generator: Improve handling of command-line parameters

Bundle Options.cs from the Mono source tree, and use it to parse the
command-line options for gapi-codegen. This gives us clearer code,
descriptions for each option, and a nice "--help" output.

This does not change the options syntax, except that -I|--include needs
to specified for each file to include. Two Makefiles in sample/ are
updated for that change.

generator/CodeGenerator.cs

@@ -30,12 +30,7 @@ namespace GtkSharp.Generation {
 
 		public static int Main (string[] args)
 		{
-			if (args.Length < 2) {
+			bool show_help = false;
-				Console.WriteLine ("Usage: codegen --generate <filename1...>");
-				return 0;
-			}
-
-			bool generate = false;
 			string dir = "";
 			string assembly_name = "";
 			string glue_filename = "";
@@ -44,48 +39,67 @@ namespace GtkSharp.Generation {
 
 			SymbolTable table = SymbolTable.Table;
 			var gens = new List<IGeneratable> ();
-			foreach (string arg in args) {
-				if (arg.StartsWith ("--customdir=")) {
-					Console.WriteLine ("Using .custom files is not supported anymore, use partial classes instead.");
-					return 0;
-				}
-				string filename = arg;
-				if (arg == "--generate") {
-					generate = true;
-					continue;
-				} else if (arg == "--include") {
-					generate = false;
-					continue;
-				} else if (arg.StartsWith ("-I:")) {
-					generate = false;
-					filename = filename.Substring (3);
-				} else if (arg.StartsWith ("--outdir=")) {
-					generate = false;
-					dir = arg.Substring (9);
-					continue;
-				} else if (arg.StartsWith ("--assembly-name=")) {
-					generate = false;
-					assembly_name = arg.Substring (16);
-					continue;
-				} else if (arg.StartsWith ("--glue-filename=")) {
-					generate = false;
-					glue_filename = arg.Substring (16);
-					continue;
-				} else if (arg.StartsWith ("--glue-includes=")) {
-					generate = false;
-					glue_includes = arg.Substring (16);
-					continue;
-				} else if (arg.StartsWith ("--gluelib-name=")) {
-					generate = false;
-					gluelib_name = arg.Substring (15);
-					continue;
-				}
 
-				Parser p = new Parser ();
+			var filenames = new List<string> ();
+			var includes = new List<string> ();
+
+			var options = new OptionSet () {
+				{ "generate=", "Generate the C# code for this GAPI XML file.",
+					(string v) => { filenames.Add (v); } },
+				{ "I|include=", "GAPI XML file that contain symbols used in the main GAPI XML file.",
+					(string v) => { includes.Add (v); } },
+				{ "outdir=", "Directory where the C# files will be generated.",
+					(string v) => { dir = v; } },
+				{ "assembly-name=", "Name of the assembly for which the code is generated.",
+					(string v) => { assembly_name = v; } },
+				{ "glue-filename=", "Filename for the generated C glue code.",
+					(string v) => { glue_filename = v; } },
+				{ "glue-includes=", "Content of #include directive to add in the generated C glue code.",
+					(string v) => { glue_includes = v; } },
+				{ "gluelib-name=", "Name of the C library into which the C glue code will be compiled. " +
+					"Used to generated correct DllImport attributes.",
+					(string v) => { gluelib_name = v; } },
+				{ "h|help",  "Show this message and exit",
+					v => show_help = v != null },
+			};
+
+			List<string> extra;
+			try {
+				extra = options.Parse (args);
+			}
+			catch (OptionException e) {
+				Console.Write ("gapi-codegen: ");
+				Console.WriteLine (e.Message);
+				Console.WriteLine ("Try `gapi-codegen --help' for more information.");
+				return 0;
+			}
+
+			if (show_help) {
+				ShowHelp (options);
+				return 1;
+			}
+
+			if (filenames.Count == 0) {
+				Console.WriteLine ("You need to specify a file to process using the --generate option.");
+				Console.WriteLine ("Try `gapi-codegen --help' for more information.");
+				return 0;
+			}
+
+			if (extra.Exists (v => { return v.StartsWith ("--customdir"); })) {
+				Console.WriteLine ("Using .custom files is not supported anymore, use partial classes instead.");
+				return 0;
+			}
+
+			Parser p = new Parser ();
+			foreach (string include in includes) {
+				IGeneratable[] curr_gens = p.Parse (include);
+				table.AddTypes (curr_gens);
+			}
+
+			foreach (string filename in filenames) {
 				IGeneratable[] curr_gens = p.Parse (filename);
 				table.AddTypes (curr_gens);
-				if (generate)
+				gens.AddRange (curr_gens);
-					gens.AddRange (curr_gens);
 			}
 
 			// Now that everything is loaded, validate all the to-be-
@@ -117,5 +131,13 @@ namespace GtkSharp.Generation {
 			Statistics.Report();
 			return 0;
 		}
+
+		static void ShowHelp (OptionSet p)
+		{
+			Console.WriteLine ("Usage: gapi-codegen [OPTIONS]+");
+			Console.WriteLine ();
+			Console.WriteLine ("Options:");
+			p.WriteOptionDescriptions (Console.Out);
+		}
 	}
 }

generator/Makefile.am

@@ -46,6 +46,7 @@ sources = 				\
 	ObjectBase.cs			\
 	ObjectGen.cs			\
 	OpaqueGen.cs			\
+	Options.cs			\
 	OwnableGen.cs			\
 	Parameter.cs			\
 	Parameters.cs			\

generator/generator.csproj

@@ -90,6 +90,7 @@
     <Compile Include="XmlElementExtensions.cs" />
     <Compile Include="Parameter.cs" />
     <Compile Include="ArrayParameter.cs" />
+    <Compile Include="Options.cs" />
   </ItemGroup>
   <ItemGroup>
     <None Include="DESIGN" />

sample/opaquetest/Makefile.am

@@ -18,7 +18,7 @@ libopaque_la_LIBADD = $(GTK_LIBS)
 INCLUDES = $(GTK_CFLAGS)
 
 generated/*.cs: opaque-api.xml
-	$(RUNTIME) ../../generator/gapi_codegen.exe --generate $(srcdir)/opaque-api.xml --include ../../gtk/gtk-api.xml ../../gdk/gdk-api.xml --outdir=generated --assembly-name=opaque-sharp
+	$(RUNTIME) ../../generator/gapi_codegen.exe --generate $(srcdir)/opaque-api.xml --include=../../gtk/gtk-api.xml --include=../../gdk/gdk-api.xml --outdir=generated --assembly-name=opaque-sharp
 
 api:
 	PATH=../../parser:$(PATH) $(RUNTIME) ../../parser/gapi-parser.exe opaque-sources.xml

sample/valtest/Makefile.am

@@ -18,7 +18,7 @@ libvalobj_la_LIBADD = $(GTK_LIBS)
 INCLUDES = $(GTK_CFLAGS)
 
 Valobj.cs: valobj-api.xml
-	$(RUNTIME) ../../generator/gapi_codegen.exe --generate $(srcdir)/valobj-api.xml --include ../../gtk/gtk-api.xml ../../gdk/gdk-api.xml --outdir=. --assembly-name=valobj-sharp
+	$(RUNTIME) ../../generator/gapi_codegen.exe --generate $(srcdir)/valobj-api.xml --include=../../gtk/gtk-api.xml --include=../../gdk/gdk-api.xml --outdir=. --assembly-name=valobj-sharp
 
 api:
 	PATH=../../parser:$(PATH) $(RUNTIME) ../../parser/gapi-parser.exe valobj-sources.xml