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In asciidoc 7, backticks like `foo` produced a typographic effect, but did not otherwise affect the syntax. In asciidoc 8, backticks introduce an "inline literal" inside which markup is not interpreted. To keep compatibility with existing documents, asciidoc 8 has a "no-inline-literal" attribute to keep the old behavior. We enabled this so that the documentation could be built on either version. It has been several years now, and asciidoc 7 is no longer in wide use. We can now decide whether or not we want inline literals on their own merits, which are: 1. The source is much easier to read when the literal contains punctuation. You can use `master~1` instead of `master{tilde}1`. 2. They are less error-prone. Because of point (1), we tend to make mistakes and forget the extra layer of quoting. This patch removes the no-inline-literal attribute from the Makefile and converts every use of backticks in the documentation to an inline literal (they must be cleaned up, or the example above would literally show "{tilde}" in the output). Problematic sites were found by grepping for '`.*[{\\]' and examined and fixed manually. The results were then verified by comparing the output of "html2text" on the set of generated html pages. Doing so revealed that in addition to making the source more readable, this patch fixes several formatting bugs: - HTML rendering used the ellipsis character instead of literal "..." in code examples (like "git log A...B") - some code examples used the right-arrow character instead of '->' because they failed to quote - api-config.txt did not quote tilde, and the resulting HTML contained a bogus snippet like: <tt><sub></tt> foo <tt></sub>bar</tt> which caused some parsers to choke and omit whole sections of the page. - git-commit.txt confused ``foo`` (backticks inside a literal) with ``foo'' (matched double-quotes) - mentions of `A U Thor <author@example.com>` used to erroneously auto-generate a mailto footnote for author@example.com - the description of --word-diff=plain incorrectly showed the output as "[-removed-] and {added}", not "{+added+}". - using "prime" notation like: commit `C` and its replacement `C'` confused asciidoc into thinking that everything between the first backtick and the final apostrophe were meant to be inside matched quotes - asciidoc got confused by the escaping of some of our asterisks. In particular, `credential.\*` and `credential.<url>.\*` properly escaped the asterisk in the first case, but literally passed through the backslash in the second case. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
279 lines
9.4 KiB
Plaintext
279 lines
9.4 KiB
Plaintext
parse-options API
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=================
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The parse-options API is used to parse and massage options in git
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and to provide a usage help with consistent look.
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Basics
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------
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The argument vector `argv[]` may usually contain mandatory or optional
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'non-option arguments', e.g. a filename or a branch, and 'options'.
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Options are optional arguments that start with a dash and
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that allow to change the behavior of a command.
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* There are basically three types of options:
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'boolean' options,
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options with (mandatory) 'arguments' and
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options with 'optional arguments'
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(i.e. a boolean option that can be adjusted).
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* There are basically two forms of options:
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'Short options' consist of one dash (`-`) and one alphanumeric
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character.
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'Long options' begin with two dashes (`--`) and some
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alphanumeric characters.
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* Options are case-sensitive.
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Please define 'lower-case long options' only.
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The parse-options API allows:
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* 'sticked' and 'separate form' of options with arguments.
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`-oArg` is sticked, `-o Arg` is separate form.
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`--option=Arg` is sticked, `--option Arg` is separate form.
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* Long options may be 'abbreviated', as long as the abbreviation
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is unambiguous.
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* Short options may be bundled, e.g. `-a -b` can be specified as `-ab`.
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* Boolean long options can be 'negated' (or 'unset') by prepending
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`no-`, e.g. `--no-abbrev` instead of `--abbrev`. Conversely,
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options that begin with `no-` can be 'negated' by removing it.
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* Options and non-option arguments can clearly be separated using the `--`
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option, e.g. `-a -b --option -- --this-is-a-file` indicates that
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`--this-is-a-file` must not be processed as an option.
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Steps to parse options
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----------------------
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. `#include "parse-options.h"`
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. define a NULL-terminated
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`static const char * const builtin_foo_usage[]` array
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containing alternative usage strings
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. define `builtin_foo_options` array as described below
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in section 'Data Structure'.
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. in `cmd_foo(int argc, const char **argv, const char *prefix)`
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call
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argc = parse_options(argc, argv, prefix, builtin_foo_options, builtin_foo_usage, flags);
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+
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`parse_options()` will filter out the processed options of `argv[]` and leave the
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non-option arguments in `argv[]`.
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`argc` is updated appropriately because of the assignment.
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+
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You can also pass NULL instead of a usage array as the fifth parameter of
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parse_options(), to avoid displaying a help screen with usage info and
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option list. This should only be done if necessary, e.g. to implement
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a limited parser for only a subset of the options that needs to be run
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before the full parser, which in turn shows the full help message.
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+
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Flags are the bitwise-or of:
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`PARSE_OPT_KEEP_DASHDASH`::
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Keep the `--` that usually separates options from
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non-option arguments.
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`PARSE_OPT_STOP_AT_NON_OPTION`::
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Usually the whole argument vector is massaged and reordered.
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Using this flag, processing is stopped at the first non-option
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argument.
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`PARSE_OPT_KEEP_ARGV0`::
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Keep the first argument, which contains the program name. It's
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removed from argv[] by default.
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`PARSE_OPT_KEEP_UNKNOWN`::
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Keep unknown arguments instead of erroring out. This doesn't
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work for all combinations of arguments as users might expect
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it to do. E.g. if the first argument in `--unknown --known`
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takes a value (which we can't know), the second one is
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mistakenly interpreted as a known option. Similarly, if
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`PARSE_OPT_STOP_AT_NON_OPTION` is set, the second argument in
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`--unknown value` will be mistakenly interpreted as a
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non-option, not as a value belonging to the unknown option,
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the parser early. That's why parse_options() errors out if
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both options are set.
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`PARSE_OPT_NO_INTERNAL_HELP`::
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By default, parse_options() handles `-h`, `--help` and
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`--help-all` internally, by showing a help screen. This option
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turns it off and allows one to add custom handlers for these
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options, or to just leave them unknown.
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Data Structure
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--------------
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The main data structure is an array of the `option` struct,
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say `static struct option builtin_add_options[]`.
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There are some macros to easily define options:
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`OPT__ABBREV(&int_var)`::
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Add `--abbrev[=<n>]`.
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`OPT__COLOR(&int_var, description)`::
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Add `--color[=<when>]` and `--no-color`.
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`OPT__DRY_RUN(&int_var, description)`::
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Add `-n, --dry-run`.
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`OPT__FORCE(&int_var, description)`::
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Add `-f, --force`.
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`OPT__QUIET(&int_var, description)`::
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Add `-q, --quiet`.
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`OPT__VERBOSE(&int_var, description)`::
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Add `-v, --verbose`.
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`OPT_GROUP(description)`::
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Start an option group. `description` is a short string that
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describes the group or an empty string.
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Start the description with an upper-case letter.
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`OPT_BOOL(short, long, &int_var, description)`::
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Introduce a boolean option. `int_var` is set to one with
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`--option` and set to zero with `--no-option`.
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`OPT_COUNTUP(short, long, &int_var, description)`::
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Introduce a count-up option.
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`int_var` is incremented on each use of `--option`, and
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reset to zero with `--no-option`.
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`OPT_BIT(short, long, &int_var, description, mask)`::
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Introduce a boolean option.
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If used, `int_var` is bitwise-ored with `mask`.
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`OPT_NEGBIT(short, long, &int_var, description, mask)`::
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Introduce a boolean option.
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If used, `int_var` is bitwise-anded with the inverted `mask`.
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`OPT_SET_INT(short, long, &int_var, description, integer)`::
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Introduce an integer option.
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`int_var` is set to `integer` with `--option`, and
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reset to zero with `--no-option`.
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`OPT_SET_PTR(short, long, &ptr_var, description, ptr)`::
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Introduce a boolean option.
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If used, set `ptr_var` to `ptr`.
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`OPT_STRING(short, long, &str_var, arg_str, description)`::
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Introduce an option with string argument.
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The string argument is put into `str_var`.
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`OPT_INTEGER(short, long, &int_var, description)`::
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Introduce an option with integer argument.
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The integer is put into `int_var`.
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`OPT_DATE(short, long, &int_var, description)`::
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Introduce an option with date argument, see `approxidate()`.
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The timestamp is put into `int_var`.
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`OPT_CALLBACK(short, long, &var, arg_str, description, func_ptr)`::
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Introduce an option with argument.
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The argument will be fed into the function given by `func_ptr`
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and the result will be put into `var`.
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See 'Option Callbacks' below for a more elaborate description.
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`OPT_FILENAME(short, long, &var, description)`::
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Introduce an option with a filename argument.
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The filename will be prefixed by passing the filename along with
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the prefix argument of `parse_options()` to `prefix_filename()`.
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`OPT_ARGUMENT(long, description)`::
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Introduce a long-option argument that will be kept in `argv[]`.
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`OPT_NUMBER_CALLBACK(&var, description, func_ptr)`::
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Recognize numerical options like -123 and feed the integer as
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if it was an argument to the function given by `func_ptr`.
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The result will be put into `var`. There can be only one such
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option definition. It cannot be negated and it takes no
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arguments. Short options that happen to be digits take
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precedence over it.
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`OPT_COLOR_FLAG(short, long, &int_var, description)`::
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Introduce an option that takes an optional argument that can
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have one of three values: "always", "never", or "auto". If the
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argument is not given, it defaults to "always". The `--no-` form
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works like `--long=never`; it cannot take an argument. If
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"always", set `int_var` to 1; if "never", set `int_var` to 0; if
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"auto", set `int_var` to 1 if stdout is a tty or a pager,
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0 otherwise.
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`OPT_NOOP_NOARG(short, long)`::
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Introduce an option that has no effect and takes no arguments.
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Use it to hide deprecated options that are still to be recognized
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and ignored silently.
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The last element of the array must be `OPT_END()`.
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If not stated otherwise, interpret the arguments as follows:
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* `short` is a character for the short option
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(e.g. `'e'` for `-e`, use `0` to omit),
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* `long` is a string for the long option
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(e.g. `"example"` for `--example`, use `NULL` to omit),
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* `int_var` is an integer variable,
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* `str_var` is a string variable (`char *`),
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* `arg_str` is the string that is shown as argument
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(e.g. `"branch"` will result in `<branch>`).
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If set to `NULL`, three dots (`...`) will be displayed.
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* `description` is a short string to describe the effect of the option.
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It shall begin with a lower-case letter and a full stop (`.`) shall be
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omitted at the end.
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Option Callbacks
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----------------
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The function must be defined in this form:
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int func(const struct option *opt, const char *arg, int unset)
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The callback mechanism is as follows:
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* Inside `func`, the only interesting member of the structure
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given by `opt` is the void pointer `opt->value`.
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`*opt->value` will be the value that is saved into `var`, if you
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use `OPT_CALLBACK()`.
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For example, do `*(unsigned long *)opt->value = 42;` to get 42
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into an `unsigned long` variable.
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* Return value `0` indicates success and non-zero return
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value will invoke `usage_with_options()` and, thus, die.
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* If the user negates the option, `arg` is `NULL` and `unset` is 1.
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Sophisticated option parsing
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----------------------------
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If you need, for example, option callbacks with optional arguments
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or without arguments at all, or if you need other special cases,
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that are not handled by the macros above, you need to specify the
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members of the `option` structure manually.
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This is not covered in this document, but well documented
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in `parse-options.h` itself.
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Examples
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--------
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See `test-parse-options.c` and
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`builtin-add.c`,
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`builtin-clone.c`,
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`builtin-commit.c`,
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`builtin-fetch.c`,
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`builtin-fsck.c`,
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`builtin-rm.c`
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for real-world examples.
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