Re: [RFC/PATCH 2/3] add a library of code for producing structured output
- From
Junio C Hamano <gitster@pobox.com>
- Date
- Apr 11, 2010, 18:16 UTC
- Message-ID
- <7vy6gtonwt.fsf@alter.siamese.dyndns.org>
- In-Reply-To
- <20100411113733.80010.3767.julian@quantumfyre.co.uk>
Julian Phillips <julian@quantumfyre.co.uk> writes:
Show 5 quoted lines
> Add a library that allows commands to produce structured output in any > of a range of formats using a single API. > > The API includes an OPT_OUTPUT and handle_output_arg so that the > option handling for different commands will be as similar as possible.
I was hoping that the existing low-level -z routines (e.g. "diff-* -z") follow similar enough patterns to have a corresponding output-z.c and be handled inside output.c library. But that is not a requirement, just "would have been nicer if the original were written that way".
Show 22 quoted lines
> diff --git a/output-json.c b/output-json.c
> new file mode 100644
> index 0000000..0eb66b2
> --- /dev/null
> +++ b/output-json.c
> @@ -0,0 +1,128 @@
> +#include "git-compat-util.h"
> +#include "output.h"
> +#include "strbuf.h"
> +
> +static char *json_quote(char *s)
> +{
> + struct strbuf buf = STRBUF_INIT;
> +
> + while (*s) {
> + switch (*s) {
> +...
> + default:
> + /* All control characters must be encode, even if they
> + * don't have a specific escape character of their own */
> + if (*s < 0x20)
> + strbuf_addf(&buf, "\\u%04x", *s);As you didn't say your "char" is either signed or unsigned upfront, this will behave differently when you are fed a UTF-8 string. If it is signed, you will end up showing bytes in a single letter separately at wrong codepoint, and if it is unsigned, you will give UTF-8 string unquoted, which probably is what you meant to do.
What is your design intention regarding legacy encoding? This code does not yet declare "dear user, if you plan to use json/xml output, your repository metadata (notably the pathnames) has to be in UTF-8", as the caller _could_ transliterate legacy data before feeding it to output.c layer. An alternative would be for the output.c layer to know about the encoding of incoming data and transliterate when the output format requires a particular encoding.
Show 15 quoted lines
> +static void json_obj_item_start(FILE *file, char *name, int first)
> +{
> + char *quoted = json_quote(name);
> + if (!first)
> + fprintf(file, ",\n");
> + fprintf(file, "\"%s\" : ", quoted);
> + free(quoted);
> +}
> + ...
> +static void json_str(FILE *file, char *value)
> +{
> + char *quoted = json_quote(value);
> + fprintf(file, "\"%s\"", quoted);
> + free(quoted);
> +}An obvious improvement would be to make json_quote() to take FILE * to avoid wasteful allocation and copy, as it doesn't do anything but addstr and addch, and all of its callers don't do anything but spitting the result out to FILE *.
Show 8 quoted lines
> diff --git a/output-xml.c b/output-xml.c > new file mode 100644 > index 0000000..50dd7d6 > --- /dev/null > +++ b/output-xml.c > @@ -0,0 +1,68 @@ > +#include "git-compat-util.h" > +#include "output.h"
This seems to totally lack quoting of any metacharacters for "name" and string "value".