Changed SparseFieldTableExpression.Table type from IReadOnlyDictionary to IImmutableDictionary and fixed equality comparison to discard order

Author: Bart Koelman

src/JsonApiDotNetCore/CollectionExtensions.cs

@@ -34,5 +34,41 @@ public static int FindIndex<T>(this IList<T> source, Predicate<T> match)
 
             return -1;
         }
+
+        public static bool DictionaryEqual<TKey, TValue>(this IReadOnlyDictionary<TKey, TValue> first, IReadOnlyDictionary<TKey, TValue> second,
+            IEqualityComparer<TValue> valueComparer = null)
+        {
+            if (first == second)
+            {
+                return true;
+            }
+
+            if (first == null || second == null)
+            {
+                return false;
+            }
+
+            if (first.Count != second.Count)
+            {
+                return false;
+            }
+
+            IEqualityComparer<TValue> effectiveValueComparer = valueComparer ?? EqualityComparer<TValue>.Default;
+
+            foreach ((TKey firstKey, TValue firstValue) in first)
+            {
+                if (!second.TryGetValue(firstKey, out TValue secondValue))
+                {
+                    return false;
+                }
+
+                if (!effectiveValueComparer.Equals(firstValue, secondValue))
+                {
+                    return false;
+                }
+            }
+
+            return true;
+        }
     }
 }

src/JsonApiDotNetCore/Queries/Expressions/QueryExpressionRewriter.cs

@@ -1,4 +1,5 @@
 using System.Collections.Generic;
+using System.Collections.Immutable;
 using System.Linq;
 using JetBrains.Annotations;
 using JsonApiDotNetCore.Configuration;
@@ -198,7 +199,8 @@ public override QueryExpression VisitSparseFieldTable(SparseFieldTableExpression
         {
             if (expression != null)
             {
-                var newTable = new Dictionary<ResourceContext, SparseFieldSetExpression>();
+                ImmutableDictionary<ResourceContext, SparseFieldSetExpression>.Builder newTable =
+                    ImmutableDictionary.CreateBuilder<ResourceContext, SparseFieldSetExpression>();
 
                 foreach ((ResourceContext resourceContext, SparseFieldSetExpression sparseFieldSet) in expression.Table)
                 {
@@ -210,7 +212,7 @@ public override QueryExpression VisitSparseFieldTable(SparseFieldTableExpression
 
                 if (newTable.Count > 0)
                 {
-                    var newExpression = new SparseFieldTableExpression(newTable);
+                    var newExpression = new SparseFieldTableExpression(newTable.ToImmutable());
                     return newExpression.Equals(expression) ? expression : newExpression;
                 }
             }

src/JsonApiDotNetCore/Queries/Expressions/SparseFieldTableExpression.cs

@@ -1,6 +1,5 @@
 using System;
-using System.Collections.Generic;
-using System.Linq;
+using System.Collections.Immutable;
 using System.Text;
 using JetBrains.Annotations;
 using JsonApiDotNetCore.Configuration;
@@ -13,9 +12,9 @@ namespace JsonApiDotNetCore.Queries.Expressions
     [PublicAPI]
     public class SparseFieldTableExpression : QueryExpression
     {
-        public IReadOnlyDictionary<ResourceContext, SparseFieldSetExpression> Table { get; }
+        public IImmutableDictionary<ResourceContext, SparseFieldSetExpression> Table { get; }
 
-        public SparseFieldTableExpression(IReadOnlyDictionary<ResourceContext, SparseFieldSetExpression> table)
+        public SparseFieldTableExpression(IImmutableDictionary<ResourceContext, SparseFieldSetExpression> table)
         {
             ArgumentGuard.NotNullNorEmpty(table, nameof(table), "entries");
 
@@ -61,7 +60,7 @@ public override bool Equals(object obj)
 
             var other = (SparseFieldTableExpression)obj;
 
-            return Table.SequenceEqual(other.Table);
+            return Table.DictionaryEqual(other.Table);
         }
 
         public override int GetHashCode()

src/JsonApiDotNetCore/QueryStrings/Internal/SparseFieldSetQueryStringParameterReader.cs

@@ -21,7 +21,10 @@ public class SparseFieldSetQueryStringParameterReader : QueryStringParameterRead
     {
         private readonly SparseFieldTypeParser _sparseFieldTypeParser;
         private readonly SparseFieldSetParser _sparseFieldSetParser;
-        private readonly Dictionary<ResourceContext, SparseFieldSetExpression> _sparseFieldTable = new();
+
+        private readonly ImmutableDictionary<ResourceContext, SparseFieldSetExpression>.Builder _sparseFieldTableBuilder =
+            ImmutableDictionary.CreateBuilder<ResourceContext, SparseFieldSetExpression>();
+
         private string _lastParameterName;
 
         /// <inheritdoc />
@@ -69,7 +72,7 @@ public virtual void Read(string parameterName, StringValues parameterValue)
                 ResourceContext targetResource = GetSparseFieldType(parameterName);
                 SparseFieldSetExpression sparseFieldSet = GetSparseFieldSet(parameterValue, targetResource);
 
-                _sparseFieldTable[targetResource] = sparseFieldSet;
+                _sparseFieldTableBuilder[targetResource] = sparseFieldSet;
             }
             catch (QueryParseException exception)
             {
@@ -99,8 +102,8 @@ private SparseFieldSetExpression GetSparseFieldSet(string parameterValue, Resour
         /// <inheritdoc />
         public virtual IReadOnlyCollection<ExpressionInScope> GetConstraints()
         {
-            return _sparseFieldTable.Any()
-                ? new ExpressionInScope(null, new SparseFieldTableExpression(_sparseFieldTable)).AsArray()
+            return _sparseFieldTableBuilder.Any()
+                ? new ExpressionInScope(null, new SparseFieldTableExpression(_sparseFieldTableBuilder.ToImmutable())).AsArray()
                 : Array.Empty<ExpressionInScope>();
         }
     }