4c25356e0e
As was noted in1a85b49b87(parse-options: make OPT_ARGUMENT() more useful, 2019-03-14) there's only ever been one user of the OPT_ARGUMENT(), that user was added in20de316e33(difftool: allow running outside Git worktrees with --no-index, 2019-03-14). The OPT_ARGUMENT() feature itself was added way back in580d5bffde(parse-options: new option type to treat an option-like parameter as an argument., 2008-03-02), but as discussed in1a85b49b87wasn't used until20de316e33in 2019. Now that the preceding commit has migrated this code over to using "struct strvec" to manage the "args" member of a "struct child_process", we can just use that directly instead of relying on OPT_ARGUMENT. This has a minor change in behavior in that if we'll pass --no-index we'll now always pass it as the first argument, before we'd pass it in whatever position the caller did. Preserving this was the real value of OPT_ARGUMENT(), but as it turns out we didn't need that either. We can always inject it as the first argument, the other end will parse it just the same. Note that we cannot remove the "out" and "cpidx" members of "struct parse_opt_ctx_t" added in580d5bffde, while they were introduced with OPT_ARGUMENT() we since used them for other things. Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
309 lines
11 KiB
Plaintext
309 lines
11 KiB
Plaintext
parse-options API
|
|
=================
|
|
|
|
The parse-options API is used to parse and massage options in Git
|
|
and to provide a usage help with consistent look.
|
|
|
|
Basics
|
|
------
|
|
|
|
The argument vector `argv[]` may usually contain mandatory or optional
|
|
'non-option arguments', e.g. a filename or a branch, and 'options'.
|
|
Options are optional arguments that start with a dash and
|
|
that allow to change the behavior of a command.
|
|
|
|
* There are basically three types of options:
|
|
'boolean' options,
|
|
options with (mandatory) 'arguments' and
|
|
options with 'optional arguments'
|
|
(i.e. a boolean option that can be adjusted).
|
|
|
|
* There are basically two forms of options:
|
|
'Short options' consist of one dash (`-`) and one alphanumeric
|
|
character.
|
|
'Long options' begin with two dashes (`--`) and some
|
|
alphanumeric characters.
|
|
|
|
* Options are case-sensitive.
|
|
Please define 'lower-case long options' only.
|
|
|
|
The parse-options API allows:
|
|
|
|
* 'stuck' and 'separate form' of options with arguments.
|
|
`-oArg` is stuck, `-o Arg` is separate form.
|
|
`--option=Arg` is stuck, `--option Arg` is separate form.
|
|
|
|
* Long options may be 'abbreviated', as long as the abbreviation
|
|
is unambiguous.
|
|
|
|
* Short options may be bundled, e.g. `-a -b` can be specified as `-ab`.
|
|
|
|
* Boolean long options can be 'negated' (or 'unset') by prepending
|
|
`no-`, e.g. `--no-abbrev` instead of `--abbrev`. Conversely,
|
|
options that begin with `no-` can be 'negated' by removing it.
|
|
Other long options can be unset (e.g., set string to NULL, set
|
|
integer to 0) by prepending `no-`.
|
|
|
|
* Options and non-option arguments can clearly be separated using the `--`
|
|
option, e.g. `-a -b --option -- --this-is-a-file` indicates that
|
|
`--this-is-a-file` must not be processed as an option.
|
|
|
|
Steps to parse options
|
|
----------------------
|
|
|
|
. `#include "parse-options.h"`
|
|
|
|
. define a NULL-terminated
|
|
`static const char * const builtin_foo_usage[]` array
|
|
containing alternative usage strings
|
|
|
|
. define `builtin_foo_options` array as described below
|
|
in section 'Data Structure'.
|
|
|
|
. in `cmd_foo(int argc, const char **argv, const char *prefix)`
|
|
call
|
|
|
|
argc = parse_options(argc, argv, prefix, builtin_foo_options, builtin_foo_usage, flags);
|
|
+
|
|
`parse_options()` will filter out the processed options of `argv[]` and leave the
|
|
non-option arguments in `argv[]`.
|
|
`argc` is updated appropriately because of the assignment.
|
|
+
|
|
You can also pass NULL instead of a usage array as the fifth parameter of
|
|
parse_options(), to avoid displaying a help screen with usage info and
|
|
option list. This should only be done if necessary, e.g. to implement
|
|
a limited parser for only a subset of the options that needs to be run
|
|
before the full parser, which in turn shows the full help message.
|
|
+
|
|
Flags are the bitwise-or of:
|
|
|
|
`PARSE_OPT_KEEP_DASHDASH`::
|
|
Keep the `--` that usually separates options from
|
|
non-option arguments.
|
|
|
|
`PARSE_OPT_STOP_AT_NON_OPTION`::
|
|
Usually the whole argument vector is massaged and reordered.
|
|
Using this flag, processing is stopped at the first non-option
|
|
argument.
|
|
|
|
`PARSE_OPT_KEEP_ARGV0`::
|
|
Keep the first argument, which contains the program name. It's
|
|
removed from argv[] by default.
|
|
|
|
`PARSE_OPT_KEEP_UNKNOWN`::
|
|
Keep unknown arguments instead of erroring out. This doesn't
|
|
work for all combinations of arguments as users might expect
|
|
it to do. E.g. if the first argument in `--unknown --known`
|
|
takes a value (which we can't know), the second one is
|
|
mistakenly interpreted as a known option. Similarly, if
|
|
`PARSE_OPT_STOP_AT_NON_OPTION` is set, the second argument in
|
|
`--unknown value` will be mistakenly interpreted as a
|
|
non-option, not as a value belonging to the unknown option,
|
|
the parser early. That's why parse_options() errors out if
|
|
both options are set.
|
|
|
|
`PARSE_OPT_NO_INTERNAL_HELP`::
|
|
By default, parse_options() handles `-h`, `--help` and
|
|
`--help-all` internally, by showing a help screen. This option
|
|
turns it off and allows one to add custom handlers for these
|
|
options, or to just leave them unknown.
|
|
|
|
Data Structure
|
|
--------------
|
|
|
|
The main data structure is an array of the `option` struct,
|
|
say `static struct option builtin_add_options[]`.
|
|
There are some macros to easily define options:
|
|
|
|
`OPT__ABBREV(&int_var)`::
|
|
Add `--abbrev[=<n>]`.
|
|
|
|
`OPT__COLOR(&int_var, description)`::
|
|
Add `--color[=<when>]` and `--no-color`.
|
|
|
|
`OPT__DRY_RUN(&int_var, description)`::
|
|
Add `-n, --dry-run`.
|
|
|
|
`OPT__FORCE(&int_var, description)`::
|
|
Add `-f, --force`.
|
|
|
|
`OPT__QUIET(&int_var, description)`::
|
|
Add `-q, --quiet`.
|
|
|
|
`OPT__VERBOSE(&int_var, description)`::
|
|
Add `-v, --verbose`.
|
|
|
|
`OPT_GROUP(description)`::
|
|
Start an option group. `description` is a short string that
|
|
describes the group or an empty string.
|
|
Start the description with an upper-case letter.
|
|
|
|
`OPT_BOOL(short, long, &int_var, description)`::
|
|
Introduce a boolean option. `int_var` is set to one with
|
|
`--option` and set to zero with `--no-option`.
|
|
|
|
`OPT_COUNTUP(short, long, &int_var, description)`::
|
|
Introduce a count-up option.
|
|
Each use of `--option` increments `int_var`, starting from zero
|
|
(even if initially negative), and `--no-option` resets it to
|
|
zero. To determine if `--option` or `--no-option` was encountered at
|
|
all, initialize `int_var` to a negative value, and if it is still
|
|
negative after parse_options(), then neither `--option` nor
|
|
`--no-option` was seen.
|
|
|
|
`OPT_BIT(short, long, &int_var, description, mask)`::
|
|
Introduce a boolean option.
|
|
If used, `int_var` is bitwise-ored with `mask`.
|
|
|
|
`OPT_NEGBIT(short, long, &int_var, description, mask)`::
|
|
Introduce a boolean option.
|
|
If used, `int_var` is bitwise-anded with the inverted `mask`.
|
|
|
|
`OPT_SET_INT(short, long, &int_var, description, integer)`::
|
|
Introduce an integer option.
|
|
`int_var` is set to `integer` with `--option`, and
|
|
reset to zero with `--no-option`.
|
|
|
|
`OPT_STRING(short, long, &str_var, arg_str, description)`::
|
|
Introduce an option with string argument.
|
|
The string argument is put into `str_var`.
|
|
|
|
`OPT_STRING_LIST(short, long, &struct string_list, arg_str, description)`::
|
|
Introduce an option with string argument.
|
|
The string argument is stored as an element in `string_list`.
|
|
Use of `--no-option` will clear the list of preceding values.
|
|
|
|
`OPT_INTEGER(short, long, &int_var, description)`::
|
|
Introduce an option with integer argument.
|
|
The integer is put into `int_var`.
|
|
|
|
`OPT_MAGNITUDE(short, long, &unsigned_long_var, description)`::
|
|
Introduce an option with a size argument. The argument must be a
|
|
non-negative integer and may include a suffix of 'k', 'm' or 'g' to
|
|
scale the provided value by 1024, 1024^2 or 1024^3 respectively.
|
|
The scaled value is put into `unsigned_long_var`.
|
|
|
|
`OPT_EXPIRY_DATE(short, long, ×tamp_t_var, description)`::
|
|
Introduce an option with expiry date argument, see `parse_expiry_date()`.
|
|
The timestamp is put into `timestamp_t_var`.
|
|
|
|
`OPT_CALLBACK(short, long, &var, arg_str, description, func_ptr)`::
|
|
Introduce an option with argument.
|
|
The argument will be fed into the function given by `func_ptr`
|
|
and the result will be put into `var`.
|
|
See 'Option Callbacks' below for a more elaborate description.
|
|
|
|
`OPT_FILENAME(short, long, &var, description)`::
|
|
Introduce an option with a filename argument.
|
|
The filename will be prefixed by passing the filename along with
|
|
the prefix argument of `parse_options()` to `prefix_filename()`.
|
|
|
|
`OPT_NUMBER_CALLBACK(&var, description, func_ptr)`::
|
|
Recognize numerical options like -123 and feed the integer as
|
|
if it was an argument to the function given by `func_ptr`.
|
|
The result will be put into `var`. There can be only one such
|
|
option definition. It cannot be negated and it takes no
|
|
arguments. Short options that happen to be digits take
|
|
precedence over it.
|
|
|
|
`OPT_COLOR_FLAG(short, long, &int_var, description)`::
|
|
Introduce an option that takes an optional argument that can
|
|
have one of three values: "always", "never", or "auto". If the
|
|
argument is not given, it defaults to "always". The `--no-` form
|
|
works like `--long=never`; it cannot take an argument. If
|
|
"always", set `int_var` to 1; if "never", set `int_var` to 0; if
|
|
"auto", set `int_var` to 1 if stdout is a tty or a pager,
|
|
0 otherwise.
|
|
|
|
`OPT_NOOP_NOARG(short, long)`::
|
|
Introduce an option that has no effect and takes no arguments.
|
|
Use it to hide deprecated options that are still to be recognized
|
|
and ignored silently.
|
|
|
|
`OPT_PASSTHRU(short, long, &char_var, arg_str, description, flags)`::
|
|
Introduce an option that will be reconstructed into a char* string,
|
|
which must be initialized to NULL. This is useful when you need to
|
|
pass the command-line option to another command. Any previous value
|
|
will be overwritten, so this should only be used for options where
|
|
the last one specified on the command line wins.
|
|
|
|
`OPT_PASSTHRU_ARGV(short, long, &strvec_var, arg_str, description, flags)`::
|
|
Introduce an option where all instances of it on the command-line will
|
|
be reconstructed into a strvec. This is useful when you need to
|
|
pass the command-line option, which can be specified multiple times,
|
|
to another command.
|
|
|
|
`OPT_CMDMODE(short, long, &int_var, description, enum_val)`::
|
|
Define an "operation mode" option, only one of which in the same
|
|
group of "operating mode" options that share the same `int_var`
|
|
can be given by the user. `enum_val` is set to `int_var` when the
|
|
option is used, but an error is reported if other "operating mode"
|
|
option has already set its value to the same `int_var`.
|
|
|
|
|
|
The last element of the array must be `OPT_END()`.
|
|
|
|
If not stated otherwise, interpret the arguments as follows:
|
|
|
|
* `short` is a character for the short option
|
|
(e.g. `'e'` for `-e`, use `0` to omit),
|
|
|
|
* `long` is a string for the long option
|
|
(e.g. `"example"` for `--example`, use `NULL` to omit),
|
|
|
|
* `int_var` is an integer variable,
|
|
|
|
* `str_var` is a string variable (`char *`),
|
|
|
|
* `arg_str` is the string that is shown as argument
|
|
(e.g. `"branch"` will result in `<branch>`).
|
|
If set to `NULL`, three dots (`...`) will be displayed.
|
|
|
|
* `description` is a short string to describe the effect of the option.
|
|
It shall begin with a lower-case letter and a full stop (`.`) shall be
|
|
omitted at the end.
|
|
|
|
Option Callbacks
|
|
----------------
|
|
|
|
The function must be defined in this form:
|
|
|
|
int func(const struct option *opt, const char *arg, int unset)
|
|
|
|
The callback mechanism is as follows:
|
|
|
|
* Inside `func`, the only interesting member of the structure
|
|
given by `opt` is the void pointer `opt->value`.
|
|
`*opt->value` will be the value that is saved into `var`, if you
|
|
use `OPT_CALLBACK()`.
|
|
For example, do `*(unsigned long *)opt->value = 42;` to get 42
|
|
into an `unsigned long` variable.
|
|
|
|
* Return value `0` indicates success and non-zero return
|
|
value will invoke `usage_with_options()` and, thus, die.
|
|
|
|
* If the user negates the option, `arg` is `NULL` and `unset` is 1.
|
|
|
|
Sophisticated option parsing
|
|
----------------------------
|
|
|
|
If you need, for example, option callbacks with optional arguments
|
|
or without arguments at all, or if you need other special cases,
|
|
that are not handled by the macros above, you need to specify the
|
|
members of the `option` structure manually.
|
|
|
|
This is not covered in this document, but well documented
|
|
in `parse-options.h` itself.
|
|
|
|
Examples
|
|
--------
|
|
|
|
See `test-parse-options.c` and
|
|
`builtin/add.c`,
|
|
`builtin/clone.c`,
|
|
`builtin/commit.c`,
|
|
`builtin/fetch.c`,
|
|
`builtin/fsck.c`,
|
|
`builtin/rm.c`
|
|
for real-world examples.
|