Re: A Lua pattern question about optional patterns

[Sean Conner <sean@...>]

It was thus said that the Great Peter W A Wood once stated:
> > On 10 Sep 2019, at 18:41, Jonathan Goble <jcgoble3@gmail.com> wrote:
> > On Mon, Sep 9, 2019 at 11:22 PM Sean Conner <sean@conman.org> wrote:
> >> 
> >>  In English, text, optionally followed by a semicolon and some digits.  So
> >> some valid examples:
> >> 
> >>        foo
> >>        foo;1
> >>        foo;444
> >> 
> >>  Invalid examples are
> >> 
> >>        foo;
> >>        foo23
> 
> I also came up with a two-step method but wasn’t sure if it was really
> applicable in the actual use case. My solution does not seem very elegant
> but handles Sean’s five examples properly:
> 
> > function double_match (s)
> >> local text = s:match('^(%a+)$')
> >>   if text then
> >>     return text, nil
> >>   else
> >>     return s:match('^(%a+);(%d+)')
> >>   end
> >> end
> > = double_match('foo')
> foo	nil

  This is incorrect, "foo" by itself is valid (see above).

> > = double_match('foo;1')
> foo	1
> > = double_match('foo;444')
> foo	444
> > = double_match('foo;')
> nil
> > = double_match('foo23')
> nil

  -spc (But yeah, a two-step process it looking like the solution ... sigh)