _values;
+
+        public static NameValueCollection Empty { get; } = new StringValuesReadOnlyDictionaryNameValueCollection();
+
+        public StringValuesReadOnlyDictionaryNameValueCollection()
+            : this(new Dictionary<string, StringValues>())
+        {
+        }
+
+        public StringValuesReadOnlyDictionaryNameValueCollection(IReadOnlyDictionary<string, StringValues> values)
+        {
+            _values = values;
+            IsReadOnly = true;
+        }
+
+        public override string?[] AllKeys => _values.Keys.ToArray();
+
+        public override int Count => _values.Count;
+
+        public override string[]? GetValues(string? name)
+            => name is not null && _values.TryGetValue(name, out var values) ? values : default;
+
+        public override string? Get(string? name)
+            => name is not null && _values.TryGetValue(name, out var values) ? values : default;
+
+        public override IEnumerator GetEnumerator() => _values.Keys.GetEnumerator();
+    }
+}

src/SystemWebAdapters/src/Internal/WrappingNameValueCollection.cs

@@ -0,0 +1,17 @@
+using System.Collections.Specialized;
+
+namespace System.Web.Internal
+{
+    internal abstract class WrappingNameValueCollection : NameValueCollection
+    {
+        private const string IndexErrorMessage = "ASP.NET Core doesn't support accessing server variables by index.";
+
+        public sealed override string? Get(int index) => throw new PlatformNotSupportedException(IndexErrorMessage);
+
+        public sealed override string? GetKey(int index) => throw new PlatformNotSupportedException(IndexErrorMessage);
+
+        public sealed override string[]? GetValues(int index) => throw new PlatformNotSupportedException(IndexErrorMessage);
+
+        public sealed override KeysCollection Keys => throw new PlatformNotSupportedException("KeysCollection is not supported as Get(int) is not available.");
+    }
+}

src/SystemWebAdapters/test/HttpRequestTests.cs

@@ -700,7 +700,7 @@ public void Form()
 
             // Assert
             Assert.Same(formCollection1, formCollection2);
-            Assert.IsType<StringValuesNameValueCollection>(formCollection1);
+            Assert.IsType<StringValuesReadOnlyDictionaryNameValueCollection>(formCollection1);
         }
 
         [Fact]
@@ -755,7 +755,7 @@ public void Query()
 
             // Assert
             Assert.Same(queryCollection1, queryCollection2);
-            Assert.IsType<StringValuesNameValueCollection>(queryCollection1);
+            Assert.IsType<StringValuesReadOnlyDictionaryNameValueCollection>(queryCollection1);
         }
     }
 }