3170 - multiple --options at the commandline

The mu commandline now has four parts: options, commands (of which we
only have one so far: 'test'), files/directories and ingredients to pass
to 'main'. That cleans up the hacky ordering constraint we had earlier.

I've also cleaned up the usage message.

1 files changed, 41 insertions, 25 deletions

diff --git a/001help.cc b/001help.cc
index fa5c3547..ea76db25 100644
--- a/001help.cc
+++ b/001help.cc
@@ -5,28 +5,52 @@
 if (argc <= 1 || is_equal(argv[1], "--help")) {
   // this is the functionality later layers will provide
   // currently no automated tests for commandline arg parsing
-  cerr << "To load files and run 'main':\n"
-       << "  mu file1.mu file2.mu ...\n"
-       << "To run all tests:\n"
-       << "  mu test\n"
-       << "To load files and then run all tests:\n"
-       << "  mu test file1.mu file2.mu ...\n"
-       << "To load files and run only the tests in explicitly loaded files (for apps):\n"
-       << "  mu --test-only-app test file1.mu file2.mu ...\n"
-       << "'--test-only-app' must come before all other args\n"
-       << "'test' must come before all other args except '--test-only-app'\n"
-       << "To load all files with a numeric prefix in a directory:\n"
-       << "  mu directory1\n"
-       << "You can test directories just like files.\n"
-       << "To pass ingredients to a mu program, provide them after '--':\n"
-       << "  mu file_or_dir1 file_or_dir2 ... -- ingredient1 ingredient2 ...\n"
+  if (argc <= 1) {
+    cerr << "Please provide a Mu program to run.\n"
+         << "\n";
+  }
+  cerr << "Usage:\n"
+       << "  mu [options] [test] [files]\n"
+       << "or:\n"
+       << "  mu [options] [test] [files] -- [ingredients for function/recipe 'main']\n"
+       << "Square brackets surround optional arguments.\n"
+       << "\n"
+       << "Examples:\n"
+       << "  To load files and run 'main':\n"
+       << "    mu file1.mu file2.mu ...\n"
+       << "  To run all tests:\n"
+       << "    mu test\n"
+       << "  To load files and then run all tests:\n"
+       << "    mu test file1.mu file2.mu ...\n"
+       << "  To load files and run only the tests in explicitly loaded files (for apps):\n"
+       << "    mu --test-only-app test file1.mu file2.mu ...\n"
+       << "  To load all files with a numeric prefix in a directory:\n"
+       << "    mu directory1 directory2 ...\n"
+       << "  You can test directories just like files.\n"
+       << "    mu test directory1 directory2 ...\n"
+       << "  To pass ingredients to a mu program, provide them after '--':\n"
+       << "    mu file_or_dir1 file_or_dir2 ... -- ingredient1 ingredient2 ...\n"
        << "\n"
-       << "To browse a trace generated by a previous run:\n"
-       << "  mu browse-trace file\n"
+       << "  To browse a trace generated by a previous run:\n"
+       << "    mu browse-trace file\n"
        ;
   return 0;
 }
 
+//: Support for option parsing.
+//: Options always begin with '--' and are always the first arguments. An
+//: option will never follow a non-option.
+:(before "End Commandline Parsing")
+char** arg = &argv[1];
+while (argc > 1 && starts_with(*arg, "--")) {
+  if (false)
+    ;  // no-op branch just so any further additions can consistently always start with 'else'
+  // End Commandline Options(*arg)
+  else
+    cerr << "skipping unknown option " << *arg << '\n';
+  --argc; ++argv; ++arg;
+}
+
 //:: Helper function used by the above fragment of code (and later layers too,
 //:: who knows?).
 //: The :(code) directive appends function definitions to the end of the
@@ -198,14 +222,6 @@ bool has_data(istream& in) {
   return in && !in.eof();
 }
 
-////: A hack to support faster debugging.
-:(before "End Globals")
-bool Test_only_app = false;
-:(before "End Commandline Parsing")
-if (argc > 1 && is_equal(argv[1], "--test-only-app")) {
-  Test_only_app = true;  --argc;  ++argv;
-}
-
 :(before "End Includes")
 #include <assert.h>