Re: Function to return relative path?

[kamicc olo <kamicc@...>]

I guess Lua Penlight library worth a shoot too. Especially if You're
familiar with Python analogues.

Link:
http://stevedonovan.github.io/Penlight/api/modules/pl.path.html

On 11/29/13, Jerome Vuarand <jerome.vuarand@gmail.com> wrote:
> 2013/11/29 Paul Merrell <marbux@gmail.com>:
>> To avoid reinventing the wheel, I thought I'd ask whether anyone has a
>> function that will return a relative path from absolute paths for the
>> current and destination directories? Something along the lines of:
>>
>> function(curdir, destdir)
>>   ...
>>   return reldir
>> end
>>
>> I googled around but found only a function that has dependencies.[1]
>
> I wrote a path module that might help you implement your function:
>
>     http://piratery.net/path/
>
> In case you're wondering (and didn't click the link) you can install
> it with LuaRocks.
>
> As for your specific function, it could look something like that:
>
> local path = require 'path'
>
> function relative(from, to)
>     if path.type(from)~='path' then from = path.split(from) end
>     if path.type(to)~='path' then to = path.split(to) end
>     -- determine where paths diverge
>     local i = 0
>     while from:sub(0, i) == to:sub(0, i) do
>         i = i + 1
>     end
>     -- roots may be different
>     if i == 0 then return nil end
>     from = from:sub(i)
>     to = to:sub(i)
>     -- invert from
>     local morf = path.empty
>     for i=1,#from do
>         morf = morf / '..'
>     end
>     return morf / to
> end
>
> assert(relative([[C:\Program Files (x86)\MyApp\bin]],
> [[C:\Windows\system32]]) == path.split('../../../Windows/system32'))
>
> Note that I just fixed a small bug in the == operator, which could
> give false negatives for relative paths. If that's a problem for you
> use the Mercurial tip instead of the rock.
>
>