• Subject: Re: Problem with table key iteration when string keys are unpredictable
• From: Sean Conner <sean@...>
• Date: Mon, 20 May 2013 23:32:52 -0400

```It was thus said that the Great marbux once stated:
> Hi, All,
>
> I'm working on an autoreplace script and am hoping for a tip that
> might get me past a problem in unpredictability of key names. (Users
> enter key/value pairs in a GUI to build a table of strings that will
> replace other strings.)
>
> Because the order in which Lua returns non-array keys is
> unpredictable, this type of substitution is problematic. For example,
> if Lua returns the key for the en dash (two hyphens) before the key
> for the em dash (three hyphens), the script will produce instead of an
> em dash an en dash trailed by a hyphen.
>
> So my question is how I can assure that when multiple abbreviations
> share the same leading sequence of identical characters, the keys are
> processed in longest to shortest order?  (I don't anticipate any
> problems if all keys were processed in longest to shortest order.)

You could do something like this:

list = {}
repeat
local key,value = get_next_substitution()
list[key] = value
list[#list + 1] = key
until done
table.sort(list,function(a,b) return #a > #b end

At the end, the array would look like:

list =
{
["---"] = "—",
["--"] = "–",
["sss"] = "§",
["ssss"] = "§§",
["ppp"] = "¶",
["pppp"] = "¶¶",
[1] = "pppp",
[2] = "ssss",
[3] = "---",
[4] = "ppp",
[5] = "sss",
[6] = '--'
}

With that:

function Replace_Substrings_in_Strings(s,tSubs)
for i = 1 , #tSubs do
s = s:gsub(tSubs[i],tSubs[tSubs[i]])
end
return s
end

I also did something similar in LPeg, which goes through the string once.
I describe it here:

http://boston.conman.org/2013/01/14.1

-spc

```

• References: