Improve Code Quality 2

src/UglyToad.PdfPig/AcroForms/AcroFormFactory.cs

@@ -213,7 +213,7 @@ private AcroFieldBase GetAcroField(DictionaryToken fieldDictionary, Catalog cata
             var fieldFlags = (uint) (fieldFlagsToken?.Long ?? 0);
 
             AcroFieldBase result;
-            if (fieldType == null)
+            if (fieldType is null)
             {
                 result = new AcroNonTerminalField(fieldDictionary, "Non-Terminal Field", fieldFlags, information, AcroFieldType.Unknown, children);
             }
@@ -562,7 +562,7 @@ private static bool IsChoiceSelected(IReadOnlyList<string> selectedOptionNames,
                     continue;
                 }
 
-                if (selectedOptionIndices == null)
+                if (selectedOptionIndices is null)
                 {
                     return true;
                 }

src/UglyToad.PdfPig/AcroForms/Fields/AcroFieldCommonInformation.cs

@@ -50,7 +50,7 @@ public override string ToString()
         {
             string AppendIfNotNull(string val, string label, string result)
             {
-                if (val == null)
+                if (val is null)
                 {
                     return result;
                 }

src/UglyToad.PdfPig/Annotations/AppearanceStream.cs

@@ -53,7 +53,7 @@ internal AppearanceStream(IDictionary<string, StreamToken> appearanceStreamsBySt
         /// <exception cref="ArgumentOutOfRangeException"></exception>
         public StreamToken Get(string state)
         {
-            if (appearanceStreamsByState == null)
+            if (appearanceStreamsByState is null)
             {
                 throw new Exception("Cannot get appearance by state when this is a stateless appearance stream");
             }

src/UglyToad.PdfPig/Annotations/QuadPointsQuadrilateral.cs

@@ -23,7 +23,7 @@ public class QuadPointsQuadrilateral
         /// </summary>
         public QuadPointsQuadrilateral(IReadOnlyList<PdfPoint> points)
         {
-            if (points == null)
+            if (points is null)
             {
                 throw new ArgumentNullException(nameof(points));
             }

src/UglyToad.PdfPig/Content/BasePageFactory.cs

@@ -66,7 +66,7 @@ protected BasePageFactory(
         public TPage Create(int number, DictionaryToken dictionary, PageTreeMembers pageTreeMembers,
              NamedDestinations namedDestinations)
         {
-            if (dictionary == null)
+            if (dictionary is null)
             {
                 throw new ArgumentNullException(nameof(dictionary));
             }
@@ -131,7 +131,7 @@ public TPage Create(int number, DictionaryToken dictionary, PageTreeMembers page
 
                     var contentStream = DirectObjectFinder.Get<StreamToken>(obj, PdfScanner);
 
-                    if (contentStream == null)
+                    if (contentStream is null)
                     {
                         throw new InvalidOperationException($"Could not find the contents for object {obj}.");
                     }
@@ -150,7 +150,7 @@ public TPage Create(int number, DictionaryToken dictionary, PageTreeMembers page
             {
                 var contentStream = DirectObjectFinder.Get<StreamToken>(contents, PdfScanner);
 
-                if (contentStream == null)
+                if (contentStream is null)
                 {
                     throw new InvalidOperationException("Failed to parse the content for the page: " + number);
                 }
@@ -181,7 +181,7 @@ private TPage ProcessPageInternal(
         {
             IReadOnlyList<IGraphicsStateOperation> operations;
 
-            if (contentBytes == null || contentBytes.Count == 0)
+            if (contentBytes is null || contentBytes.Count == 0)
             {
                 operations = Array.Empty<IGraphicsStateOperation>();
             }
@@ -293,7 +293,7 @@ protected MediaBox GetMediaBox(int number, DictionaryToken dictionary, PageTreeM
             {
                 mediaBox = pageTreeMembers.MediaBox;
 
-                if (mediaBox == null)
+                if (mediaBox is null)
                 {
                     ParsingOptions.Logger.Error(
                         $"The MediaBox was the wrong missing for page {number}. Using US Letter.");

src/UglyToad.PdfPig/Content/DocumentInformation.cs

@@ -124,7 +124,7 @@ public override string ToString()
 
         private static void AppendPart(string name, string value, StringBuilder builder)
         {
-            if (value == null)
+            if (value is null)
             {
                 return;
             }

src/UglyToad.PdfPig/Content/InlineImage.cs

@@ -108,7 +108,7 @@ internal InlineImage(PdfRectangle bounds, int widthInSamples, int heightInSample
         public bool TryGetBytes(out IReadOnlyList<byte> bytes)
         {
             bytes = null;
-            if (bytesFactory == null)
+            if (bytesFactory is null)
             {
                 return false;
             }

src/UglyToad.PdfPig/Content/Page.cs

@@ -122,7 +122,7 @@ internal Page(int number, DictionaryToken dictionary, MediaBox mediaBox, CropBox
 
         private static string GetText(PageContent content)
         {
-            if (content?.Letters == null)
+            if (content?.Letters is null)
             {
                 return string.Empty;
             }

src/UglyToad.PdfPig/Content/PageRotationDegrees.cs

@@ -25,19 +25,13 @@ public double Radians
         {
             get
             {
-                switch (Value)
-                {
-                    case 0:
-                        return 0;
-                    case 90:
-                        return -0.5 * Math.PI;
-                    case 180:
-                        return -Math.PI;
-                    case 270:
-                        return -1.5 * Math.PI;
-                    default:
-                        throw new InvalidOperationException($"Invalid value for rotation: {Value}.");
-                }
+                return Value switch {
+                    0   => 0,
+                    90  => -0.5 * Math.PI,
+                    180 => -Math.PI,
+                    270 => -1.5 * Math.PI,
+                    _   => throw new InvalidOperationException($"Invalid value for rotation: {Value}.")
+                };
             }
         }
 

src/UglyToad.PdfPig/Content/PageTreeNode.cs

@@ -49,7 +49,7 @@ public class PageTreeNode
         /// <summary>
         /// Whether this node is the root node.
         /// </summary>
-        public bool IsRoot => Parent == null;
+        public bool IsRoot => Parent is null;
 
         /// <summary>
         /// Create a new <see cref="PageTreeNode"/>.

src/UglyToad.PdfPig/Content/Pages.cs

@@ -132,7 +132,7 @@ internal void AddPageFactory<TPage, TPageFactory>() where TPageFactory : IPageFa
                 typeof(ParsingOptions)
             });
 
-            if (constructor == null)
+            if (constructor is null)
             {
                 throw new InvalidOperationException($"Could not find valid constructor for page factory of type '{typeof(TPageFactory)}'. " +
                                                     "The page factory should have a constructor with the following parameters: " +

src/UglyToad.PdfPig/Content/ResourceStore.cs

@@ -200,7 +200,7 @@ private void LoadFontDictionary(DictionaryToken fontDictionary)
 
                     var fontObject = DirectObjectFinder.Get<DictionaryToken>(objectKey, scanner);
 
-                    if (fontObject == null)
+                    if (fontObject is null)
                     {
                         //This is a valid use case
                         continue;
@@ -269,7 +269,7 @@ public bool TryGetNamedColorSpace(NameToken name, out ResourceColorSpace namedTo
         {
             namedToken = default(ResourceColorSpace);
 
-            if (name == null)
+            if (name is null)
             {
                 throw new ArgumentNullException(nameof(name));
             }
@@ -286,7 +286,7 @@ public bool TryGetNamedColorSpace(NameToken name, out ResourceColorSpace namedTo
 
         public ColorSpaceDetails GetColorSpaceDetails(NameToken name, DictionaryToken dictionary)
         {
-            if (dictionary == null)
+            if (dictionary is null)
             {
                 dictionary = new DictionaryToken(new Dictionary<NameToken, IToken>());
             }

src/UglyToad.PdfPig/Content/Word.cs

@@ -42,7 +42,7 @@ public class Word
         /// <param name="letters">The letters contained in the word, in the correct order.</param>
         public Word(IReadOnlyList<Letter> letters)
         {
-            if (letters == null)
+            if (letters is null)
             {
                 throw new ArgumentNullException(nameof(letters));
             }

src/UglyToad.PdfPig/CrossReference/CrossReferenceTable.cs

@@ -44,7 +44,7 @@ internal CrossReferenceTable(CrossReferenceType type, IReadOnlyDictionary<Indire
             TrailerDictionary trailer,
             IReadOnlyList<CrossReferenceOffset> crossReferenceOffsets)
         {
-            if (objectOffsets == null)
+            if (objectOffsets is null)
             {
                 throw new ArgumentNullException(nameof(objectOffsets));
             }

src/UglyToad.PdfPig/CrossReference/CrossReferenceTableBuilder.cs

@@ -20,7 +20,7 @@ internal class CrossReferenceTableBuilder
 
         public void Add(CrossReferenceTablePart part)
         {
-            if (part == null)
+            if (part is null)
             {
                 throw new ArgumentNullException(nameof(part));
             }
@@ -38,7 +38,7 @@ public CrossReferenceTable Build(long firstCrossReferenceOffset, long offsetCorr
 
             var currentPart = parts.FirstOrDefault(x => x.Offset == firstCrossReferenceOffset);
 
-            if (currentPart == null)
+            if (currentPart is null)
             {
                 // no XRef at given position
                 log.Warn($"Did not find an XRef object at the specified startxref position {firstCrossReferenceOffset}");
@@ -73,7 +73,7 @@ public CrossReferenceTable Build(long firstCrossReferenceOffset, long offsetCorr
                     }
 
                     currentPart = parts.FirstOrDefault(x => x.Offset == prevBytePos || x.Offset == prevBytePos + offsetCorrection);
-                    if (currentPart == null)
+                    if (currentPart is null)
                     {
                         log.Warn("Did not found XRef object pointed to by 'Prev' key at position " + prevBytePos);
                         break;

src/UglyToad.PdfPig/CrossReference/TrailerDictionary.cs

@@ -56,7 +56,7 @@ public class TrailerDictionary
         /// <param name="dictionary">The parsed dictionary from the document.</param>
         internal TrailerDictionary(DictionaryToken dictionary)
         {
-            if (dictionary == null)
+            if (dictionary is null)
             {
                 throw new ArgumentNullException(nameof(dictionary));
             }

src/UglyToad.PdfPig/Encryption/CryptHandler.cs

@@ -15,12 +15,12 @@ internal class CryptHandler
         public CryptHandler(DictionaryToken cryptDictionary,
             NameToken streamName, NameToken stringName)
         {
-            if (streamName == null)
+            if (streamName is null)
             {
                 throw new ArgumentNullException(nameof(streamName));
             }
 
-            if (stringName == null)
+            if (stringName is null)
             {
                 throw new ArgumentNullException(nameof(stringName));
             }
@@ -32,7 +32,7 @@ public CryptHandler(DictionaryToken cryptDictionary,
 
         public CryptDictionary GetNamedCryptDictionary(NameToken name)
         {
-            if (name == null)
+            if (name is null)
             {
                 throw new ArgumentNullException(nameof(name));
             }

src/UglyToad.PdfPig/Encryption/EncryptionDictionaryFactory.cs

@@ -11,7 +11,7 @@ internal static class EncryptionDictionaryFactory
     {
         public static EncryptionDictionary Read(DictionaryToken encryptionDictionary, IPdfTokenScanner tokenScanner)
         {
-            if (encryptionDictionary == null)
+            if (encryptionDictionary is null)
             {
                 throw new ArgumentNullException(nameof(encryptionDictionary));
             }

src/UglyToad.PdfPig/Encryption/EncryptionHandler.cs

@@ -59,26 +59,18 @@ public EncryptionHandler(EncryptionDictionary encryptionDictionary, TrailerDicti
             {
                 var token = trailerDictionary.Identifier[0];
 
-                switch (token)
-                {
-                    case HexToken hex:
-                        documentIdBytes = hex.Bytes.ToArray();
-                        break;
-                    case StringToken str:
-                        documentIdBytes = str.GetBytes();
-                        break;
-                    default:
-                        documentIdBytes = OtherEncodings.StringAsLatin1Bytes(token.Data);
-                        break;
-                }
-
+                documentIdBytes = token switch {
+                    HexToken hex => hex.Bytes.ToArray(),
+                    StringToken str => str.GetBytes(),
+                    _ => OtherEncodings.StringAsLatin1Bytes(token.Data)
+                };
             }
             else
             {
                 documentIdBytes = [];
             }
 
-            if (encryptionDictionary == null)
+            if (encryptionDictionary is null)
             {
                 return;
             }
@@ -337,7 +329,7 @@ private static bool IsOwnerPasswordRevision5And6(byte[] passwordBytes, Encryptio
 
         public IToken Decrypt(IndirectReference reference, IToken token)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -736,7 +728,7 @@ private static void UpdateMd5(MD5 md5, byte[] data)
 
         private static byte[] GetPaddedPassword(byte[] password)
         {
-            if (password == null || password.Length == 0)
+            if (password is null || password.Length == 0)
             {
                 return PaddingBytes;
             }
@@ -779,7 +771,7 @@ private static byte[] TruncatePasswordTo127Bytes(byte[] password)
         private static byte[] ComputeStupidIsoHash(byte[] password, byte[] salt, byte[] vector)
         {
             // There are some details here https://web.archive.org/web/20180311160224/esec-lab.sogeti.com/posts/2011/09/14/the-undocumented-password-validation-algorithm-of-adobe-reader-x.html
-            if (vector == null)
+            if (vector is null)
             {
                 vector = [];
             }
@@ -847,23 +839,12 @@ private static byte[] ComputeStupidIsoHash(byte[] password, byte[] salt, byte[]
 
                 var sumOfFirstSixteenBytesOfX = x.Take(16).Sum(v => (long)v);
                 var mod3 = sumOfFirstSixteenBytesOfX % 3;
-
-                HashAlgorithm nextHash;
-                switch (mod3)
-                {
-                    case 0:
-                        nextHash = SHA256.Create();
-                        break;
-                    case 1:
-                        nextHash = SHA384.Create();
-                        break;
-                    case 2:
-                        nextHash = SHA512.Create();
-                        break;
-                    default:
-                        throw new PdfDocumentEncryptedException("Invalid remainder from summing first sixteen bytes of this round's hash.");
-                }
-
+                HashAlgorithm nextHash = mod3 switch {
+                    0 => SHA256.Create(),
+                    1 => SHA384.Create(),
+                    2 => SHA512.Create(),
+                    _ => throw new PdfDocumentEncryptedException("Invalid remainder from summing first sixteen bytes of this round's hash.")
+                };
                 input = nextHash.ComputeHash(x);
                 Array.Copy(input, key, 16);
                 Array.Copy(input, 16, iv, 0, 16);