Re: [PATCH] libxl: add support for yajl 2.x

["Roger Pau Monné" <roger.pau@entel.upc.edu>]

2012/1/3 Ian Jackson <Ian.Jackson@eu.citrix.com>:
> Roger Pau Monne writes ("[Xen-devel] [PATCH] libxl: add support for yajl 2.x"):
>> This patch adds support for yajl versions 2.x, while retaining 1.x
>> compatibility. This patch adds quite a lot of #ifdefs all over the
>> json code, so I'm open to suggestions if there's a better way to
>> handle this.
>
> I have some suggestions.  The basic idea would be to try to put all of
> the ifdefs in one place in libxl_json.h.
>
>> +#ifdef HAVE_YAJL_V2
>> +static int json_callback_number(void *opaque, const char *s, size_t len)
>> +#else
>>  static int json_callback_number(void *opaque, const char *s, unsigned int len)
>> +#endif
>
> So how about:
>
>  /* libxl_json.h */
>
>  #ifdef HAVE_YAJL_V2
>  typedef size_t libxl_yajl_length;
>  ...
>  #else
>  typedef unsigned int libxl_yajl_length;
>  ...
>  #endif
>
>
>  /* libxl_json.c */
>
>  static int json_callback_number(void *opaque, const char *s,
>                                  libxl_yajl_length len) {
>     ...
>
>> +#ifdef HAVE_YAJL_V2
>> +        yajl_ctx.hand = yajl_alloc(&callbacks, NULL, &yajl_ctx);
>> +#else
>>          yajl_parser_config cfg = {
>>              .allowComments = 1,
>>              .checkUTF8 = 1,
>>          };
>>          yajl_ctx.hand = yajl_alloc(&callbacks, &cfg, NULL, &yajl_ctx);
>> +#endif
> ...
>>      status = yajl_parse(yajl_ctx.hand, (const unsigned char *)s, strlen(s));
>>      if (status != yajl_status_ok)
>>          goto out;
>> +
>
>  /* libxl_json.h */
>
>  #ifdef HAVE_YAJL_V2
>  ...
>  static inline int libxl_yajl_alloc(...) { return yajl_alloc .... }
>  ...
>  #else
>  ...
>  static inline int libxl_yajl_alloc(...) { [version with cfg] }
>  #define yajl_complete_parse yajl_parse_complete
>  ...
>  #endif
>
> etc.

I haven't really though of this anymore, but this seems much more
appropriate and less intrusive.

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