Re: Simple Lua-only JSON decoder

[Marc Balmer <marc@...>]

Am 17.04.17 um 17:53 schrieb Dirk Laurie:
> I2017-04-17 16:22 GMT+02:00 Soni L. <fakedme@gmail.com>:
>>
>>
>> On 2017-04-17 03:47 AM, Dirk Laurie wrote:
>>>
>>> My primitive JSON decoder, which operates by lexically translating
>>> a JSON code to a Lua table literal, now does three things:
>>>
>>> 1. Unicode codepoints translated, e.g. from \u00e9 to \u{00e9}.
>>> 2. List delimiters translated from […] to {…}.
>>> 3. Keys translated e.g. from "item": to ["item"]=.
>>>
>>> local function json_decode (s)
>>>    s = s:gsub("\\u(%d%d%d%d)","\\u{%1}")
>>>    local function do_json_list(s,is_list)
>>>      if is_list then s = s:sub(2,-2) end
>>>      s = s:gsub("(%b[])()",do_json_list)
>>>      if is_list then s = '{' .. s ..'}' end
>>>      return s
>>>    end
>>>    local t = load('return '..do_json_list(s):gsub('("[%w_-]-"):','[%1]='))
>>>    if t then return t() else return s end
>>> end
>>>
>>> Please show me some sample JSON code that this decoder can't handle
>>> properly.
>>>
>>> I already know about:
>>>    1. Integer overflow. (Thanks, Sean!) --> won't happen
>>>    2. JSON null is not Lua nil. --> define a suitable global called 'null'
>>>
>>
>> I don't think { "\":": {} } works... Haven't tested it tho.
> 
> It also defeats rapidjson, so at least I am in good company :-)
> 

isn't the problem here that Lua sees \" as an escape?  When I decode
'{ "\\":": {} }' it works.