LaunchArgumentParser.HelpMessageHeader

DTLib/Console/LaunchArgumentParser.cs

@@ -2,55 +2,44 @@ namespace DTLib.Console;
 
 public class LaunchArgumentParser
 {
+    public string HelpMessageHeader = "USAGE:";
     public bool IsAllowedNoArguments;
     
     private readonly Dictionary<string, LaunchArgument> argDict = new();
     private readonly List<LaunchArgument> argList = new();
 
-    public class ExitAfterHelpException : Exception
-    {
-        internal ExitAfterHelpException() : base("your program can use this exception to exit after displaying help message")
-        { }
-    }
-    
-    public string CreateHelpMessage()
-    {
-        StringBuilder b = new();
-        foreach (var arg in argList) 
-            arg.AppendHelpInfo(b).Append('\n');
-        b.Remove(b.Length-1, 1);
-        return b.ToString();
-    }
-    public string CreateHelpArgMessage(string argAlias)
-    {
-        StringBuilder b = new();
-        var arg = Parse(argAlias);
-        arg.AppendHelpInfo(b);
-        return b.ToString();
-    }
-    private void HelpHandler()
-    {
-        System.Console.WriteLine(CreateHelpMessage());
-        throw new ExitAfterHelpException();
-    }
-
-    private void HelpArgHandler(string argAlias)
-    {
-        System.Console.WriteLine(CreateHelpArgMessage(argAlias));
-        throw new ExitAfterHelpException();
-    }
-
-
     public LaunchArgumentParser() 
     {
         var help = new LaunchArgument(new[] { "h", "help" },
             "shows help message", HelpHandler);
         Add(help);
         var helpArg = new LaunchArgument(new[] { "ha", "helparg" },
-            "shows help message for particular argument", 
+            "shows help message for specific argument",
-            HelpArgHandler, "argAlias");
+            HelpArgHandler, "argument");
         Add(helpArg);
     }
+    public LaunchArgumentParser(ICollection<LaunchArgument> arguments) : this() => WithArgs(arguments);
+    public LaunchArgumentParser(params LaunchArgument[] arguments) : this() => WithArgs(arguments);
+
+    public LaunchArgumentParser WithArgs(IEnumerable<LaunchArgument> args)
+    {
+        foreach (var arg in args)
+            Add(arg);
+        return this;
+    }
+    
+    public LaunchArgumentParser WithArgs(params LaunchArgument[] args)
+    {
+        foreach (var arg in args)
+            Add(arg);
+        return this;
+    }
+
+    public LaunchArgumentParser WithHelpMessageHeader(string header)
+    {
+        HelpMessageHeader = header;
+        return this;
+    }
     
     public LaunchArgumentParser AllowNoArguments()
     {
@@ -58,15 +47,24 @@ public class LaunchArgumentParser
         return this;
     }
 
-    public LaunchArgumentParser(ICollection<LaunchArgument> arguments) : this()
+    
+    public string CreateHelpMessage()
     {
-        foreach (var arg in arguments) 
+        StringBuilder b = new(HelpMessageHeader);
-            Add(arg);
+        foreach (var arg in argList)
+        {
+            b.Append('\n');
+            arg.AppendHelpInfo(b);
         }
-    public LaunchArgumentParser(params LaunchArgument[] arguments) : this()
+        return b.ToString();
+    }
+
+    public string CreateHelpArgMessage(string argAlias)
     {
-        foreach (var arg in arguments)
+        StringBuilder b = new();
-            Add(arg);
+        var arg = ParseArg(argAlias);
+        arg.AppendHelpInfo(b);
+        return b.ToString();
     }
 
     public void Add(LaunchArgument arg)
@@ -76,7 +74,7 @@ public class LaunchArgumentParser
             argDict.Add(alias, arg);
     }
 
-    public LaunchArgument Parse(string argAlias)
+    public LaunchArgument ParseArg(string argAlias)
     {
         // different argument providing patterns
         if (!argDict.TryGetValue(argAlias, out var arg) && // arg
@@ -102,11 +100,12 @@ public class LaunchArgumentParser
 
         for (int i = 0; i < args.Length; i++)
         {
-            LaunchArgument arg = Parse(args[i]);
+            var arg = ParseArg(args[i]);
             for (int j = 0; j < arg.Params.Length; j++)
             {
                 if (++i >= args.Length)
-                    throw new Exception($"argument '{arg.Aliases[0]}' should have parameter '{arg.Params[j]}' after it");
+                    throw new Exception(
+                        $"argument '{arg.Aliases[0]}' should have parameter '{arg.Params[j]}' after it");
                 arg.Params[j].Value = args[i];
             }
 
@@ -119,4 +118,24 @@ public class LaunchArgumentParser
         foreach (var a in execQueue)
             a.Handle();
     }
+
+    private void HelpHandler()
+    {
+        System.Console.WriteLine(CreateHelpMessage());
+        throw new ExitAfterHelpException();
+    }
+
+    private void HelpArgHandler(string argAlias)
+    {
+        System.Console.WriteLine(CreateHelpArgMessage(argAlias));
+        throw new ExitAfterHelpException();
+    }
+
+    public class ExitAfterHelpException : Exception
+    {
+        public ExitAfterHelpException()
+            : base("your program can use this exception to exit after displaying help message")
+        {
+        }
+    }
 }