pretty-print variable dump lua debugging print_r() dir()

-- works like PHP's print_r(), returning the output instead of printing it to STDOUT
-- daniel speakmedia com

function dumpvar(data)
    -- cache of tables already printed, to avoid infinite recursive loops
    local tablecache = {}
    local buffer = ""
    local padder = "    "

    local function _dumpvar(d, depth)
        local t = type(d)
        local str = tostring(d)
        if (t == "table") then
            if (tablecache[str]) then
                -- table already dumped before, so we dont
                -- dump it again, just mention it
                buffer = buffer.."<"..str..">\n"
            else
                tablecache[str] = (tablecache[str] or 0) + 1
                buffer = buffer.."("..str..") {\n"
                for k, v in pairs(d) do
                    buffer = buffer..string.rep(padder, depth+1).."["..k.."] => "
                    _dumpvar(v, depth+1)
                end
                buffer = buffer..string.rep(padder, depth).."}\n"
            end
        elseif (t == "number") then
            buffer = buffer.."("..t..") "..str.."\n"
        else
            buffer = buffer.."("..t..") \""..str.."\"\n"
        end
    end
    _dumpvar(data, 0)
    return buffer
end


--[[
print(dumpvar({
    [1] = "this is the first element",
    [2] = "and this is the second",
    [3] = 3,
    [4] = 3.1415,
    ["nested"] = {
        ["lua"] = "is cool but",
        ["luajit"] = "is fucking awesome!"
    },
    ["some-files"] = {
        [0] = io.stdin,
        [1] = io.stdout,
        [2] = io.stderr
    }
}))

-- outputs:

(table: 0x41365f60) {
    [1] => (string) "this is the first element"
    [2] => (string) "and this is the second"
    [3] => (number) 3
    [4] => (number) 3.1415
    [nested] => (table: 0x41365fb0) {
        [lua] => (string) "is cool but"
        [luajit] => (string) "is fucking awesome!"
    }
    [some-files] => (table: 0x41366048) {
        [0] => (userdata) "file (0x3f1e79b6a0)"
        [1] => (userdata) "file (0x3f1e79b780)"
        [2] => (userdata) "file (0x3f1e79b860)"
    }
}

]]