Re: [PATCH v9] json_writer: new routines to create JSON data

> Add "struct json_writer" and a series of jw_ routines to compose JSON
> data into a string buffer.  The resulting string may then be printed by
> commands wanting to support a JSON-like output format.
>
> The json_writer is limited to correctly formatting structured data for
> output.  It does not attempt to build an object model of the JSON data.
>
> We say "JSON-like" because we do not enforce the Unicode (usually UTF-8)
> requirement on string fields.  Internally, Git does not necessarily have
> Unicode/UTF-8 data for most fields, so it is currently unclear the best
> way to enforce that requirement.  For example, on Linx pathnames can

> contain arbitrary 8-bit character data, so a command like "status" would
> not know how to encode the reported pathnames.  We may want to revisit
> this (or double encode such strings) in the future.
>
> Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
> ---
> diff --git a/t/helper/test-json-writer.c b/t/helper/test-json-writer.c
> @@ -0,0 +1,564 @@
> +void get_s(int line_nr, char **s_in)

> +{
> +       *s_in = strtok(NULL, " ");
> +       if (!*s_in)
> +               die("line[%d]: expected: <s>", line_nr);
> +}
> +
> +void get_i(int line_nr, intmax_t *s_in)

> +{
> +       char *s;
> +       char *endptr;
> +
> +       get_s(line_nr, &s);
> +
> +       *s_in = strtol(s, &endptr, 10);
> +       if (*endptr || errno == ERANGE)
> +               die("line[%d]: invalid integer value", line_nr);
> +}
> +
> +void get_d(int line_nr, double *s_in)

> +{
> +       char *s;
> +       char *endptr;
> +
> +       get_s(line_nr, &s);
> +
> +       *s_in = strtod(s, &endptr);
> +       if (*endptr || errno == ERANGE)
> +               die("line[%d]: invalid float value", line_nr);
> +}