• Subject: RE: dot encoded string key
• From: "Thijs Schreijer" <thijs@...>
• Date: Thu, 7 Jun 2012 19:51:32 +0200

```I made one as well once, and failed on numeric keys like this one;

local dk = dotkey
local t = { one = { two = "12", t = true, f = false, ["end"] = "end" },
[1] = { two = "23" } }
assert( dk.get(t, "1.two") == "23" )

so do you :)

-----Original Message-----
From: lua-l-bounces@lists.lua.org [mailto:lua-l-bounces@lists.lua.org] On
Behalf Of Dimiter 'malkia' Stanev
Sent: donderdag 7 juni 2012 1:14
To: lua
Subject: dot encoded string key

I wrote a little lua library that can read keys, which are dot encoded
("one.two.three") with some minimal checking:

It solves the problem, when the key (actually multiple keys) comes from a
string and needs to be looked in a table.

Here it is: (better formatted version than the one below)
https://gist.github.com/2885376

local dotkey = {}

----------------------------------------------------------
-- Returns the value of a dot encoded key from the table t
-- Example: local t = { one = { two = 12 } }
--          print( dotkey.get( t, "one.two" ) ) -- prints 12
function dotkey.get(t, key)
local b, s, p = string.byte, string.sub, 1
for i=1, key:len()+1 do
local c = b(key, i)
if c==nil or c==46 then
if p==i then
error( "DOTKEY: Invalid character '" .. string.char(c) ..
"' (" .. c ..
") found in key '"  .. tostring(key) .. "' at position: "
.. p)
end
-- Don't shortcut here. Check the whole key for errors!
t,p = type(t)~="table" and nil or t[s(key, p, i-1)],i+1
end
end
return t
end

if #{...}==0 then
print( "dotkey: standalone test..." )
local dk = dotkey
local t = { one = { two = "12", t = true, f = false, ["end"] = "end" } }
assert( dk.get(t, "one.two") == "12" )
assert( dk.get(t, "one.t") == true )
assert( dk.get(t, "one.t1") == nil )
assert( dk.get(t, "one.f") == false )
assert( dk.get(t, "one.f1") == nil )
assert( dk.get(t, "one.end") == "end" )
assert( type(dk.get(t, "one"))=="table" )
assert( dk.get(t, "blah") == nil )
assert( not xpcall(function() dk.get({}, "bad key.") end, type), "this
should fail" )
assert( not xpcall(function() dk.get({}, ".bad key") end, type), "this
should fail" )
assert( not xpcall(function() dk.get({}, ".") end, type), "this should
fail" )
assert( not xpcall(function() dk.get({}, "") end, type), "this should
fail" ) end

return dotkey

```