(consoleapp) Enable nullability checks for the Program class (#386)

perlang-org · Apr 15, 2023 · 893c5be · 893c5be
1 parent 9331a81
commit 893c5be
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Showing 3 changed files with 26 additions and 15 deletions.
diff --git a/release-notes/v0.4.0.md b/release-notes/v0.4.0.md
@@ -8,6 +8,9 @@
 - Implement `AsciiString` for ASCII-only strings [[#377][377]]
 - Implement `Utf8String` for strings with non-ASCII content [[#385][385]]
 
+#### General
+- Enable nullability checks for the `Program` class [[#386][386]]
+
 #### Maintenance
 - Bump TngTech.ArchUnitNET.xUnit from 0.5.0 to 0.10.5 [[#366][366]]
 - Bump xunit from 2.4.1 to 2.4.2 [[#369][369]]
@@ -22,3 +25,4 @@
 [377]: https://github.com/perlang-org/perlang/pull/377
 [380]: https://github.com/perlang-org/perlang/pull/380
 [385]: https://github.com/perlang-org/perlang/pull/385
+[386]: https://github.com/perlang-org/perlang/pull/386
diff --git a/src/Perlang.ConsoleApp/Program.cs b/src/Perlang.ConsoleApp/Program.cs
@@ -1,3 +1,4 @@
+#nullable enable
 using System;
 using System.Collections.Generic;
 using System.CommandLine;
@@ -86,7 +87,7 @@ public static int Main(string[] args)
         /// <param name="console">A custom `IConsole` implementation to use. May be null, in which case the standard
         /// streams of the calling process will be used.</param>
         /// <returns>Zero if the program executed successfully; non-zero otherwise.</returns>
-        public static int MainWithCustomConsole(string[] args, IConsole console)
+        public static int MainWithCustomConsole(string[] args, IConsole? console)
         {
             var versionOption = new Option<bool>(new[] { "--version", "-v" }, "Show version information");
             var detailedVersionOption = new Option<bool>("-V", "Show detailed version information");
@@ -98,7 +99,7 @@ public static int MainWithCustomConsole(string[] args, IConsole console)
 
             noWarnAsErrorOption.AddValidator(result =>
             {
-                string warningName = result.GetValueOrDefault<string>();
+                string warningName = result.GetValueOrDefault<string>()!;
 
                 if (!WarningType.KnownWarning(warningName))
                 {
@@ -166,7 +167,7 @@ public static int MainWithCustomConsole(string[] args, IConsole console)
 
                     if (parseResult.HasOption(evalOption))
                     {
-                        string source = parseResult.GetValueForOption(evalOption);
+                        string source = parseResult.GetValueForOption(evalOption)!;
 
                         var program = new Program(
                             replMode: true,
@@ -180,7 +181,7 @@ public static int MainWithCustomConsole(string[] args, IConsole console)
                     }
                     else if (parseResult.HasOption(printOption))
                     {
-                        string source = parseResult.GetValueForOption(printOption);
+                        string source = parseResult.GetValueForOption(printOption)!;
 
                         new Program(
                             replMode: true,
@@ -263,15 +264,15 @@ public static int MainWithCustomConsole(string[] args, IConsole console)
 
         internal Program(
             bool replMode,
-            IEnumerable<string> arguments = null,
-            IEnumerable<WarningType> disabledWarningsAsErrors = null,
-            Action<string> standardOutputHandler = null,
-            Action<RuntimeError> runtimeErrorHandler = null)
+            Action<string> standardOutputHandler,
+            IEnumerable<string>? arguments = null,
+            IEnumerable<WarningType>? disabledWarningsAsErrors = null,
+            Action<RuntimeError>? runtimeErrorHandler = null)
         {
             // TODO: Make these be separate handlers at some point, so the caller can separate between these types of
             // output.
-            this.standardOutputHandler = standardOutputHandler ?? Console.WriteLine;
-            this.standardErrorHandler = standardOutputHandler ?? Console.Error.WriteLine;
+            this.standardOutputHandler = standardOutputHandler;
+            this.standardErrorHandler = standardOutputHandler;
             this.disabledWarningsAsErrors = (disabledWarningsAsErrors ?? Enumerable.Empty<WarningType>()).ToHashSet();
 
             interpreter = new PerlangInterpreter(
@@ -386,19 +387,26 @@ private void ShowHelp()
 
         internal int Run(string source, CompilerWarningHandler compilerWarningHandler)
         {
-            object result = interpreter.Eval(source, ScanError, ParseError, NameResolutionError, ValidationError, ValidationError, compilerWarningHandler);
+            object? result = interpreter.Eval(source, ScanError, ParseError, NameResolutionError, ValidationError, ValidationError, compilerWarningHandler);
 
             if (result != null && result != VoidObject.Void)
             {
-                standardOutputHandler(result.ToString());
+                standardOutputHandler(result.ToString() ?? String.Empty);
             }
 
             return (int)ExitCodes.SUCCESS;
         }
 
         private void ParseAndPrint(string source)
         {
-            string result = interpreter.Parse(source, ScanError, ParseError);
+            string? result = interpreter.Parse(source, ScanError, ParseError);
+
+            if (result == null)
+            {
+                // Parse() returns `null` when one or more errors occurred. These errors have already been reported to
+                // the user at this point, so we can safely just return here.
+                return;
+            }
 
             standardOutputHandler(result);
         }

diff --git a/src/Perlang.Tests/ConsoleApp/ProgramTest.cs b/src/Perlang.Tests/ConsoleApp/ProgramTest.cs
@@ -230,9 +230,8 @@ public void invalid_expression()
                 {
                     CallWithPrintParameter("hej hej");
 
-                    // TODO: Hmm, I wonder why this prints an extra linebreak?
                     StdoutLines.Should().Equal(
-                        "[line 1] Error at 'hej': Expect ';' after expression.", String.Empty, String.Empty
+                        "[line 1] Error at 'hej': Expect ';' after expression.", String.Empty
                     );
                 }