Can anyone tell me what format this uh.. nested dictionary is?

∟⊔⊤∦∣≶@lemmy.nz to Programming@programming.dev – 34 points –

cross-posted from: https://lemmy.nz/post/4294116

I have a file with content like this:

item({
     ["attr"] = {
        ["size"] = "62091";
        ["filename"] = "qBuUP9-OTfuzibt6PQX4-g.jpg";
        ["stamp"] = "2023-12-05T19:31:37Z";
        ["xmlns"] = "urn:xmpp:http:upload:0";
        ["content-type"] = "image/jpeg";
     };
     ["key"] = "Wa4AJWFldqRZjBozponbSLRZ";
     ["with"] = "email@address";
     ["when"] = 1701804697;
     ["name"] = "request";
});

I need to know what format this is, and if there exists a tool in linux already to parse this or if I need to write one myself?

Thanks!

21

It's not really a standalone file format, it's executable Lua code.

It returns a new item with the given table contents.

That syntax with the keys in square brackets is the "long-form" method of creating a new table, that's allows the use of spaces and dashes in the key name.

https://stackoverflow.com/questions/34687498/what-is-the-function-of-square-brackets-around-table-keys-in-lua

Maybe this is the lua-equivelent of a python Pickle file?

Ohhhhh...

Ok so I just have to write a bit of Lua to utilise the file and give me the info I want.

Thanks!

assuming you run it in the right lua environment. The item function must be defined, and we're only speculating about its return value without seeing proper docs, or the source

Item is a function?

Well actually, yeah thats kinda obvious isn't it now I look at the whole thing.

Thats fine, I'll just use a bit of the old sed and json it.

Aha I have avoided learning Lua yet again!

the code is constructing a table, and passing it to a function called item. But if all you need is the data, you can just remove the function call and assign the table to a variable like so: local myvar = {...}.

then you can just manipulate the table as usual.

Unfortunately, this sequence is repeated many many times, so I would need to do a for-each and construct a new table for each inner section..

There's gotta be a better way. Time to read the source code and hijack whatever item() is doing.

actually those semicolons indicate this isn't actually lua, they are invalid in table constructors afaik

This isn't Lua code, Lua requires commas as separators for table items.

EDIT: Retracted, it seems like Lua allows this madness

Lua isn't that picky.

Wow. Seems like I will never stop learning new things about Lua.

I think it's just normal Lua code.

Here's a quick json converter (based on https://stackoverflow.com/a/55575074), assuming you have lua installed:

local function to_json(obj)
    local result = {}
    for key, value in pairs(obj) do
        if type(value) == "string" then
            value = string.format("\"%s\"", value)
        elseif type(value) == "table" then
            value = to_json(value)
        end
        table.insert(result, string.format("\"%s\":%s", key, value))
    end
    return "{" .. table.concat(result, ",") .. "}"
end

function item(obj)
    print(to_json(obj))
end

dofile(arg[1])

It just defines the item function to print json, and executes the data file.

arg[1], the first command line argument, is the path to the data file:

$  lua to_json.lua path/to/datafile.list

and pipe the output to something.json or whatever else you want to do.

Looks like somebody rewrote json to require brackets around keys and to require semicolons? Very likely custom.

The semi-colons threw me off.. why is it not commas? Could be custom. Hope it isn't..