Remove LINQ usage for IEnumerable comparisons

src/OpenApi/src/Comparers/ComparerHelpers.cs

@@ -0,0 +1,95 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+namespace Microsoft.AspNetCore.OpenApi;
+
+internal static class ComparerHelpers
+{
+    internal static bool DictionaryEquals<TKey, TValue>(IDictionary<TKey, TValue> x, IDictionary<TKey, TValue> y, IEqualityComparer<TValue> comparer)
+        where TKey : notnull
+        where TValue : notnull
+    {
+        if (x is Dictionary<TKey, TValue> xDictionary && y is Dictionary<TKey, TValue> yDictionary)
+        {
+            return DictionaryEquals(xDictionary, yDictionary, comparer);
+        }
+
+        if (x.Keys.Count != y.Keys.Count)
+        {
+            return false;
+        }
+
+        foreach (var key in x.Keys)
+        {
+            if (!y.TryGetValue(key, out var value) || !comparer.Equals(x[key], value))
+            {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
+    // Private method to avoid interface dispatch.
+    private static bool DictionaryEquals<TKey, TValue>(Dictionary<TKey, TValue> x, Dictionary<TKey, TValue> y, IEqualityComparer<TValue> comparer)
+        where TKey : notnull
+        where TValue : notnull
+    {
+        if (x.Keys.Count != y.Keys.Count)
+        {
+            return false;
+        }
+
+        foreach (var key in x.Keys)
+        {
+            if (!y.TryGetValue(key, out var value) || !comparer.Equals(x[key], value))
+            {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
+    internal static bool ListEquals<T>(IList<T> x, IList<T> y, IEqualityComparer<T> comparer)
+    {
+        if (x is List<T> xList && y is List<T> yList)
+        {
+            return ListEquals(xList, yList, comparer);
+        }
+
+        if (x.Count != y.Count)
+        {
+            return false;
+        }
+
+        for (var i = 0; i < x.Count; i++)
+        {
+            if (!comparer.Equals(x[i], y[i]))
+            {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
+    // Private method to avoid interface dispatch.
+    private static bool ListEquals<T>(List<T> x, List<T> y, IEqualityComparer<T> comparer)
+    {
+        if (x.Count != y.Count)
+        {
+            return false;
+        }
+
+        for (var i = 0; i < x.Count; i++)
+        {
+            if (!comparer.Equals(x[i], y[i]))
+            {
+                return false;
+            }
+        }
+
+        return true;
+    }
+}

src/OpenApi/src/Comparers/OpenApiAnyComparer.cs

@@ -3,10 +3,11 @@
 
 using System.Linq;
 using Microsoft.OpenApi.Any;
+using Microsoft.OpenApi.Interfaces;
 
 namespace Microsoft.AspNetCore.OpenApi;
 
-internal sealed class OpenApiAnyComparer : IEqualityComparer<IOpenApiAny>
+internal sealed class OpenApiAnyComparer : IEqualityComparer<IOpenApiAny>, IEqualityComparer<IOpenApiExtension>
 {
     public static OpenApiAnyComparer Instance { get; } = new OpenApiAnyComparer();
 
@@ -29,8 +30,8 @@ public bool Equals(IOpenApiAny? x, IOpenApiAny? y)
             (x switch
             {
                 OpenApiNull _ => y is OpenApiNull,
-                OpenApiArray arrayX => y is OpenApiArray arrayY && arrayX.SequenceEqual(arrayY, Instance),
-                OpenApiObject objectX => y is OpenApiObject objectY && objectX.Keys.Count == objectY.Keys.Count && objectX.Keys.All(key => objectY.TryGetValue(key, out var yValue) && Equals(objectX[key], yValue)),
+                OpenApiArray arrayX => y is OpenApiArray arrayY && ComparerHelpers.ListEquals(arrayX, arrayY, Instance),
+                OpenApiObject objectX => y is OpenApiObject objectY && ComparerHelpers.DictionaryEquals(objectX, objectY, Instance),
                 OpenApiBinary binaryX => y is OpenApiBinary binaryY && binaryX.Value.SequenceEqual(binaryY.Value),
                 OpenApiInteger integerX => y is OpenApiInteger integerY && integerX.Value == integerY.Value,
                 OpenApiLong longX => y is OpenApiLong longY && longX.Value == longY.Value,
@@ -78,4 +79,39 @@ public int GetHashCode(IOpenApiAny obj)
 
         return hashCode.ToHashCode();
     }
+
+    public bool Equals(IOpenApiExtension? x, IOpenApiExtension? y)
+    {
+        if (x is null && y is null)
+        {
+            return true;
+        }
+
+        if (x is null || y is null)
+        {
+            return false;
+        }
+
+        if (object.ReferenceEquals(x, y))
+        {
+            return true;
+        }
+
+        if (x is IOpenApiAny openApiAnyX && y is IOpenApiAny openApiAnyY)
+        {
+            return Equals(openApiAnyX, openApiAnyY);
+        }
+
+        return x.Equals(y);
+    }
+
+    public int GetHashCode(IOpenApiExtension obj)
+    {
+        if (obj is IOpenApiAny any)
+        {
+            return GetHashCode(any);
+        }
+
+        return obj.GetHashCode();
+    }
 }

src/OpenApi/src/Comparers/OpenApiDiscriminatorComparer.cs

@@ -1,7 +1,6 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-using System.Linq;
 using Microsoft.OpenApi.Models;
 
 namespace Microsoft.AspNetCore.OpenApi;
@@ -27,7 +26,7 @@ public bool Equals(OpenApiDiscriminator? x, OpenApiDiscriminator? y)
 
         return x.PropertyName == y.PropertyName &&
             x.Mapping.Count == y.Mapping.Count &&
-            x.Mapping.Keys.All(key => y.Mapping.TryGetValue(key, out var yValue) && x.Mapping[key] == yValue);
+            ComparerHelpers.DictionaryEquals(x.Mapping, y.Mapping, StringComparer.Ordinal);
     }
 
     public int GetHashCode(OpenApiDiscriminator obj)

src/OpenApi/src/Comparers/OpenApiExternalDocsComparer.cs

@@ -1,7 +1,6 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-using System.Linq;
 using Microsoft.OpenApi.Models;
 
 namespace Microsoft.AspNetCore.OpenApi;
@@ -27,8 +26,7 @@ public bool Equals(OpenApiExternalDocs? x, OpenApiExternalDocs? y)
 
         return x.Description == y.Description &&
             x.Url == y.Url &&
-            x.Extensions.Count == y.Extensions.Count
-            && x.Extensions.Keys.All(k => y.Extensions.TryGetValue(k, out var yValue) && yValue == x.Extensions[k]);
+            ComparerHelpers.DictionaryEquals(x.Extensions, y.Extensions, OpenApiAnyComparer.Instance);
     }
 
     public int GetHashCode(OpenApiExternalDocs obj)

src/OpenApi/src/Comparers/OpenApiSchemaComparer.cs

@@ -1,8 +1,6 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-using System.Linq;
-using Microsoft.OpenApi.Any;
 using Microsoft.OpenApi.Models;
 
 namespace Microsoft.AspNetCore.OpenApi;
@@ -31,22 +29,22 @@ public bool Equals(OpenApiSchema? x, OpenApiSchema? y)
             x.Type == y.Type &&
             x.Format == y.Format &&
             SchemaIdEquals(x, y) &&
-            x.Properties.Keys.All(k => y.Properties.TryGetValue(k, out var yValue) && Instance.Equals(x.Properties[k], yValue)) &&
+            ComparerHelpers.DictionaryEquals(x.Properties, y.Properties, Instance) &&
             OpenApiDiscriminatorComparer.Instance.Equals(x.Discriminator, y.Discriminator) &&
             Instance.Equals(x.AdditionalProperties, y.AdditionalProperties) &&
             x.AdditionalPropertiesAllowed == y.AdditionalPropertiesAllowed &&
-            x.AllOf.SequenceEqual(y.AllOf, Instance) &&
-            x.AnyOf.SequenceEqual(y.AnyOf, Instance) &&
+            ComparerHelpers.ListEquals(x.AllOf, y.AllOf, Instance) &&
+            ComparerHelpers.ListEquals(x.AnyOf, y.AnyOf, Instance) &&
             x.Deprecated == y.Deprecated &&
             OpenApiAnyComparer.Instance.Equals(x.Default, y.Default) &&
             x.Description == y.Description &&
             OpenApiAnyComparer.Instance.Equals(x.Example, y.Example) &&
             x.ExclusiveMaximum == y.ExclusiveMaximum &&
             x.ExclusiveMinimum == y.ExclusiveMinimum &&
             x.Extensions.Count == y.Extensions.Count &&
-            x.Extensions.Keys.All(k => y.Extensions.TryGetValue(k, out var yValue) && x.Extensions[k] is IOpenApiAny anyX && yValue is IOpenApiAny anyY && OpenApiAnyComparer.Instance.Equals(anyX, anyY)) &&
+            ComparerHelpers.DictionaryEquals(x.Extensions, y.Extensions, OpenApiAnyComparer.Instance) &&
             OpenApiExternalDocsComparer.Instance.Equals(x.ExternalDocs, y.ExternalDocs) &&
-            x.Enum.SequenceEqual(y.Enum, OpenApiAnyComparer.Instance) &&
+            ComparerHelpers.ListEquals(x.Enum, y.Enum, OpenApiAnyComparer.Instance) &&
             Instance.Equals(x.Items, y.Items) &&
             x.Title == y.Title &&
             x.Maximum == y.Maximum &&
@@ -58,7 +56,7 @@ public bool Equals(OpenApiSchema? x, OpenApiSchema? y)
             x.MinLength == y.MinLength &&
             x.MinProperties == y.MinProperties &&
             x.MultipleOf == y.MultipleOf &&
-            x.OneOf.SequenceEqual(y.OneOf, Instance) &&
+            ComparerHelpers.ListEquals(x.OneOf, y.OneOf, Instance) &&
             Instance.Equals(x.Not, y.Not) &&
             x.Nullable == y.Nullable &&
             x.Pattern == y.Pattern &&

src/OpenApi/src/Comparers/OpenApiXmlComparer.cs

@@ -1,7 +1,6 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-using System.Linq;
 using Microsoft.OpenApi.Models;
 
 namespace Microsoft.AspNetCore.OpenApi;
@@ -30,8 +29,7 @@ public bool Equals(OpenApiXml? x, OpenApiXml? y)
             x.Prefix == y.Prefix &&
             x.Attribute == y.Attribute &&
             x.Wrapped == y.Wrapped &&
-            x.Extensions.Count == y.Extensions.Count
-            && x.Extensions.Keys.All(k => y.Extensions.TryGetValue(k, out var yValue) && yValue == x.Extensions[k]);
+            ComparerHelpers.DictionaryEquals(x.Extensions, y.Extensions, OpenApiAnyComparer.Instance);
     }
 
     public int GetHashCode(OpenApiXml obj)