Patrick Steinhardt <ps@xxxxxx> writes:
> +static const struct parse_cmd {
> + const char *prefix;
> + const char *(*fn)(struct ref_transaction *, struct strbuf *, const char *);
> +} commands[] = {
Do not call an array the represents a set of THINGs "type things[]";
instead call it "type thing[]", so that the 0th thing can be
referred to as thing[0], not things[0].
One exception is when the set as a whole is referred to more often
than individual element of an array, in which case "things" (without
the [index]) becomes a sensible way to refer to the set.
> + { "update", parse_cmd_update },
> + { "create", parse_cmd_create },
> + { "delete", parse_cmd_delete },
> + { "verify", parse_cmd_verify },
> + { "option", parse_cmd_option },
> +};
> +
> static void update_refs_stdin(struct ref_transaction *transaction)
> {
> struct strbuf input = STRBUF_INIT;
> const char *next;
> + int i;
>
> if (strbuf_read(&input, 0, 1000) < 0)
> die_errno("could not read from stdin");
> next = input.buf;
> /* Read each line dispatch its command */
> while (next < input.buf + input.len) {
> + const struct parse_cmd *cmd = NULL;
> +
> if (*next == line_termination)
> die("empty command in input");
> else if (isspace(*next))
> die("whitespace before command: %s", next);
> - else if (skip_prefix(next, "update ", &next))
> - next = parse_cmd_update(transaction, &input, next);
> - else if (skip_prefix(next, "create ", &next))
> - next = parse_cmd_create(transaction, &input, next);
> - else if (skip_prefix(next, "delete ", &next))
> - next = parse_cmd_delete(transaction, &input, next);
> - else if (skip_prefix(next, "verify ", &next))
> - next = parse_cmd_verify(transaction, &input, next);
> - else if (skip_prefix(next, "option ", &next))
> - next = parse_cmd_option(&input, next);
> - else
> +
> + for (i = 0; i < ARRAY_SIZE(commands); i++) {
> + if (!skip_prefix(next, commands[i].prefix , &next))
> + continue;
> + cmd = &commands[i];
> + break;
> + }
The only reason why you had to sprinkle
if (!skip_prefix(next, " ", &next))
die(_("%s: missing space after command"), cmd);
all over the place is because the table lacks the trailing SP (which
makes sense---after all, you are making a table of commands). In
other words, it's not like some command called from this dispatcher
would require " " after the command name and some others would not.
So why not avoid touching the parse_cmd_<cmd>() at all (except for
the "option" thing that now needs to take the transaction object for
uniformity), and then verify the presence of " " here, perhaps like
this:
for (i = 0; i < ARRAY_SIZE(command); i++) {
const char *eoc;
if (!skip_prefix(next, commands[i].prefix, &eoc) ||
*eoc != ' ')
continue;
cmd = &command[i];
next = eoc;
break;
}
Note that you cannot reuse &next here to future-proof the code;
otherwise, you wouldn't be able to add a new command, e.g. "options",
that sits next to the existing command "option", in the future.
> + if (!cmd)
> die("unknown command: %s", next);
>
> + if (input.buf[strlen(cmd->prefix)] != line_termination &&
> + input.buf[strlen(cmd->prefix)] != '\0' &&
> + input.buf[strlen(cmd->prefix)] != ' ')
> + die("%s: no separator after command", cmd->prefix);
This part of your version does not make sense to me. If the input
line began with "update" with some separator that is not a SP, the
original would not have matched. But with this code, "update\0"
would pass this code and cause cmd->fn() to be called, only to get
the input rejected, because next is not pointing to SP. So why do
you even need this if statement?
> +
> + next = cmd->fn(transaction, &input, next);
> next++;
> }
Thanks.
