Re: json library

[Martin Holst Swende <martin () swende se>]

Yes, that's a really clever solution! Nice!

/Martin Holst Swende

On 06/30/2011 04:42 PM, Gorjan Petrovski wrote:
> So cool!
>
> On Wed, Jun 29, 2011 at 5:34 PM, Toni Ruottu <toni.ruottu () iki fi> wrote:
> > Ok. This seems like the way to go. Thank you!
> >
> > On Wed, Jun 29, 2011 at 6:29 PM, Daniel Miller <bonsaiviking () gmail com> wrote:
> > > Lua has a built-in way to signal different behaviors: metatables. Here's a
> > > patch for the json library that checks the metatable for a "json" key. It
> > > can be set to "array" or "object", to override the default behavior.
> > >
> > > > Index: nselib/json.lua
> > > > ===================================================================
> > > > --- nselib/json.lua     (revision 24436)
> > > > +++ nselib/json.lua     (working copy)
> > > > @@ -95,21 +95,22 @@
> > > >         elseif type(obj) == "string" then
> > > >                 return escape(obj)
> > > >         elseif type(obj) == "table" then
> > > > -               local k, v, elems
> > > > +               local k, v, elems, mtval
> > > >                 elems = {}
> > > > -               if #obj > 0 then
> > > > -                       -- Array
> > > > -                       for _, v in ipairs(obj) do
> > > > -                               elems[#elems + 1] = generate(v)
> > > > -                       end
> > > > -                       return "[" .. table.concat(elems, ", ") .. "]"
> > > > -               else
> > > > -                       -- Object
> > > > -                       for k, v in pairs(obj) do
> > > > -                               elems[#elems + 1] = escape(k) .. ": " ..
> > > > generate(v)
> > > > -                       end
> > > > -                       return "{" .. table.concat(elems, ", ") .. "}"
> > > > -               end
> > > > +    mtval = rawget(getmetatable(obj) or {}, "json")
> > > > +    if mtval == "array" or (mtval ~= "object" and #obj > 0) then
> > > > +      -- Array
> > > > +      for _, v in ipairs(obj) do
> > > > +        elems[#elems + 1] = generate(v)
> > > > +      end
> > > > +      return "[" .. table.concat(elems, ", ") .. "]"
> > > > +    else
> > > > +      -- Object
> > > > +      for k, v in pairs(obj) do
> > > > +        elems[#elems + 1] = escape(k) .. ": " .. generate(v)
> > > > +      end
> > > > +      return "{" .. table.concat(elems, ", ") .. "}"
> > > > +    end
> > > >         else
> > > >                 error("Unknown data type in generate")
> > > >         end
> > > Here's example code using this feature:
> > >
> > > local t = {'one', 'two', name="foo"}
> > > print(json.generate(t)) -- prints ["one", "two"]
> > > setmetatable(t, {json="object"})
> > > print(json.generate(t)) -- prints {"1": "one", "2": "two", "name": "foo"}
> > > t={}
> > > setmetatable(t, {json="array"})
> > > print(json.generate(t)) -- prints []
> > >
> > > Hope this helps!
> > > Dan
> > > On Wed, Jun 29, 2011 at 10:00 AM, Toni Ruottu <toni.ruottu () iki fi> wrote:
> > > > "{}" is probably needed as well. I've been looking at ways we could
> > > > escape the normal behaviour. Lua has byte strings while json has
> > > > unicode strings. One option might be using a Lua-object with an
> > > > invalid utf-8 string to signal, that we want that object to be treated
> > > > in some specific manner. I am not sure, if this is the best way,
> > > > though. :-/
> > > >
> > > > On Wed, Jun 29, 2011 at 5:01 PM, Gorjan Petrovski <mogi57 () gmail com>
> > > > wrote:
> > > > > I've looked into the json library and found that if it encounters a
> > > > > NULL object, then it just returns string with a value "null", so that
> > > > > would make the "{}" representation redundant.
> > > > > Well JSON-wise, is there such a thing as a string representing a
> > > > > nameless empty object when there is a definition for nil?
> > > > > Has anyone ever encountered the use of "{}"?
> > > > > If the answer to either of these questions is no, then we can make the
> > > > > json library default to "[]" when it sees an empty table.
> > > > >
> > > > > On the other hand if the "{}" is used more than "[]",  a hack has to
> > > > > be used, and we should probably note this case in the NSEDoc.
> > > > >
> > > > > Cheers,
> > > > > Gorjan
> > > > >
> > > > > On Wed, Jun 29, 2011 at 12:41 AM, Toni Ruottu <toni.ruottu () iki fi>
> > > > > wrote:
> > > > > > I am trying to use the json library to interact with a server that
> > > > > > uses json-rpc. The server expects me ot pass an empty argument list,
> > > > > > i.e. "[]". My problem is that json.generate({}) results in "{}", and
> > > > > > the server gives me an error for sending an object instead of an
> > > > > > array. Is this something we should fix in the json library, or should
> > > > > > I just come up with some kind of a hack?
> > > > > >
> > > > > >  --Toni
> > > > > > _______________________________________________
> > > > > > Sent through the nmap-dev mailing list
> > > > > > http://cgi.insecure.org/mailman/listinfo/nmap-dev
> > > > > > Archived at http://seclists.org/nmap-dev/
> > > > >
> > > > >
> > > > > --
> > > > > Gorjan
> > > > _______________________________________________
> > > > Sent through the nmap-dev mailing list
> > > > http://cgi.insecure.org/mailman/listinfo/nmap-dev
> > > > Archived at http://seclists.org/nmap-dev/

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