C#: Enable nullability in Semmle.Util

Author: calumgrant

csharp/extractor/Semmle.Util/ActionMap.cs

@@ -9,20 +9,19 @@ namespace Semmle.Util
     /// </summary>
     /// <typeparam name="Key"></typeparam>
     /// <typeparam name="Value"></typeparam>
-    public class ActionMap<Key, Value>
+    public class ActionMap<Key, Value> where Key : notnull
     {
         public void Add(Key key, Value value)
         {
-            Action<Value> a;
-            if (actions.TryGetValue(key, out a))
+
+            if (actions.TryGetValue(key, out var a))
                 a(value);
             values[key] = value;
         }
 
         public void OnAdd(Key key, Action<Value> action)
         {
-            Action<Value> a;
-            if (actions.TryGetValue(key, out a))
+            if (actions.TryGetValue(key, out var a))
             {
                 actions[key] = a + action;
             }

csharp/extractor/Semmle.Util/CanonicalPathCache.cs

@@ -127,8 +127,8 @@ public override string GetCanonicalPath(string path, IPathCache cache)
 
             if (parent != null)
             {
-                string name = Path.GetFileName(path);
-                string parentPath = cache.GetCanonicalPath(parent.FullName);
+                string? name = Path.GetFileName(path);
+                string? parentPath = cache.GetCanonicalPath(parent.FullName);
                 try
                 {
                     string[] entries = Directory.GetFileSystemEntries(parentPath, name);
@@ -313,14 +313,15 @@ void AddToCache(string path, string canonical)
         /// <returns>The canonical path.</returns>
         public string GetCanonicalPath(string path)
         {
-            string canonicalPath;
             lock (cache)
-                if (!cache.TryGetValue(path, out canonicalPath))
+            {
+                if (!cache.TryGetValue(path, out var canonicalPath))
                 {
                     canonicalPath = pathStrategy.GetCanonicalPath(path, this);
                     AddToCache(path, canonicalPath);
                 }
-            return canonicalPath;
+                return canonicalPath;
+            }
         }
     }
 }

csharp/extractor/Semmle.Util/CommandLineExtensions.cs

@@ -18,7 +18,7 @@ public static bool WriteCommandLine(this IEnumerable<string> commandLineArgument
             var found = false;
             foreach (var arg in commandLineArguments.Where(arg => arg.StartsWith('@')).Select(arg => arg.Substring(1)))
             {
-                string line;
+                string? line;
                 using (StreamReader file = new StreamReader(arg))
                     while ((line = file.ReadLine()) != null)
                         textWriter.WriteLine(line);

csharp/extractor/Semmle.Util/DictionaryExtensions.cs

@@ -9,10 +9,9 @@ public static class DictionaryExtensions
         /// dictionary. If a list does not already exist, a new list is
         /// created.
         /// </summary>
-        public static void AddAnother<T1, T2>(this Dictionary<T1, List<T2>> dict, T1 key, T2 element)
+        public static void AddAnother<T1, T2>(this Dictionary<T1, List<T2>> dict, T1 key, T2 element) where T1:notnull
         {
-            List<T2> list;
-            if (!dict.TryGetValue(key, out list))
+            if (!dict.TryGetValue(key, out var list))
             {
                 list = new List<T2>();
                 dict[key] = list;

csharp/extractor/Semmle.Util/FileUtils.cs

@@ -62,7 +62,7 @@ public static void TryDelete(string file)
         ///
         /// Returns <code>null</code> of no path can be found.
         /// </summary>
-        public static string FindProgramOnPath(string prog)
+        public static string? FindProgramOnPath(string prog)
         {
             var paths = Environment.GetEnvironmentVariable("PATH")?.Split(Path.PathSeparator);
             string[] exes;

csharp/extractor/Semmle.Util/FuzzyDictionary.cs

@@ -37,7 +37,7 @@ namespace Semmle.Util
     /// </remarks>
     ///
     /// <typeparam name="T">The value type.</typeparam>
-    public class FuzzyDictionary<T>
+    public class FuzzyDictionary<T> where T:class
     {
         // All data items indexed by the "base string" (stripped of numbers)
         readonly Dictionary<string, List<KeyValuePair<string, T>>> index = new Dictionary<string, List<KeyValuePair<string, T>>>();
@@ -61,7 +61,7 @@ public void Add(string k, T v)
         /// <param name="v1">Vector 1</param>
         /// <param name="v2">Vector 2</param>
         /// <returns>The Hamming Distance.</returns>
-        static int HammingDistance<U>(IEnumerable<U> v1, IEnumerable<U> v2)
+        static int HammingDistance<U>(IEnumerable<U> v1, IEnumerable<U> v2) where U: notnull
         {
             return v1.Zip(v2, (x, y) => x.Equals(y) ? 0 : 1).Sum();
         }
@@ -72,11 +72,10 @@ static int HammingDistance<U>(IEnumerable<U> v1, IEnumerable<U> v2)
         /// <param name="query">The query string.</param>
         /// <param name="distance">The distance between the query string and the stored string.</param>
         /// <returns>The best match, or null (default).</returns>
-        public T FindMatch(string query, out int distance)
+        public T? FindMatch(string query, out int distance)
         {
             string root = StripDigits(query);
-            List<KeyValuePair<string, T>> list;
-            if (!index.TryGetValue(root, out list))
+            if (!index.TryGetValue(root, out var list))
             {
                 distance = 0;
                 return default(T);
@@ -93,9 +92,9 @@ public T FindMatch(string query, out int distance)
         /// <param name="distance">The distance function.</param>
         /// <param name="bestDistance">The distance between the query and the stored string.</param>
         /// <returns>The stored value.</returns>
-        static T BestMatch(string query, IEnumerable<KeyValuePair<string, T>> candidates, Func<string, string, int> distance, out int bestDistance)
+        static T? BestMatch(string query, IEnumerable<KeyValuePair<string, T>> candidates, Func<string, string, int> distance, out int bestDistance)
         {
-            T bestMatch = default(T);
+            T? bestMatch = default(T);
             bestDistance = 0;
             bool first = true;
 

csharp/extractor/Semmle.Util/IEnumerableExtensions.cs

@@ -93,7 +93,7 @@ public static void Enumerate<T>(this IEnumerable<T> items)
         /// <typeparam name="T">The type of the item.</typeparam>
         /// <param name="items">The list of items to hash.</param>
         /// <returns>The hash code.</returns>
-        public static int SequenceHash<T>(this IEnumerable<T> items)
+        public static int SequenceHash<T>(this IEnumerable<T> items) where T: notnull
         {
             int h = 0;
             foreach (var i in items)

csharp/extractor/Semmle.Util/LineCounter.cs

@@ -31,9 +31,9 @@ public sealed class LineCounts
         //#################### PUBLIC METHODS ####################
         #region
 
-        public override bool Equals(Object other)
+        public override bool Equals(object? other)
         {
-            LineCounts rhs = other as LineCounts;
+            var rhs = other as LineCounts;
             return rhs != null && Total == rhs.Total && Code == rhs.Code && Comment == rhs.Comment;
         }
 

csharp/extractor/Semmle.Util/Logger.cs

@@ -67,8 +67,8 @@ public FileLogger(Verbosity verbosity, string outputFile)
 
             try
             {
-                var dir = Path.GetDirectoryName(outputFile);
-                if (dir.Length > 0 && !System.IO.Directory.Exists(dir))
+                string? dir = Path.GetDirectoryName(outputFile);
+                if (!string.IsNullOrEmpty(dir) && !System.IO.Directory.Exists(dir))
                     Directory.CreateDirectory(dir);
                 writer = new PidStreamWriter(new FileStream(outputFile, FileMode.Append, FileAccess.Write,
                     FileShare.ReadWrite, 8192));

csharp/extractor/Semmle.Util/LoggerUtils.cs

@@ -21,17 +21,17 @@ public PidStreamWriter(Stream stream) : base(stream) { }
 
         private readonly string prefix = "[" + Process.GetCurrentProcess().Id + "] ";
 
-        public override void WriteLine(string value)
+        public override void WriteLine(string? value)
         {
             lock (mutex)
             {
                 base.WriteLine(prefix + value);
             }
         }
 
-        public override void WriteLine(string value, object[] args)
+        public override void WriteLine(string? value, object?[] args)
         {
-            WriteLine(String.Format(value, args));
+            WriteLine(value is null ? value : String.Format(value, args));
         }
 
         readonly object mutex = new object();