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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>
				26	<li><a href="#description">Adding freeform text to help output</a></li>
				27	</ol></li>
				28
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	29	<li><a href="#referenceguide">Reference Guide</a>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	30	<ol>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	31	<li><a href="#positional">Positional Arguments</a>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	32	<ul>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	33	<li><a href="#--">Specifying positional options with hyphens</a></li>
Reid Spencer	2c8ab58	2004-08-13 20:19:14 +0000	[diff] [blame]	34	<li><a href="#getPosition">Determining absolute position with
				35	getPosition</a></li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	36	<li><a href="#cl::ConsumeAfter">The <tt>cl::ConsumeAfter</tt>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	37	modifier</a></li>
				38	</ul></li>
				39
				40	<li><a href="#storage">Internal vs External Storage</a></li>
				41
				42	<li><a href="#attributes">Option Attributes</a></li>
				43
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	44	<li><a href="#modifiers">Option Modifiers</a>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	45	<ul>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	46	<li><a href="#hiding">Hiding an option from <tt>--help</tt>
				47	output</a></li>
				48	<li><a href="#numoccurrences">Controlling the number of occurrences
				49	required and allowed</a></li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	50	<li><a href="#valrequired">Controlling whether or not a value must be
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	51	specified</a></li>
				52	<li><a href="#formatting">Controlling other formatting options</a></li>
				53	<li><a href="#misc">Miscellaneous option modifiers</a></li>
				54	</ul></li>
				55
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	56	<li><a href="#toplevel">Top-Level Classes and Functions</a>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	57	<ul>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	58	<li><a href="#cl::ParseCommandLineOptions">The
				59	<tt>cl::ParseCommandLineOptions</tt> function</a></li>
				60	<li><a href="#cl::ParseEnvironmentOptions">The
				61	<tt>cl::ParseEnvironmentOptions</tt> function</a></li>
				62	<li><a href="#cl::opt">The <tt>cl::opt</tt> class</a></li>
				63	<li><a href="#cl::list">The <tt>cl::list</tt> class</a></li>
				64	<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]	65	<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]	66	</ul></li>
				67
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	68	<li><a href="#builtinparsers">Builtin parsers</a>
				69	<ul>
				70	<li><a href="#genericparser">The Generic <tt>parser<t></tt>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	71	parser</a></li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	72	<li><a href="#boolparser">The <tt>parser<bool></tt>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	73	specialization</a></li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	74	<li><a href="#stringparser">The <tt>parser<string></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="#intparser">The <tt>parser<int></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="#doubleparser">The <tt>parser<double></tt> and
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	79	<tt>parser<float></tt> specializations</a></li>
				80	</ul></li>
				81	</ol></li>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	82	<li><a href="#extensionguide">Extension Guide</a>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	83	<ol>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	84	<li><a href="#customparser">Writing a custom parser</a></li>
				85	<li><a href="#explotingexternal">Exploiting external storage</a></li>
				86	<li><a href="#dynamicopts">Dynamically adding command line
				87	options</a></li>
				88	</ol></li>
				89	</ol>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	90
Chris Lattner	7911ce2	2004-05-23 21:07:27 +0000	[diff] [blame]	91	<div class="doc_author">
				92	<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]	93	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	94
				95	<!-- *********************************************************************** -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	96	<div class="doc_section">
Misha Brukman	8becd71	2003-11-07 19:42:44 +0000	[diff] [blame]	97	<a name="introduction">Introduction</a>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	98	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	99	<!-- *********************************************************************** -->
				100
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	101	<div class="doc_text">
				102
				103	<p>This document describes the CommandLine argument processing library. It will
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	104	show you how to use it, and what it can do. The CommandLine library uses a
				105	declarative approach to specifying the command line options that your program
				106	takes. By default, these options declarations implicitly hold the value parsed
				107	for the option declared (of course this <a href="#storage">can be
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	108	changed</a>).</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	109
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	110	<p>Although there are a <b>lot</b> of command line argument parsing libraries
				111	out there in many different languages, none of them fit well with what I needed.
				112	By looking at the features and problems of other libraries, I designed the
				113	CommandLine library to have the following features:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	114
				115	<ol>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	116	<li>Speed: The CommandLine library is very quick and uses little resources. The
				117	parsing time of the library is directly proportional to the number of arguments
				118	parsed, not the the number of options recognized. Additionally, command line
Chris Lattner	edf351f	2003-06-21 21:45:56 +0000	[diff] [blame]	119	argument values are captured transparently into user defined global variables,
				120	which can be accessed like any other variable (and with the same
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	121	performance).</li>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	122
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	123	<li>Type Safe: As a user of CommandLine, you don't have to worry about
				124	remembering the type of arguments that you want (is it an int? a string? a
				125	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]	126	error prone constructs, it also leads to dramatically cleaner source code.</li>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	127
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	128	<li>No subclasses required: To use CommandLine, you instantiate variables that
				129	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]	130	parser. This means that you don't have to write <b>any</b> boilerplate
				131	code.</li>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	132
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	133	<li>Globally accessible: Libraries can specify command line arguments that are
				134	automatically enabled in any tool that links to the library. This is possible
				135	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]	136	the parser. This also makes supporting <a href="#dynamicopts">dynamically
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	137	loaded options</a> trivial.</li>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	138
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	139	<li>Cleaner: CommandLine supports enum and other types directly, meaning that
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	140	there is less error and more security built into the library. You don't have to
				141	worry about whether your integral command line argument accidentally got
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	142	assigned a value that is not valid for your enum type.</li>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	143
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	144	<li>Powerful: The CommandLine library supports many different types of
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	145	arguments, from simple <a href="#boolparser">boolean flags</a> to <a
				146	href="#cl::opt">scalars arguments</a> (<a href="#stringparser">strings</a>, <a
				147	href="#intparser">integers</a>, <a href="#genericparser">enums</a>, <a
				148	href="#doubleparser">doubles</a>), to <a href="#cl::list">lists of
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	149	arguments</a>. This is possible because CommandLine is...</li>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	150
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	151	<li>Extensible: It is very simple to add a new argument type to CommandLine.
				152	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]	153	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]	154
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	155	<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]	156	that you, the user, have to do. For example, it automatically provides a
				157	<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]	158	tool. Additionally, it does most of the basic correctness checking for
				159	you.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	160
				161	<li>Capable: The CommandLine library can handle lots of different forms of
				162	options often found in real programs. For example, <a
				163	href="#positional">positional</a> arguments, <tt>ls</tt> style <a
				164	href="#cl::Grouping">grouping</a> options (to allow processing '<tt>ls
				165	-lad</tt>' naturally), <tt>ld</tt> style <a href="#cl::Prefix">prefix</a>
				166	options (to parse '<tt>-lmalloc -L/usr/lib</tt>'), and <a
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	167	href="#cl::ConsumeAfter">interpreter style options</a>.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	168
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	169	</ol>
				170
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	171	<p>This document will hopefully let you jump in and start using CommandLine in
				172	your utility quickly and painlessly. Additionally it should be a simple
				173	reference manual to figure out how stuff works. If it is failing in some area
				174	(or you want an extension to the library), nag the author, <a
				175	href="mailto:sabre@nondot.org">Chris Lattner</a>.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	176
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	177	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	178
				179	<!-- *********************************************************************** -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	180	<div class="doc_section">
				181	<a name="quickstart">Quick Start Guide</a>
				182	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	183	<!-- *********************************************************************** -->
				184
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	185	<div class="doc_text">
				186
				187	<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]	188	basic compiler tool. This is intended to show you how to jump into using the
				189	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]	190	can do.</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	191
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	192	<p>To start out, you need to include the CommandLine header file into your
				193	program:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	194
				195	<pre>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	196	#include "Support/CommandLine.h"
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	197	</pre>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	198
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	199	<p>Additionally, you need to add this as the first line of your main
				200	program:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	201
				202	<pre>
				203	int main(int argc, char **argv) {
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	204	<a href="#cl::ParseCommandLineOptions">cl::ParseCommandLineOptions</a>(argc, argv);
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	205	...
				206	}
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	207	</pre>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	208
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	209	<p>... which actually parses the arguments and fills in the variable
				210	declarations.</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	211
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	212	<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]	213	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]	214	library uses a declarative syntax to model command line arguments with the
				215	global variable declarations that capture the parsed values. This means that
				216	for every command line option that you would like to support, there should be a
				217	global variable declaration to capture the result. For example, in a compiler,
				218	we would like to support the unix standard '<tt>-o <filename></tt>' option
				219	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]	220	represented like this:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	221
Misha Brukman	c53aefb	2004-05-12 18:42:35 +0000	[diff] [blame]	222	<a name="value_desc_example"></a>
				223	<pre>
				224	<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>"));
				225	</pre>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	226
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	227	<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]	228	capture the result of the "<tt>o</tt>" argument (first parameter). We specify
				229	that this is a simple scalar option by using the "<tt><a
				230	href="#cl::opt">cl::opt</a></tt>" template (as opposed to the <a
				231	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]	232	that the data type that we are parsing is a string.</p>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	233
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	234	<p>The second and third parameters (which are optional) are used to specify what
				235	to output for the "<tt>--help</tt>" option. In this case, we get a line that
				236	looks like this:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	237
				238	<pre>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	239	USAGE: compiler [options]
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	240
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	241	OPTIONS:
				242	-help - display available options (--help-hidden for more)
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	243	<b>-o <filename> - Specify output filename</b>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	244	</pre>
				245
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	246	<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]	247	<tt>string</tt> data type, the variable declared is automatically usable as a
				248	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]	249	example:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	250
				251	<pre>
				252	...
				253	ofstream Output(OutputFilename.c_str());
				254	if (Out.good()) ...
				255	...
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	256	</pre>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	257
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	258	<p>There are many different options that you can use to customize the command
				259	line option handling library, but the above example shows the general interface
				260	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]	261	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]	262	there are no positional dependencies to remember. The available options are
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	263	discussed in detail in the <a href="#referenceguide">Reference Guide</a>.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	264
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	265	<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]	266	filename as well as an output filename, but we do not want the input filename to
				267	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]	268	style of argument, the CommandLine library allows for <a
				269	href="#positional">positional</a> arguments to be specified for the program.
				270	These positional arguments are filled with command line parameters that are not
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	271	in option form. We use this feature like this:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	272
				273	<pre>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	274	<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>"));
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	275	</pre>
				276
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	277	<p>This declaration indicates that the first positional argument should be
				278	treated as the input filename. Here we use the <tt><a
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	279	href="#cl::init">cl::init</a></tt> option to specify an initial value for the
				280	command line option, which is used if the option is not specified (if you do not
				281	specify a <tt><a href="#cl::init">cl::init</a></tt> modifier for an option, then
				282	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]	283	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]	284	that the user always specify an input filename, we would add the <tt><a
				285	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]	286	<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]	287
				288	<pre>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	289	<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>);
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	290	</pre>
				291
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	292	<p>Again, the CommandLine library does not require the options to be specified
				293	in any particular order, so the above declaration is equivalent to:</p>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	294
				295	<pre>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	296	<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>"));
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	297	</pre>
				298
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	299	<p>By simply adding the <tt><a href="#cl::Required">cl::Required</a></tt> flag,
				300	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]	301	specified, which shifts all of the command line option verification code out of
				302	your application into the library. This is just one example of how using flags
				303	can alter the default behaviour of the library, on a per-option basis. By
				304	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]	305	extended to:</p>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	306
				307	<pre>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	308	USAGE: compiler [options] <b><input file></b>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	309
				310	OPTIONS:
				311	-help - display available options (--help-hidden for more)
				312	-o <filename> - Specify output filename
				313	</pre>
				314
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	315	<p>... indicating that an input filename is expected.</p>
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	</div>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	318
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	319	<!-- ======================================================================= -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	320	<div class="doc_subsection">
				321	<a name="bool">Boolean Arguments</a>
				322	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	323
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	324	<div class="doc_text">
				325
				326	<p>In addition to input and output filenames, we would like the compiler example
				327	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]	328	file, "<tt>--quiet</tt>" to enable quiet mode, and "<tt>-q</tt>" for backwards
				329	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]	330	of boolean type like this:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	331
				332	<pre>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	333	<a href="#cl::opt">cl::opt</a><bool> Force ("<i>f</i>", <a href="#cl::desc">cl::desc</a>("<i>Overwrite output files</i>"));
				334	<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>"));
				335	<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	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	336	</pre>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	337
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	338	<p>This does what you would expect: it declares three boolean variables
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	339	("<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]	340	options. Note that the "<tt>-q</tt>" option is specified with the "<a
				341	href="#cl::Hidden"><tt>cl::Hidden</tt></a>" flag. This modifier prevents it
				342	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]	343	shown in the "<tt>--help-hidden</tt>" output).</p>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	344
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	345	<p>The CommandLine library uses a <a href="#builtinparsers">different parser</a>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	346	for different data types. For example, in the string case, the argument passed
				347	to the option is copied literally into the content of the string variable... we
				348	obviously cannot do that in the boolean case, however, so we must use a smarter
				349	parser. In the case of the boolean parser, it allows no options (in which case
				350	it assigns the value of true to the variable), or it allows the values
				351	"<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]	352	following inputs:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	353
				354	<pre>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	355	compiler -f # No value, 'Force' == true
				356	compiler -f=true # Value specified, 'Force' == true
				357	compiler -f=TRUE # Value specified, 'Force' == true
				358	compiler -f=FALSE # Value specified, 'Force' == false
				359	</pre>
				360
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	361	<p>... you get the idea. The <a href="#boolparser">bool parser</a> just turns
				362	the string values into boolean values, and rejects things like '<tt>compiler
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	363	-f=foo</tt>'. Similarly, the <a href="#doubleparser">float</a>, <a
				364	href="#doubleparser">double</a>, and <a href="#intparser">int</a> parsers work
				365	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]	366	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]	367
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	368	<p>With the declarations above, "<tt>compiler --help</tt>" emits this:</p>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	369
				370	<pre>
				371	USAGE: compiler [options] <input file>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	372
				373	OPTIONS:
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	374	<b>-f - Overwrite output files</b>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	375	-o - Override output filename
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	376	<b>-quiet - Don't print informational messages</b>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	377	-help - display available options (--help-hidden for more)
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	378	</pre>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	379
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	380	<p>and "<tt>opt --help-hidden</tt>" prints this:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	381
				382	<pre>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	383	USAGE: compiler [options] <input file>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	384
				385	OPTIONS:
				386	-f - Overwrite output files
				387	-o - Override output filename
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	388	<b>-q - Don't print informational messages</b>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	389	-quiet - Don't print informational messages
				390	-help - display available options (--help-hidden for more)
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	391	</pre>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	392
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	393	<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]	394	href="#cl::opt">cl::opt</a></tt>' class to parse simple scalar command line
				395	arguments. In addition to simple scalar arguments, the CommandLine library also
				396	provides primitives to support CommandLine option <a href="#alias">aliases</a>,
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	397	and <a href="#list">lists</a> of options.</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	398
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	399	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	400
				401	<!-- ======================================================================= -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	402	<div class="doc_subsection">
				403	<a name="alias">Argument Aliases</a>
				404	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	405
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	406	<div class="doc_text">
				407
				408	<p>So far, the example works well, except for the fact that we need to check the
				409	quiet condition like this now:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	410
				411	<pre>
				412	...
				413	if (!Quiet && !Quiet2) printInformationalMessage(...);
				414	...
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	415	</pre>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	416
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	417	<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]	418	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]	419	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]	420	a value itself:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	421
				422	<pre>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	423	<a href="#cl::opt">cl::opt</a><bool> Force ("<i>f</i>", <a href="#cl::desc">cl::desc</a>("<i>Overwrite output files</i>"));
				424	<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>"));
				425	<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	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	426	</pre>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	427
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	428	<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]	429	"<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]	430	the <tt><a href="#cl::aliasopt">cl::aliasopt</a></tt> modifier) whenever it is
				431	specified. Because aliases do not hold state, the only thing the program has to
				432	query is the <tt>Quiet</tt> variable now. Another nice feature of aliases is
				433	that they automatically hide themselves from the <tt>-help</tt> output
				434	(although, again, they are still visible in the <tt>--help-hidden
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	435	output</tt>).</p>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	436
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	437	<p>Now the application code can simply use:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	438
				439	<pre>
				440	...
				441	if (!Quiet) printInformationalMessage(...);
				442	...
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	443	</pre>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	444
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	445	<p>... which is much nicer! The "<tt><a href="#cl::alias">cl::alias</a></tt>"
				446	can be used to specify an alternative name for any variable type, and has many
				447	uses.</p>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	448
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	449	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	450
				451	<!-- ======================================================================= -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	452	<div class="doc_subsection">
				453	<a name="onealternative">Selecting an alternative from a set of
				454	possibilities</a>
				455	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	456
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	457	<div class="doc_text">
				458
				459	<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]	460	<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]	461	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]	462
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	463	<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]	464	your own parser, as described in the <a href="#extensionguide">Extension
Reid Spencer	d847337	2004-08-10 16:38:18 +0000	[diff] [blame]	465	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]	466	requires you to tell it what this mapping should be.</p>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	467
Reid Spencer	d847337	2004-08-10 16:38:18 +0000	[diff] [blame]	468	<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]	469	optimizer, using the standard flags "<tt>-g</tt>", "<tt>-O0</tt>",
				470	"<tt>-O1</tt>", and "<tt>-O2</tt>". We could easily implement this with boolean
				471	options like above, but there are several problems with this strategy:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	472
				473	<ol>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	474	<li>A user could specify more than one of the options at a time, for example,
				475	"<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]	476	erroneous input for us.</li>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	477
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	478	<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]	479
				480	<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]	481	see if some level >= "<tt>-O1</tt>" is enabled.</li>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	482
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	483	</ol>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	484
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	485	<p>To cope with these problems, we can use an enum value, and have the
				486	CommandLine library fill it in with the appropriate level directly, which is
				487	used like this:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	488
				489	<pre>
				490	enum OptLevel {
				491	g, O1, O2, O3
				492	};
				493
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	494	<a href="#cl::opt">cl::opt</a><OptLevel> OptimizationLevel(<a href="#cl::desc">cl::desc</a>("<i>Choose optimization level:</i>"),
				495	<a href="#cl::values">cl::values</a>(
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	496	clEnumVal(g , "<i>No optimizations, enable debugging</i>"),
				497	clEnumVal(O1, "<i>Enable trivial optimizations</i>"),
				498	clEnumVal(O2, "<i>Enable default optimizations</i>"),
				499	clEnumVal(O3, "<i>Enable expensive optimizations</i>"),
Chris Lattner	b406ead	2004-07-16 00:10:54 +0000	[diff] [blame]	500	clEnumValEnd));
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	501
				502	...
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	503	if (OptimizationLevel >= O2) doPartialRedundancyElimination(...);
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	504	...
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	505	</pre>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	506
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	507	<p>This declaration defines a variable "<tt>OptimizationLevel</tt>" of the
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	508	"<tt>OptLevel</tt>" enum type. This variable can be assigned any of the values
				509	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]	510	terminated with the "<tt>clEnumValEnd</tt>" argument!). The CommandLine
				511	library enforces
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	512	that the user can only specify one of the options, and it ensure that only valid
				513	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]	514	command line arguments matched the enum values. With this option added, our
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	515	help output now is:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	516
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	517	<pre>
				518	USAGE: compiler [options] <input file>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	519
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	520	OPTIONS:
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	521	<b>Choose optimization level:
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	522	-g - No optimizations, enable debugging
				523	-O1 - Enable trivial optimizations
				524	-O2 - Enable default optimizations
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	525	-O3 - Enable expensive optimizations</b>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	526	-f - Overwrite output files
				527	-help - display available options (--help-hidden for more)
				528	-o <filename> - Specify output filename
				529	-quiet - Don't print informational messages
				530	</pre>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	531
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	532	<p>In this case, it is sort of awkward that flag names correspond directly to
				533	enum names, because we probably don't want a enum definition named "<tt>g</tt>"
				534	in our program. Because of this, we can alternatively write this example like
				535	this:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	536
				537	<pre>
				538	enum OptLevel {
				539	Debug, O1, O2, O3
				540	};
				541
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	542	<a href="#cl::opt">cl::opt</a><OptLevel> OptimizationLevel(<a href="#cl::desc">cl::desc</a>("<i>Choose optimization level:</i>"),
				543	<a href="#cl::values">cl::values</a>(
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	544	clEnumValN(Debug, "g", "<i>No optimizations, enable debugging</i>"),
				545	clEnumVal(O1 , "<i>Enable trivial optimizations</i>"),
				546	clEnumVal(O2 , "<i>Enable default optimizations</i>"),
				547	clEnumVal(O3 , "<i>Enable expensive optimizations</i>"),
Chris Lattner	b406ead	2004-07-16 00:10:54 +0000	[diff] [blame]	548	clEnumValEnd));
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	549
				550	...
				551	if (OptimizationLevel == Debug) outputDebugInfo(...);
				552	...
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	553	</pre>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	554
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	555	<p>By using the "<tt>clEnumValN</tt>" macro instead of "<tt>clEnumVal</tt>", we
				556	can directly specify the name that the flag should get. In general a direct
				557	mapping is nice, but sometimes you can't or don't want to preserve the mapping,
				558	which is when you would use it.</p>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	559
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	560	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	561
				562	<!-- ======================================================================= -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	563	<div class="doc_subsection">
				564	<a name="namedalternatives">Named Alternatives</a>
				565	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	566
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	567	<div class="doc_text">
				568
				569	<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]	570	style in our compiler to specify different debug levels that can be used.
				571	Instead of each debug level being its own switch, we want to support the
				572	following options, of which only one can be specified at a time:
				573	"<tt>--debug-level=none</tt>", "<tt>--debug-level=quick</tt>",
				574	"<tt>--debug-level=detailed</tt>". To do this, we use the exact same format as
				575	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]	576	case, the code looks like this:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	577
				578	<pre>
				579	enum DebugLev {
				580	nodebuginfo, quick, detailed
				581	};
				582
				583	// Enable Debug Options to be specified on the command line
Chris Lattner	dc844fa	2003-06-03 04:40:06 +0000	[diff] [blame]	584	<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]	585	<a href="#cl::values">cl::values</a>(
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	586	clEnumValN(nodebuginfo, "none", "<i>disable debug information</i>"),
				587	clEnumVal(quick, "<i>enable quick debug information</i>"),
				588	clEnumVal(detailed, "<i>enable detailed debug information</i>"),
Chris Lattner	b406ead	2004-07-16 00:10:54 +0000	[diff] [blame]	589	clEnumValEnd));
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	590	</pre>
				591
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	592	<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]	593	DebugLev</tt>", which works exactly the same way as before. The difference here
				594	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]	595	the "<tt>--help</tt>" option:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	596
				597	<pre>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	598	USAGE: compiler [options] <input file>
				599
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	600	OPTIONS:
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	601	Choose optimization level:
				602	-g - No optimizations, enable debugging
				603	-O1 - Enable trivial optimizations
				604	-O2 - Enable default optimizations
				605	-O3 - Enable expensive optimizations
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	606	<b>-debug_level - Set the debugging level:
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	607	=none - disable debug information
				608	=quick - enable quick debug information
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	609	=detailed - enable detailed debug information</b>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	610	-f - Overwrite output files
				611	-help - display available options (--help-hidden for more)
				612	-o <filename> - Specify output filename
				613	-quiet - Don't print informational messages
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	614	</pre>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	615
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	616	<p>Again, the only structural difference between the debug level declaration and
John Criswell	c24d482	2004-11-21 14:34:34 +0000	[diff] [blame]	617	the optimization level declaration is that the debug level declaration includes
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	618	an option name (<tt>"debug_level"</tt>), which automatically changes how the
				619	library processes the argument. The CommandLine library supports both forms so
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	620	that you can choose the form most appropriate for your application.</p>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	621
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	622	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	623
				624	<!-- ======================================================================= -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	625	<div class="doc_subsection">
				626	<a name="list">Parsing a list of options</a>
				627	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	628
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	629	<div class="doc_text">
				630
				631	<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]	632	lets get a little wild and crazy. Lets say that we want our optimizer to accept
				633	a <b>list</b> of optimizations to perform, allowing duplicates. For example, we
				634	might want to run: "<tt>compiler -dce -constprop -inline -dce -strip</tt>". In
				635	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]	636	important. This is what the "<tt><a href="#cl::list">cl::list</a></tt>"
				637	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]	638	would like to perform:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	639
				640	<pre>
				641	enum Opts {
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	642	// 'inline' is a C++ keyword, so name it 'inlining'
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	643	dce, constprop, inlining, strip
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	644	};
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	645	</pre>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	646
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	647	<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]	648
				649	<pre>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	650	<a href="#cl::list">cl::list</a><Opts> OptimizationList(<a href="#cl::desc">cl::desc</a>("<i>Available Optimizations:</i>"),
				651	<a href="#cl::values">cl::values</a>(
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	652	clEnumVal(dce , "<i>Dead Code Elimination</i>"),
Misha Brukman	82c89b9	2003-05-20 21:01:22 +0000	[diff] [blame]	653	clEnumVal(constprop , "<i>Constant Propagation</i>"),
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	654	clEnumValN(inlining, "<i>inline</i>", "<i>Procedure Integration</i>"),
				655	clEnumVal(strip , "<i>Strip Symbols</i>"),
Chris Lattner	b406ead	2004-07-16 00:10:54 +0000	[diff] [blame]	656	clEnumValEnd));
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	657	</pre>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	658
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	659	<p>This defines a variable that is conceptually of the type
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	660	"<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]	661	vector methods:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	662
				663	<pre>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	664	for (unsigned i = 0; i != OptimizationList.size(); ++i)
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	665	switch (OptimizationList[i])
				666	...
				667	</pre>
				668
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	669	<p>... to iterate through the list of options specified.</p>
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>Note that the "<tt><a href="#cl::list">cl::list</a></tt>" template is
				672	completely general and may be used with any data types or other arguments that
				673	you can use with the "<tt><a href="#cl::opt">cl::opt</a></tt>" template. One
				674	especially useful way to use a list is to capture all of the positional
				675	arguments together if there may be more than one specified. In the case of a
				676	linker, for example, the linker takes several '<tt>.o</tt>' files, and needs to
				677	capture them into a list. This is naturally specified as:</p>
Chris Lattner	3e5fe17	2002-04-13 18:35:59 +0000	[diff] [blame]	678
				679	<pre>
				680	...
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	681	<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]	682	...
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	683	</pre>
Chris Lattner	3e5fe17	2002-04-13 18:35:59 +0000	[diff] [blame]	684
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	685	<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]	686	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]	687	the <tt><a href="#cl::OneOrMore">cl::OneOrMore</a></tt> modifier to inform the
				688	CommandLine library that it is an error if the user does not specify any
				689	<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]	690	checking we have to do.</p>
Chris Lattner	3e5fe17	2002-04-13 18:35:59 +0000	[diff] [blame]	691
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	692	</div>
Chris Lattner	3e5fe17	2002-04-13 18:35:59 +0000	[diff] [blame]	693
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	694	<!-- ======================================================================= -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	695	<div class="doc_subsection">
				696	<a name="description">Adding freeform text to help output</a>
				697	</div>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	698
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	699	<div class="doc_text">
				700
				701	<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]	702	information about what it does into the help output. The help output is styled
				703	to look similar to a Unix <tt>man</tt> page, providing concise information about
				704	a program. Unix <tt>man</tt> pages, however often have a description about what
				705	the program does. To add this to your CommandLine program, simply pass a third
				706	argument to the <a
				707	href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>
				708	call in main. This additional argument is then printed as the overview
				709	information for your program, allowing you to include any additional information
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	710	that you want. For example:</p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	711
				712	<pre>
				713	int main(int argc, char **argv) {
				714	<a href="#cl::ParseCommandLineOptions">cl::ParseCommandLineOptions</a>(argc, argv, " CommandLine compiler example\n\n"
				715	" This program blah blah blah...\n");
				716	...
				717	}
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	718	</pre>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	719
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	720	<p>Would yield the help output:</p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	721
				722	<pre>
				723	<b>OVERVIEW: CommandLine compiler example
				724
				725	This program blah blah blah...</b>
				726
				727	USAGE: compiler [options] <input file>
				728
				729	OPTIONS:
				730	...
				731	-help - display available options (--help-hidden for more)
				732	-o <filename> - Specify output filename
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	733	</pre>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	734
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	735	</div>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	736
				737
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	738	<!-- *********************************************************************** -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	739	<div class="doc_section">
				740	<a name="referenceguide">Reference Guide</a>
				741	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	742	<!-- *********************************************************************** -->
				743
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	744	<div class="doc_text">
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	745
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	746	<p>Now that you know the basics of how to use the CommandLine library, this
				747	section will give you the detailed information you need to tune how command line
				748	options work, as well as information on more "advanced" command line option
				749	processing capabilities.</p>
				750
				751	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	752
				753	<!-- ======================================================================= -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	754	<div class="doc_subsection">
				755	<a name="positional">Positional Arguments</a>
				756	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	757
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	758	<div class="doc_text">
				759
				760	<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]	761	specified with a hyphen. Positional arguments should be used when an option is
				762	specified by its position alone. For example, the standard Unix <tt>grep</tt>
				763	tool takes a regular expression argument, and an optional filename to search
				764	through (which defaults to standard input if a filename is not specified).
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	765	Using the CommandLine library, this would be specified as:</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	766
				767	<pre>
				768	<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>);
				769	<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>"));
				770	</pre>
				771
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	772	<p>Given these two option declarations, the <tt>--help</tt> output for our grep
				773	replacement would look like this:</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	774
				775	<pre>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	776	USAGE: spiffygrep [options] <b><regular expression> <input file></b>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	777
				778	OPTIONS:
				779	-help - display available options (--help-hidden for more)
				780	</pre>
				781
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	782	<p>... and the resultant program could be used just like the standard
				783	<tt>grep</tt> tool.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	784
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	785	<p>Positional arguments are sorted by their order of construction. This means
				786	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]	787	.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]	788	are defined in multiple .cpp files. The fix for this problem is simply to
				789	define all of your positional arguments in one .cpp file.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	790
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	791	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	792
				793
				794	<!-- _______________________________________________________________________ -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	795	<div class="doc_subsubsection">
				796	<a name="--">Specifying positional options with hyphens</a>
				797	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	798
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	799	<div class="doc_text">
				800
				801	<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]	802	starts with a hyphen (for example, searching for '<tt>-foo</tt>' in a file). At
				803	first, you will have trouble doing this, because it will try to find an argument
				804	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]	805	Note that the system <tt>grep</tt> has the same problem:</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	806
				807	<pre>
				808	$ spiffygrep '-foo' test.txt
				809	Unknown command line argument '-foo'. Try: spiffygrep --help'
				810
				811	$ grep '-foo' test.txt
				812	grep: illegal option -- f
				813	grep: illegal option -- o
				814	grep: illegal option -- o
				815	Usage: grep -hblcnsviw pattern file . . .
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	816	</pre>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	817
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	818	<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]	819	version: use the '<tt>--</tt>' marker. When the user specifies '<tt>--</tt>' on
				820	the command line, it is telling the program that all options after the
				821	'<tt>--</tt>' should be treated as positional arguments, not options. Thus, we
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	822	can use it like this:</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	823
				824	<pre>
				825	$ spiffygrep -- -foo test.txt
				826	...output...
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	827	</pre>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	828
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	829	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	830
				831	<!-- _______________________________________________________________________ -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	832	<div class="doc_subsubsection">
Reid Spencer	2c8ab58	2004-08-13 20:19:14 +0000	[diff] [blame]	833	<a name="getPosition">Determining absolute position with getPosition()</a>
				834	</div>
				835	<div class="doc_text">
				836	<p>Sometimes an option can affect or modify the meaning of another option. For
				837	example, consider <tt>gcc</tt>'s <tt>-x LANG</tt> option. This tells
				838	<tt>gcc</tt> to ignore the suffix of subsequent positional arguments and force
				839	the file to be interpreted as if it contained source code in language
				840	<tt>LANG</tt>. In order to handle this properly , you need to know the
				841	absolute position of each argument, especially those in lists, so their
				842	interaction(s) can be applied correctly. This is also useful for options like
				843	<tt>-llibname</tt> which is actually a positional argument that starts with
				844	a dash.</p>
				845	<p>So, generally, the problem is that you have two <tt>cl::list</tt> variables
				846	that interact in some way. To ensure the correct interaction, you can use the
				847	<tt>cl::list::getPosition(optnum)</tt> method. This method returns the
				848	absolute position (as found on the command line) of the <tt>optnum</tt>
				849	item in the <tt>cl::list</tt>.</p>
				850	<p>The idiom for usage is like this:<pre><tt>
				851	static cl::list<std::string> Files(cl::Positional, cl::OneOrMore);
				852	static cl::listlt;std::string> Libraries("l", cl::ZeroOrMore);
				853
				854	int main(int argc, char**argv) {
				855	// ...
				856	std::vector<std::string>::iterator fileIt = Files.begin();
				857	std::vector<std::string>::iterator libIt = Libraries.begin();
				858	unsigned libPos = 0, filePos = 0;
				859	while ( 1 ) {
				860	if ( libIt != Libraries.end() )
				861	libPos = Libraries.getPosition( libIt - Libraries.begin() );
				862	else
				863	libPos = 0;
				864	if ( fileIt != Files.end() )
				865	filePos = Files.getPosition( fileIt - Files.begin() );
				866	else
				867	filePos = 0;
				868
				869	if ( filePos != 0 && (libPos == 0 \|\| filePos < libPos) ) {
				870	// Source File Is next
				871	++fileIt;
				872	}
				873	else if ( libPos != 0 && (filePos == 0 \|\| libPos < filePos) ) {
				874	// Library is next
				875	++libIt;
				876	}
				877	else
				878	break; // we're done with the list
				879	}
Reid Spencer	c7d1d82	2004-11-01 09:16:30 +0000	[diff] [blame]	880	}
				881	</tt></pre></p>
Reid Spencer	2c8ab58	2004-08-13 20:19:14 +0000	[diff] [blame]	882	<p>Note that, for compatibility reasons, the <tt>cl::opt</tt> also supports an
				883	<tt>unsigned getPosition()</tt> option that will provide the absolute position
				884	of that option. You can apply the same approach as above with a
				885	<tt>cl::opt</tt> and a <tt>cl::list</tt> option as you can with two lists.</p>
				886	</div>
				887
				888	<!-- _______________________________________________________________________ -->
				889	<div class="doc_subsubsection">
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	890	<a name="cl::ConsumeAfter">The <tt>cl::ConsumeAfter</tt> modifier</a>
				891	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	892
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	893	<div class="doc_text">
				894
				895	<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]	896	used to construct programs that use "interpreter style" option processing. With
				897	this style of option processing, all arguments specified after the last
				898	positional argument are treated as special interpreter arguments that are not
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	899	interpreted by the command line argument.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	900
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	901	<p>As a concrete example, lets say we are developing a replacement for the
				902	standard Unix Bourne shell (<tt>/bin/sh</tt>). To run <tt>/bin/sh</tt>, first
				903	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]	904	output), then you specify the name of the script to run, then you specify
				905	arguments to the script. These arguments to the script are parsed by the bourne
				906	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]	907	shell itself. Using the CommandLine library, we would specify this as:</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	908
				909	<pre>
				910	<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>("-"));
				911	<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>"));
				912	<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	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	913	</pre>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	914
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	915	<p>which automatically provides the help output:</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	916
				917	<pre>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	918	USAGE: spiffysh [options] <b><input script> <program arguments>...</b>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	919
				920	OPTIONS:
				921	-help - display available options (--help-hidden for more)
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	922	<b>-x - Enable trace output</b>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	923	</pre>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	924
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	925	<p>At runtime, if we run our new shell replacement as '<tt>spiffysh -x test.sh
				926	-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]	927	<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]	928	<tt>Argv</tt> list will contain <tt>["-a", "-x", "-y", "bar"]</tt>, because they
				929	were specified after the last positional argument (which is the script
				930	name).</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	931
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	932	<p>There are several limitations to when <tt>cl::ConsumeAfter</tt> options can
				933	be specified. For example, only one <tt>cl::ConsumeAfter</tt> can be specified
				934	per program, there must be at least one <a href="#positional">positional
Chris Lattner	be801bf	2004-05-06 22:03:59 +0000	[diff] [blame]	935	argument</a> specified, there must not be any <a href="#cl::list">cl::list</a>
				936	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]	937	href="#cl::list">cl::list</a> option.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	938
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	939	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	940
				941	<!-- ======================================================================= -->
Chris Lattner	be801bf	2004-05-06 22:03:59 +0000	[diff] [blame]	942	<div class="doc_subsection">
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	943	<a name="storage">Internal vs External Storage</a>
				944	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	945
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	946	<div class="doc_text">
				947
				948	<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]	949	parse from the command line. This is very convenient in the common case,
				950	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]	951	files that use them. This is called the internal storage model.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	952
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	953	<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]	954	code from the storage of the value parsed. For example, lets say that we have a
				955	'<tt>-debug</tt>' option that we would like to use to enable debug information
				956	across the entire body of our program. In this case, the boolean value
				957	controlling the debug code should be globally accessable (in a header file, for
				958	example) yet the command line option processing code should not be exposed to
				959	all of these clients (requiring lots of .cpp files to #include
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	960	<tt>CommandLine.h</tt>).</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	961
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	962	<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]	963
				964	<pre>
				965	<i>// DebugFlag.h - Get access to the '-debug' command line option
				966	//
				967
				968	// DebugFlag - This boolean is set to true if the '-debug' command line option
				969	// is specified. This should probably not be referenced directly, instead, use
				970	// the DEBUG macro below.
				971	//</i>
				972	extern bool DebugFlag;
				973
				974	<i>// DEBUG macro - This macro should be used by code to emit debug information.
				975	// In the '-debug' option is specified on the command line, and if this is a
				976	// debug build, then the code specified as the option to the macro will be
				977	// executed. Otherwise it will not be. Example:
				978	//
				979	// DEBUG(cerr << "Bitset contains: " << Bitset << "\n");
				980	//</i>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	981	<span class="doc_red">#ifdef NDEBUG
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	982	#define DEBUG(X)
				983	#else
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	984	#define DEBUG(X)</span> \
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	985	do { if (DebugFlag) { X; } } while (0)
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	986	<span class="doc_red">#endif</span>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	987	</pre>
				988
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	989	<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]	990	<tt>DebugFlag</tt> explicitly if they want to. Now we just need to be able to
				991	set the <tt>DebugFlag</tt> boolean when the option is set. To do this, we pass
				992	an additial argument to our command line argument processor, and we specify
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	993	where to fill in with the <a href="#cl::location">cl::location</a>
				994	attribute:</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	995
				996	<pre>
				997	bool DebugFlag; <i>// the actual value</i>
Chris Lattner	589a4cc	2003-08-01 21:30:37 +0000	[diff] [blame]	998	static <a href="#cl::opt">cl::opt</a><bool, true> <i>// The parser</i>
Misha Brukman	c53aefb	2004-05-12 18:42:35 +0000	[diff] [blame]	999	Debug("<i>debug</i>", <a href="#cl::desc">cl::desc</a>("<i>Enable debug output</i>"), <a href="#cl::Hidden">cl::Hidden</a>,
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1000	<a href="#cl::location">cl::location</a>(DebugFlag));
				1001	</pre>
				1002
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1003	<p>In the above example, we specify "<tt>true</tt>" as the second argument to
				1004	the <a href="#cl::opt">cl::opt</a> template, indicating that the template should
				1005	not maintain a copy of the value itself. In addition to this, we specify the <a
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1006	href="#cl::location">cl::location</a> attribute, so that <tt>DebugFlag</tt> is
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1007	automatically set.</p>
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>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1010
				1011	<!-- ======================================================================= -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1012	<div class="doc_subsection">
				1013	<a name="attributes">Option Attributes</a>
				1014	</div>
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	<div class="doc_text">
				1017
				1018	<p>This section describes the basic attributes that you can specify on
				1019	options.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1020
				1021	<ul>
				1022
				1023	<li>The option name attribute (which is required for all options, except <a
				1024	href="#positional">positional options</a>) specifies what the option name is.
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1025	This option is specified in simple double quotes:
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1026
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1027	<pre>
				1028	<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]	1029	</pre>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1030
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1031	</li>
				1032
				1033	<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]	1034	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]	1035	program.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1036
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1037	<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]	1038	specifies a string that can be used to fine tune the <tt>--help</tt> output for
				1039	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]	1040	example.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1041
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1042	<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]	1043	inital value for a <a href="#cl::opt">scalar</a> option. If this attribute is
				1044	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]	1045	by the default constructor for the type. <b>Warning</b>: If you specify both
				1046	<b><tt>cl::init</tt></b> and <b><tt>cl::location</tt></b> for an option,
				1047	you must specify <b><tt>cl::location</tt></b> first, so that when the
				1048	command-line parser sees <b><tt>cl::init</tt></b>, it knows where to put the
				1049	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]	1050	the right order.)</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1051
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1052	<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]	1053	store the value for a parsed command line option if using external storage. See
				1054	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]	1055	information.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1056
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1057	<li><a name="cl::aliasopt">The <b><tt>cl::aliasopt</tt></b></a> attribute
				1058	specifies which option a <a href="#cl::alias">cl::alias</a> option is an alias
				1059	for.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1060
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1061	<li><a name="cl::values">The <b><tt>cl::values</tt></b></a> attribute specifies
				1062	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]	1063	<b>clEnumValEnd terminated</b> list of (option, value, description) triplets
				1064	that
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1065	specify the option name, the value mapped to, and the description shown in the
				1066	<tt>--help</tt> for the tool. Because the generic parser is used most
				1067	frequently with enum values, two macros are often useful:
				1068
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1069	<ol>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1070
				1071	<li><a name="clEnumVal">The <b><tt>clEnumVal</tt></b></a> macro is used as a
				1072	nice simple way to specify a triplet for an enum. This macro automatically
				1073	makes the option name be the same as the enum name. The first option to the
				1074	macro is the enum, the second is the description for the command line
				1075	option.</li>
				1076
				1077	<li><a name="clEnumValN">The <b><tt>clEnumValN</tt></b></a> macro is used to
				1078	specify macro options where the option name doesn't equal the enum name. For
				1079	this macro, the first argument is the enum value, the second is the flag name,
				1080	and the second is the description.</li>
				1081
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1082	</ol>
				1083
				1084	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]	1085	that does not support it.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1086
				1087	</ul>
				1088
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1089	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1090
				1091	<!-- ======================================================================= -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1092	<div class="doc_subsection">
				1093	<a name="modifiers">Option Modifiers</a>
				1094	</div>
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	<div class="doc_text">
				1097
				1098	<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]	1099	constructors for <tt><a href="#cl::opt">cl::opt</a></tt> and <tt><a
				1100	href="#cl::list">cl::list</a></tt>. These modifiers give you the ability to
				1101	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]	1102	your application well.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1103
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1104	<p>These options fall into five main catagories:</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1105
				1106	<ol>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1107	<li><a href="#hiding">Hiding an option from <tt>--help</tt> output</a></li>
				1108	<li><a href="#numoccurrences">Controlling the number of occurrences
				1109	required and allowed</a></li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1110	<li><a href="#valrequired">Controlling whether or not a value must be
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1111	specified</a></li>
				1112	<li><a href="#formatting">Controlling other formatting options</a></li>
				1113	<li><a href="#misc">Miscellaneous option modifiers</a></li>
				1114	</ol>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1115
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1116	<p>It is not possible to specify two options from the same catagory (you'll get
				1117	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]	1118	catagory. The CommandLine library specifies defaults for all of these settings
				1119	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]	1120	usually shouldn't have to worry about these.</p>
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	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1123
				1124	<!-- _______________________________________________________________________ -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1125	<div class="doc_subsubsection">
				1126	<a name="hiding">Hiding an option from <tt>--help</tt> output</a>
				1127	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1128
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1129	<div class="doc_text">
				1130
				1131	<p>The <tt>cl::NotHidden</tt>, <tt>cl::Hidden</tt>, and
				1132	<tt>cl::ReallyHidden</tt> modifiers are used to control whether or not an option
				1133	appears in the <tt>--help</tt> and <tt>--help-hidden</tt> output for the
				1134	compiled program:</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1135
				1136	<ul>
				1137
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1138	<li><a name="cl::NotHidden">The <b><tt>cl::NotHidden</tt></b></a> modifier
				1139	(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]	1140	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]	1141	in both help listings.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1142
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1143	<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]	1144	default for <tt><a href="#cl::alias">cl::alias</a></tt> options), indicates that
				1145	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]	1146	the <tt>--help-hidden</tt> output.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1147
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1148	<li><a name="cl::ReallyHidden">The <b><tt>cl::ReallyHidden</tt></b></a> modifier,
				1149	indicates that the option should not appear in any help output.</li>
				1150
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1151	</ul>
				1152
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1153	</div>
				1154
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1155	<!-- _______________________________________________________________________ -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1156	<div class="doc_subsubsection">
				1157	<a name="numoccurrences">Controlling the number of occurrences required and
				1158	allowed</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>This group of options is used to control how many time an option is allowed
				1164	(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]	1165	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]	1166	you.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1167
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1168	<p>The allowed values for this option group are:</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1169
				1170	<ul>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1171
				1172	<li><a name="cl::Optional">The <b><tt>cl::Optional</tt></b></a> modifier (which
				1173	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]	1174	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]	1175	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]	1176
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1177	<li><a name="cl::ZeroOrMore">The <b><tt>cl::ZeroOrMore</tt></b></a> modifier
				1178	(which is the default for the <tt><a href="#cl::list">cl::list</a></tt> class)
				1179	indicates that your program will allow the option to be specified zero or more
				1180	times.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1181
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1182	<li><a name="cl::Required">The <b><tt>cl::Required</tt></b></a> modifier
				1183	indicates that the specified option must be specified exactly one time.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1184
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1185	<li><a name="cl::OneOrMore">The <b><tt>cl::OneOrMore</tt></b></a> modifier
				1186	indicates that the option must be specified at least one time.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1187
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1188	<li>The <b><tt>cl::ConsumeAfter</tt></b> modifier is described in the <a
				1189	href="#positional">Positional arguments section</a></li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1190
				1191	</ul>
				1192
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1193	<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]	1194	value specified by the <tt><a href="#cl::init">cl::init</a></tt> attribute. If
				1195	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]	1196	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]	1197
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1198	<p>If an option is specified multiple times for an option of the <tt><a
				1199	href="#cl::opt">cl::opt</a></tt> class, only the last value will be
				1200	retained.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1201
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1202	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1203
				1204	<!-- _______________________________________________________________________ -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1205	<div class="doc_subsubsection">
				1206	<a name="valrequired">Controlling whether or not a value must be specified</a>
				1207	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1208
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1209	<div class="doc_text">
				1210
				1211	<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]	1212	value to be present. In the case of the CommandLine library, a value is either
				1213	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]	1214	string (e.g. '<tt>-o a.out</tt>').</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1215
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1216	<p>The allowed values for this option group are:</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1217
				1218	<ul>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1219
				1220	<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]	1221	(which is the default for <tt>bool</tt> typed options) specifies that it is
				1222	acceptable to have a value, or not. A boolean argument can be enabled just by
				1223	appearing on the command line, or it can have an explicit '<tt>-foo=true</tt>'.
				1224	If an option is specified with this mode, it is illegal for the value to be
				1225	provided without the equal sign. Therefore '<tt>-foo true</tt>' is illegal. To
				1226	get this behavior, you must use the <a
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1227	href="#cl::ValueRequired">cl::ValueRequired</a> modifier.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1228
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1229	<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]	1230	(which is the default for all other types except for <a
				1231	href="#onealternative">unnamed alternatives using the generic parser</a>)
				1232	specifies that a value must be provided. This mode informs the command line
				1233	library that if an option is not provides with an equal sign, that the next
				1234	argument provided must be the value. This allows things like '<tt>-o
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1235	a.out</tt>' to work.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1236
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1237	<li><a name="cl::ValueDisallowed">The <b><tt>cl::ValueDisallowed</tt></b></a>
				1238	modifier (which is the default for <a href="#onealternative">unnamed
				1239	alternatives using the generic parser</a>) indicates that it is a runtime error
				1240	for the user to specify a value. This can be provided to disallow users from
				1241	providing options to boolean options (like '<tt>-foo=true</tt>').</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1242
				1243	</ul>
				1244
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1245	<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]	1246	want them to. As mentioned above, you can specify the <a
				1247	href="#cl::ValueDisallowed">cl::ValueDisallowed</a> modifier to a boolean
				1248	argument to restrict your command line parser. These options are mostly useful
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1249	when <a href="#extensionguide">extending the library</a>.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1250
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1251	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1252
				1253	<!-- _______________________________________________________________________ -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1254	<div class="doc_subsubsection">
				1255	<a name="formatting">Controlling other formatting options</a>
				1256	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1257
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1258	<div class="doc_text">
				1259
				1260	<p>The formatting option group is used to specify that the command line option
				1261	has special abilities and is otherwise different from other command line
				1262	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]	1263
				1264	<ul>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1265
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1266	<li><a name="cl::NormalFormatting">The <b><tt>cl::NormalFormatting</tt></b></a>
				1267	modifier (which is the default all options) specifies that this option is
				1268	"normal".</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1269
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1270	<li><a name="cl::Positional">The <b><tt>cl::Positional</tt></b></a> modifier
				1271	specifies that this is a positional argument, that does not have a command line
				1272	option associated with it. See the <a href="#positional">Positional
				1273	Arguments</a> section for more information.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1274
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1275	<li>The <b><a href="#cl::ConsumeAfter"><tt>cl::ConsumeAfter</tt></a></b> modifier
				1276	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]	1277
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1278	<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]	1279	that this option prefixes its value. With 'Prefix' options, the equal sign does
				1280	not separate the value from the option name specified. Instead, the value is
				1281	everything after the prefix, including any equal sign if present. This is useful
				1282	for processing odd arguments like <tt>-lmalloc</tt> and <tt>-L/usr/lib</tt> in a
				1283	linker tool or <tt>-DNAME=value</tt> in a compiler tool. Here, the
				1284	'<tt>l</tt>', '<tt>D</tt>' and '<tt>L</tt>' options are normal string (or list)
				1285	options, that have the <a href="#cl::Prefix">cl::Prefix</a> modifier added to
				1286	allow the CommandLine library to recognize them. Note that
				1287	<a href="#cl::Prefix">cl::Prefix</a> options must not have the <a
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1288	href="#cl::ValueDisallowed">cl::ValueDisallowed</a> modifier specified.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1289
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1290	<li><a name="cl::Grouping">The <b><tt>cl::Grouping</tt></b></a> modifier is used
				1291	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]	1292	arguments, but only require a single dash. For example, the '<tt>ls -labF</tt>'
				1293	command actually enables four different options, all of which are single
				1294	letters. Note that <a href="#cl::Grouping">cl::Grouping</a> options cannot have
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1295	values.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1296
				1297	</ul>
				1298
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1299	<p>The CommandLine library does not restrict how you use the <a
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1300	href="#cl::Prefix">cl::Prefix</a> or <a href="#cl::Grouping">cl::Grouping</a>
				1301	modifiers, but it is possible to specify ambiguous argument settings. Thus, it
				1302	is possible to have multiple letter options that are prefix or grouping options,
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1303	and they will still work as designed.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1304
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1305	<p>To do this, the CommandLine library uses a greedy algorithm to parse the
				1306	input option into (potentially multiple) prefix and grouping options. The
				1307	strategy basically looks like this:</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1308
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1309	<p><tt>parse(string OrigInput) {</tt>
Misha Brukman	c53aefb	2004-05-12 18:42:35 +0000	[diff] [blame]	1310
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1311	<ol>
				1312	<li><tt>string input = OrigInput;</tt>
				1313	<li><tt>if (isOption(input)) return getOption(input).parse();</tt>    <i>// Normal option</i>
				1314	<li><tt>while (!isOption(input) && !input.empty()) input.pop_back();</tt>    <i>// Remove the last letter</i>
				1315	<li><tt>if (input.empty()) return error();</tt>    <i>// No matching option</i>
				1316	<li><tt>if (getOption(input).isPrefix())<br>
				1317	return getOption(input).parse(input);</tt>
				1318	<li><tt>while (!input.empty()) {    <i>// Must be grouping options</i><br>
				1319	getOption(input).parse();<br>
				1320	OrigInput.erase(OrigInput.begin(), OrigInput.begin()+input.length());<br>
				1321	input = OrigInput;<br>
				1322	while (!isOption(input) && !input.empty()) input.pop_back();<br>
				1323	}</tt>
Misha Brukman	c53aefb	2004-05-12 18:42:35 +0000	[diff] [blame]	1324	<li><tt>if (!OrigInput.empty()) error();</tt></li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1325
				1326	</ol>
Misha Brukman	c53aefb	2004-05-12 18:42:35 +0000	[diff] [blame]	1327
				1328	<p><tt>}</tt></p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1329
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1330	</div>
Chris Lattner	32a3284	2003-05-22 20:36:06 +0000	[diff] [blame]	1331
				1332	<!-- _______________________________________________________________________ -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1333	<div class="doc_subsubsection">
				1334	<a name="misc">Miscellaneous option modifiers</a>
				1335	</div>
Chris Lattner	32a3284	2003-05-22 20:36:06 +0000	[diff] [blame]	1336
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1337	<div class="doc_text">
				1338
				1339	<p>The miscellaneous option modifiers are the only flags where you can specify
				1340	more than one flag from the set: they are not mutually exclusive. These flags
				1341	specify boolean properties that modify the option.</p>
Chris Lattner	32a3284	2003-05-22 20:36:06 +0000	[diff] [blame]	1342
				1343	<ul>
				1344
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1345	<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]	1346	indicates that any commas specified for an option's value should be used to
				1347	split the value up into multiple values for the option. For example, these two
				1348	options are equivalent when <tt>cl::CommaSeparated</tt> is specified:
				1349	"<tt>-foo=a -foo=b -foo=c</tt>" and "<tt>-foo=a,b,c</tt>". This option only
				1350	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]	1351	more values (i.e. it is a <a href="#cl::list">cl::list</a> option).</li>
				1352
Chris Lattner	be801bf	2004-05-06 22:03:59 +0000	[diff] [blame]	1353	<li><a name="cl::PositionalEatsArgs">The
				1354	<b><tt>cl::PositionalEatsArgs</tt></b></a> modifier (which only applies to
				1355	positional arguments, and only makes sense for lists) indicates that positional
				1356	argument should consume any strings after it (including strings that start with
				1357	a "-") up until another recognized positional argument. For example, if you
				1358	have two "eating" positional arguments "<tt>pos1</tt>" and "<tt>pos2</tt>" the
				1359	string "<tt>-pos1 -foo -bar baz -pos2 -bork</tt>" would cause the "<tt>-foo -bar
				1360	-baz</tt>" strings to be applied to the "<tt>-pos1</tt>" option and the
				1361	"<tt>-bork</tt>" string to be applied to the "<tt>-pos2</tt>" option.</li>
				1362
Chris Lattner	32a3284	2003-05-22 20:36:06 +0000	[diff] [blame]	1363	</ul>
				1364
Chris Lattner	be801bf	2004-05-06 22:03:59 +0000	[diff] [blame]	1365	<p>So far, these are the only two miscellaneous option modifiers.</p>
Chris Lattner	32a3284	2003-05-22 20:36:06 +0000	[diff] [blame]	1366
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1367	</div>
Chris Lattner	32a3284	2003-05-22 20:36:06 +0000	[diff] [blame]	1368
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1369	<!-- ======================================================================= -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1370	<div class="doc_subsection">
				1371	<a name="toplevel">Top-Level Classes and Functions</a>
				1372	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1373
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1374	<div class="doc_text">
				1375
				1376	<p>Despite all of the built-in flexibility, the CommandLine option library
				1377	really only consists of one function (<a
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1378	href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>)
				1379	and three main classes: <a href="#cl::opt"><tt>cl::opt</tt></a>, <a
				1380	href="#cl::list"><tt>cl::list</tt></a>, and <a
				1381	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]	1382	classes in detail.</p>
				1383
				1384	</div>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1385
				1386	<!-- _______________________________________________________________________ -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1387	<div class="doc_subsubsection">
				1388	<a name="cl::ParseCommandLineOptions">The <tt>cl::ParseCommandLineOptions</tt>
				1389	function</a>
				1390	</div>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1391
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1392	<div class="doc_text">
				1393
				1394	<p>The <tt>cl::ParseCommandLineOptions</tt> function is designed to be called
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1395	directly from <tt>main</tt>, and is used to fill in the values of all of the
				1396	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]	1397	available.</p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1398
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1399	<p>The <tt>cl::ParseCommandLineOptions</tt> function requires two parameters
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1400	(<tt>argc</tt> and <tt>argv</tt>), but may also take an optional third parameter
				1401	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]	1402	<tt>--help</tt> option is invoked.</p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1403
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1404	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1405
				1406	<!-- _______________________________________________________________________ -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1407	<div class="doc_subsubsection">
				1408	<a name="cl::ParseEnvironmentOptions">The <tt>cl::ParseEnvironmentOptions</tt>
				1409	function</a>
				1410	</div>
Brian Gaeke	e584285	2003-08-19 23:11:43 +0000	[diff] [blame]	1411
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1412	<div class="doc_text">
Brian Gaeke	e584285	2003-08-19 23:11:43 +0000	[diff] [blame]	1413
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1414	<p>The <tt>cl::ParseEnvironmentOptions</tt> function has mostly the same effects
				1415	as <a
				1416	href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>,
				1417	except that it is designed to take values for options from an environment
				1418	variable, for those cases in which reading the command line is not convenient or
				1419	not desired. It fills in the values of all the command line option variables
				1420	just like <a
				1421	href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>
				1422	does.</p>
				1423
				1424	<p>It takes three parameters: first, the name of the program (since
				1425	<tt>argv</tt> may not be available, it can't just look in <tt>argv[0]</tt>),
				1426	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]	1427	<a href="#description">additional extra text</a> to emit when the
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1428	<tt>--help</tt> option is invoked.</p>
Brian Gaeke	e584285	2003-08-19 23:11:43 +0000	[diff] [blame]	1429
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1430	<p><tt>cl::ParseEnvironmentOptions</tt> will break the environment
Brian Gaeke	e584285	2003-08-19 23:11:43 +0000	[diff] [blame]	1431	variable's value up into words and then process them using
				1432	<a href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>.
				1433	<b>Note:</b> Currently <tt>cl::ParseEnvironmentOptions</tt> does not support
				1434	quoting, so an environment variable containing <tt>-option "foo bar"</tt> will
				1435	be parsed as three words, <tt>-option</tt>, <tt>"foo</tt>, and <tt>bar"</tt>,
				1436	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]	1437	input.</p>
				1438
				1439	</div>
Brian Gaeke	e584285	2003-08-19 23:11:43 +0000	[diff] [blame]	1440
				1441	<!-- _______________________________________________________________________ -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1442	<div class="doc_subsubsection">
				1443	<a name="cl::opt">The <tt>cl::opt</tt> class</a>
				1444	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1445
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1446	<div class="doc_text">
				1447
				1448	<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]	1449	options, and is the one used most of the time. It is a templated class which
				1450	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]	1451	though):</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1452
				1453	<pre>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1454	<b>namespace</b> cl {
				1455	<b>template</b> <<b>class</b> DataType, <b>bool</b> ExternalStorage = <b>false</b>,
				1456	<b>class</b> ParserClass = parser<DataType> >
				1457	<b>class</b> opt;
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1458	}
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1459	</pre>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1460
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1461	<p>The first template argument specifies what underlying data type the command
				1462	line argument is, and is used to select a default parser implementation. The
				1463	second template argument is used to specify whether the option should contain
				1464	the storage for the option (the default) or whether external storage should be
				1465	used to contain the value parsed for the option (see <a href="#storage">Internal
				1466	vs External Storage</a> for more information).</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1467
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1468	<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]	1469	selects an instantiation of the <tt>parser</tt> class based on the underlying
				1470	data type of the option. In general, this default works well for most
				1471	applications, so this option is only used when using a <a
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1472	href="#customparser">custom parser</a>.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1473
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1474	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1475
				1476	<!-- _______________________________________________________________________ -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1477	<div class="doc_subsubsection">
				1478	<a name="cl::list">The <tt>cl::list</tt> class</a>
				1479	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1480
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1481	<div class="doc_text">
				1482
				1483	<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]	1484	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]	1485	arguments:</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1486
				1487	<pre>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1488	<b>namespace</b> cl {
				1489	<b>template</b> <<b>class</b> DataType, <b>class</b> Storage = <b>bool</b>,
				1490	<b>class</b> ParserClass = parser<DataType> >
				1491	<b>class</b> list;
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1492	}
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1493	</pre>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1494
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1495	<p>This class works the exact same as the <a
				1496	href="#cl::opt"><tt>cl::opt</tt></a> class, except that the second argument is
				1497	the <b>type</b> of the external storage, not a boolean value. For this class,
				1498	the marker type '<tt>bool</tt>' is used to indicate that internal storage should
				1499	be used.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1500
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1501	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1502
				1503	<!-- _______________________________________________________________________ -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1504	<div class="doc_subsubsection">
				1505	<a name="cl::alias">The <tt>cl::alias</tt> class</a>
				1506	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1507
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1508	<div class="doc_text">
				1509
				1510	<p>The <tt>cl::alias</tt> class is a nontemplated class that is used to form
				1511	aliases for other arguments.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1512
				1513	<pre>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1514	<b>namespace</b> cl {
				1515	<b>class</b> alias;
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1516	}
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1517	</pre>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1518
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1519	<p>The <a href="#cl::aliasopt"><tt>cl::aliasopt</tt></a> attribute should be
				1520	used to specify which option this is an alias for. Alias arguments default to
				1521	being <a href="#cl::Hidden">Hidden</a>, and use the aliased options parser to do
				1522	the conversion from string to data.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1523
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1524	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1525
Reid Spencer	9bbba091	2004-11-16 06:11:52 +0000	[diff] [blame]	1526	<!-- _______________________________________________________________________ -->
				1527	<div class="doc_subsubsection">
				1528	<a name="cl::extrahelp">The <tt>cl::extrahelp</tt> class</a>
				1529	</div>
				1530
				1531	<div class="doc_text">
				1532
				1533	<p>The <tt>cl::extrahelp</tt> class is a nontemplated class that allows extra
				1534	help text to be printed out for the <tt>--help</tt> option.</p>
				1535
				1536	<pre>
				1537	<b>namespace</b> cl {
				1538	<b>struct</b> extrahelp;
				1539	}
				1540	</pre>
				1541
				1542	<p>To use the extrahelp, simply construct one with a <tt>const char*</tt>
				1543	parameter to the constructor. The text passed to the constructor will be printed
				1544	at the bottom of the help message, verbatim. Note that multiple
				1545	<tt>cl::extrahelp</tt> <b>can</b> be used but this practice is discouraged. If
				1546	your tool needs to print additional help information, put all that help into a
				1547	single <tt>cl::extrahelp</tt> instance.</p>
				1548	<p>For example:</p>
				1549	<pre>
				1550	cl::extrahelp("\nADDITIONAL HELP:\n\n This is the extra help\n");
				1551	</pre>
				1552	</div>
				1553
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1554	<!-- ======================================================================= -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1555	<div class="doc_subsection">
				1556	<a name="builtinparsers">Builtin parsers</a>
				1557	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1558
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1559	<div class="doc_text">
				1560
				1561	<p>Parsers control how the string value taken from the command line is
				1562	translated into a typed value, suitable for use in a C++ program. By default,
				1563	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]	1564	command line option specifies that it uses values of type '<tt>type</tt>'.
				1565	Because of this, custom option processing is specified with specializations of
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1566	the '<tt>parser</tt>' class.</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	<p>The CommandLine library provides the following builtin parser
				1569	specializations, which are sufficient for most applications. It can, however,
				1570	also be extended to work with new data types and new ways of interpreting the
				1571	same data. See the <a href="#customparser">Writing a Custom Parser</a> for more
				1572	details on this type of library extension.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1573
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1574	<ul>
				1575
				1576	<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]	1577	can be used to map strings values to any data type, through the use of the <a
				1578	href="#cl::values">cl::values</a> property, which specifies the mapping
				1579	information. The most common use of this parser is for parsing enum values,
				1580	which allows you to use the CommandLine library for all of the error checking to
				1581	make sure that only valid enum values are specified (as opposed to accepting
				1582	arbitrary strings). Despite this, however, the generic parser class can be used
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1583	for any data type.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1584
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1585	<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]	1586	is used to convert boolean strings to a boolean value. Currently accepted
				1587	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]	1588	"<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]	1589
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1590	<li><a name="stringparser">The <b><tt>parser<string></tt>
				1591	specialization</b></a> simply stores the parsed string into the string value
				1592	specified. No conversion or modification of the data is performed.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1593
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1594	<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]	1595	uses the C <tt>strtol</tt> function to parse the string input. As such, it will
				1596	accept a decimal number (with an optional '+' or '-' prefix) which must start
				1597	with a non-zero digit. It accepts octal numbers, which are identified with a
				1598	'<tt>0</tt>' prefix digit, and hexadecimal numbers with a prefix of
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1599	'<tt>0x</tt>' or '<tt>0X</tt>'.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1600
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1601	<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]	1602	<b><tt>parser<float></tt> specializations</b> use the standard C
				1603	<tt>strtod</tt> function to convert floating point strings into floating point
				1604	values. As such, a broad range of string formats is supported, including
				1605	exponential notation (ex: <tt>1.7e15</tt>) and properly supports locales.
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1606	</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1607
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1608	</ul>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	1609
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1610	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	1611
				1612	<!-- *********************************************************************** -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1613	<div class="doc_section">
				1614	<a name="extensionguide">Extension Guide</a>
				1615	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	1616	<!-- *********************************************************************** -->
				1617
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1618	<div class="doc_text">
				1619
				1620	<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]	1621	already (as discussed previously), one of its true strengths lie in its
				1622	extensibility. This section discusses how the CommandLine library works under
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1623	the covers and illustrates how to do some simple, common, extensions.</p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1624
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1625	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	1626
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1627	<!-- ======================================================================= -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1628	<div class="doc_subsection">
				1629	<a name="customparser">Writing a custom parser</a>
				1630	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1631
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1632	<div class="doc_text">
				1633
				1634	<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]	1635	As <a href="#builtinparsers">discussed previously</a>, parsers are the portion
				1636	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]	1637	particular parsed data type, validating the input in the process.</p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1638
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1639	<p>There are two ways to use a new parser:</p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1640
				1641	<ol>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1642
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1643	<li>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1644
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1645	<p>Specialize the <a href="#genericparser"><tt>cl::parser</tt></a> template for
				1646	your custom data type.<p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1647
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1648	<p>This approach has the advantage that users of your custom data type will
				1649	automatically use your custom parser whenever they define an option with a value
				1650	type of your data type. The disadvantage of this approach is that it doesn't
				1651	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]	1652
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1653	</li>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1654
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1655	<li>
				1656
				1657	<p>Write an independent class, using it explicitly from options that need
				1658	it.</p>
				1659
				1660	<p>This approach works well in situations where you would line to parse an
				1661	option using special syntax for a not-very-special data-type. The drawback of
				1662	this approach is that users of your parser have to be aware that they are using
				1663	your parser, instead of the builtin ones.</p>
				1664
				1665	</li>
				1666
				1667	</ol>
				1668
				1669	<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]	1670	sizes, specified with an optional unit after the numeric size. For example, we
				1671	would like to parse "102kb", "41M", "1G" into the appropriate integer value. In
				1672	this case, the underlying data type we want to parse into is
				1673	'<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]	1674	this the default for all <tt>unsigned</tt> options.</p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1675
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1676	<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]	1677
				1678	<pre>
				1679	<b>struct</b> FileSizeParser : <b>public</b> cl::basic_parser<<b>unsigned</b>> {
				1680	<i>// parse - Return true on error.</i>
				1681	<b>bool</b> parse(cl::Option &O, <b>const char</b> *ArgName, <b>const</b> std::string &ArgValue,
				1682	<b>unsigned</b> &Val);
				1683	};
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1684	</pre>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1685
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1686	<p>Our new class inherits from the <tt>cl::basic_parser</tt> template class to
				1687	fill in the default, boiler plate, code for us. We give it the data type that
				1688	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]	1689	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]	1690	declare that we parse into '<tt>unsigned</tt>' variables.</p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1691
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1692	<p>For most purposes, the only method that must be implemented in a custom
				1693	parser is the <tt>parse</tt> method. The <tt>parse</tt> method is called
				1694	whenever the option is invoked, passing in the option itself, the option name,
				1695	the string to parse, and a reference to a return value. If the string to parse
				1696	is not well formed, the parser should output an error message and return true.
				1697	Otherwise it should return false and set '<tt>Val</tt>' to the parsed value. In
				1698	our example, we implement <tt>parse</tt> as:</p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1699
				1700	<pre>
				1701	<b>bool</b> FileSizeParser::parse(cl::Option &O, <b>const char</b> *ArgName,
				1702	<b>const</b> std::string &Arg, <b>unsigned</b> &Val) {
				1703	<b>const char</b> *ArgStart = Arg.c_str();
				1704	<b>char</b> *End;
				1705
				1706	<i>// Parse integer part, leaving 'End' pointing to the first non-integer char</i>
				1707	Val = (unsigned)strtol(ArgStart, &End, 0);
				1708
				1709	<b>while</b> (1) {
				1710	<b>switch</b> (*End++) {
				1711	<b>case</b> 0: <b>return</b> false; <i>// No error</i>
				1712	<b>case</b> 'i': <i>// Ignore the 'i' in KiB if people use that</i>
				1713	<b>case</b> 'b': <b>case</b> 'B': <i>// Ignore B suffix</i>
				1714	<b>break</b>;
				1715
				1716	<b>case</b> 'g': <b>case</b> 'G': Val = 10241024*1024; <b>break</b>;
				1717	<b>case</b> 'm': <b>case</b> 'M': Val = 10241024; <b>break</b>;
				1718	<b>case</b> 'k': <b>case</b> 'K': Val *= 1024; <b>break</b>;
				1719
				1720	default:
				1721	<i>// Print an error message if unrecognized character!</i>
				1722	<b>return</b> O.error(": '" + Arg + "' value invalid for file size argument!");
				1723	}
				1724	}
				1725	}
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1726	</pre>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1727
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1728	<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]	1729	interested in. Although it has some holes (it allows "<tt>123KKK</tt>" for
				1730	example), it is good enough for this example. Note that we use the option
				1731	itself to print out the error message (the <tt>error</tt> method always returns
				1732	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]	1733	parser class, we can use it like this:</p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1734
				1735	<pre>
				1736	<b>static</b> <a href="#cl::opt">cl::opt</a><<b>unsigned</b>, <b>false</b>, FileSizeParser>
				1737	MFS(<i>"max-file-size"</i>, <a href="#cl::desc">cl::desc</a>(<i>"Maximum file size to accept"</i>),
				1738	<a href="#cl::value_desc">cl::value_desc</a>("<i>size</i>"));
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1739	</pre>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1740
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1741	<p>Which adds this to the output of our program:</p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1742
				1743	<pre>
				1744	OPTIONS:
				1745	-help - display available options (--help-hidden for more)
				1746	...
				1747	<b>-max-file-size=<size> - Maximum file size to accept</b>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1748	</pre>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1749
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1750	<p>And we can test that our parse works correctly now (the test program just
				1751	prints out the max-file-size argument value):</p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1752
				1753	<pre>
				1754	$ ./test
				1755	MFS: 0
				1756	$ ./test -max-file-size=123MB
				1757	MFS: 128974848
				1758	$ ./test -max-file-size=3G
				1759	MFS: 3221225472
				1760	$ ./test -max-file-size=dog
				1761	-max-file-size option: 'dog' value invalid for file size argument!
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1762	</pre>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1763
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1764	<p>It looks like it works. The error message that we get is nice and helpful,
				1765	and we seem to accept reasonable file sizes. This wraps up the "custom parser"
				1766	tutorial.</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	</div>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1769
				1770	<!-- ======================================================================= -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1771	<div class="doc_subsection">
				1772	<a name="explotingexternal">Exploiting external storage</a>
				1773	</div>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1774
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1775	<div class="doc_text">
Reid Spencer	b993feb	2004-08-30 05:56:51 +0000	[diff] [blame]	1776	<p>Several of the LLVM libraries define static <tt>cl::opt</tt> instances that
				1777	will automatically be included in any program that links with that library.
				1778	This is a feature. However, sometimes it is necessary to know the value of the
				1779	command line option outside of the library. In these cases the library does or
				1780	should provide an external storage location that is accessible to users of the
				1781	library. Examples of this include the <tt>llvm::DebugFlag</tt> exported by the
				1782	<tt>lib/Support/Debug.cpp</tt> file and the <tt>llvm::TimePassesIsEnabled</tt>
				1783	flag exported by the <tt>lib/VMCore/Pass.cpp</tt> file.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1784
Reid Spencer	b993feb	2004-08-30 05:56:51 +0000	[diff] [blame]	1785	<p>TODO: complete this section</p>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1786
				1787	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1788
				1789	<!-- ======================================================================= -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1790	<div class="doc_subsection">
				1791	<a name="dynamicopts">Dynamically adding command line options</a>
				1792	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1793
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1794	<div class="doc_text">
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1795
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1796	<p>TODO: fill in this section</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	1797
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1798	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	1799
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	1800	<!-- *********************************************************************** -->
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Misha Brukman	c53aefb	2004-05-12 18:42:35 +0000	[diff] [blame]	1803	<address>
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				1809	<a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
				1810	<a href="http://llvm.cs.uiuc.edu">LLVM Compiler Infrastructure</a><br>
Misha Brukman	3c29911	2003-11-07 18:11:14 +0000	[diff] [blame]	1811	Last modified: $Date$
Misha Brukman	c53aefb	2004-05-12 18:42:35 +0000	[diff] [blame]	1812	</address>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1813
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