parse-options: allow git commands to invent new option types
parse-options provides a variety of option behaviors, including OPTION_CALLBACK, which should take care of just about any sane behavior. All supported behaviors obey the following constraint: A --foo option can only accept (and base its behavior on) one argument, which would be the following command-line argument in the "unsticked" form. Alas, some existing git commands have options that do not obey that constraint. For example, update-index --cacheinfo takes three arguments, and update-index --resolve takes all later parameters as arguments. Introduces an OPTION_LOWLEVEL_CALLBACK backdoor to parse-options so such option types can be supported without tempting inventors of other commands through mention in the public API. Commands can set the callback field to a function accepting three arguments: the option parsing context, the option itself, and a flag indicating whether the the option was negated. When the option is encountered, that function is called to take over from get_value(). The return value should be zero for success, -1 for usage errors. Thanks to Stephen Boyd for API guidance. Improved-by: Stephen Boyd <bebarino@gmail.com> Signed-off-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
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@ -66,6 +66,9 @@ static int get_value(struct parse_opt_ctx_t *p,
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return opterror(opt, "takes no value", flags);
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switch (opt->type) {
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case OPTION_LOWLEVEL_CALLBACK:
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return (*(parse_opt_ll_cb *)opt->callback)(p, opt, unset);
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case OPTION_BIT:
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if (unset)
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*(int *)opt->value &= ~opt->defval;
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@ -17,6 +17,7 @@ enum parse_opt_type {
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OPTION_STRING,
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OPTION_INTEGER,
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OPTION_CALLBACK,
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OPTION_LOWLEVEL_CALLBACK,
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OPTION_FILENAME
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};
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@ -43,6 +44,10 @@ enum parse_opt_option_flags {
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struct option;
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typedef int parse_opt_cb(const struct option *, const char *arg, int unset);
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struct parse_opt_ctx_t;
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typedef int parse_opt_ll_cb(struct parse_opt_ctx_t *ctx,
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const struct option *opt, int unset);
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/*
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* `type`::
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* holds the type of the option, you must have an OPTION_END last in your
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@ -87,7 +92,8 @@ typedef int parse_opt_cb(const struct option *, const char *arg, int unset);
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* useful for users of OPTION_NEGBIT.
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*
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* `callback`::
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* pointer to the callback to use for OPTION_CALLBACK.
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* pointer to the callback to use for OPTION_CALLBACK or
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* OPTION_LOWLEVEL_CALLBACK.
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*
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* `defval`::
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* default value to fill (*->value) with for PARSE_OPT_OPTARG.
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