lang: add basic argument validation

src/lang.zig

@@ -6,6 +6,7 @@ pub const ParseError = error{
     NoCommandGiven,
     UnknownCommand,
     ArgRequired,
+    FloatParseFail,
 };
 
 pub const CommandType = enum {
@@ -232,6 +233,40 @@ pub const Lang = struct {
         return null;
     }
 
+    fn expectSingle(self: *Lang, args: ArgList) !void {
+        if (args.len != 1) {
+            std.debug.warn("expected 1 argument, found {}\n", args.len);
+            return error.ArgRequired;
+        }
+    }
+
+    fn expectFloat(self: *Lang, count: usize, args: ArgList) !void {
+        var i: usize = 0;
+
+        if (args.len != count) {
+            std.debug.warn("expected {} arguments, found {}\n", count, args.len);
+            return error.ArgRequired;
+        }
+
+        while (i < count) : (i += 1) {
+            var arg = args.at(i);
+
+            _ = std.fmt.parseFloat(f32, arg) catch |err| {
+                std.debug.warn("failed to parse f32: {}\n", err);
+                return error.FloatParseFail;
+            };
+        }
+    }
+
+    fn validateCommand(self: *Lang, cmd: *Command) !void {
+        switch (cmd.command) {
+            .Quicksave, .Noop => {},
+            .Load, .RunQS => try self.expectSingle(cmd.args),
+            .Amp => try self.expectFloat(3, cmd.args),
+            else => std.debug.warn("WARN unchecked command {}\n", cmd.command),
+        }
+    }
+
     pub fn parse(self: *Lang, data: []const u8) !CommandList {
         var splitted_it = std.mem.separate(data, ";");
         try self.fillKeywords();
@@ -261,14 +296,17 @@ pub const Lang = struct {
             }
 
             var args = ArgList.init(self.allocator);
-
             while (tok_it.next()) |arg| {
                 try args.append(arg);
             }
 
             // construct final Command based on command
             var cmd_ptr = try self.allocator.create(Command);
+            errdefer self.allocator.destroy(cmd_ptr);
+
             cmd_ptr.* = Command{ .command = ctype, .args = args };
+            try self.validateCommand(cmd_ptr);
+
             try cmds.append(cmd_ptr);
         }