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Reid Spencer	9bbba091	2004-11-16 06:11:52 +0000	[diff] [blame]	5	<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	6	<title>CommandLine 2.0 Library Manual</title>
Misha Brukman	3c29911	2003-11-07 18:11:14 +0000	[diff] [blame]	7	<link rel="stylesheet" href="llvm.css" type="text/css">
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	8	</head>
				9	<body>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	10
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	11	<div class="doc_title">
				12	CommandLine 2.0 Library Manual
				13	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	14
				15	<ol>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	16	<li><a href="#introduction">Introduction</a></li>
				17
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	18	<li><a href="#quickstart">Quick Start Guide</a>
				19	<ol>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	20	<li><a href="#bool">Boolean Arguments</a></li>
				21	<li><a href="#alias">Argument Aliases</a></li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	22	<li><a href="#onealternative">Selecting an alternative from a
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	23	set of possibilities</a></li>
				24	<li><a href="#namedalternatives">Named alternatives</a></li>
				25	<li><a href="#list">Parsing a list of options</a></li>
Jim Laskey	1d8f626	2005-08-25 22:52:43 +0000	[diff] [blame]	26	<li><a href="#bits">Collecting options as a set of flags</a></li>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	27	<li><a href="#description">Adding freeform text to help output</a></li>
				28	</ol></li>
				29
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	30	<li><a href="#referenceguide">Reference Guide</a>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	31	<ol>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	32	<li><a href="#positional">Positional Arguments</a>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	33	<ul>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	34	<li><a href="#--">Specifying positional options with hyphens</a></li>
Reid Spencer	2c8ab58	2004-08-13 20:19:14 +0000	[diff] [blame]	35	<li><a href="#getPosition">Determining absolute position with
				36	getPosition</a></li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	37	<li><a href="#cl::ConsumeAfter">The <tt>cl::ConsumeAfter</tt>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	38	modifier</a></li>
				39	</ul></li>
				40
				41	<li><a href="#storage">Internal vs External Storage</a></li>
				42
				43	<li><a href="#attributes">Option Attributes</a></li>
				44
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	45	<li><a href="#modifiers">Option Modifiers</a>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	46	<ul>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	47	<li><a href="#hiding">Hiding an option from <tt>--help</tt>
				48	output</a></li>
				49	<li><a href="#numoccurrences">Controlling the number of occurrences
				50	required and allowed</a></li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	51	<li><a href="#valrequired">Controlling whether or not a value must be
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	52	specified</a></li>
				53	<li><a href="#formatting">Controlling other formatting options</a></li>
				54	<li><a href="#misc">Miscellaneous option modifiers</a></li>
				55	</ul></li>
				56
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	57	<li><a href="#toplevel">Top-Level Classes and Functions</a>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	58	<ul>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	59	<li><a href="#cl::ParseCommandLineOptions">The
				60	<tt>cl::ParseCommandLineOptions</tt> function</a></li>
				61	<li><a href="#cl::ParseEnvironmentOptions">The
				62	<tt>cl::ParseEnvironmentOptions</tt> function</a></li>
				63	<li><a href="#cl::opt">The <tt>cl::opt</tt> class</a></li>
				64	<li><a href="#cl::list">The <tt>cl::list</tt> class</a></li>
Jim Laskey	1d8f626	2005-08-25 22:52:43 +0000	[diff] [blame]	65	<li><a href="#cl::bits">The <tt>cl::bits</tt> class</a></li>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	66	<li><a href="#cl::alias">The <tt>cl::alias</tt> class</a></li>
Reid Spencer	9bbba091	2004-11-16 06:11:52 +0000	[diff] [blame]	67	<li><a href="#cl::extrahelp">The <tt>cl::extrahelp</tt> class</a></li>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	68	</ul></li>
				69
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	70	<li><a href="#builtinparsers">Builtin parsers</a>
				71	<ul>
				72	<li><a href="#genericparser">The Generic <tt>parser<t></tt>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	73	parser</a></li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	74	<li><a href="#boolparser">The <tt>parser<bool></tt>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	75	specialization</a></li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	76	<li><a href="#stringparser">The <tt>parser<string></tt>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	77	specialization</a></li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	78	<li><a href="#intparser">The <tt>parser<int></tt>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	79	specialization</a></li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	80	<li><a href="#doubleparser">The <tt>parser<double></tt> and
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	81	<tt>parser<float></tt> specializations</a></li>
				82	</ul></li>
				83	</ol></li>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	84	<li><a href="#extensionguide">Extension Guide</a>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	85	<ol>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	86	<li><a href="#customparser">Writing a custom parser</a></li>
				87	<li><a href="#explotingexternal">Exploiting external storage</a></li>
				88	<li><a href="#dynamicopts">Dynamically adding command line
				89	options</a></li>
				90	</ol></li>
				91	</ol>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	92
Chris Lattner	7911ce2	2004-05-23 21:07:27 +0000	[diff] [blame]	93	<div class="doc_author">
				94	<p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a></p>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	95	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	96
				97	<!-- *********************************************************************** -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	98	<div class="doc_section">
Misha Brukman	8becd71	2003-11-07 19:42:44 +0000	[diff] [blame]	99	<a name="introduction">Introduction</a>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	100	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	101	<!-- *********************************************************************** -->
				102
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	103	<div class="doc_text">
				104
				105	<p>This document describes the CommandLine argument processing library. It will
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	106	show you how to use it, and what it can do. The CommandLine library uses a
				107	declarative approach to specifying the command line options that your program
				108	takes. By default, these options declarations implicitly hold the value parsed
				109	for the option declared (of course this <a href="#storage">can be
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	110	changed</a>).</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	111
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	112	<p>Although there are a <b>lot</b> of command line argument parsing libraries
				113	out there in many different languages, none of them fit well with what I needed.
				114	By looking at the features and problems of other libraries, I designed the
				115	CommandLine library to have the following features:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	116
				117	<ol>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	118	<li>Speed: The CommandLine library is very quick and uses little resources. The
				119	parsing time of the library is directly proportional to the number of arguments
				120	parsed, not the the number of options recognized. Additionally, command line
Chris Lattner	edf351f	2003-06-21 21:45:56 +0000	[diff] [blame]	121	argument values are captured transparently into user defined global variables,
				122	which can be accessed like any other variable (and with the same
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	123	performance).</li>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	124
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	125	<li>Type Safe: As a user of CommandLine, you don't have to worry about
				126	remembering the type of arguments that you want (is it an int? a string? a
				127	bool? an enum?) and keep casting it around. Not only does this help prevent
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	128	error prone constructs, it also leads to dramatically cleaner source code.</li>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	129
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	130	<li>No subclasses required: To use CommandLine, you instantiate variables that
				131	correspond to the arguments that you would like to capture, you don't subclass a
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	132	parser. This means that you don't have to write <b>any</b> boilerplate
				133	code.</li>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	134
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	135	<li>Globally accessible: Libraries can specify command line arguments that are
				136	automatically enabled in any tool that links to the library. This is possible
				137	because the application doesn't have to keep a "list" of arguments to pass to
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	138	the parser. This also makes supporting <a href="#dynamicopts">dynamically
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	139	loaded options</a> trivial.</li>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	140
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	141	<li>Cleaner: CommandLine supports enum and other types directly, meaning that
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	142	there is less error and more security built into the library. You don't have to
				143	worry about whether your integral command line argument accidentally got
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	144	assigned a value that is not valid for your enum type.</li>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	145
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	146	<li>Powerful: The CommandLine library supports many different types of
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	147	arguments, from simple <a href="#boolparser">boolean flags</a> to <a
				148	href="#cl::opt">scalars arguments</a> (<a href="#stringparser">strings</a>, <a
				149	href="#intparser">integers</a>, <a href="#genericparser">enums</a>, <a
				150	href="#doubleparser">doubles</a>), to <a href="#cl::list">lists of
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	151	arguments</a>. This is possible because CommandLine is...</li>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	152
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	153	<li>Extensible: It is very simple to add a new argument type to CommandLine.
				154	Simply specify the parser that you want to use with the command line option when
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	155	you declare it. <a href="#customparser">Custom parsers</a> are no problem.</li>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	156
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	157	<li>Labor Saving: The CommandLine library cuts down on the amount of grunt work
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	158	that you, the user, have to do. For example, it automatically provides a
				159	<tt>--help</tt> option that shows the available command line options for your
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	160	tool. Additionally, it does most of the basic correctness checking for
				161	you.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	162
				163	<li>Capable: The CommandLine library can handle lots of different forms of
				164	options often found in real programs. For example, <a
				165	href="#positional">positional</a> arguments, <tt>ls</tt> style <a
				166	href="#cl::Grouping">grouping</a> options (to allow processing '<tt>ls
				167	-lad</tt>' naturally), <tt>ld</tt> style <a href="#cl::Prefix">prefix</a>
				168	options (to parse '<tt>-lmalloc -L/usr/lib</tt>'), and <a
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	169	href="#cl::ConsumeAfter">interpreter style options</a>.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	170
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	171	</ol>
				172
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	173	<p>This document will hopefully let you jump in and start using CommandLine in
				174	your utility quickly and painlessly. Additionally it should be a simple
				175	reference manual to figure out how stuff works. If it is failing in some area
				176	(or you want an extension to the library), nag the author, <a
				177	href="mailto:sabre@nondot.org">Chris Lattner</a>.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	178
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	179	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	180
				181	<!-- *********************************************************************** -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	182	<div class="doc_section">
				183	<a name="quickstart">Quick Start Guide</a>
				184	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	185	<!-- *********************************************************************** -->
				186
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	187	<div class="doc_text">
				188
				189	<p>This section of the manual runs through a simple CommandLine'ification of a
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	190	basic compiler tool. This is intended to show you how to jump into using the
				191	CommandLine library in your own program, and show you some of the cool things it
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	192	can do.</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	193
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	194	<p>To start out, you need to include the CommandLine header file into your
				195	program:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	196
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	197	<div class="doc_code"><pre>
Andrew Lenharth	94f3d1a	2005-11-14 19:32:05 +0000	[diff] [blame]	198	#include "llvm/Support/CommandLine.h"
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	199	</pre></div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	200
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	201	<p>Additionally, you need to add this as the first line of your main
				202	program:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	203
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	204	<div class="doc_code"><pre>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	205	int main(int argc, char **argv) {
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	206	<a href="#cl::ParseCommandLineOptions">cl::ParseCommandLineOptions</a>(argc, argv);
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	207	...
				208	}
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	209	</pre></div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	210
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	211	<p>... which actually parses the arguments and fills in the variable
				212	declarations.</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	213
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	214	<p>Now that you are ready to support command line arguments, we need to tell the
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	215	system which ones we want, and what type of argument they are. The CommandLine
Chris Lattner	edf351f	2003-06-21 21:45:56 +0000	[diff] [blame]	216	library uses a declarative syntax to model command line arguments with the
				217	global variable declarations that capture the parsed values. This means that
				218	for every command line option that you would like to support, there should be a
				219	global variable declaration to capture the result. For example, in a compiler,
				220	we would like to support the unix standard '<tt>-o <filename></tt>' option
				221	to specify where to put the output. With the CommandLine library, this is
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	222	represented like this:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	223
Misha Brukman	c53aefb	2004-05-12 18:42:35 +0000	[diff] [blame]	224	<a name="value_desc_example"></a>
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	225	<div class="doc_code"><pre>
Misha Brukman	c53aefb	2004-05-12 18:42:35 +0000	[diff] [blame]	226	<a href="#cl::opt">cl::opt</a><string> OutputFilename("<i>o</i>", <a href="#cl::desc">cl::desc</a>("<i>Specify output filename</i>"), <a href="#cl::value_desc">cl::value_desc</a>("<i>filename</i>"));
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	227	</pre></div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	228
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	229	<p>This declares a global variable "<tt>OutputFilename</tt>" that is used to
Chris Lattner	edf351f	2003-06-21 21:45:56 +0000	[diff] [blame]	230	capture the result of the "<tt>o</tt>" argument (first parameter). We specify
				231	that this is a simple scalar option by using the "<tt><a
				232	href="#cl::opt">cl::opt</a></tt>" template (as opposed to the <a
				233	href="#list">"<tt>cl::list</tt> template</a>), and tell the CommandLine library
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	234	that the data type that we are parsing is a string.</p>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	235
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	236	<p>The second and third parameters (which are optional) are used to specify what
				237	to output for the "<tt>--help</tt>" option. In this case, we get a line that
				238	looks like this:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	239
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	240	<div class="doc_code"><pre>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	241	USAGE: compiler [options]
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	242
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	243	OPTIONS:
				244	-help - display available options (--help-hidden for more)
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	245	<b>-o <filename> - Specify output filename</b>
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	246	</pre></div>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	247
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	248	<p>Because we specified that the command line option should parse using the
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	249	<tt>string</tt> data type, the variable declared is automatically usable as a
				250	real string in all contexts that a normal C++ string object may be used. For
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	251	example:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	252
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	253	<div class="doc_code"><pre>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	254	...
				255	ofstream Output(OutputFilename.c_str());
				256	if (Out.good()) ...
				257	...
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	258	</pre></div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	259
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	260	<p>There are many different options that you can use to customize the command
				261	line option handling library, but the above example shows the general interface
				262	to these options. The options can be specified in any order, and are specified
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	263	with helper functions like <a href="#cl::desc"><tt>cl::desc(...)</tt></a>, so
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	264	there are no positional dependencies to remember. The available options are
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	265	discussed in detail in the <a href="#referenceguide">Reference Guide</a>.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	266
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	267	<p>Continuing the example, we would like to have our compiler take an input
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	268	filename as well as an output filename, but we do not want the input filename to
				269	be specified with a hyphen (ie, not <tt>-filename.c</tt>). To support this
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	270	style of argument, the CommandLine library allows for <a
				271	href="#positional">positional</a> arguments to be specified for the program.
				272	These positional arguments are filled with command line parameters that are not
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	273	in option form. We use this feature like this:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	274
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	275	<div class="doc_code"><pre>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	276	<a href="#cl::opt">cl::opt</a><string> InputFilename(<a href="#cl::Positional">cl::Positional</a>, <a href="#cl::desc">cl::desc</a>("<i><input file></i>"), <a href="#cl::init">cl::init</a>("<i>-</i>"));
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	277	</pre></div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	278
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	279	<p>This declaration indicates that the first positional argument should be
				280	treated as the input filename. Here we use the <tt><a
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	281	href="#cl::init">cl::init</a></tt> option to specify an initial value for the
				282	command line option, which is used if the option is not specified (if you do not
				283	specify a <tt><a href="#cl::init">cl::init</a></tt> modifier for an option, then
				284	the default constructor for the data type is used to initialize the value).
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	285	Command line options default to being optional, so if we would like to require
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	286	that the user always specify an input filename, we would add the <tt><a
				287	href="#cl::Required">cl::Required</a></tt> flag, and we could eliminate the
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	288	<tt><a href="#cl::init">cl::init</a></tt> modifier, like this:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	289
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	290	<div class="doc_code"><pre>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	291	<a href="#cl::opt">cl::opt</a><string> InputFilename(<a href="#cl::Positional">cl::Positional</a>, <a href="#cl::desc">cl::desc</a>("<i><input file></i>"), <b><a href="#cl::Required">cl::Required</a></b>);
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	292	</pre></div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	293
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	294	<p>Again, the CommandLine library does not require the options to be specified
				295	in any particular order, so the above declaration is equivalent to:</p>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	296
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	297	<div class="doc_code"><pre>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	298	<a href="#cl::opt">cl::opt</a><string> InputFilename(<a href="#cl::Positional">cl::Positional</a>, <a href="#cl::Required">cl::Required</a>, <a href="#cl::desc">cl::desc</a>("<i><input file></i>"));
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	299	</pre></div>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	300
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	301	<p>By simply adding the <tt><a href="#cl::Required">cl::Required</a></tt> flag,
				302	the CommandLine library will automatically issue an error if the argument is not
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	303	specified, which shifts all of the command line option verification code out of
				304	your application into the library. This is just one example of how using flags
				305	can alter the default behaviour of the library, on a per-option basis. By
				306	adding one of the declarations above, the <tt>--help</tt> option synopsis is now
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	307	extended to:</p>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	308
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	309	<div class="doc_code"><pre>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	310	USAGE: compiler [options] <b><input file></b>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	311
				312	OPTIONS:
				313	-help - display available options (--help-hidden for more)
				314	-o <filename> - Specify output filename
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	315	</pre></div>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	316
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	317	<p>... indicating that an input filename is expected.</p>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	318
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	319	</div>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	320
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	321	<!-- ======================================================================= -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	322	<div class="doc_subsection">
				323	<a name="bool">Boolean Arguments</a>
				324	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	325
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	326	<div class="doc_text">
				327
				328	<p>In addition to input and output filenames, we would like the compiler example
				329	to support three boolean flags: "<tt>-f</tt>" to force overwriting of the output
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	330	file, "<tt>--quiet</tt>" to enable quiet mode, and "<tt>-q</tt>" for backwards
				331	compatibility with some of our users. We can support these by declaring options
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	332	of boolean type like this:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	333
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	334	<div class="doc_code"><pre>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	335	<a href="#cl::opt">cl::opt</a><bool> Force ("<i>f</i>", <a href="#cl::desc">cl::desc</a>("<i>Overwrite output files</i>"));
				336	<a href="#cl::opt">cl::opt</a><bool> Quiet ("<i>quiet</i>", <a href="#cl::desc">cl::desc</a>("<i>Don't print informational messages</i>"));
				337	<a href="#cl::opt">cl::opt</a><bool> Quiet2("<i>q</i>", <a href="#cl::desc">cl::desc</a>("<i>Don't print informational messages</i>"), <a href="#cl::Hidden">cl::Hidden</a>);
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	338	</pre></div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	339
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	340	<p>This does what you would expect: it declares three boolean variables
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	341	("<tt>Force</tt>", "<tt>Quiet</tt>", and "<tt>Quiet2</tt>") to recognize these
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	342	options. Note that the "<tt>-q</tt>" option is specified with the "<a
				343	href="#cl::Hidden"><tt>cl::Hidden</tt></a>" flag. This modifier prevents it
				344	from being shown by the standard "<tt>--help</tt>" output (note that it is still
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	345	shown in the "<tt>--help-hidden</tt>" output).</p>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	346
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	347	<p>The CommandLine library uses a <a href="#builtinparsers">different parser</a>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	348	for different data types. For example, in the string case, the argument passed
				349	to the option is copied literally into the content of the string variable... we
				350	obviously cannot do that in the boolean case, however, so we must use a smarter
				351	parser. In the case of the boolean parser, it allows no options (in which case
				352	it assigns the value of true to the variable), or it allows the values
				353	"<tt>true</tt>" or "<tt>false</tt>" to be specified, allowing any of the
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	354	following inputs:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	355
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	356	<div class="doc_code"><pre>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	357	compiler -f # No value, 'Force' == true
				358	compiler -f=true # Value specified, 'Force' == true
				359	compiler -f=TRUE # Value specified, 'Force' == true
				360	compiler -f=FALSE # Value specified, 'Force' == false
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	361	</pre></div>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	362
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	363	<p>... you get the idea. The <a href="#boolparser">bool parser</a> just turns
				364	the string values into boolean values, and rejects things like '<tt>compiler
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	365	-f=foo</tt>'. Similarly, the <a href="#doubleparser">float</a>, <a
				366	href="#doubleparser">double</a>, and <a href="#intparser">int</a> parsers work
				367	like you would expect, using the '<tt>strtol</tt>' and '<tt>strtod</tt>' C
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	368	library calls to parse the string value into the specified data type.</p>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	369
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	370	<p>With the declarations above, "<tt>compiler --help</tt>" emits this:</p>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	371
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	372	<div class="doc_code"><pre>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	373	USAGE: compiler [options] <input file>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	374
				375	OPTIONS:
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	376	<b>-f - Overwrite output files</b>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	377	-o - Override output filename
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	378	<b>-quiet - Don't print informational messages</b>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	379	-help - display available options (--help-hidden for more)
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	380	</pre></div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	381
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	382	<p>and "<tt>opt --help-hidden</tt>" prints this:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	383
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	384	<div class="doc_code"><pre>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	385	USAGE: compiler [options] <input file>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	386
				387	OPTIONS:
				388	-f - Overwrite output files
				389	-o - Override output filename
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	390	<b>-q - Don't print informational messages</b>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	391	-quiet - Don't print informational messages
				392	-help - display available options (--help-hidden for more)
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	393	</pre></div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	394
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	395	<p>This brief example has shown you how to use the '<tt><a
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	396	href="#cl::opt">cl::opt</a></tt>' class to parse simple scalar command line
				397	arguments. In addition to simple scalar arguments, the CommandLine library also
				398	provides primitives to support CommandLine option <a href="#alias">aliases</a>,
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	399	and <a href="#list">lists</a> of options.</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	400
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	401	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	402
				403	<!-- ======================================================================= -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	404	<div class="doc_subsection">
				405	<a name="alias">Argument Aliases</a>
				406	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	407
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	408	<div class="doc_text">
				409
				410	<p>So far, the example works well, except for the fact that we need to check the
				411	quiet condition like this now:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	412
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	413	<div class="doc_code"><pre>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	414	...
				415	if (!Quiet && !Quiet2) printInformationalMessage(...);
				416	...
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	417	</pre></div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	418
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	419	<p>... which is a real pain! Instead of defining two values for the same
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	420	condition, we can use the "<tt><a href="#cl::alias">cl::alias</a></tt>" class to make the "<tt>-q</tt>"
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	421	option an <b>alias</b> for the "<tt>-quiet</tt>" option, instead of providing
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	422	a value itself:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	423
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	424	<div class="doc_code"><pre>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	425	<a href="#cl::opt">cl::opt</a><bool> Force ("<i>f</i>", <a href="#cl::desc">cl::desc</a>("<i>Overwrite output files</i>"));
				426	<a href="#cl::opt">cl::opt</a><bool> Quiet ("<i>quiet</i>", <a href="#cl::desc">cl::desc</a>("<i>Don't print informational messages</i>"));
				427	<a href="#cl::alias">cl::alias</a> QuietA("<i>q</i>", <a href="#cl::desc">cl::desc</a>("<i>Alias for -quiet</i>"), <a href="#cl::aliasopt">cl::aliasopt</a>(Quiet));
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	428	</pre></div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	429
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	430	<p>The third line (which is the only one we modified from above) defines a
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	431	"<tt>-q</tt> alias that updates the "<tt>Quiet</tt>" variable (as specified by
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	432	the <tt><a href="#cl::aliasopt">cl::aliasopt</a></tt> modifier) whenever it is
				433	specified. Because aliases do not hold state, the only thing the program has to
				434	query is the <tt>Quiet</tt> variable now. Another nice feature of aliases is
				435	that they automatically hide themselves from the <tt>-help</tt> output
				436	(although, again, they are still visible in the <tt>--help-hidden
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	437	output</tt>).</p>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	438
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	439	<p>Now the application code can simply use:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	440
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	441	<div class="doc_code"><pre>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	442	...
				443	if (!Quiet) printInformationalMessage(...);
				444	...
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	445	</pre></div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	446
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	447	<p>... which is much nicer! The "<tt><a href="#cl::alias">cl::alias</a></tt>"
				448	can be used to specify an alternative name for any variable type, and has many
				449	uses.</p>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	450
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	451	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	452
				453	<!-- ======================================================================= -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	454	<div class="doc_subsection">
				455	<a name="onealternative">Selecting an alternative from a set of
				456	possibilities</a>
				457	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	458
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	459	<div class="doc_text">
				460
				461	<p>So far, we have seen how the CommandLine library handles builtin types like
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	462	<tt>std::string</tt>, <tt>bool</tt> and <tt>int</tt>, but how does it handle
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	463	things it doesn't know about, like enums or '<tt>int*</tt>'s?</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	464
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	465	<p>The answer is that it uses a table driven generic parser (unless you specify
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	466	your own parser, as described in the <a href="#extensionguide">Extension
Reid Spencer	d847337	2004-08-10 16:38:18 +0000	[diff] [blame]	467	Guide</a>). This parser maps literal strings to whatever type is required, and
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	468	requires you to tell it what this mapping should be.</p>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	469
Reid Spencer	d847337	2004-08-10 16:38:18 +0000	[diff] [blame]	470	<p>Lets say that we would like to add four optimization levels to our
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	471	optimizer, using the standard flags "<tt>-g</tt>", "<tt>-O0</tt>",
				472	"<tt>-O1</tt>", and "<tt>-O2</tt>". We could easily implement this with boolean
				473	options like above, but there are several problems with this strategy:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	474
				475	<ol>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	476	<li>A user could specify more than one of the options at a time, for example,
				477	"<tt>opt -O3 -O2</tt>". The CommandLine library would not be able to catch this
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	478	erroneous input for us.</li>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	479
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	480	<li>We would have to test 4 different variables to see which ones are set.</li>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	481
				482	<li>This doesn't map to the numeric levels that we want... so we cannot easily
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	483	see if some level >= "<tt>-O1</tt>" is enabled.</li>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	484
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	485	</ol>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	486
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	487	<p>To cope with these problems, we can use an enum value, and have the
				488	CommandLine library fill it in with the appropriate level directly, which is
				489	used like this:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	490
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	491	<div class="doc_code"><pre>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	492	enum OptLevel {
				493	g, O1, O2, O3
				494	};
				495
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	496	<a href="#cl::opt">cl::opt</a><OptLevel> OptimizationLevel(<a href="#cl::desc">cl::desc</a>("<i>Choose optimization level:</i>"),
				497	<a href="#cl::values">cl::values</a>(
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	498	clEnumVal(g , "<i>No optimizations, enable debugging</i>"),
				499	clEnumVal(O1, "<i>Enable trivial optimizations</i>"),
				500	clEnumVal(O2, "<i>Enable default optimizations</i>"),
				501	clEnumVal(O3, "<i>Enable expensive optimizations</i>"),
Chris Lattner	b406ead	2004-07-16 00:10:54 +0000	[diff] [blame]	502	clEnumValEnd));
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	503
				504	...
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	505	if (OptimizationLevel >= O2) doPartialRedundancyElimination(...);
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	506	...
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	507	</pre></div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	508
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	509	<p>This declaration defines a variable "<tt>OptimizationLevel</tt>" of the
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	510	"<tt>OptLevel</tt>" enum type. This variable can be assigned any of the values
				511	that are listed in the declaration (Note that the declaration list must be
Chris Lattner	b406ead	2004-07-16 00:10:54 +0000	[diff] [blame]	512	terminated with the "<tt>clEnumValEnd</tt>" argument!). The CommandLine
				513	library enforces
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	514	that the user can only specify one of the options, and it ensure that only valid
				515	enum values can be specified. The "<tt>clEnumVal</tt>" macros ensure that the
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	516	command line arguments matched the enum values. With this option added, our
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	517	help output now is:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	518
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	519	<div class="doc_code"><pre>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	520	USAGE: compiler [options] <input file>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	521
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	522	OPTIONS:
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	523	<b>Choose optimization level:
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	524	-g - No optimizations, enable debugging
				525	-O1 - Enable trivial optimizations
				526	-O2 - Enable default optimizations
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	527	-O3 - Enable expensive optimizations</b>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	528	-f - Overwrite output files
				529	-help - display available options (--help-hidden for more)
				530	-o <filename> - Specify output filename
				531	-quiet - Don't print informational messages
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	532	</pre></div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	533
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	534	<p>In this case, it is sort of awkward that flag names correspond directly to
				535	enum names, because we probably don't want a enum definition named "<tt>g</tt>"
				536	in our program. Because of this, we can alternatively write this example like
				537	this:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	538
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	539	<div class="doc_code"><pre>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	540	enum OptLevel {
				541	Debug, O1, O2, O3
				542	};
				543
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	544	<a href="#cl::opt">cl::opt</a><OptLevel> OptimizationLevel(<a href="#cl::desc">cl::desc</a>("<i>Choose optimization level:</i>"),
				545	<a href="#cl::values">cl::values</a>(
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	546	clEnumValN(Debug, "g", "<i>No optimizations, enable debugging</i>"),
				547	clEnumVal(O1 , "<i>Enable trivial optimizations</i>"),
				548	clEnumVal(O2 , "<i>Enable default optimizations</i>"),
				549	clEnumVal(O3 , "<i>Enable expensive optimizations</i>"),
Chris Lattner	b406ead	2004-07-16 00:10:54 +0000	[diff] [blame]	550	clEnumValEnd));
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	551
				552	...
				553	if (OptimizationLevel == Debug) outputDebugInfo(...);
				554	...
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	555	</pre></div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	556
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	557	<p>By using the "<tt>clEnumValN</tt>" macro instead of "<tt>clEnumVal</tt>", we
				558	can directly specify the name that the flag should get. In general a direct
				559	mapping is nice, but sometimes you can't or don't want to preserve the mapping,
				560	which is when you would use it.</p>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	561
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	562	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	563
				564	<!-- ======================================================================= -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	565	<div class="doc_subsection">
				566	<a name="namedalternatives">Named Alternatives</a>
				567	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	568
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	569	<div class="doc_text">
				570
				571	<p>Another useful argument form is a named alternative style. We shall use this
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	572	style in our compiler to specify different debug levels that can be used.
				573	Instead of each debug level being its own switch, we want to support the
				574	following options, of which only one can be specified at a time:
				575	"<tt>--debug-level=none</tt>", "<tt>--debug-level=quick</tt>",
				576	"<tt>--debug-level=detailed</tt>". To do this, we use the exact same format as
				577	our optimization level flags, but we also specify an option name. For this
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	578	case, the code looks like this:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	579
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	580	<div class="doc_code"><pre>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	581	enum DebugLev {
				582	nodebuginfo, quick, detailed
				583	};
				584
				585	// Enable Debug Options to be specified on the command line
Chris Lattner	dc844fa	2003-06-03 04:40:06 +0000	[diff] [blame]	586	<a href="#cl::opt">cl::opt</a><DebugLev> DebugLevel("<i>debug_level</i>", <a href="#cl::desc">cl::desc</a>("<i>Set the debugging level:</i>"),
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	587	<a href="#cl::values">cl::values</a>(
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	588	clEnumValN(nodebuginfo, "none", "<i>disable debug information</i>"),
				589	clEnumVal(quick, "<i>enable quick debug information</i>"),
				590	clEnumVal(detailed, "<i>enable detailed debug information</i>"),
Chris Lattner	b406ead	2004-07-16 00:10:54 +0000	[diff] [blame]	591	clEnumValEnd));
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	592	</pre></div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	593
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	594	<p>This definition defines an enumerated command line variable of type "<tt>enum
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	595	DebugLev</tt>", which works exactly the same way as before. The difference here
				596	is just the interface exposed to the user of your program and the help output by
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	597	the "<tt>--help</tt>" option:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	598
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	599	<div class="doc_code"><pre>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	600	USAGE: compiler [options] <input file>
				601
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	602	OPTIONS:
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	603	Choose optimization level:
				604	-g - No optimizations, enable debugging
				605	-O1 - Enable trivial optimizations
				606	-O2 - Enable default optimizations
				607	-O3 - Enable expensive optimizations
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	608	<b>-debug_level - Set the debugging level:
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	609	=none - disable debug information
				610	=quick - enable quick debug information
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	611	=detailed - enable detailed debug information</b>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	612	-f - Overwrite output files
				613	-help - display available options (--help-hidden for more)
				614	-o <filename> - Specify output filename
				615	-quiet - Don't print informational messages
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	616	</pre></div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	617
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	618	<p>Again, the only structural difference between the debug level declaration and
John Criswell	c24d482	2004-11-21 14:34:34 +0000	[diff] [blame]	619	the optimization level declaration is that the debug level declaration includes
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	620	an option name (<tt>"debug_level"</tt>), which automatically changes how the
				621	library processes the argument. The CommandLine library supports both forms so
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	622	that you can choose the form most appropriate for your application.</p>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	623
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	624	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	625
				626	<!-- ======================================================================= -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	627	<div class="doc_subsection">
				628	<a name="list">Parsing a list of options</a>
				629	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	630
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	631	<div class="doc_text">
				632
				633	<p>Now that we have the standard run of the mill argument types out of the way,
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	634	lets get a little wild and crazy. Lets say that we want our optimizer to accept
				635	a <b>list</b> of optimizations to perform, allowing duplicates. For example, we
				636	might want to run: "<tt>compiler -dce -constprop -inline -dce -strip</tt>". In
				637	this case, the order of the arguments and the number of appearances is very
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	638	important. This is what the "<tt><a href="#cl::list">cl::list</a></tt>"
				639	template is for. First, start by defining an enum of the optimizations that you
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	640	would like to perform:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	641
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	642	<div class="doc_code"><pre>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	643	enum Opts {
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	644	// 'inline' is a C++ keyword, so name it 'inlining'
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	645	dce, constprop, inlining, strip
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	646	};
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	647	</pre></div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	648
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	649	<p>Then define your "<tt><a href="#cl::list">cl::list</a></tt>" variable:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	650
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	651	<div class="doc_code"><pre>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	652	<a href="#cl::list">cl::list</a><Opts> OptimizationList(<a href="#cl::desc">cl::desc</a>("<i>Available Optimizations:</i>"),
				653	<a href="#cl::values">cl::values</a>(
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	654	clEnumVal(dce , "<i>Dead Code Elimination</i>"),
Misha Brukman	82c89b9	2003-05-20 21:01:22 +0000	[diff] [blame]	655	clEnumVal(constprop , "<i>Constant Propagation</i>"),
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	656	clEnumValN(inlining, "<i>inline</i>", "<i>Procedure Integration</i>"),
				657	clEnumVal(strip , "<i>Strip Symbols</i>"),
Chris Lattner	b406ead	2004-07-16 00:10:54 +0000	[diff] [blame]	658	clEnumValEnd));
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	659	</pre></div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	660
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	661	<p>This defines a variable that is conceptually of the type
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	662	"<tt>std::vector<enum Opts></tt>". Thus, you can access it with standard
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	663	vector methods:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	664
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	665	<div class="doc_code"><pre>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	666	for (unsigned i = 0; i != OptimizationList.size(); ++i)
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	667	switch (OptimizationList[i])
				668	...
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	669	</pre></div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	670
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	671	<p>... to iterate through the list of options specified.</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	672
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	673	<p>Note that the "<tt><a href="#cl::list">cl::list</a></tt>" template is
				674	completely general and may be used with any data types or other arguments that
				675	you can use with the "<tt><a href="#cl::opt">cl::opt</a></tt>" template. One
				676	especially useful way to use a list is to capture all of the positional
				677	arguments together if there may be more than one specified. In the case of a
				678	linker, for example, the linker takes several '<tt>.o</tt>' files, and needs to
				679	capture them into a list. This is naturally specified as:</p>
Chris Lattner	3e5fe17	2002-04-13 18:35:59 +0000	[diff] [blame]	680
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	681	<div class="doc_code"><pre>
Chris Lattner	3e5fe17	2002-04-13 18:35:59 +0000	[diff] [blame]	682	...
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	683	<a href="#cl::list">cl::list</a><std::string> InputFilenames(<a href="#cl::Positional">cl::Positional</a>, <a href="#cl::desc">cl::desc</a>("<Input files>"), <a href="#cl::OneOrMore">cl::OneOrMore</a>);
Chris Lattner	3e5fe17	2002-04-13 18:35:59 +0000	[diff] [blame]	684	...
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	685	</pre></div>
Chris Lattner	3e5fe17	2002-04-13 18:35:59 +0000	[diff] [blame]	686
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	687	<p>This variable works just like a "<tt>vector<string></tt>" object. As
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	688	such, accessing the list is simple, just like above. In this example, we used
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	689	the <tt><a href="#cl::OneOrMore">cl::OneOrMore</a></tt> modifier to inform the
				690	CommandLine library that it is an error if the user does not specify any
				691	<tt>.o</tt> files on our command line. Again, this just reduces the amount of
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	692	checking we have to do.</p>
Chris Lattner	3e5fe17	2002-04-13 18:35:59 +0000	[diff] [blame]	693
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	694	</div>
Chris Lattner	3e5fe17	2002-04-13 18:35:59 +0000	[diff] [blame]	695
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	696	<!-- ======================================================================= -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	697	<div class="doc_subsection">
Jim Laskey	1d8f626	2005-08-25 22:52:43 +0000	[diff] [blame]	698	<a name="bits">Collecting options as a set of flags</a>
				699	</div>
				700
				701	<div class="doc_text">
				702
				703	<p>Instead of collecting sets of options in a list, it is also possible to
Jim Laskey	22b7dfa	2005-08-26 09:25:54 +0000	[diff] [blame]	704	gather information for enum values in a <b>bit vector</b>. The represention used by
				705	the <a href="#bits"><tt>cl::bits</tt></a> class is an <tt>unsigned</tt>
Jim Laskey	1d8f626	2005-08-25 22:52:43 +0000	[diff] [blame]	706	integer. An enum value is represented by a 0/1 in the enum's ordinal value bit
				707	position. 1 indicating that the enum was specified, 0 otherwise. As each
				708	specified value is parsed, the resulting enum's bit is set in the option's bit
				709	vector:</p>
				710
				711	<div class="doc_code"><pre>
				712	<i>bits</i> \|= 1 << (unsigned)<i>enum</i>;
				713	</pre></div>
				714
Jim Laskey	2602922	2005-08-25 23:01:25 +0000	[diff] [blame]	715	<p>Options that are specified multiple times are redundant. Any instances after
				716	the first are discarded.</p>
Jim Laskey	1d8f626	2005-08-25 22:52:43 +0000	[diff] [blame]	717
				718	<p>Reworking the above list example, we could replace <a href="#list">
				719	<tt>cl::list</tt></a> with <a href="#bits"><tt>cl::bits</tt></a>:</p>
				720
				721	<div class="doc_code"><pre>
				722	<a href="#cl::bits">cl::bits</a><Opts> OptimizationBits(<a href="#cl::desc">cl::desc</a>("<i>Available Optimizations:</i>"),
				723	<a href="#cl::values">cl::values</a>(
				724	clEnumVal(dce , "<i>Dead Code Elimination</i>"),
				725	clEnumVal(constprop , "<i>Constant Propagation</i>"),
				726	clEnumValN(inlining, "<i>inline</i>", "<i>Procedure Integration</i>"),
				727	clEnumVal(strip , "<i>Strip Symbols</i>"),
				728	clEnumValEnd));
				729	</pre></div>
				730
				731	<p>To test to see if <tt>constprop</tt> was specified, we can use the
				732	<tt>cl:bits::isSet</tt> function:</p>
				733
				734	<div class="doc_code"><pre>
				735	if (OptimizationBits.isSet(constprop)) {
				736	...
				737	}
				738	</pre></div>
				739
				740	<p>It's also possible to get the raw bit vector using the
				741	<tt>cl::bits::getBits</tt> function:</p>
				742
				743	<div class="doc_code"><pre>
Jim Laskey	22b7dfa	2005-08-26 09:25:54 +0000	[diff] [blame]	744	unsigned bits = OptimizationBits.getBits();
Jim Laskey	1d8f626	2005-08-25 22:52:43 +0000	[diff] [blame]	745	</pre></div>
				746
				747	<p>Finally, if external storage is used, then the location specified must be of
Jim Laskey	22b7dfa	2005-08-26 09:25:54 +0000	[diff] [blame]	748	<b>type</b> <tt>unsigned</tt>. In all other ways a <a
Jim Laskey	1d8f626	2005-08-25 22:52:43 +0000	[diff] [blame]	749	href="#bits"><tt>cl::bits</tt></a> option is morally equivalent to a <a
Jim Laskey	22b7dfa	2005-08-26 09:25:54 +0000	[diff] [blame]	750	href="#list"> <tt>cl::list</tt></a> option.</p>
Jim Laskey	1d8f626	2005-08-25 22:52:43 +0000	[diff] [blame]	751
				752	</div>
				753
				754
				755	<!-- ======================================================================= -->
				756	<div class="doc_subsection">
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	757	<a name="description">Adding freeform text to help output</a>
				758	</div>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	759
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	760	<div class="doc_text">
				761
				762	<p>As our program grows and becomes more mature, we may decide to put summary
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	763	information about what it does into the help output. The help output is styled
				764	to look similar to a Unix <tt>man</tt> page, providing concise information about
				765	a program. Unix <tt>man</tt> pages, however often have a description about what
				766	the program does. To add this to your CommandLine program, simply pass a third
				767	argument to the <a
				768	href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>
				769	call in main. This additional argument is then printed as the overview
				770	information for your program, allowing you to include any additional information
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	771	that you want. For example:</p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	772
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	773	<div class="doc_code"><pre>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	774	int main(int argc, char **argv) {
				775	<a href="#cl::ParseCommandLineOptions">cl::ParseCommandLineOptions</a>(argc, argv, " CommandLine compiler example\n\n"
				776	" This program blah blah blah...\n");
				777	...
				778	}
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	779	</pre></div>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	780
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	781	<p>would yield the help output:</p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	782
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	783	<div class="doc_code"><pre>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	784	<b>OVERVIEW: CommandLine compiler example
				785
				786	This program blah blah blah...</b>
				787
				788	USAGE: compiler [options] <input file>
				789
				790	OPTIONS:
				791	...
				792	-help - display available options (--help-hidden for more)
				793	-o <filename> - Specify output filename
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	794	</pre></div>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	795
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	796	</div>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	797
				798
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	799	<!-- *********************************************************************** -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	800	<div class="doc_section">
				801	<a name="referenceguide">Reference Guide</a>
				802	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	803	<!-- *********************************************************************** -->
				804
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	805	<div class="doc_text">
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	806
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	807	<p>Now that you know the basics of how to use the CommandLine library, this
				808	section will give you the detailed information you need to tune how command line
				809	options work, as well as information on more "advanced" command line option
				810	processing capabilities.</p>
				811
				812	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	813
				814	<!-- ======================================================================= -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	815	<div class="doc_subsection">
				816	<a name="positional">Positional Arguments</a>
				817	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	818
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	819	<div class="doc_text">
				820
				821	<p>Positional arguments are those arguments that are not named, and are not
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	822	specified with a hyphen. Positional arguments should be used when an option is
				823	specified by its position alone. For example, the standard Unix <tt>grep</tt>
				824	tool takes a regular expression argument, and an optional filename to search
				825	through (which defaults to standard input if a filename is not specified).
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	826	Using the CommandLine library, this would be specified as:</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	827
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	828	<div class="doc_code"><pre>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	829	<a href="#cl::opt">cl::opt</a><string> Regex (<a href="#cl::Positional">cl::Positional</a>, <a href="#cl::desc">cl::desc</a>("<i><regular expression></i>"), <a href="#cl::Required">cl::Required</a>);
				830	<a href="#cl::opt">cl::opt</a><string> Filename(<a href="#cl::Positional">cl::Positional</a>, <a href="#cl::desc">cl::desc</a>("<i><input file></i>"), <a href="#cl::init">cl::init</a>("<i>-</i>"));
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	831	</pre></div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	832
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	833	<p>Given these two option declarations, the <tt>--help</tt> output for our grep
				834	replacement would look like this:</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	835
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	836	<div class="doc_code"><pre>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	837	USAGE: spiffygrep [options] <b><regular expression> <input file></b>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	838
				839	OPTIONS:
				840	-help - display available options (--help-hidden for more)
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	841	</pre></div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	842
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	843	<p>... and the resultant program could be used just like the standard
				844	<tt>grep</tt> tool.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	845
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	846	<p>Positional arguments are sorted by their order of construction. This means
				847	that command line options will be ordered according to how they are listed in a
Reid Spencer	2c8ab58	2004-08-13 20:19:14 +0000	[diff] [blame]	848	.cpp file, but will not have an ordering defined if the positional arguments
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	849	are defined in multiple .cpp files. The fix for this problem is simply to
				850	define all of your positional arguments in one .cpp file.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	851
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	852	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	853
				854
				855	<!-- _______________________________________________________________________ -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	856	<div class="doc_subsubsection">
				857	<a name="--">Specifying positional options with hyphens</a>
				858	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	859
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	860	<div class="doc_text">
				861
				862	<p>Sometimes you may want to specify a value to your positional argument that
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	863	starts with a hyphen (for example, searching for '<tt>-foo</tt>' in a file). At
				864	first, you will have trouble doing this, because it will try to find an argument
				865	named '<tt>-foo</tt>', and will fail (and single quotes will not save you).
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	866	Note that the system <tt>grep</tt> has the same problem:</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	867
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	868	<div class="doc_code"><pre>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	869	$ spiffygrep '-foo' test.txt
				870	Unknown command line argument '-foo'. Try: spiffygrep --help'
				871
				872	$ grep '-foo' test.txt
				873	grep: illegal option -- f
				874	grep: illegal option -- o
				875	grep: illegal option -- o
				876	Usage: grep -hblcnsviw pattern file . . .
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	877	</pre></div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	878
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	879	<p>The solution for this problem is the same for both your tool and the system
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	880	version: use the '<tt>--</tt>' marker. When the user specifies '<tt>--</tt>' on
				881	the command line, it is telling the program that all options after the
				882	'<tt>--</tt>' should be treated as positional arguments, not options. Thus, we
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	883	can use it like this:</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	884
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	885	<div class="doc_code"><pre>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	886	$ spiffygrep -- -foo test.txt
				887	...output...
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	888	</pre></div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	889
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	890	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	891
				892	<!-- _______________________________________________________________________ -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	893	<div class="doc_subsubsection">
Reid Spencer	2c8ab58	2004-08-13 20:19:14 +0000	[diff] [blame]	894	<a name="getPosition">Determining absolute position with getPosition()</a>
				895	</div>
				896	<div class="doc_text">
				897	<p>Sometimes an option can affect or modify the meaning of another option. For
				898	example, consider <tt>gcc</tt>'s <tt>-x LANG</tt> option. This tells
				899	<tt>gcc</tt> to ignore the suffix of subsequent positional arguments and force
				900	the file to be interpreted as if it contained source code in language
				901	<tt>LANG</tt>. In order to handle this properly , you need to know the
				902	absolute position of each argument, especially those in lists, so their
				903	interaction(s) can be applied correctly. This is also useful for options like
				904	<tt>-llibname</tt> which is actually a positional argument that starts with
				905	a dash.</p>
				906	<p>So, generally, the problem is that you have two <tt>cl::list</tt> variables
				907	that interact in some way. To ensure the correct interaction, you can use the
				908	<tt>cl::list::getPosition(optnum)</tt> method. This method returns the
				909	absolute position (as found on the command line) of the <tt>optnum</tt>
				910	item in the <tt>cl::list</tt>.</p>
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	911	<p>The idiom for usage is like this:</p>
				912
				913	<div class="doc_code"><pre>
Reid Spencer	2c8ab58	2004-08-13 20:19:14 +0000	[diff] [blame]	914	static cl::list<std::string> Files(cl::Positional, cl::OneOrMore);
				915	static cl::listlt;std::string> Libraries("l", cl::ZeroOrMore);
				916
				917	int main(int argc, char**argv) {
				918	// ...
				919	std::vector<std::string>::iterator fileIt = Files.begin();
				920	std::vector<std::string>::iterator libIt = Libraries.begin();
				921	unsigned libPos = 0, filePos = 0;
				922	while ( 1 ) {
				923	if ( libIt != Libraries.end() )
				924	libPos = Libraries.getPosition( libIt - Libraries.begin() );
				925	else
				926	libPos = 0;
				927	if ( fileIt != Files.end() )
				928	filePos = Files.getPosition( fileIt - Files.begin() );
				929	else
				930	filePos = 0;
				931
				932	if ( filePos != 0 && (libPos == 0 \|\| filePos < libPos) ) {
				933	// Source File Is next
				934	++fileIt;
				935	}
				936	else if ( libPos != 0 && (filePos == 0 \|\| libPos < filePos) ) {
				937	// Library is next
				938	++libIt;
				939	}
				940	else
				941	break; // we're done with the list
				942	}
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	943	}</pre></div>
				944
Reid Spencer	2c8ab58	2004-08-13 20:19:14 +0000	[diff] [blame]	945	<p>Note that, for compatibility reasons, the <tt>cl::opt</tt> also supports an
				946	<tt>unsigned getPosition()</tt> option that will provide the absolute position
				947	of that option. You can apply the same approach as above with a
				948	<tt>cl::opt</tt> and a <tt>cl::list</tt> option as you can with two lists.</p>
				949	</div>
				950
				951	<!-- _______________________________________________________________________ -->
				952	<div class="doc_subsubsection">
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	953	<a name="cl::ConsumeAfter">The <tt>cl::ConsumeAfter</tt> modifier</a>
				954	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	955
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	956	<div class="doc_text">
				957
				958	<p>The <tt>cl::ConsumeAfter</tt> <a href="#formatting">formatting option</a> is
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	959	used to construct programs that use "interpreter style" option processing. With
				960	this style of option processing, all arguments specified after the last
				961	positional argument are treated as special interpreter arguments that are not
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	962	interpreted by the command line argument.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	963
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	964	<p>As a concrete example, lets say we are developing a replacement for the
				965	standard Unix Bourne shell (<tt>/bin/sh</tt>). To run <tt>/bin/sh</tt>, first
				966	you specify options to the shell itself (like <tt>-x</tt> which turns on trace
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	967	output), then you specify the name of the script to run, then you specify
				968	arguments to the script. These arguments to the script are parsed by the bourne
				969	shell command line option processor, but are not interpreted as options to the
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	970	shell itself. Using the CommandLine library, we would specify this as:</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	971
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	972	<div class="doc_code"><pre>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	973	<a href="#cl::opt">cl::opt</a><string> Script(<a href="#cl::Positional">cl::Positional</a>, <a href="#cl::desc">cl::desc</a>("<i><input script></i>"), <a href="#cl::init">cl::init</a>("-"));
				974	<a href="#cl::list">cl::list</a><string> Argv(<a href="#cl::ConsumeAfter">cl::ConsumeAfter</a>, <a href="#cl::desc">cl::desc</a>("<i><program arguments>...</i>"));
				975	<a href="#cl::opt">cl::opt</a><bool> Trace("<i>x</i>", <a href="#cl::desc">cl::desc</a>("<i>Enable trace output</i>"));
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	976	</pre></div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	977
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	978	<p>which automatically provides the help output:</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	979
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	980	<div class="doc_code"><pre>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	981	USAGE: spiffysh [options] <b><input script> <program arguments>...</b>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	982
				983	OPTIONS:
				984	-help - display available options (--help-hidden for more)
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	985	<b>-x - Enable trace output</b>
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	986	</pre></div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	987
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	988	<p>At runtime, if we run our new shell replacement as `<tt>spiffysh -x test.sh
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	989	-a -x -y bar</tt>', the <tt>Trace</tt> variable will be set to true, the
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	990	<tt>Script</tt> variable will be set to "<tt>test.sh</tt>", and the
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	991	<tt>Argv</tt> list will contain <tt>["-a", "-x", "-y", "bar"]</tt>, because they
				992	were specified after the last positional argument (which is the script
				993	name).</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	994
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	995	<p>There are several limitations to when <tt>cl::ConsumeAfter</tt> options can
				996	be specified. For example, only one <tt>cl::ConsumeAfter</tt> can be specified
				997	per program, there must be at least one <a href="#positional">positional
Chris Lattner	be801bf	2004-05-06 22:03:59 +0000	[diff] [blame]	998	argument</a> specified, there must not be any <a href="#cl::list">cl::list</a>
				999	positional arguments, and the <tt>cl::ConsumeAfter</tt> option should be a <a
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1000	href="#cl::list">cl::list</a> option.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1001
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1002	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1003
				1004	<!-- ======================================================================= -->
Chris Lattner	be801bf	2004-05-06 22:03:59 +0000	[diff] [blame]	1005	<div class="doc_subsection">
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1006	<a name="storage">Internal vs External Storage</a>
				1007	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1008
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1009	<div class="doc_text">
				1010
				1011	<p>By default, all command line options automatically hold the value that they
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1012	parse from the command line. This is very convenient in the common case,
				1013	especially when combined with the ability to define command line options in the
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1014	files that use them. This is called the internal storage model.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1015
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1016	<p>Sometimes, however, it is nice to separate the command line option processing
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1017	code from the storage of the value parsed. For example, lets say that we have a
				1018	'<tt>-debug</tt>' option that we would like to use to enable debug information
				1019	across the entire body of our program. In this case, the boolean value
				1020	controlling the debug code should be globally accessable (in a header file, for
				1021	example) yet the command line option processing code should not be exposed to
				1022	all of these clients (requiring lots of .cpp files to #include
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1023	<tt>CommandLine.h</tt>).</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1024
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1025	<p>To do this, set up your .h file with your option, like this for example:</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1026
Misha Brukman	1fc9f8e	2005-02-09 22:49:05 +0000	[diff] [blame]	1027	<div class="doc_code">
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1028	<pre>
				1029	<i>// DebugFlag.h - Get access to the '-debug' command line option
				1030	//
				1031
				1032	// DebugFlag - This boolean is set to true if the '-debug' command line option
				1033	// is specified. This should probably not be referenced directly, instead, use
				1034	// the DEBUG macro below.
				1035	//</i>
				1036	extern bool DebugFlag;
				1037
				1038	<i>// DEBUG macro - This macro should be used by code to emit debug information.
				1039	// In the '-debug' option is specified on the command line, and if this is a
				1040	// debug build, then the code specified as the option to the macro will be
				1041	// executed. Otherwise it will not be. Example:
				1042	//
Misha Brukman	1fc9f8e	2005-02-09 22:49:05 +0000	[diff] [blame]	1043	// DEBUG(std::cerr << "Bitset contains: " << Bitset << "\n");
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1044	//</i>
Misha Brukman	1fc9f8e	2005-02-09 22:49:05 +0000	[diff] [blame]	1045	<span class="doc_hilite">#ifdef NDEBUG
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1046	#define DEBUG(X)
				1047	#else
Misha Brukman	1fc9f8e	2005-02-09 22:49:05 +0000	[diff] [blame]	1048	#define DEBUG(X)</span> do { if (DebugFlag) { X; } } while (0)
				1049	<span class="doc_hilite">#endif</span>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1050	</pre>
Misha Brukman	1fc9f8e	2005-02-09 22:49:05 +0000	[diff] [blame]	1051	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1052
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1053	<p>This allows clients to blissfully use the <tt>DEBUG()</tt> macro, or the
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1054	<tt>DebugFlag</tt> explicitly if they want to. Now we just need to be able to
				1055	set the <tt>DebugFlag</tt> boolean when the option is set. To do this, we pass
				1056	an additial argument to our command line argument processor, and we specify
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1057	where to fill in with the <a href="#cl::location">cl::location</a>
				1058	attribute:</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1059
Misha Brukman	1fc9f8e	2005-02-09 22:49:05 +0000	[diff] [blame]	1060	<div class="doc_code">
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1061	<pre>
Misha Brukman	1fc9f8e	2005-02-09 22:49:05 +0000	[diff] [blame]	1062	bool DebugFlag; <i>// the actual value</i>
Chris Lattner	589a4cc	2003-08-01 21:30:37 +0000	[diff] [blame]	1063	static <a href="#cl::opt">cl::opt</a><bool, true> <i>// The parser</i>
Misha Brukman	1fc9f8e	2005-02-09 22:49:05 +0000	[diff] [blame]	1064	Debug("<i>debug</i>", <a href="#cl::desc">cl::desc</a>("<i>Enable debug output</i>"), <a href="#cl::Hidden">cl::Hidden</a>, <a href="#cl::location">cl::location</a>(DebugFlag));
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1065	</pre>
Misha Brukman	1fc9f8e	2005-02-09 22:49:05 +0000	[diff] [blame]	1066	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1067
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1068	<p>In the above example, we specify "<tt>true</tt>" as the second argument to
Misha Brukman	1fc9f8e	2005-02-09 22:49:05 +0000	[diff] [blame]	1069	the <tt><a href="#cl::opt">cl::opt</a></tt> template, indicating that the
				1070	template should not maintain a copy of the value itself. In addition to this,
				1071	we specify the <tt><a href="#cl::location">cl::location</a></tt> attribute, so
				1072	that <tt>DebugFlag</tt> is automatically set.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1073
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1074	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1075
				1076	<!-- ======================================================================= -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1077	<div class="doc_subsection">
				1078	<a name="attributes">Option Attributes</a>
				1079	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1080
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1081	<div class="doc_text">
				1082
				1083	<p>This section describes the basic attributes that you can specify on
				1084	options.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1085
				1086	<ul>
				1087
				1088	<li>The option name attribute (which is required for all options, except <a
				1089	href="#positional">positional options</a>) specifies what the option name is.
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1090	This option is specified in simple double quotes:
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1091
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1092	<pre>
				1093	<a href="#cl::opt">cl::opt</a><<b>bool</b>> Quiet("<i>quiet</i>");
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1094	</pre>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1095
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1096	</li>
				1097
				1098	<li><a name="cl::desc">The <b><tt>cl::desc</tt></b></a> attribute specifies a
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1099	description for the option to be shown in the <tt>--help</tt> output for the
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1100	program.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1101
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1102	<li><a name="cl::value_desc">The <b><tt>cl::value_desc</tt></b></a> attribute
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1103	specifies a string that can be used to fine tune the <tt>--help</tt> output for
				1104	a command line option. Look <a href="#value_desc_example">here</a> for an
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1105	example.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1106
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1107	<li><a name="cl::init">The <b><tt>cl::init</tt></b></a> attribute specifies an
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1108	inital value for a <a href="#cl::opt">scalar</a> option. If this attribute is
				1109	not specified then the command line option value defaults to the value created
Brian Gaeke	9d292ff	2003-08-19 22:56:22 +0000	[diff] [blame]	1110	by the default constructor for the type. <b>Warning</b>: If you specify both
				1111	<b><tt>cl::init</tt></b> and <b><tt>cl::location</tt></b> for an option,
				1112	you must specify <b><tt>cl::location</tt></b> first, so that when the
				1113	command-line parser sees <b><tt>cl::init</tt></b>, it knows where to put the
				1114	initial value. (You will get an error at runtime if you don't put them in
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1115	the right order.)</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1116
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1117	<li><a name="cl::location">The <b><tt>cl::location</tt></b></a> attribute where to
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1118	store the value for a parsed command line option if using external storage. See
				1119	the section on <a href="#storage">Internal vs External Storage</a> for more
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1120	information.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1121
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1122	<li><a name="cl::aliasopt">The <b><tt>cl::aliasopt</tt></b></a> attribute
Misha Brukman	1fc9f8e	2005-02-09 22:49:05 +0000	[diff] [blame]	1123	specifies which option a <tt><a href="#cl::alias">cl::alias</a></tt> option is
				1124	an alias for.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1125
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1126	<li><a name="cl::values">The <b><tt>cl::values</tt></b></a> attribute specifies
				1127	the string-to-value mapping to be used by the generic parser. It takes a
Chris Lattner	b406ead	2004-07-16 00:10:54 +0000	[diff] [blame]	1128	<b>clEnumValEnd terminated</b> list of (option, value, description) triplets
				1129	that
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1130	specify the option name, the value mapped to, and the description shown in the
				1131	<tt>--help</tt> for the tool. Because the generic parser is used most
				1132	frequently with enum values, two macros are often useful:
				1133
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1134	<ol>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1135
				1136	<li><a name="clEnumVal">The <b><tt>clEnumVal</tt></b></a> macro is used as a
				1137	nice simple way to specify a triplet for an enum. This macro automatically
				1138	makes the option name be the same as the enum name. The first option to the
				1139	macro is the enum, the second is the description for the command line
				1140	option.</li>
				1141
				1142	<li><a name="clEnumValN">The <b><tt>clEnumValN</tt></b></a> macro is used to
				1143	specify macro options where the option name doesn't equal the enum name. For
				1144	this macro, the first argument is the enum value, the second is the flag name,
				1145	and the second is the description.</li>
				1146
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1147	</ol>
				1148
				1149	You will get a compile time error if you try to use cl::values with a parser
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1150	that does not support it.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1151
				1152	</ul>
				1153
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1154	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1155
				1156	<!-- ======================================================================= -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1157	<div class="doc_subsection">
				1158	<a name="modifiers">Option Modifiers</a>
				1159	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1160
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1161	<div class="doc_text">
				1162
				1163	<p>Option modifiers are the flags and expressions that you pass into the
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1164	constructors for <tt><a href="#cl::opt">cl::opt</a></tt> and <tt><a
				1165	href="#cl::list">cl::list</a></tt>. These modifiers give you the ability to
				1166	tweak how options are parsed and how <tt>--help</tt> output is generated to fit
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1167	your application well.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1168
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1169	<p>These options fall into five main catagories:</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1170
				1171	<ol>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1172	<li><a href="#hiding">Hiding an option from <tt>--help</tt> output</a></li>
				1173	<li><a href="#numoccurrences">Controlling the number of occurrences
				1174	required and allowed</a></li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1175	<li><a href="#valrequired">Controlling whether or not a value must be
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1176	specified</a></li>
				1177	<li><a href="#formatting">Controlling other formatting options</a></li>
				1178	<li><a href="#misc">Miscellaneous option modifiers</a></li>
				1179	</ol>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1180
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1181	<p>It is not possible to specify two options from the same catagory (you'll get
				1182	a runtime error) to a single option, except for options in the miscellaneous
Chris Lattner	32a3284	2003-05-22 20:36:06 +0000	[diff] [blame]	1183	catagory. The CommandLine library specifies defaults for all of these settings
				1184	that are the most useful in practice and the most common, which mean that you
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1185	usually shouldn't have to worry about these.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1186
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1187	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1188
				1189	<!-- _______________________________________________________________________ -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1190	<div class="doc_subsubsection">
				1191	<a name="hiding">Hiding an option from <tt>--help</tt> output</a>
				1192	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1193
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1194	<div class="doc_text">
				1195
				1196	<p>The <tt>cl::NotHidden</tt>, <tt>cl::Hidden</tt>, and
				1197	<tt>cl::ReallyHidden</tt> modifiers are used to control whether or not an option
				1198	appears in the <tt>--help</tt> and <tt>--help-hidden</tt> output for the
				1199	compiled program:</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1200
				1201	<ul>
				1202
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1203	<li><a name="cl::NotHidden">The <b><tt>cl::NotHidden</tt></b></a> modifier
				1204	(which is the default for <tt><a href="#cl::opt">cl::opt</a></tt> and <tt><a
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1205	href="#cl::list">cl::list</a></tt> options), indicates the option is to appear
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1206	in both help listings.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1207
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1208	<li><a name="cl::Hidden">The <b><tt>cl::Hidden</tt></b></a> modifier (which is the
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1209	default for <tt><a href="#cl::alias">cl::alias</a></tt> options), indicates that
				1210	the option should not appear in the <tt>--help</tt> output, but should appear in
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1211	the <tt>--help-hidden</tt> output.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1212
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1213	<li><a name="cl::ReallyHidden">The <b><tt>cl::ReallyHidden</tt></b></a> modifier,
				1214	indicates that the option should not appear in any help output.</li>
				1215
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1216	</ul>
				1217
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1218	</div>
				1219
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1220	<!-- _______________________________________________________________________ -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1221	<div class="doc_subsubsection">
				1222	<a name="numoccurrences">Controlling the number of occurrences required and
				1223	allowed</a>
				1224	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1225
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1226	<div class="doc_text">
				1227
				1228	<p>This group of options is used to control how many time an option is allowed
				1229	(or required) to be specified on the command line of your program. Specifying a
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1230	value for this setting allows the CommandLine library to do error checking for
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1231	you.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1232
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1233	<p>The allowed values for this option group are:</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1234
				1235	<ul>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1236
				1237	<li><a name="cl::Optional">The <b><tt>cl::Optional</tt></b></a> modifier (which
				1238	is the default for the <tt><a href="#cl::opt">cl::opt</a></tt> and <tt><a
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1239	href="#cl::alias">cl::alias</a></tt> classes) indicates that your program will
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1240	allow either zero or one occurrence of the option to be specified.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1241
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1242	<li><a name="cl::ZeroOrMore">The <b><tt>cl::ZeroOrMore</tt></b></a> modifier
				1243	(which is the default for the <tt><a href="#cl::list">cl::list</a></tt> class)
				1244	indicates that your program will allow the option to be specified zero or more
				1245	times.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1246
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1247	<li><a name="cl::Required">The <b><tt>cl::Required</tt></b></a> modifier
				1248	indicates that the specified option must be specified exactly one time.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1249
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1250	<li><a name="cl::OneOrMore">The <b><tt>cl::OneOrMore</tt></b></a> modifier
				1251	indicates that the option must be specified at least one time.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1252
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1253	<li>The <b><tt>cl::ConsumeAfter</tt></b> modifier is described in the <a
				1254	href="#positional">Positional arguments section</a></li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1255
				1256	</ul>
				1257
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1258	<p>If an option is not specified, then the value of the option is equal to the
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1259	value specified by the <tt><a href="#cl::init">cl::init</a></tt> attribute. If
				1260	the <tt><a href="#cl::init">cl::init</a></tt> attribute is not specified, the
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1261	option value is initialized with the default constructor for the data type.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1262
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1263	<p>If an option is specified multiple times for an option of the <tt><a
				1264	href="#cl::opt">cl::opt</a></tt> class, only the last value will be
				1265	retained.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1266
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1267	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1268
				1269	<!-- _______________________________________________________________________ -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1270	<div class="doc_subsubsection">
				1271	<a name="valrequired">Controlling whether or not a value must be specified</a>
				1272	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1273
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1274	<div class="doc_text">
				1275
				1276	<p>This group of options is used to control whether or not the option allows a
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1277	value to be present. In the case of the CommandLine library, a value is either
				1278	specified with an equal sign (e.g. '<tt>-index-depth=17</tt>') or as a trailing
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1279	string (e.g. '<tt>-o a.out</tt>').</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1280
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1281	<p>The allowed values for this option group are:</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1282
				1283	<ul>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1284
				1285	<li><a name="cl::ValueOptional">The <b><tt>cl::ValueOptional</tt></b></a> modifier
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1286	(which is the default for <tt>bool</tt> typed options) specifies that it is
				1287	acceptable to have a value, or not. A boolean argument can be enabled just by
				1288	appearing on the command line, or it can have an explicit '<tt>-foo=true</tt>'.
				1289	If an option is specified with this mode, it is illegal for the value to be
				1290	provided without the equal sign. Therefore '<tt>-foo true</tt>' is illegal. To
				1291	get this behavior, you must use the <a
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1292	href="#cl::ValueRequired">cl::ValueRequired</a> modifier.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1293
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1294	<li><a name="cl::ValueRequired">The <b><tt>cl::ValueRequired</tt></b></a> modifier
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1295	(which is the default for all other types except for <a
				1296	href="#onealternative">unnamed alternatives using the generic parser</a>)
				1297	specifies that a value must be provided. This mode informs the command line
				1298	library that if an option is not provides with an equal sign, that the next
				1299	argument provided must be the value. This allows things like '<tt>-o
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1300	a.out</tt>' to work.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1301
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1302	<li><a name="cl::ValueDisallowed">The <b><tt>cl::ValueDisallowed</tt></b></a>
				1303	modifier (which is the default for <a href="#onealternative">unnamed
				1304	alternatives using the generic parser</a>) indicates that it is a runtime error
				1305	for the user to specify a value. This can be provided to disallow users from
				1306	providing options to boolean options (like '<tt>-foo=true</tt>').</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1307
				1308	</ul>
				1309
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1310	<p>In general, the default values for this option group work just like you would
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1311	want them to. As mentioned above, you can specify the <a
				1312	href="#cl::ValueDisallowed">cl::ValueDisallowed</a> modifier to a boolean
				1313	argument to restrict your command line parser. These options are mostly useful
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1314	when <a href="#extensionguide">extending the library</a>.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1315
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1316	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1317
				1318	<!-- _______________________________________________________________________ -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1319	<div class="doc_subsubsection">
				1320	<a name="formatting">Controlling other formatting options</a>
				1321	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1322
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1323	<div class="doc_text">
				1324
				1325	<p>The formatting option group is used to specify that the command line option
				1326	has special abilities and is otherwise different from other command line
				1327	arguments. As usual, you can only specify at most one of these arguments.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1328
				1329	<ul>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1330
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1331	<li><a name="cl::NormalFormatting">The <b><tt>cl::NormalFormatting</tt></b></a>
				1332	modifier (which is the default all options) specifies that this option is
				1333	"normal".</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1334
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1335	<li><a name="cl::Positional">The <b><tt>cl::Positional</tt></b></a> modifier
				1336	specifies that this is a positional argument, that does not have a command line
				1337	option associated with it. See the <a href="#positional">Positional
				1338	Arguments</a> section for more information.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1339
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1340	<li>The <b><a href="#cl::ConsumeAfter"><tt>cl::ConsumeAfter</tt></a></b> modifier
				1341	specifies that this option is used to capture "interpreter style" arguments. See <a href="#cl::ConsumeAfter">this section for more information</a>.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1342
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1343	<li><a name="cl::Prefix">The <b><tt>cl::Prefix</tt></b></a> modifier specifies
Reid Spencer	5f8448f	2004-11-24 06:13:42 +0000	[diff] [blame]	1344	that this option prefixes its value. With 'Prefix' options, the equal sign does
				1345	not separate the value from the option name specified. Instead, the value is
				1346	everything after the prefix, including any equal sign if present. This is useful
				1347	for processing odd arguments like <tt>-lmalloc</tt> and <tt>-L/usr/lib</tt> in a
Misha Brukman	c43d914	2005-05-10 22:05:27 +0000	[diff] [blame]	1348	linker tool or <tt>-DNAME=value</tt> in a compiler tool. Here, the
Reid Spencer	5f8448f	2004-11-24 06:13:42 +0000	[diff] [blame]	1349	'<tt>l</tt>', '<tt>D</tt>' and '<tt>L</tt>' options are normal string (or list)
Misha Brukman	c43d914	2005-05-10 22:05:27 +0000	[diff] [blame]	1350	options, that have the <b><tt><a href="#cl::Prefix">cl::Prefix</a></tt></b>
				1351	modifier added to allow the CommandLine library to recognize them. Note that
				1352	<b><tt><a href="#cl::Prefix">cl::Prefix</a></tt></b> options must not have the
				1353	<b><tt><a href="#cl::ValueDisallowed">cl::ValueDisallowed</a></tt></b> modifier
				1354	specified.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1355
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1356	<li><a name="cl::Grouping">The <b><tt>cl::Grouping</tt></b></a> modifier is used
				1357	to implement unix style tools (like <tt>ls</tt>) that have lots of single letter
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1358	arguments, but only require a single dash. For example, the '<tt>ls -labF</tt>'
				1359	command actually enables four different options, all of which are single
Misha Brukman	c43d914	2005-05-10 22:05:27 +0000	[diff] [blame]	1360	letters. Note that <b><tt><a href="#cl::Grouping">cl::Grouping</a></tt></b>
				1361	options cannot have values.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1362
				1363	</ul>
				1364
Misha Brukman	c43d914	2005-05-10 22:05:27 +0000	[diff] [blame]	1365	<p>The CommandLine library does not restrict how you use the <b><tt><a
				1366	href="#cl::Prefix">cl::Prefix</a></tt></b> or <b><tt><a
				1367	href="#cl::Grouping">cl::Grouping</a></tt></b> modifiers, but it is possible to
				1368	specify ambiguous argument settings. Thus, it is possible to have multiple
				1369	letter options that are prefix or grouping options, and they will still work as
				1370	designed.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1371
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1372	<p>To do this, the CommandLine library uses a greedy algorithm to parse the
				1373	input option into (potentially multiple) prefix and grouping options. The
				1374	strategy basically looks like this:</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1375
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	1376	<div class="doc_code"><tt>parse(string OrigInput) {</tt>
Misha Brukman	c53aefb	2004-05-12 18:42:35 +0000	[diff] [blame]	1377
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1378	<ol>
				1379	<li><tt>string input = OrigInput;</tt>
				1380	<li><tt>if (isOption(input)) return getOption(input).parse();</tt>    <i>// Normal option</i>
				1381	<li><tt>while (!isOption(input) && !input.empty()) input.pop_back();</tt>    <i>// Remove the last letter</i>
				1382	<li><tt>if (input.empty()) return error();</tt>    <i>// No matching option</i>
				1383	<li><tt>if (getOption(input).isPrefix())<br>
				1384	return getOption(input).parse(input);</tt>
				1385	<li><tt>while (!input.empty()) {    <i>// Must be grouping options</i><br>
				1386	getOption(input).parse();<br>
				1387	OrigInput.erase(OrigInput.begin(), OrigInput.begin()+input.length());<br>
				1388	input = OrigInput;<br>
				1389	while (!isOption(input) && !input.empty()) input.pop_back();<br>
				1390	}</tt>
Misha Brukman	c53aefb	2004-05-12 18:42:35 +0000	[diff] [blame]	1391	<li><tt>if (!OrigInput.empty()) error();</tt></li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1392	</ol>
Misha Brukman	c53aefb	2004-05-12 18:42:35 +0000	[diff] [blame]	1393
				1394	<p><tt>}</tt></p>
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	1395	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1396
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1397	</div>
Chris Lattner	32a3284	2003-05-22 20:36:06 +0000	[diff] [blame]	1398
				1399	<!-- _______________________________________________________________________ -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1400	<div class="doc_subsubsection">
				1401	<a name="misc">Miscellaneous option modifiers</a>
				1402	</div>
Chris Lattner	32a3284	2003-05-22 20:36:06 +0000	[diff] [blame]	1403
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1404	<div class="doc_text">
				1405
				1406	<p>The miscellaneous option modifiers are the only flags where you can specify
				1407	more than one flag from the set: they are not mutually exclusive. These flags
				1408	specify boolean properties that modify the option.</p>
Chris Lattner	32a3284	2003-05-22 20:36:06 +0000	[diff] [blame]	1409
				1410	<ul>
				1411
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1412	<li><a name="cl::CommaSeparated">The <b><tt>cl::CommaSeparated</tt></b></a> modifier
Chris Lattner	32a3284	2003-05-22 20:36:06 +0000	[diff] [blame]	1413	indicates that any commas specified for an option's value should be used to
				1414	split the value up into multiple values for the option. For example, these two
				1415	options are equivalent when <tt>cl::CommaSeparated</tt> is specified:
				1416	"<tt>-foo=a -foo=b -foo=c</tt>" and "<tt>-foo=a,b,c</tt>". This option only
				1417	makes sense to be used in a case where the option is allowed to accept one or
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1418	more values (i.e. it is a <a href="#cl::list">cl::list</a> option).</li>
				1419
Chris Lattner	be801bf	2004-05-06 22:03:59 +0000	[diff] [blame]	1420	<li><a name="cl::PositionalEatsArgs">The
				1421	<b><tt>cl::PositionalEatsArgs</tt></b></a> modifier (which only applies to
				1422	positional arguments, and only makes sense for lists) indicates that positional
				1423	argument should consume any strings after it (including strings that start with
				1424	a "-") up until another recognized positional argument. For example, if you
				1425	have two "eating" positional arguments "<tt>pos1</tt>" and "<tt>pos2</tt>" the
				1426	string "<tt>-pos1 -foo -bar baz -pos2 -bork</tt>" would cause the "<tt>-foo -bar
				1427	-baz</tt>" strings to be applied to the "<tt>-pos1</tt>" option and the
				1428	"<tt>-bork</tt>" string to be applied to the "<tt>-pos2</tt>" option.</li>
				1429
Chris Lattner	32a3284	2003-05-22 20:36:06 +0000	[diff] [blame]	1430	</ul>
				1431
Chris Lattner	be801bf	2004-05-06 22:03:59 +0000	[diff] [blame]	1432	<p>So far, these are the only two miscellaneous option modifiers.</p>
Chris Lattner	32a3284	2003-05-22 20:36:06 +0000	[diff] [blame]	1433
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1434	</div>
Chris Lattner	32a3284	2003-05-22 20:36:06 +0000	[diff] [blame]	1435
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1436	<!-- ======================================================================= -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1437	<div class="doc_subsection">
				1438	<a name="toplevel">Top-Level Classes and Functions</a>
				1439	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1440
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1441	<div class="doc_text">
				1442
				1443	<p>Despite all of the built-in flexibility, the CommandLine option library
				1444	really only consists of one function (<a
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1445	href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>)
				1446	and three main classes: <a href="#cl::opt"><tt>cl::opt</tt></a>, <a
				1447	href="#cl::list"><tt>cl::list</tt></a>, and <a
				1448	href="#cl::alias"><tt>cl::alias</tt></a>. This section describes these three
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1449	classes in detail.</p>
				1450
				1451	</div>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1452
				1453	<!-- _______________________________________________________________________ -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1454	<div class="doc_subsubsection">
				1455	<a name="cl::ParseCommandLineOptions">The <tt>cl::ParseCommandLineOptions</tt>
				1456	function</a>
				1457	</div>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1458
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1459	<div class="doc_text">
				1460
				1461	<p>The <tt>cl::ParseCommandLineOptions</tt> function is designed to be called
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1462	directly from <tt>main</tt>, and is used to fill in the values of all of the
				1463	command line option variables once <tt>argc</tt> and <tt>argv</tt> are
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1464	available.</p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1465
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1466	<p>The <tt>cl::ParseCommandLineOptions</tt> function requires two parameters
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1467	(<tt>argc</tt> and <tt>argv</tt>), but may also take an optional third parameter
				1468	which holds <a href="#description">additional extra text</a> to emit when the
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1469	<tt>--help</tt> option is invoked.</p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1470
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1471	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1472
				1473	<!-- _______________________________________________________________________ -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1474	<div class="doc_subsubsection">
				1475	<a name="cl::ParseEnvironmentOptions">The <tt>cl::ParseEnvironmentOptions</tt>
				1476	function</a>
				1477	</div>
Brian Gaeke	e584285	2003-08-19 23:11:43 +0000	[diff] [blame]	1478
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1479	<div class="doc_text">
Brian Gaeke	e584285	2003-08-19 23:11:43 +0000	[diff] [blame]	1480
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1481	<p>The <tt>cl::ParseEnvironmentOptions</tt> function has mostly the same effects
				1482	as <a
				1483	href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>,
				1484	except that it is designed to take values for options from an environment
				1485	variable, for those cases in which reading the command line is not convenient or
				1486	not desired. It fills in the values of all the command line option variables
				1487	just like <a
				1488	href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>
				1489	does.</p>
				1490
				1491	<p>It takes three parameters: first, the name of the program (since
				1492	<tt>argv</tt> may not be available, it can't just look in <tt>argv[0]</tt>),
				1493	second, the name of the environment variable to examine, and third, the optional
Brian Gaeke	e584285	2003-08-19 23:11:43 +0000	[diff] [blame]	1494	<a href="#description">additional extra text</a> to emit when the
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1495	<tt>--help</tt> option is invoked.</p>
Brian Gaeke	e584285	2003-08-19 23:11:43 +0000	[diff] [blame]	1496
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1497	<p><tt>cl::ParseEnvironmentOptions</tt> will break the environment
Brian Gaeke	e584285	2003-08-19 23:11:43 +0000	[diff] [blame]	1498	variable's value up into words and then process them using
				1499	<a href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>.
				1500	<b>Note:</b> Currently <tt>cl::ParseEnvironmentOptions</tt> does not support
				1501	quoting, so an environment variable containing <tt>-option "foo bar"</tt> will
				1502	be parsed as three words, <tt>-option</tt>, <tt>"foo</tt>, and <tt>bar"</tt>,
				1503	which is different from what you would get from the shell with the same
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1504	input.</p>
				1505
				1506	</div>
Brian Gaeke	e584285	2003-08-19 23:11:43 +0000	[diff] [blame]	1507
				1508	<!-- _______________________________________________________________________ -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1509	<div class="doc_subsubsection">
				1510	<a name="cl::opt">The <tt>cl::opt</tt> class</a>
				1511	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1512
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1513	<div class="doc_text">
				1514
				1515	<p>The <tt>cl::opt</tt> class is the class used to represent scalar command line
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1516	options, and is the one used most of the time. It is a templated class which
				1517	can take up to three arguments (all except for the first have default values
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1518	though):</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1519
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	1520	<div class="doc_code"><pre>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1521	<b>namespace</b> cl {
				1522	<b>template</b> <<b>class</b> DataType, <b>bool</b> ExternalStorage = <b>false</b>,
				1523	<b>class</b> ParserClass = parser<DataType> >
				1524	<b>class</b> opt;
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1525	}
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	1526	</pre></div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1527
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1528	<p>The first template argument specifies what underlying data type the command
				1529	line argument is, and is used to select a default parser implementation. The
				1530	second template argument is used to specify whether the option should contain
				1531	the storage for the option (the default) or whether external storage should be
				1532	used to contain the value parsed for the option (see <a href="#storage">Internal
				1533	vs External Storage</a> for more information).</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1534
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1535	<p>The third template argument specifies which parser to use. The default value
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1536	selects an instantiation of the <tt>parser</tt> class based on the underlying
				1537	data type of the option. In general, this default works well for most
				1538	applications, so this option is only used when using a <a
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1539	href="#customparser">custom parser</a>.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1540
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1541	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1542
				1543	<!-- _______________________________________________________________________ -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1544	<div class="doc_subsubsection">
				1545	<a name="cl::list">The <tt>cl::list</tt> class</a>
				1546	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1547
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1548	<div class="doc_text">
				1549
				1550	<p>The <tt>cl::list</tt> class is the class used to represent a list of command
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1551	line options. It too is a templated class which can take up to three
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1552	arguments:</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1553
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	1554	<div class="doc_code"><pre>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1555	<b>namespace</b> cl {
				1556	<b>template</b> <<b>class</b> DataType, <b>class</b> Storage = <b>bool</b>,
				1557	<b>class</b> ParserClass = parser<DataType> >
				1558	<b>class</b> list;
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1559	}
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	1560	</pre></div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1561
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1562	<p>This class works the exact same as the <a
				1563	href="#cl::opt"><tt>cl::opt</tt></a> class, except that the second argument is
				1564	the <b>type</b> of the external storage, not a boolean value. For this class,
				1565	the marker type '<tt>bool</tt>' is used to indicate that internal storage should
				1566	be used.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1567
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1568	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1569
				1570	<!-- _______________________________________________________________________ -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1571	<div class="doc_subsubsection">
Jim Laskey	1d8f626	2005-08-25 22:52:43 +0000	[diff] [blame]	1572	<a name="cl::bits">The <tt>cl::bits</tt> class</a>
				1573	</div>
				1574
				1575	<div class="doc_text">
				1576
				1577	<p>The <tt>cl::bits</tt> class is the class used to represent a list of command
				1578	line options in the form of a bit vector. It is also a templated class which
				1579	can take up to three arguments:</p>
				1580
				1581	<div class="doc_code"><pre>
				1582	<b>namespace</b> cl {
				1583	<b>template</b> <<b>class</b> DataType, <b>class</b> Storage = <b>bool</b>,
				1584	<b>class</b> ParserClass = parser<DataType> >
				1585	<b>class</b> bits;
				1586	}
				1587	</pre></div>
				1588
				1589	<p>This class works the exact same as the <a
				1590	href="#cl::opt"><tt>cl::lists</tt></a> class, except that the second argument
Jim Laskey	22b7dfa	2005-08-26 09:25:54 +0000	[diff] [blame]	1591	must be of <b>type</b> <tt>unsigned</tt> if external storage is used.</p>
Jim Laskey	1d8f626	2005-08-25 22:52:43 +0000	[diff] [blame]	1592
				1593	</div>
				1594
				1595	<!-- _______________________________________________________________________ -->
				1596	<div class="doc_subsubsection">
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1597	<a name="cl::alias">The <tt>cl::alias</tt> class</a>
				1598	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1599
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1600	<div class="doc_text">
				1601
				1602	<p>The <tt>cl::alias</tt> class is a nontemplated class that is used to form
				1603	aliases for other arguments.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1604
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	1605	<div class="doc_code"><pre>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1606	<b>namespace</b> cl {
				1607	<b>class</b> alias;
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1608	}
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	1609	</pre></div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1610
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1611	<p>The <a href="#cl::aliasopt"><tt>cl::aliasopt</tt></a> attribute should be
				1612	used to specify which option this is an alias for. Alias arguments default to
				1613	being <a href="#cl::Hidden">Hidden</a>, and use the aliased options parser to do
				1614	the conversion from string to data.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1615
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1616	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1617
Reid Spencer	9bbba091	2004-11-16 06:11:52 +0000	[diff] [blame]	1618	<!-- _______________________________________________________________________ -->
				1619	<div class="doc_subsubsection">
				1620	<a name="cl::extrahelp">The <tt>cl::extrahelp</tt> class</a>
				1621	</div>
				1622
				1623	<div class="doc_text">
				1624
				1625	<p>The <tt>cl::extrahelp</tt> class is a nontemplated class that allows extra
				1626	help text to be printed out for the <tt>--help</tt> option.</p>
				1627
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	1628	<div class="doc_code"><pre>
Reid Spencer	9bbba091	2004-11-16 06:11:52 +0000	[diff] [blame]	1629	<b>namespace</b> cl {
				1630	<b>struct</b> extrahelp;
				1631	}
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	1632	</pre></div>
Reid Spencer	9bbba091	2004-11-16 06:11:52 +0000	[diff] [blame]	1633
				1634	<p>To use the extrahelp, simply construct one with a <tt>const char*</tt>
				1635	parameter to the constructor. The text passed to the constructor will be printed
				1636	at the bottom of the help message, verbatim. Note that multiple
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	1637	<tt>cl::extrahelp</tt> <b>can</b> be used, but this practice is discouraged. If
Reid Spencer	9bbba091	2004-11-16 06:11:52 +0000	[diff] [blame]	1638	your tool needs to print additional help information, put all that help into a
				1639	single <tt>cl::extrahelp</tt> instance.</p>
				1640	<p>For example:</p>
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	1641	<div class="doc_code"><pre>
Reid Spencer	9bbba091	2004-11-16 06:11:52 +0000	[diff] [blame]	1642	cl::extrahelp("\nADDITIONAL HELP:\n\n This is the extra help\n");
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	1643	</pre></div>
Reid Spencer	9bbba091	2004-11-16 06:11:52 +0000	[diff] [blame]	1644	</div>
				1645
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1646	<!-- ======================================================================= -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1647	<div class="doc_subsection">
				1648	<a name="builtinparsers">Builtin parsers</a>
				1649	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1650
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1651	<div class="doc_text">
				1652
				1653	<p>Parsers control how the string value taken from the command line is
				1654	translated into a typed value, suitable for use in a C++ program. By default,
				1655	the CommandLine library uses an instance of <tt>parser<type></tt> if the
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1656	command line option specifies that it uses values of type '<tt>type</tt>'.
				1657	Because of this, custom option processing is specified with specializations of
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1658	the '<tt>parser</tt>' class.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1659
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1660	<p>The CommandLine library provides the following builtin parser
				1661	specializations, which are sufficient for most applications. It can, however,
				1662	also be extended to work with new data types and new ways of interpreting the
				1663	same data. See the <a href="#customparser">Writing a Custom Parser</a> for more
				1664	details on this type of library extension.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1665
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1666	<ul>
				1667
				1668	<li><a name="genericparser">The <b>generic <tt>parser<t></tt> parser</b></a>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1669	can be used to map strings values to any data type, through the use of the <a
				1670	href="#cl::values">cl::values</a> property, which specifies the mapping
				1671	information. The most common use of this parser is for parsing enum values,
				1672	which allows you to use the CommandLine library for all of the error checking to
				1673	make sure that only valid enum values are specified (as opposed to accepting
				1674	arbitrary strings). Despite this, however, the generic parser class can be used
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1675	for any data type.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1676
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1677	<li><a name="boolparser">The <b><tt>parser<bool></tt> specialization</b></a>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1678	is used to convert boolean strings to a boolean value. Currently accepted
				1679	strings are "<tt>true</tt>", "<tt>TRUE</tt>", "<tt>True</tt>", "<tt>1</tt>",
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1680	"<tt>false</tt>", "<tt>FALSE</tt>", "<tt>False</tt>", and "<tt>0</tt>".</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1681
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1682	<li><a name="stringparser">The <b><tt>parser<string></tt>
				1683	specialization</b></a> simply stores the parsed string into the string value
				1684	specified. No conversion or modification of the data is performed.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1685
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1686	<li><a name="intparser">The <b><tt>parser<int></tt> specialization</b></a>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1687	uses the C <tt>strtol</tt> function to parse the string input. As such, it will
				1688	accept a decimal number (with an optional '+' or '-' prefix) which must start
				1689	with a non-zero digit. It accepts octal numbers, which are identified with a
				1690	'<tt>0</tt>' prefix digit, and hexadecimal numbers with a prefix of
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1691	'<tt>0x</tt>' or '<tt>0X</tt>'.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1692
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1693	<li><a name="doubleparser">The <b><tt>parser<double></tt></b></a> and
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1694	<b><tt>parser<float></tt> specializations</b> use the standard C
				1695	<tt>strtod</tt> function to convert floating point strings into floating point
				1696	values. As such, a broad range of string formats is supported, including
				1697	exponential notation (ex: <tt>1.7e15</tt>) and properly supports locales.
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1698	</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1699
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1700	</ul>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	1701
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1702	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	1703
				1704	<!-- *********************************************************************** -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1705	<div class="doc_section">
				1706	<a name="extensionguide">Extension Guide</a>
				1707	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	1708	<!-- *********************************************************************** -->
				1709
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1710	<div class="doc_text">
				1711
				1712	<p>Although the CommandLine library has a lot of functionality built into it
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1713	already (as discussed previously), one of its true strengths lie in its
				1714	extensibility. This section discusses how the CommandLine library works under
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1715	the covers and illustrates how to do some simple, common, extensions.</p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1716
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1717	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	1718
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1719	<!-- ======================================================================= -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1720	<div class="doc_subsection">
				1721	<a name="customparser">Writing a custom parser</a>
				1722	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1723
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1724	<div class="doc_text">
				1725
				1726	<p>One of the simplest and most common extensions is the use of a custom parser.
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1727	As <a href="#builtinparsers">discussed previously</a>, parsers are the portion
				1728	of the CommandLine library that turns string input from the user into a
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1729	particular parsed data type, validating the input in the process.</p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1730
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1731	<p>There are two ways to use a new parser:</p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1732
				1733	<ol>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1734
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1735	<li>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1736
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1737	<p>Specialize the <a href="#genericparser"><tt>cl::parser</tt></a> template for
				1738	your custom data type.<p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1739
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1740	<p>This approach has the advantage that users of your custom data type will
				1741	automatically use your custom parser whenever they define an option with a value
				1742	type of your data type. The disadvantage of this approach is that it doesn't
				1743	work if your fundemental data type is something that is already supported.</p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1744
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1745	</li>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1746
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1747	<li>
				1748
				1749	<p>Write an independent class, using it explicitly from options that need
				1750	it.</p>
				1751
				1752	<p>This approach works well in situations where you would line to parse an
				1753	option using special syntax for a not-very-special data-type. The drawback of
				1754	this approach is that users of your parser have to be aware that they are using
				1755	your parser, instead of the builtin ones.</p>
				1756
				1757	</li>
				1758
				1759	</ol>
				1760
				1761	<p>To guide the discussion, we will discuss a custom parser that accepts file
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1762	sizes, specified with an optional unit after the numeric size. For example, we
				1763	would like to parse "102kb", "41M", "1G" into the appropriate integer value. In
				1764	this case, the underlying data type we want to parse into is
				1765	'<tt>unsigned</tt>'. We choose approach #2 above because we don't want to make
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1766	this the default for all <tt>unsigned</tt> options.</p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1767
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1768	<p>To start out, we declare our new <tt>FileSizeParser</tt> class:</p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1769
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	1770	<div class="doc_code"><pre>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1771	<b>struct</b> FileSizeParser : <b>public</b> cl::basic_parser<<b>unsigned</b>> {
				1772	<i>// parse - Return true on error.</i>
				1773	<b>bool</b> parse(cl::Option &O, <b>const char</b> *ArgName, <b>const</b> std::string &ArgValue,
				1774	<b>unsigned</b> &Val);
				1775	};
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	1776	</pre></div>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1777
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1778	<p>Our new class inherits from the <tt>cl::basic_parser</tt> template class to
				1779	fill in the default, boiler plate, code for us. We give it the data type that
				1780	we parse into (the last argument to the <tt>parse</tt> method so that clients of
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1781	our custom parser know what object type to pass in to the parse method (here we
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1782	declare that we parse into '<tt>unsigned</tt>' variables.</p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1783
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1784	<p>For most purposes, the only method that must be implemented in a custom
				1785	parser is the <tt>parse</tt> method. The <tt>parse</tt> method is called
				1786	whenever the option is invoked, passing in the option itself, the option name,
				1787	the string to parse, and a reference to a return value. If the string to parse
				1788	is not well formed, the parser should output an error message and return true.
				1789	Otherwise it should return false and set '<tt>Val</tt>' to the parsed value. In
				1790	our example, we implement <tt>parse</tt> as:</p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1791
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	1792	<div class="doc_code"><pre>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1793	<b>bool</b> FileSizeParser::parse(cl::Option &O, <b>const char</b> *ArgName,
				1794	<b>const</b> std::string &Arg, <b>unsigned</b> &Val) {
				1795	<b>const char</b> *ArgStart = Arg.c_str();
				1796	<b>char</b> *End;
				1797
				1798	<i>// Parse integer part, leaving 'End' pointing to the first non-integer char</i>
				1799	Val = (unsigned)strtol(ArgStart, &End, 0);
				1800
				1801	<b>while</b> (1) {
				1802	<b>switch</b> (*End++) {
Chris Lattner	ce5fcc3	2005-08-22 16:24:25 +0000	[diff] [blame]	1803	<b>case</b> 0: <b>return</b> false; <i>// No error</i>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1804	<b>case</b> 'i': <i>// Ignore the 'i' in KiB if people use that</i>
				1805	<b>case</b> 'b': <b>case</b> 'B': <i>// Ignore B suffix</i>
				1806	<b>break</b>;
				1807
				1808	<b>case</b> 'g': <b>case</b> 'G': Val = 10241024*1024; <b>break</b>;
				1809	<b>case</b> 'm': <b>case</b> 'M': Val = 10241024; <b>break</b>;
				1810	<b>case</b> 'k': <b>case</b> 'K': Val *= 1024; <b>break</b>;
				1811
				1812	default:
				1813	<i>// Print an error message if unrecognized character!</i>
				1814	<b>return</b> O.error(": '" + Arg + "' value invalid for file size argument!");
				1815	}
				1816	}
				1817	}
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	1818	</pre></div>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1819
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1820	<p>This function implements a very simple parser for the kinds of strings we are
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1821	interested in. Although it has some holes (it allows "<tt>123KKK</tt>" for
				1822	example), it is good enough for this example. Note that we use the option
				1823	itself to print out the error message (the <tt>error</tt> method always returns
				1824	true) in order to get a nice error message (shown below). Now that we have our
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1825	parser class, we can use it like this:</p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1826
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	1827	<div class="doc_code"><pre>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1828	<b>static</b> <a href="#cl::opt">cl::opt</a><<b>unsigned</b>, <b>false</b>, FileSizeParser>
				1829	MFS(<i>"max-file-size"</i>, <a href="#cl::desc">cl::desc</a>(<i>"Maximum file size to accept"</i>),
				1830	<a href="#cl::value_desc">cl::value_desc</a>("<i>size</i>"));
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	1831	</pre></div>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1832
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1833	<p>Which adds this to the output of our program:</p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1834
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	1835	<div class="doc_code"><pre>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1836	OPTIONS:
				1837	-help - display available options (--help-hidden for more)
				1838	...
				1839	<b>-max-file-size=<size> - Maximum file size to accept</b>
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	1840	</pre></div>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1841
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1842	<p>And we can test that our parse works correctly now (the test program just
				1843	prints out the max-file-size argument value):</p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1844
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	1845	<div class="doc_code"><pre>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1846	$ ./test
				1847	MFS: 0
				1848	$ ./test -max-file-size=123MB
				1849	MFS: 128974848
				1850	$ ./test -max-file-size=3G
				1851	MFS: 3221225472
				1852	$ ./test -max-file-size=dog
				1853	-max-file-size option: 'dog' value invalid for file size argument!
Misha Brukman	f75c4b4	2005-03-11 00:00:33 +0000	[diff] [blame]	1854	</pre></div>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1855
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1856	<p>It looks like it works. The error message that we get is nice and helpful,
				1857	and we seem to accept reasonable file sizes. This wraps up the "custom parser"
				1858	tutorial.</p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1859
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1860	</div>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1861
				1862	<!-- ======================================================================= -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1863	<div class="doc_subsection">
				1864	<a name="explotingexternal">Exploiting external storage</a>
				1865	</div>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1866
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1867	<div class="doc_text">
Reid Spencer	b993feb	2004-08-30 05:56:51 +0000	[diff] [blame]	1868	<p>Several of the LLVM libraries define static <tt>cl::opt</tt> instances that
				1869	will automatically be included in any program that links with that library.
				1870	This is a feature. However, sometimes it is necessary to know the value of the
				1871	command line option outside of the library. In these cases the library does or
				1872	should provide an external storage location that is accessible to users of the
				1873	library. Examples of this include the <tt>llvm::DebugFlag</tt> exported by the
				1874	<tt>lib/Support/Debug.cpp</tt> file and the <tt>llvm::TimePassesIsEnabled</tt>
				1875	flag exported by the <tt>lib/VMCore/Pass.cpp</tt> file.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1876
Reid Spencer	b993feb	2004-08-30 05:56:51 +0000	[diff] [blame]	1877	<p>TODO: complete this section</p>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1878
				1879	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1880
				1881	<!-- ======================================================================= -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1882	<div class="doc_subsection">
				1883	<a name="dynamicopts">Dynamically adding command line options</a>
				1884	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1885
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1886	<div class="doc_text">
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1887
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1888	<p>TODO: fill in this section</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	1889
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1890	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	1891
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	1892	<!-- *********************************************************************** -->
				1893
				1894	<hr>
Misha Brukman	c53aefb	2004-05-12 18:42:35 +0000	[diff] [blame]	1895	<address>
				1896	<a href="http://jigsaw.w3.org/css-validator/check/referer"><img
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				1900
				1901	<a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
Reid Spencer	05fe4b0	2006-03-14 05:39:39 +0000	[diff] [blame]	1902	<a href="http://llvm.org">LLVM Compiler Infrastructure</a><br>
Misha Brukman	3c29911	2003-11-07 18:11:14 +0000	[diff] [blame]	1903	Last modified: $Date$
Misha Brukman	c53aefb	2004-05-12 18:42:35 +0000	[diff] [blame]	1904	</address>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1905
				1906	</body>
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