implement non-alias long form params

now long form parameters can exist by themselves without being an alias
for a required equivalent short form param

library/lua/argparse.lua

@@ -80,6 +80,7 @@ end
 -- it will be passed to the handler function.
 -- longOptionAlias is optional.
 -- hasArg defaults to false.
+-- to have an option that has only a long form, pass '' as the shortOptionName.
 --
 -- example usage:
 --
@@ -100,17 +101,28 @@ function processArgsGetopt(args, optionActions)
     local handlers = {}
     for _,optionAction in ipairs(optionActions) do
         local sh_opt,long_opt = optionAction[1], optionAction[2]
-        if not sh_opt or type(sh_opt) ~= 'string' or #sh_opt ~= 1 then
-            error('optionAction missing option letter at index 1')
+        -- sh_opt can be zero-length if long_opt is specified
+        if not sh_opt or type(sh_opt) ~= 'string'  or
+                (#sh_opt ~= 1 and not (#sh_opt == 0 and long_opt)) then
+            error('option letter not found')
+        end
+        if long_opt and (type(long_opt) ~= 'string' or #long_opt == 0) then
+            error('long option name must be a string with length >0')
         end
         if not optionAction.handler then
             error(string.format('handler missing for option "%s"', sh_opt))
         end
+        if #sh_opt > 0 then
             sh_opts = sh_opts .. sh_opt
             if optionAction.hasArg then sh_opts = sh_opts .. ':' end
             handlers[sh_opt] = optionAction.handler
+        end
         if long_opt then
+            if #sh_opt > 0 then
                 long_opts[long_opt] = sh_opt
+            else
+                long_opts[long_opt] = optionAction.hasArg and 1 or 0
+            end
             handlers[long_opt] = optionAction.handler
         end
     end

test/library/argparse.lua

@@ -58,17 +58,23 @@ function test.processArgsGetopt_happy_path()
 end
 
 function test.processArgsGetopt_action_errors()
-    expect.error_match('missing option letter',
+    expect.error_match('option letter not found',
         function()
             argparse.processArgsGetopt({}, {{handler=function() end}})
         end)
 
-    expect.error_match('missing option letter',
+    expect.error_match('option letter not found',
         function() argparse.processArgsGetopt({}, {{'notoneletter'}}) end)
 
-    expect.error_match('missing option letter',
+    expect.error_match('option letter not found',
         function() argparse.processArgsGetopt({}, {{function() end}}) end)
 
+    expect.error_match('long option name',
+        function() argparse.processArgsGetopt({}, {{'', ''}}) end)
+
+    expect.error_match('long option name',
+        function() argparse.processArgsGetopt({}, {{'a', ''}}) end)
+
     expect.error_match('handler missing',
         function() argparse.processArgsGetopt({}, {{'r'}}) end)
 end
@@ -107,6 +113,15 @@ function test.processArgsGetopt_parsing_errors()
                        'fail to pass value to long param that requires one')
 end
 
+function test.processArgsGetopt_long_opt_without_short_opt()
+    local var = false
+    local nonoptions = argparse.processArgsGetopt(
+                            {'--long'},
+                            {{'', 'long', handler=function() var = true end}})
+    expect.true_(var)
+    expect.table_eq({}, nonoptions)
+end
+
 function test.stringList()
     expect.table_eq({'happy', 'path'}, argparse.stringList(' happy  ,   path'),
                     'ensure elements are trimmed')