technical/api-parse-options.html - external/gitster/git-htmldocs - Git at Google

 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"
  "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
 <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
 <head>
 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
 <meta name="generator" content="AsciiDoc 8.2.5" />
 <style type="text/css">
 /* Debug borders */
 p, li, dt, dd, div, pre, h1, h2, h3, h4, h5, h6 {
 /*
  border: 1px solid red;
 */
 }

 body {
  margin: 1em 5% 1em 5%;
 }

 a {
  color: blue;
  text-decoration: underline;
 }
 a:visited {
  color: fuchsia;
 }

 em {
  font-style: italic;
 }

 strong {
  font-weight: bold;
 }

 tt {
  color: navy;
 }

 h1, h2, h3, h4, h5, h6 {
  color: #527bbd;
  font-family: sans-serif;
  margin-top: 1.2em;
  margin-bottom: 0.5em;
  line-height: 1.3;
 }

 h1, h2, h3 {
  border-bottom: 2px solid silver;
 }
 h2 {
  padding-top: 0.5em;
 }
 h3 {
  float: left;
 }
 h3 + * {
  clear: left;
 }

 div.sectionbody {
  font-family: serif;
  margin-left: 0;
 }

 hr {
  border: 1px solid silver;
 }

 p {
  margin-top: 0.5em;
  margin-bottom: 0.5em;
 }

 pre {
  padding: 0;
  margin: 0;
 }

 span#author {
  color: #527bbd;
  font-family: sans-serif;
  font-weight: bold;
  font-size: 1.1em;
 }
 span#email {
 }
 span#revision {
  font-family: sans-serif;
 }

 div#footer {
  font-family: sans-serif;
  font-size: small;
  border-top: 2px solid silver;
  padding-top: 0.5em;
  margin-top: 4.0em;
 }
 div#footer-text {
  float: left;
  padding-bottom: 0.5em;
 }
 div#footer-badges {
  float: right;
  padding-bottom: 0.5em;
 }

 div#preamble,
 div.tableblock, div.imageblock, div.exampleblock, div.verseblock,
 div.quoteblock, div.literalblock, div.listingblock, div.sidebarblock,
 div.admonitionblock {
  margin-right: 10%;
  margin-top: 1.5em;
  margin-bottom: 1.5em;
 }
 div.admonitionblock {
  margin-top: 2.5em;
  margin-bottom: 2.5em;
 }

 div.content { /* Block element content. */
  padding: 0;
 }

 /* Block element titles. */
 div.title, caption.title {
  font-family: sans-serif;
  font-weight: bold;
  text-align: left;
  margin-top: 1.0em;
  margin-bottom: 0.5em;
 }
 div.title + * {
  margin-top: 0;
 }

 td div.title:first-child {
  margin-top: 0.0em;
 }
 div.content div.title:first-child {
  margin-top: 0.0em;
 }
 div.content + div.title {
  margin-top: 0.0em;
 }

 div.sidebarblock > div.content {
  background: #ffffee;
  border: 1px solid silver;
  padding: 0.5em;
 }

 div.listingblock {
  margin-right: 0%;
 }
 div.listingblock > div.content {
  border: 1px solid silver;
  background: #f4f4f4;
  padding: 0.5em;
 }

 div.quoteblock > div.content {
  padding-left: 2.0em;
 }

 div.attribution {
  text-align: right;
 }
 div.verseblock + div.attribution {
  text-align: left;
 }

 div.admonitionblock .icon {
  vertical-align: top;
  font-size: 1.1em;
  font-weight: bold;
  text-decoration: underline;
  color: #527bbd;
  padding-right: 0.5em;
 }
 div.admonitionblock td.content {
  padding-left: 0.5em;
  border-left: 2px solid silver;
 }

 div.exampleblock > div.content {
  border-left: 2px solid silver;
  padding: 0.5em;
 }

 div.verseblock div.content {
  white-space: pre;
 }

 div.imageblock div.content { padding-left: 0; }
 div.imageblock img { border: 1px solid silver; }
 span.image img { border-style: none; }

 dl {
  margin-top: 0.8em;
  margin-bottom: 0.8em;
 }
 dt {
  margin-top: 0.5em;
  margin-bottom: 0;
  font-style: italic;
 }
 dd > *:first-child {
  margin-top: 0;
 }

 ul, ol {
  list-style-position: outside;
 }
 div.olist2 ol {
  list-style-type: lower-alpha;
 }

 div.tableblock > table {
  border: 3px solid #527bbd;
 }
 thead {
  font-family: sans-serif;
  font-weight: bold;
 }
 tfoot {
  font-weight: bold;
 }

 div.hlist {
  margin-top: 0.8em;
  margin-bottom: 0.8em;
 }
 div.hlist td {
  padding-bottom: 5px;
 }
 td.hlist1 {
  vertical-align: top;
  font-style: italic;
  padding-right: 0.8em;
 }
 td.hlist2 {
  vertical-align: top;
 }

 @media print {
  div#footer-badges { display: none; }
 }

 div#toctitle {
  color: #527bbd;
  font-family: sans-serif;
  font-size: 1.1em;
  font-weight: bold;
  margin-top: 1.0em;
  margin-bottom: 0.1em;
 }

 div.toclevel1, div.toclevel2, div.toclevel3, div.toclevel4 {
  margin-top: 0;
  margin-bottom: 0;
 }
 div.toclevel2 {
  margin-left: 2em;
  font-size: 0.9em;
 }
 div.toclevel3 {
  margin-left: 4em;
  font-size: 0.9em;
 }
 div.toclevel4 {
  margin-left: 6em;
  font-size: 0.9em;
 }
 /* Workarounds for IE6's broken and incomplete CSS2. */

 div.sidebar-content {
  background: #ffffee;
  border: 1px solid silver;
  padding: 0.5em;
 }
 div.sidebar-title, div.image-title {
  font-family: sans-serif;
  font-weight: bold;
  margin-top: 0.0em;
  margin-bottom: 0.5em;
 }

 div.listingblock div.content {
  border: 1px solid silver;
  background: #f4f4f4;
  padding: 0.5em;
 }

 div.quoteblock-content {
  padding-left: 2.0em;
 }

 div.exampleblock-content {
  border-left: 2px solid silver;
  padding-left: 0.5em;
 }

 /* IE6 sets dynamically generated links as visited. */
 div#toc a:visited { color: blue; }
 </style>
 <title>parse-options API</title>
 </head>
 <body>
 <div id="header">
 <h1>parse-options API</h1>
 </div>
 <div id="preamble">
 <div class="sectionbody">
 <div class="para"><p>The parse-options API is used to parse and massage options in git
 and to provide a usage help with consistent look.</p></div>
 </div>
 </div>
 <h2 id="_basics">Basics</h2>
 <div class="sectionbody">
 <div class="para"><p>The argument vector <tt>argv[]</tt> may usually contain mandatory or optional
 <em>non-option arguments</em>, e.g. a filename or a branch, and <em>options</em>.
 Options are optional arguments that start with a dash and
 that allow to change the behavior of a command.</p></div>
 <div class="ilist"><ul>
 <li>
 <p>
 There are basically three types of options:
  <em>boolean</em> options,
  options with (mandatory) <em>arguments</em> and
  options with <em>optional arguments</em>
  (i.e. a boolean option that can be adjusted).
 </p>
 </li>
 <li>
 <p>
 There are basically two forms of options:
  <em>Short options</em> consist of one dash (<tt>-</tt>) and one alphanumeric
  character.
  <em>Long options</em> begin with two dashes (<tt>--</tt>) and some
  alphanumeric characters.
 </p>
 </li>
 <li>
 <p>
 Options are case-sensitive.
  Please define <em>lower-case long options</em> only.
 </p>
 </li>
 </ul></div>
 <div class="para"><p>The parse-options API allows:</p></div>
 <div class="ilist"><ul>
 <li>
 <p>
 <em>sticked</em> and <em>separate form</em> of options with arguments.
  <tt>-oArg</tt> is sticked, <tt>-o Arg</tt> is separate form.
  <tt>--option=Arg</tt> is sticked, <tt>--option Arg</tt> is separate form.
 </p>
 </li>
 <li>
 <p>
 Long options may be <em>abbreviated</em>, as long as the abbreviation
  is unambiguous.
 </p>
 </li>
 <li>
 <p>
 Short options may be bundled, e.g. <tt>-a -b</tt> can be specified as <tt>-ab</tt>.
 </p>
 </li>
 <li>
 <p>
 Boolean long options can be <em>negated</em> (or <em>unset</em>) by prepending
  <tt>no-</tt>, e.g. <tt>--no-abbrev</tt> instead of <tt>--abbrev</tt>.
 </p>
 </li>
 <li>
 <p>
 Options and non-option arguments can clearly be separated using the <tt>--</tt>
  option, e.g. <tt>-a -b --option -- --this-is-a-file</tt> indicates that
  <tt>--this-is-a-file</tt> must not be processed as an option.
 </p>
 </li>
 </ul></div>
 </div>
 <h2 id="_steps_to_parse_options">Steps to parse options</h2>
 <div class="sectionbody">
 <div class="olist"><ol>
 <li>
 <p>
 <tt>#include "parse-options.h"</tt>
 </p>
 </li>
 <li>
 <p>
 define a NULL-terminated
  <tt>static const char * const builtin_foo_usage[]</tt> array
  containing alternative usage strings
 </p>
 </li>
 <li>
 <p>
 define <tt>builtin_foo_options</tt> array as described below
  in section <em>Data Structure</em>.
 </p>
 </li>
 <li>
 <p>
 in <tt>cmd_foo(int argc, const char **argv, const char *prefix)</tt>
  call
 </p>
 <div class="literalblock">
 <div class="content">
 <pre><tt>argc = parse_options(argc, argv, builtin_foo_options, builtin_foo_usage, flags);</tt></pre>
 </div></div>
 <div class="para"><p><tt>parse_options()</tt> will filter out the processed options of <tt>argv[]</tt> and leave the
 non-option arguments in <tt>argv[]</tt>.
 <tt>argc</tt> is updated appropriately because of the assignment.</p></div>
 <div class="para"><p>Flags are the bitwise-or of:</p></div>
 <div class="vlist"><dl>
 <dt>
 <tt>PARSE_OPT_KEEP_DASHDASH</tt>
 </dt>
 <dd>
 <p>
  Keep the <tt>--</tt> that usually separates options from
  non-option arguments.
 </p>
 </dd>
 <dt>
 <tt>PARSE_OPT_STOP_AT_NON_OPTION</tt>
 </dt>
 <dd>
 <p>
  Usually the whole argument vector is massaged and reordered.
  Using this flag, processing is stopped at the first non-option
  argument.
 </p>
 </dd>
 </dl></div>
 </li>
 </ol></div>
 </div>
 <h2 id="_data_structure">Data Structure</h2>
 <div class="sectionbody">
 <div class="para"><p>The main data structure is an array of the <tt>option</tt> struct,
 say <tt>static struct option builtin_add_options[]</tt>.
 There are some macros to easily define options:</p></div>
 <div class="vlist"><dl>
 <dt>
 <tt>OPT__ABBREV(&amp;int_var)</tt>
 </dt>
 <dd>
 <p>
  Add <tt>--abbrev[=&lt;n&gt;]</tt>.
 </p>
 </dd>
 <dt>
 <tt>OPT__DRY_RUN(&amp;int_var)</tt>
 </dt>
 <dd>
 <p>
  Add <tt>-n, --dry-run</tt>.
 </p>
 </dd>
 <dt>
 <tt>OPT__QUIET(&amp;int_var)</tt>
 </dt>
 <dd>
 <p>
  Add <tt>-q, --quiet</tt>.
 </p>
 </dd>
 <dt>
 <tt>OPT__VERBOSE(&amp;int_var)</tt>
 </dt>
 <dd>
 <p>
  Add <tt>-v, --verbose</tt>.
 </p>
 </dd>
 <dt>
 <tt>OPT_GROUP(description)</tt>
 </dt>
 <dd>
 <p>
  Start an option group. <tt>description</tt> is a short string that
  describes the group or an empty string.
  Start the description with an upper-case letter.
 </p>
 </dd>
 <dt>
 <tt>OPT_BOOLEAN(short, long, &amp;int_var, description)</tt>
 </dt>
 <dd>
 <p>
  Introduce a boolean option.
  <tt>int_var</tt> is incremented on each use.
 </p>
 </dd>
 <dt>
 <tt>OPT_BIT(short, long, &amp;int_var, description, mask)</tt>
 </dt>
 <dd>
 <p>
  Introduce a boolean option.
  If used, <tt>int_var</tt> is bitwise-ored with <tt>mask</tt>.
 </p>
 </dd>
 <dt>
 <tt>OPT_SET_INT(short, long, &amp;int_var, description, integer)</tt>
 </dt>
 <dd>
 <p>
  Introduce a boolean option.
  If used, set <tt>int_var</tt> to <tt>integer</tt>.
 </p>
 </dd>
 <dt>
 <tt>OPT_SET_PTR(short, long, &amp;ptr_var, description, ptr)</tt>
 </dt>
 <dd>
 <p>
  Introduce a boolean option.
  If used, set <tt>ptr_var</tt> to <tt>ptr</tt>.
 </p>
 </dd>
 <dt>
 <tt>OPT_STRING(short, long, &amp;str_var, arg_str, description)</tt>
 </dt>
 <dd>
 <p>
  Introduce an option with string argument.
  The string argument is put into <tt>str_var</tt>.
 </p>
 </dd>
 <dt>
 <tt>OPT_INTEGER(short, long, &amp;int_var, description)</tt>
 </dt>
 <dd>
 <p>
  Introduce an option with integer argument.
  The integer is put into <tt>int_var</tt>.
 </p>
 </dd>
 <dt>
 <tt>OPT_DATE(short, long, &amp;int_var, description)</tt>
 </dt>
 <dd>
 <p>
  Introduce an option with date argument, see <tt>approxidate()</tt>.
  The timestamp is put into <tt>int_var</tt>.
 </p>
 </dd>
 <dt>
 <tt>OPT_CALLBACK(short, long, &amp;var, arg_str, description, func_ptr)</tt>
 </dt>
 <dd>
 <p>
  Introduce an option with argument.
  The argument will be fed into the function given by <tt>func_ptr</tt>
  and the result will be put into <tt>var</tt>.
  See <em>Option Callbacks</em> below for a more elaborate description.
 </p>
 </dd>
 <dt>
 <tt>OPT_ARGUMENT(long, description)</tt>
 </dt>
 <dd>
 <p>
  Introduce a long-option argument that will be kept in <tt>argv[]</tt>.
 </p>
 </dd>
 </dl></div>
 <div class="para"><p>The last element of the array must be <tt>OPT_END()</tt>.</p></div>
 <div class="para"><p>If not stated otherwise, interpret the arguments as follows:</p></div>
 <div class="ilist"><ul>
 <li>
 <p>
 <tt>short</tt> is a character for the short option
  (e.g. <tt>'e'</tt> for <tt>-e</tt>, use <tt>0</tt> to omit),
 </p>
 </li>
 <li>
 <p>
 <tt>long</tt> is a string for the long option
  (e.g. <tt>"example"</tt> for <tt>--example</tt>, use <tt>NULL</tt> to omit),
 </p>
 </li>
 <li>
 <p>
 <tt>int_var</tt> is an integer variable,
 </p>
 </li>
 <li>
 <p>
 <tt>str_var</tt> is a string variable (<tt>char *</tt>),
 </p>
 </li>
 <li>
 <p>
 <tt>arg_str</tt> is the string that is shown as argument
  (e.g. <tt>"branch"</tt> will result in <tt>&lt;branch&gt;</tt>).
  If set to <tt>NULL</tt>, three dots (<tt>&#8230;</tt>) will be displayed.
 </p>
 </li>
 <li>
 <p>
 <tt>description</tt> is a short string to describe the effect of the option.
  It shall begin with a lower-case letter and a full stop (<tt>.</tt>) shall be
  omitted at the end.
 </p>
 </li>
 </ul></div>
 </div>
 <h2 id="_option_callbacks">Option Callbacks</h2>
 <div class="sectionbody">
 <div class="para"><p>The function must be defined in this form:</p></div>
 <div class="literalblock">
 <div class="content">
 <pre><tt>int func(const struct option *opt, const char *arg, int unset)</tt></pre>
 </div></div>
 <div class="para"><p>The callback mechanism is as follows:</p></div>
 <div class="ilist"><ul>
 <li>
 <p>
 Inside <tt>funct</tt>, the only interesting member of the structure
  given by <tt>opt</tt> is the void pointer <tt>opt-&gt;value</tt>.
  <tt>*opt-&gt;value</tt> will be the value that is saved into <tt>var</tt>, if you
  use <tt>OPT_CALLBACK()</tt>.
  For example, do <tt>*(unsigned long *)opt-&gt;value = 42;</tt> to get 42
  into an <tt>unsigned long</tt> variable.
 </p>
 </li>
 <li>
 <p>
 Return value <tt>0</tt> indicates success and non-zero return
  value will invoke <tt>usage_with_options()</tt> and, thus, die.
 </p>
 </li>
 <li>
 <p>
 If the user negates the option, <tt>arg</tt> is <tt>NULL</tt> and <tt>unset</tt> is 1.
 </p>
 </li>
 </ul></div>
 </div>
 <h2 id="_sophisticated_option_parsing">Sophisticated option parsing</h2>
 <div class="sectionbody">
 <div class="para"><p>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 <tt>option</tt> structure manually.</p></div>
 <div class="para"><p>This is not covered in this document, but well documented
 in <tt>parse-options.h</tt> itself.</p></div>
 </div>
 <h2 id="_examples">Examples</h2>
 <div class="sectionbody">
 <div class="para"><p>See <tt>test-parse-options.c</tt> and
 <tt>builtin-add.c</tt>,
 <tt>builtin-clone.c</tt>,
 <tt>builtin-commit.c</tt>,
 <tt>builtin-fetch.c</tt>,
 <tt>builtin-fsck.c</tt>,
 <tt>builtin-rm.c</tt>
 for real-world examples.</p></div>
 </div>
 <div id="footer">
 <div id="footer-text">
 Last updated 2008-09-19 06:33:30 UTC
 </div>
 </div>
 </body>
 </html>
	<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"
	"http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
	<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
	<head>
	<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
	<meta name="generator" content="AsciiDoc 8.2.5" />
	<style type="text/css">
	/* Debug borders */
	p, li, dt, dd, div, pre, h1, h2, h3, h4, h5, h6 {
	/*
	border: 1px solid red;
	*/
	}

	body {
	margin: 1em 5% 1em 5%;
	}

	a {
	color: blue;
	text-decoration: underline;
	}
	a:visited {
	color: fuchsia;
	}

	em {
	font-style: italic;
	}

	strong {
	font-weight: bold;
	}

	tt {
	color: navy;
	}

	h1, h2, h3, h4, h5, h6 {
	color: #527bbd;
	font-family: sans-serif;
	margin-top: 1.2em;
	margin-bottom: 0.5em;
	line-height: 1.3;
	}

	h1, h2, h3 {
	border-bottom: 2px solid silver;
	}
	h2 {
	padding-top: 0.5em;
	}
	h3 {
	float: left;
	}
	h3 + * {
	clear: left;
	}

	div.sectionbody {
	font-family: serif;
	margin-left: 0;
	}

	hr {
	border: 1px solid silver;
	}

	p {
	margin-top: 0.5em;
	margin-bottom: 0.5em;
	}

	pre {
	padding: 0;
	margin: 0;
	}

	span#author {
	color: #527bbd;
	font-family: sans-serif;
	font-weight: bold;
	font-size: 1.1em;
	}
	span#email {
	}
	span#revision {
	font-family: sans-serif;
	}

	div#footer {
	font-family: sans-serif;
	font-size: small;
	border-top: 2px solid silver;
	padding-top: 0.5em;
	margin-top: 4.0em;
	}
	div#footer-text {
	float: left;
	padding-bottom: 0.5em;
	}
	div#footer-badges {
	float: right;
	padding-bottom: 0.5em;
	}

	div#preamble,
	div.tableblock, div.imageblock, div.exampleblock, div.verseblock,
	div.quoteblock, div.literalblock, div.listingblock, div.sidebarblock,
	div.admonitionblock {
	margin-right: 10%;
	margin-top: 1.5em;
	margin-bottom: 1.5em;
	}
	div.admonitionblock {
	margin-top: 2.5em;
	margin-bottom: 2.5em;
	}

	div.content { /* Block element content. */
	padding: 0;
	}

	/* Block element titles. */
	div.title, caption.title {
	font-family: sans-serif;
	font-weight: bold;
	text-align: left;
	margin-top: 1.0em;
	margin-bottom: 0.5em;
	}
	div.title + * {
	margin-top: 0;
	}

	td div.title:first-child {
	margin-top: 0.0em;
	}
	div.content div.title:first-child {
	margin-top: 0.0em;
	}
	div.content + div.title {
	margin-top: 0.0em;
	}

	div.sidebarblock > div.content {
	background: #ffffee;
	border: 1px solid silver;
	padding: 0.5em;
	}

	div.listingblock {
	margin-right: 0%;
	}
	div.listingblock > div.content {
	border: 1px solid silver;
	background: #f4f4f4;
	padding: 0.5em;
	}

	div.quoteblock > div.content {
	padding-left: 2.0em;
	}

	div.attribution {
	text-align: right;
	}
	div.verseblock + div.attribution {
	text-align: left;
	}

	div.admonitionblock .icon {
	vertical-align: top;
	font-size: 1.1em;
	font-weight: bold;
	text-decoration: underline;
	color: #527bbd;
	padding-right: 0.5em;
	}
	div.admonitionblock td.content {
	padding-left: 0.5em;
	border-left: 2px solid silver;
	}

	div.exampleblock > div.content {
	border-left: 2px solid silver;
	padding: 0.5em;
	}

	div.verseblock div.content {
	white-space: pre;
	}

	div.imageblock div.content { padding-left: 0; }
	div.imageblock img { border: 1px solid silver; }
	span.image img { border-style: none; }

	dl {
	margin-top: 0.8em;
	margin-bottom: 0.8em;
	}
	dt {
	margin-top: 0.5em;
	margin-bottom: 0;
	font-style: italic;
	}
	dd > *:first-child {
	margin-top: 0;
	}

	ul, ol {
	list-style-position: outside;
	}
	div.olist2 ol {
	list-style-type: lower-alpha;
	}

	div.tableblock > table {
	border: 3px solid #527bbd;
	}
	thead {
	font-family: sans-serif;
	font-weight: bold;
	}
	tfoot {
	font-weight: bold;
	}

	div.hlist {
	margin-top: 0.8em;
	margin-bottom: 0.8em;
	}
	div.hlist td {
	padding-bottom: 5px;
	}
	td.hlist1 {
	vertical-align: top;
	font-style: italic;
	padding-right: 0.8em;
	}
	td.hlist2 {
	vertical-align: top;
	}

	@media print {
	div#footer-badges { display: none; }
	}

	div#toctitle {
	color: #527bbd;
	font-family: sans-serif;
	font-size: 1.1em;
	font-weight: bold;
	margin-top: 1.0em;
	margin-bottom: 0.1em;
	}

	div.toclevel1, div.toclevel2, div.toclevel3, div.toclevel4 {
	margin-top: 0;
	margin-bottom: 0;
	}
	div.toclevel2 {
	margin-left: 2em;
	font-size: 0.9em;
	}
	div.toclevel3 {
	margin-left: 4em;
	font-size: 0.9em;
	}
	div.toclevel4 {
	margin-left: 6em;
	font-size: 0.9em;
	}
	/* Workarounds for IE6's broken and incomplete CSS2. */

	div.sidebar-content {
	background: #ffffee;
	border: 1px solid silver;
	padding: 0.5em;
	}
	div.sidebar-title, div.image-title {
	font-family: sans-serif;
	font-weight: bold;
	margin-top: 0.0em;
	margin-bottom: 0.5em;
	}

	div.listingblock div.content {
	border: 1px solid silver;
	background: #f4f4f4;
	padding: 0.5em;
	}

	div.quoteblock-content {
	padding-left: 2.0em;
	}

	div.exampleblock-content {
	border-left: 2px solid silver;
	padding-left: 0.5em;
	}

	/* IE6 sets dynamically generated links as visited. */
	div#toc a:visited { color: blue; }
	</style>
	<title>parse-options API</title>
	</head>
	<body>
	<div id="header">
	<h1>parse-options API</h1>
	</div>
	<div id="preamble">
	<div class="sectionbody">
	<div class="para"><p>The parse-options API is used to parse and massage options in git
	and to provide a usage help with consistent look.</p></div>
	</div>
	</div>
	<h2 id="_basics">Basics</h2>
	<div class="sectionbody">
	<div class="para"><p>The argument vector <tt>argv[]</tt> may usually contain mandatory or optional
	<em>non-option arguments</em>, e.g. a filename or a branch, and <em>options</em>.
	Options are optional arguments that start with a dash and
	that allow to change the behavior of a command.</p></div>
	<div class="ilist"><ul>
	<li>
	<p>
	There are basically three types of options:
	<em>boolean</em> options,
	options with (mandatory) <em>arguments</em> and
	options with <em>optional arguments</em>
	(i.e. a boolean option that can be adjusted).
	</p>
	</li>
	<li>
	<p>
	There are basically two forms of options:
	<em>Short options</em> consist of one dash (<tt>-</tt>) and one alphanumeric
	character.
	<em>Long options</em> begin with two dashes (<tt>--</tt>) and some
	alphanumeric characters.
	</p>
	</li>
	<li>
	<p>
	Options are case-sensitive.
	Please define <em>lower-case long options</em> only.
	</p>
	</li>
	</ul></div>
	<div class="para"><p>The parse-options API allows:</p></div>
	<div class="ilist"><ul>
	<li>
	<p>
	<em>sticked</em> and <em>separate form</em> of options with arguments.
	<tt>-oArg</tt> is sticked, <tt>-o Arg</tt> is separate form.
	<tt>--option=Arg</tt> is sticked, <tt>--option Arg</tt> is separate form.
	</p>
	</li>
	<li>
	<p>
	Long options may be <em>abbreviated</em>, as long as the abbreviation
	is unambiguous.
	</p>
	</li>
	<li>
	<p>
	Short options may be bundled, e.g. <tt>-a -b</tt> can be specified as <tt>-ab</tt>.
	</p>
	</li>
	<li>
	<p>
	Boolean long options can be <em>negated</em> (or <em>unset</em>) by prepending
	<tt>no-</tt>, e.g. <tt>--no-abbrev</tt> instead of <tt>--abbrev</tt>.
	</p>
	</li>
	<li>
	<p>
	Options and non-option arguments can clearly be separated using the <tt>--</tt>
	option, e.g. <tt>-a -b --option -- --this-is-a-file</tt> indicates that
	<tt>--this-is-a-file</tt> must not be processed as an option.
	</p>
	</li>
	</ul></div>
	</div>
	<h2 id="_steps_to_parse_options">Steps to parse options</h2>
	<div class="sectionbody">
	<div class="olist"><ol>
	<li>
	<p>
	<tt>#include "parse-options.h"</tt>
	</p>
	</li>
	<li>
	<p>
	define a NULL-terminated
	<tt>static const char * const builtin_foo_usage[]</tt> array
	containing alternative usage strings
	</p>
	</li>
	<li>
	<p>
	define <tt>builtin_foo_options</tt> array as described below
	in section <em>Data Structure</em>.
	</p>
	</li>
	<li>
	<p>
	in <tt>cmd_foo(int argc, const char *argv, const char prefix)</tt>
	call
	</p>
	<div class="literalblock">
	<div class="content">
	<pre><tt>argc = parse_options(argc, argv, builtin_foo_options, builtin_foo_usage, flags);</tt></pre>
	</div></div>
	<div class="para"><p><tt>parse_options()</tt> will filter out the processed options of <tt>argv[]</tt> and leave the
	non-option arguments in <tt>argv[]</tt>.
	<tt>argc</tt> is updated appropriately because of the assignment.</p></div>
	<div class="para"><p>Flags are the bitwise-or of:</p></div>
	<div class="vlist"><dl>
	<dt>
	<tt>PARSE_OPT_KEEP_DASHDASH</tt>
	</dt>
	<dd>
	<p>
	Keep the <tt>--</tt> that usually separates options from
	non-option arguments.
	</p>
	</dd>
	<dt>
	<tt>PARSE_OPT_STOP_AT_NON_OPTION</tt>
	</dt>
	<dd>
	<p>
	Usually the whole argument vector is massaged and reordered.
	Using this flag, processing is stopped at the first non-option
	argument.
	</p>
	</dd>
	</dl></div>
	</li>
	</ol></div>
	</div>
	<h2 id="_data_structure">Data Structure</h2>
	<div class="sectionbody">
	<div class="para"><p>The main data structure is an array of the <tt>option</tt> struct,
	say <tt>static struct option builtin_add_options[]</tt>.
	There are some macros to easily define options:</p></div>
	<div class="vlist"><dl>
	<dt>
	<tt>OPT__ABBREV(&int_var)</tt>
	</dt>
	<dd>
	<p>
	Add <tt>--abbrev[=<n>]</tt>.
	</p>
	</dd>
	<dt>
	<tt>OPT__DRY_RUN(&int_var)</tt>
	</dt>
	<dd>
	<p>
	Add <tt>-n, --dry-run</tt>.
	</p>
	</dd>
	<dt>
	<tt>OPT__QUIET(&int_var)</tt>
	</dt>
	<dd>
	<p>
	Add <tt>-q, --quiet</tt>.
	</p>
	</dd>
	<dt>
	<tt>OPT__VERBOSE(&int_var)</tt>
	</dt>
	<dd>
	<p>
	Add <tt>-v, --verbose</tt>.
	</p>
	</dd>
	<dt>
	<tt>OPT_GROUP(description)</tt>
	</dt>
	<dd>
	<p>
	Start an option group. <tt>description</tt> is a short string that
	describes the group or an empty string.
	Start the description with an upper-case letter.
	</p>
	</dd>
	<dt>
	<tt>OPT_BOOLEAN(short, long, &int_var, description)</tt>
	</dt>
	<dd>
	<p>
	Introduce a boolean option.
	<tt>int_var</tt> is incremented on each use.
	</p>
	</dd>
	<dt>
	<tt>OPT_BIT(short, long, &int_var, description, mask)</tt>
	</dt>
	<dd>
	<p>
	Introduce a boolean option.
	If used, <tt>int_var</tt> is bitwise-ored with <tt>mask</tt>.
	</p>
	</dd>
	<dt>
	<tt>OPT_SET_INT(short, long, &int_var, description, integer)</tt>
	</dt>
	<dd>
	<p>
	Introduce a boolean option.
	If used, set <tt>int_var</tt> to <tt>integer</tt>.
	</p>
	</dd>
	<dt>
	<tt>OPT_SET_PTR(short, long, &ptr_var, description, ptr)</tt>
	</dt>
	<dd>
	<p>
	Introduce a boolean option.
	If used, set <tt>ptr_var</tt> to <tt>ptr</tt>.
	</p>
	</dd>
	<dt>
	<tt>OPT_STRING(short, long, &str_var, arg_str, description)</tt>
	</dt>
	<dd>
	<p>
	Introduce an option with string argument.
	The string argument is put into <tt>str_var</tt>.
	</p>
	</dd>
	<dt>
	<tt>OPT_INTEGER(short, long, &int_var, description)</tt>
	</dt>
	<dd>
	<p>
	Introduce an option with integer argument.
	The integer is put into <tt>int_var</tt>.
	</p>
	</dd>
	<dt>
	<tt>OPT_DATE(short, long, &int_var, description)</tt>
	</dt>
	<dd>
	<p>
	Introduce an option with date argument, see <tt>approxidate()</tt>.
	The timestamp is put into <tt>int_var</tt>.
	</p>
	</dd>
	<dt>
	<tt>OPT_CALLBACK(short, long, &var, arg_str, description, func_ptr)</tt>
	</dt>
	<dd>
	<p>
	Introduce an option with argument.
	The argument will be fed into the function given by <tt>func_ptr</tt>
	and the result will be put into <tt>var</tt>.
	See <em>Option Callbacks</em> below for a more elaborate description.
	</p>
	</dd>
	<dt>
	<tt>OPT_ARGUMENT(long, description)</tt>
	</dt>
	<dd>
	<p>
	Introduce a long-option argument that will be kept in <tt>argv[]</tt>.
	</p>
	</dd>
	</dl></div>
	<div class="para"><p>The last element of the array must be <tt>OPT_END()</tt>.</p></div>
	<div class="para"><p>If not stated otherwise, interpret the arguments as follows:</p></div>
	<div class="ilist"><ul>
	<li>
	<p>
	<tt>short</tt> is a character for the short option
	(e.g. <tt>'e'</tt> for <tt>-e</tt>, use <tt>0</tt> to omit),
	</p>
	</li>
	<li>
	<p>
	<tt>long</tt> is a string for the long option
	(e.g. <tt>"example"</tt> for <tt>--example</tt>, use <tt>NULL</tt> to omit),
	</p>
	</li>
	<li>
	<p>
	<tt>int_var</tt> is an integer variable,
	</p>
	</li>
	<li>
	<p>
	<tt>str_var</tt> is a string variable (<tt>char *</tt>),
	</p>
	</li>
	<li>
	<p>
	<tt>arg_str</tt> is the string that is shown as argument
	(e.g. <tt>"branch"</tt> will result in <tt><branch></tt>).
	If set to <tt>NULL</tt>, three dots (<tt>…</tt>) will be displayed.
	</p>
	</li>
	<li>
	<p>
	<tt>description</tt> is a short string to describe the effect of the option.
	It shall begin with a lower-case letter and a full stop (<tt>.</tt>) shall be
	omitted at the end.
	</p>
	</li>
	</ul></div>
	</div>
	<h2 id="_option_callbacks">Option Callbacks</h2>
	<div class="sectionbody">
	<div class="para"><p>The function must be defined in this form:</p></div>
	<div class="literalblock">
	<div class="content">
	<pre><tt>int func(const struct option opt, const char arg, int unset)</tt></pre>
	</div></div>
	<div class="para"><p>The callback mechanism is as follows:</p></div>
	<div class="ilist"><ul>
	<li>
	<p>
	Inside <tt>funct</tt>, the only interesting member of the structure
	given by <tt>opt</tt> is the void pointer <tt>opt->value</tt>.
	<tt>*opt->value</tt> will be the value that is saved into <tt>var</tt>, if you
	use <tt>OPT_CALLBACK()</tt>.
	For example, do <tt>(unsigned long )opt->value = 42;</tt> to get 42
	into an <tt>unsigned long</tt> variable.
	</p>
	</li>
	<li>
	<p>
	Return value <tt>0</tt> indicates success and non-zero return
	value will invoke <tt>usage_with_options()</tt> and, thus, die.
	</p>
	</li>
	<li>
	<p>
	If the user negates the option, <tt>arg</tt> is <tt>NULL</tt> and <tt>unset</tt> is 1.
	</p>
	</li>
	</ul></div>
	</div>
	<h2 id="_sophisticated_option_parsing">Sophisticated option parsing</h2>
	<div class="sectionbody">
	<div class="para"><p>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 <tt>option</tt> structure manually.</p></div>
	<div class="para"><p>This is not covered in this document, but well documented
	in <tt>parse-options.h</tt> itself.</p></div>
	</div>
	<h2 id="_examples">Examples</h2>
	<div class="sectionbody">
	<div class="para"><p>See <tt>test-parse-options.c</tt> and
	<tt>builtin-add.c</tt>,
	<tt>builtin-clone.c</tt>,
	<tt>builtin-commit.c</tt>,
	<tt>builtin-fetch.c</tt>,
	<tt>builtin-fsck.c</tt>,
	<tt>builtin-rm.c</tt>
	for real-world examples.</p></div>
	</div>
	<div id="footer">
	<div id="footer-text">
	Last updated 2008-09-19 06:33:30 UTC
	</div>
	</div>
	</body>
	</html>