diff options
Diffstat (limited to 'third_party/git/Documentation/technical/api-parse-options.txt')
| -rw-r--r-- | third_party/git/Documentation/technical/api-parse-options.txt | 313 |
1 files changed, 0 insertions, 313 deletions
diff --git a/third_party/git/Documentation/technical/api-parse-options.txt b/third_party/git/Documentation/technical/api-parse-options.txt deleted file mode 100644 index 5a60bbfa7f41..000000000000 --- a/third_party/git/Documentation/technical/api-parse-options.txt +++ /dev/null @@ -1,313 +0,0 @@ -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_ARGUMENT(long, &int_var, description)`:: - Introduce a long-option argument that will be kept in `argv[]`. - If this option was seen, `int_var` will be set to one (except - if a `NULL` pointer was passed). - -`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. |