feat: 将LR分析表生成到代码中 (#27)

Reviewed-on: PostGuard/Canon#27

Canon.Generator/Extensions/RootCommandExtension.cs

@@ -0,0 +1,40 @@
+using System.CommandLine;
+using Canon.Generator.GrammarGenerator;
+
+namespace Canon.Generator.Extensions;
+
+public static class RootCommandExtension
+{
+    public static void AddGenerateCommand(this RootCommand rootCommand)
+    {
+        Command generateCommand = new("generate", "Generate source files.");
+
+        Argument<string> filenameArgument = new(name: "filename",
+            description: "determines the generated file name.",
+            getDefaultValue: () => "Canon.g.cs");
+        generateCommand.AddArgument(filenameArgument);
+
+        Option<string> namespaceOption = new(name: "--namespace",
+            description: "determines the namespace of generated code.",
+            getDefaultValue: () => "Canon.Generator.GrammarGenerator");
+        generateCommand.AddOption(namespaceOption);
+
+        generateCommand.SetHandler(async (context) =>
+        {
+            string filename = context.ParseResult.GetValueForArgument(filenameArgument);
+            FileInfo generatedFile = new(Path.Combine(Environment.CurrentDirectory, filename));
+            if (generatedFile.Exists)
+            {
+                generatedFile.Delete();
+            }
+
+            await using FileStream stream = generatedFile.OpenWrite();
+            GenerateCommand command = new();
+
+            string namespaceValue = context.ParseResult.GetValueForOption(namespaceOption) ?? "Canon.Generator.GrammarGenerator";
+            await command.GenerateCode(stream, namespaceValue);
+        });
+
+        rootCommand.AddCommand(generateCommand);
+    }
+}