add 'help' command

src/main.zig

@@ -230,6 +230,13 @@ pub fn doRepl(allocator: *std.mem.Allocator, args_it: anytype) !void {
     }
 }
 
+fn doHelp() void {
+    std.debug.warn("scritcher!\n", .{});
+    std.debug.warn("usage: scritcher [run|help|repl]\n", .{});
+    std.debug.warn("\tscritcher run path_to_script.scri path_to_input_file.bmp\n", .{});
+    std.debug.warn("\tscritcher repl path_to_script.scri path_to_input_file.bmp\n", .{});
+}
+
 pub fn main() !void {
     // const allocator = std.heap.page_allocator;
     var allocator_instance = std.heap.GeneralPurposeAllocator(.{}){};
@@ -248,25 +255,38 @@ pub fn main() !void {
 
     // TODO print help
     _ = args_it.skip();
-    const scri_path = try (args_it.next(allocator) orelse @panic("expected scri path or 'repl'"));
-    defer allocator.free(scri_path);
-
-    if (std.mem.eql(u8, scri_path, "repl")) {
-        return try doRepl(allocator, &args_it);
+    const cli_command_opt = args_it.next(allocator);
+    if (cli_command_opt == null) {
+        return doHelp();
     }
 
-    var file = try std.fs.cwd().openFile(scri_path, .{});
-    defer file.close();
+    const cli_command = try cli_command_opt.?;
+    defer allocator.free(cli_command);
 
-    // sadly, we read it all into memory. such is life
-    const total_bytes = try file.getEndPos();
+    if (std.mem.eql(u8, cli_command, "help")) {
+        return doHelp();
+    } else if (std.mem.eql(u8, cli_command, "repl")) {
+        return try doRepl(allocator, &args_it);
+    } else if (std.mem.eql(u8, cli_command, "run")) {
+        const scri_path = try (args_it.next(allocator) orelse @panic("run: expected scri path"));
+        defer allocator.free(scri_path);
 
-    var data = try allocator.alloc(u8, total_bytes);
-    defer allocator.free(data);
-    _ = try file.read(data);
+        var file = try std.fs.cwd().openFile(scri_path, .{});
+        defer file.close();
 
-    var cmds = try lang.parse(data);
-    defer cmds.deinit();
+        // sadly, we read it all into memory. such is life
+        const total_bytes = try file.getEndPos();
 
-    try runner.runCommands(cmds, true);
+        var data = try allocator.alloc(u8, total_bytes);
+        defer allocator.free(data);
+        _ = try file.read(data);
+
+        var cmds = try lang.parse(data);
+        defer cmds.deinit();
+
+        try runner.runCommands(cmds, true);
+    } else {
+        std.debug.warn("unknown command: '{s}'\n", .{cli_command});
+        return error.UnknownCommand;
+    }
 }

src/runner.zig

@@ -65,7 +65,7 @@ pub const Runner = struct {
             // 'scritcher repl ./script ./image'
 
             // ':0' should ALWAYS point to the image.
-            if (self.repl) index += 3 else index += 2;
+            if (self.repl) index += 4 else index += 3;
 
             for (self.args) |arg, idx| {
                 std.debug.warn("arg{d} = {s}\n", .{ idx, arg });