raise exception on unknown option

lib/yawpa.rb

@@ -1,8 +1,30 @@
 require "yawpa/version"
 
+# Example options configuration:
+# {
+#   version: {},
+#   verbose: {aliases: ['-v']},
+#   get: {nargs: 1},
+#   set: {nargs: 2},
+# }
 module Yawpa
+  class UnknownOptionException < Exception; end
+
   module_function
-  def parse(config, params)
-    return [[], params]
+  def parse(params, options)
+    opts = {}
+    args = []
+    i = 0
+    while i < params.length
+      param = params[i]
+      if param[0] != '-'
+        args << params[i]
+      else
+        opt_config = options[param] || options[param.to_sym]
+        raise UnknownOptionException.new("Unknown option '#{param}'") if opt_config.nil?
+      end
+      i += 1
+    end
+    return [opts, args]
   end
 end