Re: [PATCH v2] json_writer: new routines to create data in JSON format

From: René Scharfe <l.s.r@web.de>
Date: Mar 23, 2018, 20:11 UTC
Message-ID: <306104ac-37ac-8198-1988-03efa818cde3@web.de>
In-Reply-To: <14bbf223-a4d1-3c11-cd2e-dff044e01fef@jeffhostetler.com>

Am 23.03.2018 um 20:55 schrieb Jeff Hostetler:

Show 24 quoted lines

>>> +struct json_writer_level
>>> +{
>>> +    unsigned level_is_array : 1;
>>> +    unsigned level_is_empty : 1;
>>> +};
>>> +
>>> +struct json_writer
>>> +{
>>> +    struct json_writer_level *levels;
>>> +    int nr, alloc;
>>> +    struct strbuf json;
>>> +};
>>
>> A simpler and probably more compact representation of is_array would
>> be a strbuf with one char per level, e.g. '[' for an array and '{'
>> for an object (or ']' and '}').
>>
>> I don't understand the need to track emptiness per level.  Only the
>> top level array/object can ever be empty, can it?
> 
> My expectation was that any sub-object or sub-array could be empty.
> That is, this should be valid (and the JSON parser in Python allows):
> 
>      {"a":{}, "b":[], "c":[[]], "d":[{}]}

Sure, but the emptiness of finished arrays and objects doesn't matter for the purposes of error checking, comma setting or closing. At most one of them is empty *and* unclosed while writing the overall JSON object -- the last one opened:

	{
	{"a":{
	{"a":{}, "b":[
	{"a":{}, "b":[], "c":[
	{"a":{}, "b":[], "c":[[
	{"a":{}, "b":[], "c":[[]], "d":[
	{"a":{}, "b":[], "c":[[]], "d":[{

Any of the earlier written arrays/objects are either closed or contain at least a half-done sub-array/object, which makes them non-empty.

René