Refactor to clean up CA1851 warnings

src/DocumentFormat.OpenXml.Framework/EnumerableExtensions.cs

@@ -0,0 +1,33 @@
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace DocumentFormat.OpenXml;
+
+internal static class EnumerableExtensions
+{
+    /// <summary>
+    /// Similar to <see cref="Enumerable.FirstOrDefault{TSource}(IEnumerable{TSource})"/> but will also verify that at most there is one.
+    /// </summary>
+    public static T? FirstOrDefaultAndMaxOne<T>(this IEnumerable<T> enumerable, Func<Exception>? exceptionFactory = null)
+    {
+        using var e = enumerable.GetEnumerator();
+
+        if (e.MoveNext())
+        {
+            var first = e.Current;
+
+            if (e.MoveNext())
+            {
+                throw exceptionFactory?.Invoke() ?? throw new InvalidOperationException(ExceptionMessages.FirstOrDefaultMaxOne);
+            }
+
+            return first;
+        }
+
+        return default;
+    }
+}

src/DocumentFormat.OpenXml.Framework/Resources/ExceptionMessages.resx

@@ -411,4 +411,7 @@
   <data name="FailedToOpenPackage" xml:space="preserve">
     <value>Package could not be opened for stream. See inner exception for details and be aware that there are behavior differences in stream support between .NET Framework and Core.</value>
   </data>
+  <data name="FirstOrDefaultMaxOne" xml:space="preserve">
+    <value>The enumerable contained more than a single element when only zero or one are allowed.</value>
+  </data>
 </root>

src/DocumentFormat.OpenXml.Framework/Validation/Semantic/RelationshipTypeConstraint.cs

@@ -21,7 +21,6 @@ public RelationshipTypeConstraint(OpenXmlQualifiedName attribute, string type)
             _type = type;
         }
 
-        [System.Diagnostics.CodeAnalysis.SuppressMessage("Performance", "CA1851:Possible multiple enumerations of 'IEnumerable' collection", Justification = "https://github.com/dotnet/Open-XML-SDK/issues/1325")]
         public override ValidationErrorInfo? ValidateCore(ValidationContext context)
         {
             var current = context.Stack.Current;
@@ -57,20 +56,20 @@ public RelationshipTypeConstraint(OpenXmlQualifiedName attribute, string type)
 
             var rels = current.Part.ExternalRelationships.Where(r => r.Id == attribute.Value.InnerText);
 
-            if (!rels.Any())
+            if (rels.FirstOrDefault() is { } rel)
             {
-                var pairs = current.Part.Parts.Where(p => p.RelationshipId == attribute.Value.InnerText);
-
-                if (pairs.Any())
-                {
-                    Debug.Assert(pairs.Count() == 1);
-                    actualType = pairs.First().OpenXmlPart.RelationshipType;
-                }
+                actualType = rel.RelationshipType;
             }
             else
             {
-                Debug.Assert(rels.Count() == 1);
-                actualType = rels.First().RelationshipType;
+                var pair = current.Part.Parts
+                    .Where(p => p.RelationshipId == attribute.Value.InnerText)
+                    .FirstOrDefaultAndMaxOne();
+
+                if (pair is { })
+                {
+                    actualType = pair.OpenXmlPart.RelationshipType;
+                }
             }
 
             if (actualType == _type)

src/DocumentFormat.OpenXml.Framework/Validation/Semantic/SemanticConstraint.cs

@@ -16,7 +16,6 @@ namespace DocumentFormat.OpenXml.Validation.Semantic
     /// <summary>
     /// Base class for each semantic constraint category.
     /// </summary>
-    [System.Diagnostics.CodeAnalysis.SuppressMessage("Performance", "CA1851:Possible multiple enumerations of 'IEnumerable' collection", Justification = "https://github.com/dotnet/Open-XML-SDK/issues/1325")]
     internal abstract class SemanticConstraint : IValidator
     {
         public SemanticConstraint(SemanticValidationLevel level)
@@ -130,13 +129,10 @@ private static void Get(ValidationContext context, out SemanticValidationLevel l
             }
             else if (parts[0] == "..")
             {
-                var refParts = current.Package
+                return current.Package
                     .GetAllParts()
-                    .Where(p => p.Parts.Any(r => r.OpenXmlPart.PackagePart.Uri == current.Part.PackagePart.Uri));
-
-                Debug.Assert(refParts.Count() == 1);
-
-                return refParts.First();
+                    .Where(p => p.Parts.Any(r => r.OpenXmlPart.PackagePart.Uri == current.Part.PackagePart.Uri))
+                    .First();
             }
             else
             {
@@ -247,29 +243,25 @@ protected static bool GetAttrNumVal(OpenXmlSimpleType attributeValue, out double
 
         private static OpenXmlPart? GetPartThroughPartPath(IEnumerable<IdPartPair> pairs, string[] path)
         {
-            var temp = default(OpenXmlPart);
+            var foundPart = default(OpenXmlPart);
             var parts = pairs;
 
             for (int i = 0; i < path.Length; i++)
             {
-                var s = parts.Where(p => p.OpenXmlPart.GetType().Name == path[i]).Select(t => t.OpenXmlPart);
-                var count = s.Count();
-
-                if (count > 1)
-                {
-                    throw new System.IO.FileFormatException(ValidationResources.MoreThanOnePartForOneUri);
-                }
+                foundPart = parts
+                    .Where(p => p.OpenXmlPart.GetType().Name == path[i])
+                    .Select(t => t.OpenXmlPart)
+                    .FirstOrDefaultAndMaxOne(static () => new System.IO.FileFormatException(ValidationResources.MoreThanOnePartForOneUri));
 
-                if (count == 0)
+                if (foundPart is not { })
                 {
                     return null;
                 }
 
-                temp = s.First();
-                parts = temp.Parts;
+                parts = foundPart.Parts;
             }
 
-            return temp;
+            return foundPart;
         }
 
         protected readonly struct PartHolder<T>