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Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1	<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
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Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	5	<title>CommandLine 2.0 Library Manual</title>
Misha Brukman	3c29911	2003-11-07 18:11:14 +0000	[diff] [blame]	6	<link rel="stylesheet" href="llvm.css" type="text/css">
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	7	</head>
				8	<body>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	9
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	10	<div class="doc_title">
				11	CommandLine 2.0 Library Manual
				12	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	13
				14	<ol>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	15	<li><a href="#introduction">Introduction</a></li>
				16
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	17	<li><a href="#quickstart">Quick Start Guide</a>
				18	<ol>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	19	<li><a href="#bool">Boolean Arguments</a></li>
				20	<li><a href="#alias">Argument Aliases</a></li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	21	<li><a href="#onealternative">Selecting an alternative from a
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	22	set of possibilities</a></li>
				23	<li><a href="#namedalternatives">Named alternatives</a></li>
				24	<li><a href="#list">Parsing a list of options</a></li>
				25	<li><a href="#description">Adding freeform text to help output</a></li>
				26	</ol></li>
				27
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	28	<li><a href="#referenceguide">Reference Guide</a>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	29	<ol>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	30	<li><a href="#positional">Positional Arguments</a>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	31	<ul>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	32	<li><a href="#--">Specifying positional options with hyphens</a></li>
Reid Spencer	2c8ab58	2004-08-13 20:19:14 +0000	[diff] [blame]	33	<li><a href="#getPosition">Determining absolute position with
				34	getPosition</a></li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	35	<li><a href="#cl::ConsumeAfter">The <tt>cl::ConsumeAfter</tt>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	36	modifier</a></li>
				37	</ul></li>
				38
				39	<li><a href="#storage">Internal vs External Storage</a></li>
				40
				41	<li><a href="#attributes">Option Attributes</a></li>
				42
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	43	<li><a href="#modifiers">Option Modifiers</a>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	44	<ul>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	45	<li><a href="#hiding">Hiding an option from <tt>--help</tt>
				46	output</a></li>
				47	<li><a href="#numoccurrences">Controlling the number of occurrences
				48	required and allowed</a></li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	49	<li><a href="#valrequired">Controlling whether or not a value must be
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	50	specified</a></li>
				51	<li><a href="#formatting">Controlling other formatting options</a></li>
				52	<li><a href="#misc">Miscellaneous option modifiers</a></li>
				53	</ul></li>
				54
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	55	<li><a href="#toplevel">Top-Level Classes and Functions</a>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	56	<ul>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	57	<li><a href="#cl::ParseCommandLineOptions">The
				58	<tt>cl::ParseCommandLineOptions</tt> function</a></li>
				59	<li><a href="#cl::ParseEnvironmentOptions">The
				60	<tt>cl::ParseEnvironmentOptions</tt> function</a></li>
				61	<li><a href="#cl::opt">The <tt>cl::opt</tt> class</a></li>
				62	<li><a href="#cl::list">The <tt>cl::list</tt> class</a></li>
				63	<li><a href="#cl::alias">The <tt>cl::alias</tt> class</a></li>
				64	</ul></li>
				65
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	66	<li><a href="#builtinparsers">Builtin parsers</a>
				67	<ul>
				68	<li><a href="#genericparser">The Generic <tt>parser<t></tt>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	69	parser</a></li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	70	<li><a href="#boolparser">The <tt>parser<bool></tt>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	71	specialization</a></li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	72	<li><a href="#stringparser">The <tt>parser<string></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="#intparser">The <tt>parser<int></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="#doubleparser">The <tt>parser<double></tt> and
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	77	<tt>parser<float></tt> specializations</a></li>
				78	</ul></li>
				79	</ol></li>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	80	<li><a href="#extensionguide">Extension Guide</a>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	81	<ol>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	82	<li><a href="#customparser">Writing a custom parser</a></li>
				83	<li><a href="#explotingexternal">Exploiting external storage</a></li>
				84	<li><a href="#dynamicopts">Dynamically adding command line
				85	options</a></li>
				86	</ol></li>
				87	</ol>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	88
Chris Lattner	7911ce2	2004-05-23 21:07:27 +0000	[diff] [blame]	89	<div class="doc_author">
				90	<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]	91	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	92
				93	<!-- *********************************************************************** -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	94	<div class="doc_section">
Misha Brukman	8becd71	2003-11-07 19:42:44 +0000	[diff] [blame]	95	<a name="introduction">Introduction</a>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	96	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	97	<!-- *********************************************************************** -->
				98
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	99	<div class="doc_text">
				100
				101	<p>This document describes the CommandLine argument processing library. It will
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	102	show you how to use it, and what it can do. The CommandLine library uses a
				103	declarative approach to specifying the command line options that your program
				104	takes. By default, these options declarations implicitly hold the value parsed
				105	for the option declared (of course this <a href="#storage">can be
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	106	changed</a>).</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	107
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	108	<p>Although there are a <b>lot</b> of command line argument parsing libraries
				109	out there in many different languages, none of them fit well with what I needed.
				110	By looking at the features and problems of other libraries, I designed the
				111	CommandLine library to have the following features:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	112
				113	<ol>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	114	<li>Speed: The CommandLine library is very quick and uses little resources. The
				115	parsing time of the library is directly proportional to the number of arguments
				116	parsed, not the the number of options recognized. Additionally, command line
Chris Lattner	edf351f	2003-06-21 21:45:56 +0000	[diff] [blame]	117	argument values are captured transparently into user defined global variables,
				118	which can be accessed like any other variable (and with the same
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	119	performance).</li>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	120
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	121	<li>Type Safe: As a user of CommandLine, you don't have to worry about
				122	remembering the type of arguments that you want (is it an int? a string? a
				123	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]	124	error prone constructs, it also leads to dramatically cleaner source code.</li>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	125
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	126	<li>No subclasses required: To use CommandLine, you instantiate variables that
				127	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]	128	parser. This means that you don't have to write <b>any</b> boilerplate
				129	code.</li>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	130
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	131	<li>Globally accessible: Libraries can specify command line arguments that are
				132	automatically enabled in any tool that links to the library. This is possible
				133	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]	134	the parser. This also makes supporting <a href="#dynamicopts">dynamically
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	135	loaded options</a> trivial.</li>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	136
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	137	<li>Cleaner: CommandLine supports enum and other types directly, meaning that
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	138	there is less error and more security built into the library. You don't have to
				139	worry about whether your integral command line argument accidentally got
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	140	assigned a value that is not valid for your enum type.</li>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	141
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	142	<li>Powerful: The CommandLine library supports many different types of
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	143	arguments, from simple <a href="#boolparser">boolean flags</a> to <a
				144	href="#cl::opt">scalars arguments</a> (<a href="#stringparser">strings</a>, <a
				145	href="#intparser">integers</a>, <a href="#genericparser">enums</a>, <a
				146	href="#doubleparser">doubles</a>), to <a href="#cl::list">lists of
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	147	arguments</a>. This is possible because CommandLine is...</li>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	148
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	149	<li>Extensible: It is very simple to add a new argument type to CommandLine.
				150	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]	151	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]	152
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	153	<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]	154	that you, the user, have to do. For example, it automatically provides a
				155	<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]	156	tool. Additionally, it does most of the basic correctness checking for
				157	you.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	158
				159	<li>Capable: The CommandLine library can handle lots of different forms of
				160	options often found in real programs. For example, <a
				161	href="#positional">positional</a> arguments, <tt>ls</tt> style <a
				162	href="#cl::Grouping">grouping</a> options (to allow processing '<tt>ls
				163	-lad</tt>' naturally), <tt>ld</tt> style <a href="#cl::Prefix">prefix</a>
				164	options (to parse '<tt>-lmalloc -L/usr/lib</tt>'), and <a
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	165	href="#cl::ConsumeAfter">interpreter style options</a>.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	166
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	167	</ol>
				168
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	169	<p>This document will hopefully let you jump in and start using CommandLine in
				170	your utility quickly and painlessly. Additionally it should be a simple
				171	reference manual to figure out how stuff works. If it is failing in some area
				172	(or you want an extension to the library), nag the author, <a
				173	href="mailto:sabre@nondot.org">Chris Lattner</a>.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	174
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	175	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	176
				177	<!-- *********************************************************************** -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	178	<div class="doc_section">
				179	<a name="quickstart">Quick Start Guide</a>
				180	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	181	<!-- *********************************************************************** -->
				182
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	183	<div class="doc_text">
				184
				185	<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]	186	basic compiler tool. This is intended to show you how to jump into using the
				187	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]	188	can do.</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	189
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	190	<p>To start out, you need to include the CommandLine header file into your
				191	program:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	192
				193	<pre>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	194	#include "Support/CommandLine.h"
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	195	</pre>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	196
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	197	<p>Additionally, you need to add this as the first line of your main
				198	program:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	199
				200	<pre>
				201	int main(int argc, char **argv) {
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	202	<a href="#cl::ParseCommandLineOptions">cl::ParseCommandLineOptions</a>(argc, argv);
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	203	...
				204	}
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	205	</pre>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	206
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	207	<p>... which actually parses the arguments and fills in the variable
				208	declarations.</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	209
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	210	<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]	211	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]	212	library uses a declarative syntax to model command line arguments with the
				213	global variable declarations that capture the parsed values. This means that
				214	for every command line option that you would like to support, there should be a
				215	global variable declaration to capture the result. For example, in a compiler,
				216	we would like to support the unix standard '<tt>-o <filename></tt>' option
				217	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]	218	represented like this:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	219
Misha Brukman	c53aefb	2004-05-12 18:42:35 +0000	[diff] [blame]	220	<a name="value_desc_example"></a>
				221	<pre>
				222	<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>"));
				223	</pre>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	224
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	225	<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]	226	capture the result of the "<tt>o</tt>" argument (first parameter). We specify
				227	that this is a simple scalar option by using the "<tt><a
				228	href="#cl::opt">cl::opt</a></tt>" template (as opposed to the <a
				229	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]	230	that the data type that we are parsing is a string.</p>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	231
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	232	<p>The second and third parameters (which are optional) are used to specify what
				233	to output for the "<tt>--help</tt>" option. In this case, we get a line that
				234	looks like this:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	235
				236	<pre>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	237	USAGE: compiler [options]
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	238
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	239	OPTIONS:
				240	-help - display available options (--help-hidden for more)
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	241	<b>-o <filename> - Specify output filename</b>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	242	</pre>
				243
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	244	<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]	245	<tt>string</tt> data type, the variable declared is automatically usable as a
				246	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]	247	example:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	248
				249	<pre>
				250	...
				251	ofstream Output(OutputFilename.c_str());
				252	if (Out.good()) ...
				253	...
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	254	</pre>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	255
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	256	<p>There are many different options that you can use to customize the command
				257	line option handling library, but the above example shows the general interface
				258	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]	259	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]	260	there are no positional dependencies to remember. The available options are
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	261	discussed in detail in the <a href="#referenceguide">Reference Guide</a>.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	262
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	263	<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]	264	filename as well as an output filename, but we do not want the input filename to
				265	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]	266	style of argument, the CommandLine library allows for <a
				267	href="#positional">positional</a> arguments to be specified for the program.
				268	These positional arguments are filled with command line parameters that are not
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	269	in option form. We use this feature like this:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	270
				271	<pre>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	272	<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]	273	</pre>
				274
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	275	<p>This declaration indicates that the first positional argument should be
				276	treated as the input filename. Here we use the <tt><a
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	277	href="#cl::init">cl::init</a></tt> option to specify an initial value for the
				278	command line option, which is used if the option is not specified (if you do not
				279	specify a <tt><a href="#cl::init">cl::init</a></tt> modifier for an option, then
				280	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]	281	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]	282	that the user always specify an input filename, we would add the <tt><a
				283	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]	284	<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]	285
				286	<pre>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	287	<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]	288	</pre>
				289
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	290	<p>Again, the CommandLine library does not require the options to be specified
				291	in any particular order, so the above declaration is equivalent to:</p>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	292
				293	<pre>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	294	<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]	295	</pre>
				296
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	297	<p>By simply adding the <tt><a href="#cl::Required">cl::Required</a></tt> flag,
				298	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]	299	specified, which shifts all of the command line option verification code out of
				300	your application into the library. This is just one example of how using flags
				301	can alter the default behaviour of the library, on a per-option basis. By
				302	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]	303	extended to:</p>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	304
				305	<pre>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	306	USAGE: compiler [options] <b><input file></b>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	307
				308	OPTIONS:
				309	-help - display available options (--help-hidden for more)
				310	-o <filename> - Specify output filename
				311	</pre>
				312
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	313	<p>... indicating that an input filename is expected.</p>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	314
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	315	</div>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	316
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	317	<!-- ======================================================================= -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	318	<div class="doc_subsection">
				319	<a name="bool">Boolean Arguments</a>
				320	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	321
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	322	<div class="doc_text">
				323
				324	<p>In addition to input and output filenames, we would like the compiler example
				325	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]	326	file, "<tt>--quiet</tt>" to enable quiet mode, and "<tt>-q</tt>" for backwards
				327	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]	328	of boolean type like this:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	329
				330	<pre>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	331	<a href="#cl::opt">cl::opt</a><bool> Force ("<i>f</i>", <a href="#cl::desc">cl::desc</a>("<i>Overwrite output files</i>"));
				332	<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>"));
				333	<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]	334	</pre>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	335
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	336	<p>This does what you would expect: it declares three boolean variables
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	337	("<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]	338	options. Note that the "<tt>-q</tt>" option is specified with the "<a
				339	href="#cl::Hidden"><tt>cl::Hidden</tt></a>" flag. This modifier prevents it
				340	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]	341	shown in the "<tt>--help-hidden</tt>" output).</p>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	342
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	343	<p>The CommandLine library uses a <a href="#builtinparsers">different parser</a>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	344	for different data types. For example, in the string case, the argument passed
				345	to the option is copied literally into the content of the string variable... we
				346	obviously cannot do that in the boolean case, however, so we must use a smarter
				347	parser. In the case of the boolean parser, it allows no options (in which case
				348	it assigns the value of true to the variable), or it allows the values
				349	"<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]	350	following inputs:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	351
				352	<pre>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	353	compiler -f # No value, 'Force' == true
				354	compiler -f=true # Value specified, 'Force' == true
				355	compiler -f=TRUE # Value specified, 'Force' == true
				356	compiler -f=FALSE # Value specified, 'Force' == false
				357	</pre>
				358
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	359	<p>... you get the idea. The <a href="#boolparser">bool parser</a> just turns
				360	the string values into boolean values, and rejects things like '<tt>compiler
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	361	-f=foo</tt>'. Similarly, the <a href="#doubleparser">float</a>, <a
				362	href="#doubleparser">double</a>, and <a href="#intparser">int</a> parsers work
				363	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]	364	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]	365
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	366	<p>With the declarations above, "<tt>compiler --help</tt>" emits this:</p>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	367
				368	<pre>
				369	USAGE: compiler [options] <input file>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	370
				371	OPTIONS:
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	372	<b>-f - Overwrite output files</b>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	373	-o - Override output filename
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	374	<b>-quiet - Don't print informational messages</b>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	375	-help - display available options (--help-hidden for more)
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	376	</pre>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	377
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	378	<p>and "<tt>opt --help-hidden</tt>" prints this:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	379
				380	<pre>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	381	USAGE: compiler [options] <input file>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	382
				383	OPTIONS:
				384	-f - Overwrite output files
				385	-o - Override output filename
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	386	<b>-q - Don't print informational messages</b>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	387	-quiet - Don't print informational messages
				388	-help - display available options (--help-hidden for more)
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	389	</pre>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	390
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	391	<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]	392	href="#cl::opt">cl::opt</a></tt>' class to parse simple scalar command line
				393	arguments. In addition to simple scalar arguments, the CommandLine library also
				394	provides primitives to support CommandLine option <a href="#alias">aliases</a>,
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	395	and <a href="#list">lists</a> of options.</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	396
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	397	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	398
				399	<!-- ======================================================================= -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	400	<div class="doc_subsection">
				401	<a name="alias">Argument Aliases</a>
				402	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	403
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	404	<div class="doc_text">
				405
				406	<p>So far, the example works well, except for the fact that we need to check the
				407	quiet condition like this now:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	408
				409	<pre>
				410	...
				411	if (!Quiet && !Quiet2) printInformationalMessage(...);
				412	...
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	413	</pre>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	414
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	415	<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]	416	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]	417	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]	418	a value itself:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	419
				420	<pre>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	421	<a href="#cl::opt">cl::opt</a><bool> Force ("<i>f</i>", <a href="#cl::desc">cl::desc</a>("<i>Overwrite output files</i>"));
				422	<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>"));
				423	<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]	424	</pre>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	425
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	426	<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]	427	"<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]	428	the <tt><a href="#cl::aliasopt">cl::aliasopt</a></tt> modifier) whenever it is
				429	specified. Because aliases do not hold state, the only thing the program has to
				430	query is the <tt>Quiet</tt> variable now. Another nice feature of aliases is
				431	that they automatically hide themselves from the <tt>-help</tt> output
				432	(although, again, they are still visible in the <tt>--help-hidden
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	433	output</tt>).</p>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	434
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	435	<p>Now the application code can simply use:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	436
				437	<pre>
				438	...
				439	if (!Quiet) printInformationalMessage(...);
				440	...
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	441	</pre>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	442
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	443	<p>... which is much nicer! The "<tt><a href="#cl::alias">cl::alias</a></tt>"
				444	can be used to specify an alternative name for any variable type, and has many
				445	uses.</p>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	446
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	447	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	448
				449	<!-- ======================================================================= -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	450	<div class="doc_subsection">
				451	<a name="onealternative">Selecting an alternative from a set of
				452	possibilities</a>
				453	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	454
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	455	<div class="doc_text">
				456
				457	<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]	458	<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]	459	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]	460
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	461	<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]	462	your own parser, as described in the <a href="#extensionguide">Extension
Reid Spencer	d847337	2004-08-10 16:38:18 +0000	[diff] [blame]	463	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]	464	requires you to tell it what this mapping should be.</p>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	465
Reid Spencer	d847337	2004-08-10 16:38:18 +0000	[diff] [blame]	466	<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]	467	optimizer, using the standard flags "<tt>-g</tt>", "<tt>-O0</tt>",
				468	"<tt>-O1</tt>", and "<tt>-O2</tt>". We could easily implement this with boolean
				469	options like above, but there are several problems with this strategy:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	470
				471	<ol>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	472	<li>A user could specify more than one of the options at a time, for example,
				473	"<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]	474	erroneous input for us.</li>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	475
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	476	<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]	477
				478	<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]	479	see if some level >= "<tt>-O1</tt>" is enabled.</li>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	480
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	481	</ol>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	482
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	483	<p>To cope with these problems, we can use an enum value, and have the
				484	CommandLine library fill it in with the appropriate level directly, which is
				485	used like this:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	486
				487	<pre>
				488	enum OptLevel {
				489	g, O1, O2, O3
				490	};
				491
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	492	<a href="#cl::opt">cl::opt</a><OptLevel> OptimizationLevel(<a href="#cl::desc">cl::desc</a>("<i>Choose optimization level:</i>"),
				493	<a href="#cl::values">cl::values</a>(
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	494	clEnumVal(g , "<i>No optimizations, enable debugging</i>"),
				495	clEnumVal(O1, "<i>Enable trivial optimizations</i>"),
				496	clEnumVal(O2, "<i>Enable default optimizations</i>"),
				497	clEnumVal(O3, "<i>Enable expensive optimizations</i>"),
Chris Lattner	b406ead	2004-07-16 00:10:54 +0000	[diff] [blame]	498	clEnumValEnd));
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	499
				500	...
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	501	if (OptimizationLevel >= O2) doPartialRedundancyElimination(...);
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	502	...
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	503	</pre>
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	<p>This declaration defines a variable "<tt>OptimizationLevel</tt>" of the
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	506	"<tt>OptLevel</tt>" enum type. This variable can be assigned any of the values
				507	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]	508	terminated with the "<tt>clEnumValEnd</tt>" argument!). The CommandLine
				509	library enforces
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	510	that the user can only specify one of the options, and it ensure that only valid
				511	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]	512	command line arguments matched the enum values. With this option added, our
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	513	help output now is:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	514
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	515	<pre>
				516	USAGE: compiler [options] <input file>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	517
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	518	OPTIONS:
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	519	<b>Choose optimization level:
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	520	-g - No optimizations, enable debugging
				521	-O1 - Enable trivial optimizations
				522	-O2 - Enable default optimizations
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	523	-O3 - Enable expensive optimizations</b>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	524	-f - Overwrite output files
				525	-help - display available options (--help-hidden for more)
				526	-o <filename> - Specify output filename
				527	-quiet - Don't print informational messages
				528	</pre>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	529
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	530	<p>In this case, it is sort of awkward that flag names correspond directly to
				531	enum names, because we probably don't want a enum definition named "<tt>g</tt>"
				532	in our program. Because of this, we can alternatively write this example like
				533	this:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	534
				535	<pre>
				536	enum OptLevel {
				537	Debug, O1, O2, O3
				538	};
				539
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	540	<a href="#cl::opt">cl::opt</a><OptLevel> OptimizationLevel(<a href="#cl::desc">cl::desc</a>("<i>Choose optimization level:</i>"),
				541	<a href="#cl::values">cl::values</a>(
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	542	clEnumValN(Debug, "g", "<i>No optimizations, enable debugging</i>"),
				543	clEnumVal(O1 , "<i>Enable trivial optimizations</i>"),
				544	clEnumVal(O2 , "<i>Enable default optimizations</i>"),
				545	clEnumVal(O3 , "<i>Enable expensive optimizations</i>"),
Chris Lattner	b406ead	2004-07-16 00:10:54 +0000	[diff] [blame]	546	clEnumValEnd));
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	547
				548	...
				549	if (OptimizationLevel == Debug) outputDebugInfo(...);
				550	...
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	551	</pre>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	552
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	553	<p>By using the "<tt>clEnumValN</tt>" macro instead of "<tt>clEnumVal</tt>", we
				554	can directly specify the name that the flag should get. In general a direct
				555	mapping is nice, but sometimes you can't or don't want to preserve the mapping,
				556	which is when you would use it.</p>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	557
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	558	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	559
				560	<!-- ======================================================================= -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	561	<div class="doc_subsection">
				562	<a name="namedalternatives">Named Alternatives</a>
				563	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	564
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	565	<div class="doc_text">
				566
				567	<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]	568	style in our compiler to specify different debug levels that can be used.
				569	Instead of each debug level being its own switch, we want to support the
				570	following options, of which only one can be specified at a time:
				571	"<tt>--debug-level=none</tt>", "<tt>--debug-level=quick</tt>",
				572	"<tt>--debug-level=detailed</tt>". To do this, we use the exact same format as
				573	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]	574	case, the code looks like this:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	575
				576	<pre>
				577	enum DebugLev {
				578	nodebuginfo, quick, detailed
				579	};
				580
				581	// Enable Debug Options to be specified on the command line
Chris Lattner	dc844fa	2003-06-03 04:40:06 +0000	[diff] [blame]	582	<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]	583	<a href="#cl::values">cl::values</a>(
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	584	clEnumValN(nodebuginfo, "none", "<i>disable debug information</i>"),
				585	clEnumVal(quick, "<i>enable quick debug information</i>"),
				586	clEnumVal(detailed, "<i>enable detailed debug information</i>"),
Chris Lattner	b406ead	2004-07-16 00:10:54 +0000	[diff] [blame]	587	clEnumValEnd));
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	588	</pre>
				589
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	590	<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]	591	DebugLev</tt>", which works exactly the same way as before. The difference here
				592	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]	593	the "<tt>--help</tt>" option:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	594
				595	<pre>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	596	USAGE: compiler [options] <input file>
				597
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	598	OPTIONS:
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	599	Choose optimization level:
				600	-g - No optimizations, enable debugging
				601	-O1 - Enable trivial optimizations
				602	-O2 - Enable default optimizations
				603	-O3 - Enable expensive optimizations
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	604	<b>-debug_level - Set the debugging level:
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	605	=none - disable debug information
				606	=quick - enable quick debug information
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	607	=detailed - enable detailed debug information</b>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	608	-f - Overwrite output files
				609	-help - display available options (--help-hidden for more)
				610	-o <filename> - Specify output filename
				611	-quiet - Don't print informational messages
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	612	</pre>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	613
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	614	<p>Again, the only structural difference between the debug level declaration and
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	615	the optimiation level declaration is that the debug level declaration includes
				616	an option name (<tt>"debug_level"</tt>), which automatically changes how the
				617	library processes the argument. The CommandLine library supports both forms so
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	618	that you can choose the form most appropriate for your application.</p>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	619
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	620	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	621
				622	<!-- ======================================================================= -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	623	<div class="doc_subsection">
				624	<a name="list">Parsing a list of options</a>
				625	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	626
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	627	<div class="doc_text">
				628
				629	<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]	630	lets get a little wild and crazy. Lets say that we want our optimizer to accept
				631	a <b>list</b> of optimizations to perform, allowing duplicates. For example, we
				632	might want to run: "<tt>compiler -dce -constprop -inline -dce -strip</tt>". In
				633	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]	634	important. This is what the "<tt><a href="#cl::list">cl::list</a></tt>"
				635	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]	636	would like to perform:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	637
				638	<pre>
				639	enum Opts {
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	640	// 'inline' is a C++ keyword, so name it 'inlining'
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	641	dce, constprop, inlining, strip
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	642	};
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	643	</pre>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	644
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	645	<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]	646
				647	<pre>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	648	<a href="#cl::list">cl::list</a><Opts> OptimizationList(<a href="#cl::desc">cl::desc</a>("<i>Available Optimizations:</i>"),
				649	<a href="#cl::values">cl::values</a>(
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	650	clEnumVal(dce , "<i>Dead Code Elimination</i>"),
Misha Brukman	82c89b9	2003-05-20 21:01:22 +0000	[diff] [blame]	651	clEnumVal(constprop , "<i>Constant Propagation</i>"),
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	652	clEnumValN(inlining, "<i>inline</i>", "<i>Procedure Integration</i>"),
				653	clEnumVal(strip , "<i>Strip Symbols</i>"),
Chris Lattner	b406ead	2004-07-16 00:10:54 +0000	[diff] [blame]	654	clEnumValEnd));
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	655	</pre>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	656
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	657	<p>This defines a variable that is conceptually of the type
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	658	"<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]	659	vector methods:</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	660
				661	<pre>
Chris Lattner	ae85363	2002-07-25 19:27:01 +0000	[diff] [blame]	662	for (unsigned i = 0; i != OptimizationList.size(); ++i)
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	663	switch (OptimizationList[i])
				664	...
				665	</pre>
				666
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	667	<p>... to iterate through the list of options specified.</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	668
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	669	<p>Note that the "<tt><a href="#cl::list">cl::list</a></tt>" template is
				670	completely general and may be used with any data types or other arguments that
				671	you can use with the "<tt><a href="#cl::opt">cl::opt</a></tt>" template. One
				672	especially useful way to use a list is to capture all of the positional
				673	arguments together if there may be more than one specified. In the case of a
				674	linker, for example, the linker takes several '<tt>.o</tt>' files, and needs to
				675	capture them into a list. This is naturally specified as:</p>
Chris Lattner	3e5fe17	2002-04-13 18:35:59 +0000	[diff] [blame]	676
				677	<pre>
				678	...
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	679	<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]	680	...
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	681	</pre>
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	<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]	684	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]	685	the <tt><a href="#cl::OneOrMore">cl::OneOrMore</a></tt> modifier to inform the
				686	CommandLine library that it is an error if the user does not specify any
				687	<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]	688	checking we have to do.</p>
Chris Lattner	3e5fe17	2002-04-13 18:35:59 +0000	[diff] [blame]	689
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	690	</div>
Chris Lattner	3e5fe17	2002-04-13 18:35:59 +0000	[diff] [blame]	691
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	692	<!-- ======================================================================= -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	693	<div class="doc_subsection">
				694	<a name="description">Adding freeform text to help output</a>
				695	</div>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	696
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	697	<div class="doc_text">
				698
				699	<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]	700	information about what it does into the help output. The help output is styled
				701	to look similar to a Unix <tt>man</tt> page, providing concise information about
				702	a program. Unix <tt>man</tt> pages, however often have a description about what
				703	the program does. To add this to your CommandLine program, simply pass a third
				704	argument to the <a
				705	href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>
				706	call in main. This additional argument is then printed as the overview
				707	information for your program, allowing you to include any additional information
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	708	that you want. For example:</p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	709
				710	<pre>
				711	int main(int argc, char **argv) {
				712	<a href="#cl::ParseCommandLineOptions">cl::ParseCommandLineOptions</a>(argc, argv, " CommandLine compiler example\n\n"
				713	" This program blah blah blah...\n");
				714	...
				715	}
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	716	</pre>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	717
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	718	<p>Would yield the help output:</p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	719
				720	<pre>
				721	<b>OVERVIEW: CommandLine compiler example
				722
				723	This program blah blah blah...</b>
				724
				725	USAGE: compiler [options] <input file>
				726
				727	OPTIONS:
				728	...
				729	-help - display available options (--help-hidden for more)
				730	-o <filename> - Specify output filename
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	731	</pre>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	732
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	733	</div>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	734
				735
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	736	<!-- *********************************************************************** -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	737	<div class="doc_section">
				738	<a name="referenceguide">Reference Guide</a>
				739	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	740	<!-- *********************************************************************** -->
				741
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	742	<div class="doc_text">
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	743
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	744	<p>Now that you know the basics of how to use the CommandLine library, this
				745	section will give you the detailed information you need to tune how command line
				746	options work, as well as information on more "advanced" command line option
				747	processing capabilities.</p>
				748
				749	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	750
				751	<!-- ======================================================================= -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	752	<div class="doc_subsection">
				753	<a name="positional">Positional Arguments</a>
				754	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	755
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	756	<div class="doc_text">
				757
				758	<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]	759	specified with a hyphen. Positional arguments should be used when an option is
				760	specified by its position alone. For example, the standard Unix <tt>grep</tt>
				761	tool takes a regular expression argument, and an optional filename to search
				762	through (which defaults to standard input if a filename is not specified).
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	763	Using the CommandLine library, this would be specified as:</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	764
				765	<pre>
				766	<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>);
				767	<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>"));
				768	</pre>
				769
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	770	<p>Given these two option declarations, the <tt>--help</tt> output for our grep
				771	replacement would look like this:</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	772
				773	<pre>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	774	USAGE: spiffygrep [options] <b><regular expression> <input file></b>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	775
				776	OPTIONS:
				777	-help - display available options (--help-hidden for more)
				778	</pre>
				779
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	780	<p>... and the resultant program could be used just like the standard
				781	<tt>grep</tt> tool.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	782
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	783	<p>Positional arguments are sorted by their order of construction. This means
				784	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]	785	.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]	786	are defined in multiple .cpp files. The fix for this problem is simply to
				787	define all of your positional arguments in one .cpp file.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	788
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	789	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	790
				791
				792	<!-- _______________________________________________________________________ -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	793	<div class="doc_subsubsection">
				794	<a name="--">Specifying positional options with hyphens</a>
				795	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	796
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	797	<div class="doc_text">
				798
				799	<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]	800	starts with a hyphen (for example, searching for '<tt>-foo</tt>' in a file). At
				801	first, you will have trouble doing this, because it will try to find an argument
				802	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]	803	Note that the system <tt>grep</tt> has the same problem:</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	804
				805	<pre>
				806	$ spiffygrep '-foo' test.txt
				807	Unknown command line argument '-foo'. Try: spiffygrep --help'
				808
				809	$ grep '-foo' test.txt
				810	grep: illegal option -- f
				811	grep: illegal option -- o
				812	grep: illegal option -- o
				813	Usage: grep -hblcnsviw pattern file . . .
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	814	</pre>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	815
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	816	<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]	817	version: use the '<tt>--</tt>' marker. When the user specifies '<tt>--</tt>' on
				818	the command line, it is telling the program that all options after the
				819	'<tt>--</tt>' should be treated as positional arguments, not options. Thus, we
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	820	can use it like this:</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	821
				822	<pre>
				823	$ spiffygrep -- -foo test.txt
				824	...output...
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	825	</pre>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	826
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	827	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	828
				829	<!-- _______________________________________________________________________ -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	830	<div class="doc_subsubsection">
Reid Spencer	2c8ab58	2004-08-13 20:19:14 +0000	[diff] [blame]	831	<a name="getPosition">Determining absolute position with getPosition()</a>
				832	</div>
				833	<div class="doc_text">
				834	<p>Sometimes an option can affect or modify the meaning of another option. For
				835	example, consider <tt>gcc</tt>'s <tt>-x LANG</tt> option. This tells
				836	<tt>gcc</tt> to ignore the suffix of subsequent positional arguments and force
				837	the file to be interpreted as if it contained source code in language
				838	<tt>LANG</tt>. In order to handle this properly , you need to know the
				839	absolute position of each argument, especially those in lists, so their
				840	interaction(s) can be applied correctly. This is also useful for options like
				841	<tt>-llibname</tt> which is actually a positional argument that starts with
				842	a dash.</p>
				843	<p>So, generally, the problem is that you have two <tt>cl::list</tt> variables
				844	that interact in some way. To ensure the correct interaction, you can use the
				845	<tt>cl::list::getPosition(optnum)</tt> method. This method returns the
				846	absolute position (as found on the command line) of the <tt>optnum</tt>
				847	item in the <tt>cl::list</tt>.</p>
				848	<p>The idiom for usage is like this:<pre><tt>
				849	static cl::list<std::string> Files(cl::Positional, cl::OneOrMore);
				850	static cl::listlt;std::string> Libraries("l", cl::ZeroOrMore);
				851
				852	int main(int argc, char**argv) {
				853	// ...
				854	std::vector<std::string>::iterator fileIt = Files.begin();
				855	std::vector<std::string>::iterator libIt = Libraries.begin();
				856	unsigned libPos = 0, filePos = 0;
				857	while ( 1 ) {
				858	if ( libIt != Libraries.end() )
				859	libPos = Libraries.getPosition( libIt - Libraries.begin() );
				860	else
				861	libPos = 0;
				862	if ( fileIt != Files.end() )
				863	filePos = Files.getPosition( fileIt - Files.begin() );
				864	else
				865	filePos = 0;
				866
				867	if ( filePos != 0 && (libPos == 0 \|\| filePos < libPos) ) {
				868	// Source File Is next
				869	++fileIt;
				870	}
				871	else if ( libPos != 0 && (filePos == 0 \|\| libPos < filePos) ) {
				872	// Library is next
				873	++libIt;
				874	}
				875	else
				876	break; // we're done with the list
				877	}
Reid Spencer	c7d1d82	2004-11-01 09:16:30 +0000	[diff] [blame]	878	}
				879	</tt></pre></p>
Reid Spencer	2c8ab58	2004-08-13 20:19:14 +0000	[diff] [blame]	880	<p>Note that, for compatibility reasons, the <tt>cl::opt</tt> also supports an
				881	<tt>unsigned getPosition()</tt> option that will provide the absolute position
				882	of that option. You can apply the same approach as above with a
				883	<tt>cl::opt</tt> and a <tt>cl::list</tt> option as you can with two lists.</p>
				884	</div>
				885
				886	<!-- _______________________________________________________________________ -->
				887	<div class="doc_subsubsection">
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	888	<a name="cl::ConsumeAfter">The <tt>cl::ConsumeAfter</tt> modifier</a>
				889	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	890
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	891	<div class="doc_text">
				892
				893	<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]	894	used to construct programs that use "interpreter style" option processing. With
				895	this style of option processing, all arguments specified after the last
				896	positional argument are treated as special interpreter arguments that are not
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	897	interpreted by the command line argument.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	898
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	899	<p>As a concrete example, lets say we are developing a replacement for the
				900	standard Unix Bourne shell (<tt>/bin/sh</tt>). To run <tt>/bin/sh</tt>, first
				901	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]	902	output), then you specify the name of the script to run, then you specify
				903	arguments to the script. These arguments to the script are parsed by the bourne
				904	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]	905	shell itself. Using the CommandLine library, we would specify this as:</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	906
				907	<pre>
				908	<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>("-"));
				909	<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>"));
				910	<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]	911	</pre>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	912
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	913	<p>which automatically provides the help output:</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	914
				915	<pre>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	916	USAGE: spiffysh [options] <b><input script> <program arguments>...</b>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	917
				918	OPTIONS:
				919	-help - display available options (--help-hidden for more)
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	920	<b>-x - Enable trace output</b>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	921	</pre>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	922
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	923	<p>At runtime, if we run our new shell replacement as '<tt>spiffysh -x test.sh
				924	-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]	925	<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]	926	<tt>Argv</tt> list will contain <tt>["-a", "-x", "-y", "bar"]</tt>, because they
				927	were specified after the last positional argument (which is the script
				928	name).</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	929
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	930	<p>There are several limitations to when <tt>cl::ConsumeAfter</tt> options can
				931	be specified. For example, only one <tt>cl::ConsumeAfter</tt> can be specified
				932	per program, there must be at least one <a href="#positional">positional
Chris Lattner	be801bf	2004-05-06 22:03:59 +0000	[diff] [blame]	933	argument</a> specified, there must not be any <a href="#cl::list">cl::list</a>
				934	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]	935	href="#cl::list">cl::list</a> option.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	936
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	937	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	938
				939	<!-- ======================================================================= -->
Chris Lattner	be801bf	2004-05-06 22:03:59 +0000	[diff] [blame]	940	<div class="doc_subsection">
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	941	<a name="storage">Internal vs External Storage</a>
				942	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	943
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	944	<div class="doc_text">
				945
				946	<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]	947	parse from the command line. This is very convenient in the common case,
				948	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]	949	files that use them. This is called the internal storage model.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	950
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	951	<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]	952	code from the storage of the value parsed. For example, lets say that we have a
				953	'<tt>-debug</tt>' option that we would like to use to enable debug information
				954	across the entire body of our program. In this case, the boolean value
				955	controlling the debug code should be globally accessable (in a header file, for
				956	example) yet the command line option processing code should not be exposed to
				957	all of these clients (requiring lots of .cpp files to #include
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	958	<tt>CommandLine.h</tt>).</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	959
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	960	<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]	961
				962	<pre>
				963	<i>// DebugFlag.h - Get access to the '-debug' command line option
				964	//
				965
				966	// DebugFlag - This boolean is set to true if the '-debug' command line option
				967	// is specified. This should probably not be referenced directly, instead, use
				968	// the DEBUG macro below.
				969	//</i>
				970	extern bool DebugFlag;
				971
				972	<i>// DEBUG macro - This macro should be used by code to emit debug information.
				973	// In the '-debug' option is specified on the command line, and if this is a
				974	// debug build, then the code specified as the option to the macro will be
				975	// executed. Otherwise it will not be. Example:
				976	//
				977	// DEBUG(cerr << "Bitset contains: " << Bitset << "\n");
				978	//</i>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	979	<span class="doc_red">#ifdef NDEBUG
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	980	#define DEBUG(X)
				981	#else
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	982	#define DEBUG(X)</span> \
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	983	do { if (DebugFlag) { X; } } while (0)
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	984	<span class="doc_red">#endif</span>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	985	</pre>
				986
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	987	<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]	988	<tt>DebugFlag</tt> explicitly if they want to. Now we just need to be able to
				989	set the <tt>DebugFlag</tt> boolean when the option is set. To do this, we pass
				990	an additial argument to our command line argument processor, and we specify
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	991	where to fill in with the <a href="#cl::location">cl::location</a>
				992	attribute:</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	993
				994	<pre>
				995	bool DebugFlag; <i>// the actual value</i>
Chris Lattner	589a4cc	2003-08-01 21:30:37 +0000	[diff] [blame]	996	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]	997	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]	998	<a href="#cl::location">cl::location</a>(DebugFlag));
				999	</pre>
				1000
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1001	<p>In the above example, we specify "<tt>true</tt>" as the second argument to
				1002	the <a href="#cl::opt">cl::opt</a> template, indicating that the template should
				1003	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]	1004	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]	1005	automatically set.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1006
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1007	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1008
				1009	<!-- ======================================================================= -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1010	<div class="doc_subsection">
				1011	<a name="attributes">Option Attributes</a>
				1012	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1013
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1014	<div class="doc_text">
				1015
				1016	<p>This section describes the basic attributes that you can specify on
				1017	options.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1018
				1019	<ul>
				1020
				1021	<li>The option name attribute (which is required for all options, except <a
				1022	href="#positional">positional options</a>) specifies what the option name is.
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1023	This option is specified in simple double quotes:
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1024
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1025	<pre>
				1026	<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]	1027	</pre>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1028
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1029	</li>
				1030
				1031	<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]	1032	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]	1033	program.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1034
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1035	<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]	1036	specifies a string that can be used to fine tune the <tt>--help</tt> output for
				1037	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]	1038	example.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1039
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1040	<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]	1041	inital value for a <a href="#cl::opt">scalar</a> option. If this attribute is
				1042	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]	1043	by the default constructor for the type. <b>Warning</b>: If you specify both
				1044	<b><tt>cl::init</tt></b> and <b><tt>cl::location</tt></b> for an option,
				1045	you must specify <b><tt>cl::location</tt></b> first, so that when the
				1046	command-line parser sees <b><tt>cl::init</tt></b>, it knows where to put the
				1047	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]	1048	the right order.)</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1049
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1050	<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]	1051	store the value for a parsed command line option if using external storage. See
				1052	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]	1053	information.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1054
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1055	<li><a name="cl::aliasopt">The <b><tt>cl::aliasopt</tt></b></a> attribute
				1056	specifies which option a <a href="#cl::alias">cl::alias</a> option is an alias
				1057	for.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1058
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1059	<li><a name="cl::values">The <b><tt>cl::values</tt></b></a> attribute specifies
				1060	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]	1061	<b>clEnumValEnd terminated</b> list of (option, value, description) triplets
				1062	that
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1063	specify the option name, the value mapped to, and the description shown in the
				1064	<tt>--help</tt> for the tool. Because the generic parser is used most
				1065	frequently with enum values, two macros are often useful:
				1066
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1067	<ol>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1068
				1069	<li><a name="clEnumVal">The <b><tt>clEnumVal</tt></b></a> macro is used as a
				1070	nice simple way to specify a triplet for an enum. This macro automatically
				1071	makes the option name be the same as the enum name. The first option to the
				1072	macro is the enum, the second is the description for the command line
				1073	option.</li>
				1074
				1075	<li><a name="clEnumValN">The <b><tt>clEnumValN</tt></b></a> macro is used to
				1076	specify macro options where the option name doesn't equal the enum name. For
				1077	this macro, the first argument is the enum value, the second is the flag name,
				1078	and the second is the description.</li>
				1079
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1080	</ol>
				1081
				1082	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]	1083	that does not support it.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1084
				1085	</ul>
				1086
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1087	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1088
				1089	<!-- ======================================================================= -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1090	<div class="doc_subsection">
				1091	<a name="modifiers">Option Modifiers</a>
				1092	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1093
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1094	<div class="doc_text">
				1095
				1096	<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]	1097	constructors for <tt><a href="#cl::opt">cl::opt</a></tt> and <tt><a
				1098	href="#cl::list">cl::list</a></tt>. These modifiers give you the ability to
				1099	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]	1100	your application well.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1101
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1102	<p>These options fall into five main catagories:</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1103
				1104	<ol>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1105	<li><a href="#hiding">Hiding an option from <tt>--help</tt> output</a></li>
				1106	<li><a href="#numoccurrences">Controlling the number of occurrences
				1107	required and allowed</a></li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1108	<li><a href="#valrequired">Controlling whether or not a value must be
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1109	specified</a></li>
				1110	<li><a href="#formatting">Controlling other formatting options</a></li>
				1111	<li><a href="#misc">Miscellaneous option modifiers</a></li>
				1112	</ol>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1113
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1114	<p>It is not possible to specify two options from the same catagory (you'll get
				1115	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]	1116	catagory. The CommandLine library specifies defaults for all of these settings
				1117	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]	1118	usually shouldn't have to worry about these.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1119
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1120	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1121
				1122	<!-- _______________________________________________________________________ -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1123	<div class="doc_subsubsection">
				1124	<a name="hiding">Hiding an option from <tt>--help</tt> output</a>
				1125	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1126
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1127	<div class="doc_text">
				1128
				1129	<p>The <tt>cl::NotHidden</tt>, <tt>cl::Hidden</tt>, and
				1130	<tt>cl::ReallyHidden</tt> modifiers are used to control whether or not an option
				1131	appears in the <tt>--help</tt> and <tt>--help-hidden</tt> output for the
				1132	compiled program:</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1133
				1134	<ul>
				1135
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1136	<li><a name="cl::NotHidden">The <b><tt>cl::NotHidden</tt></b></a> modifier
				1137	(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]	1138	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]	1139	in both help listings.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1140
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1141	<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]	1142	default for <tt><a href="#cl::alias">cl::alias</a></tt> options), indicates that
				1143	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]	1144	the <tt>--help-hidden</tt> output.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1145
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1146	<li><a name="cl::ReallyHidden">The <b><tt>cl::ReallyHidden</tt></b></a> modifier,
				1147	indicates that the option should not appear in any help output.</li>
				1148
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1149	</ul>
				1150
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1151	</div>
				1152
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1153	<!-- _______________________________________________________________________ -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1154	<div class="doc_subsubsection">
				1155	<a name="numoccurrences">Controlling the number of occurrences required and
				1156	allowed</a>
				1157	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1158
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1159	<div class="doc_text">
				1160
				1161	<p>This group of options is used to control how many time an option is allowed
				1162	(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]	1163	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]	1164	you.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1165
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1166	<p>The allowed values for this option group are:</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1167
				1168	<ul>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1169
				1170	<li><a name="cl::Optional">The <b><tt>cl::Optional</tt></b></a> modifier (which
				1171	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]	1172	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]	1173	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]	1174
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1175	<li><a name="cl::ZeroOrMore">The <b><tt>cl::ZeroOrMore</tt></b></a> modifier
				1176	(which is the default for the <tt><a href="#cl::list">cl::list</a></tt> class)
				1177	indicates that your program will allow the option to be specified zero or more
				1178	times.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1179
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1180	<li><a name="cl::Required">The <b><tt>cl::Required</tt></b></a> modifier
				1181	indicates that the specified option must be specified exactly one time.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1182
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1183	<li><a name="cl::OneOrMore">The <b><tt>cl::OneOrMore</tt></b></a> modifier
				1184	indicates that the option must be specified at least one time.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1185
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1186	<li>The <b><tt>cl::ConsumeAfter</tt></b> modifier is described in the <a
				1187	href="#positional">Positional arguments section</a></li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1188
				1189	</ul>
				1190
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1191	<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]	1192	value specified by the <tt><a href="#cl::init">cl::init</a></tt> attribute. If
				1193	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]	1194	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]	1195
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1196	<p>If an option is specified multiple times for an option of the <tt><a
				1197	href="#cl::opt">cl::opt</a></tt> class, only the last value will be
				1198	retained.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1199
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1200	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1201
				1202	<!-- _______________________________________________________________________ -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1203	<div class="doc_subsubsection">
				1204	<a name="valrequired">Controlling whether or not a value must be specified</a>
				1205	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1206
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1207	<div class="doc_text">
				1208
				1209	<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]	1210	value to be present. In the case of the CommandLine library, a value is either
				1211	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]	1212	string (e.g. '<tt>-o a.out</tt>').</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1213
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1214	<p>The allowed values for this option group are:</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1215
				1216	<ul>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1217
				1218	<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]	1219	(which is the default for <tt>bool</tt> typed options) specifies that it is
				1220	acceptable to have a value, or not. A boolean argument can be enabled just by
				1221	appearing on the command line, or it can have an explicit '<tt>-foo=true</tt>'.
				1222	If an option is specified with this mode, it is illegal for the value to be
				1223	provided without the equal sign. Therefore '<tt>-foo true</tt>' is illegal. To
				1224	get this behavior, you must use the <a
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1225	href="#cl::ValueRequired">cl::ValueRequired</a> modifier.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1226
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1227	<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]	1228	(which is the default for all other types except for <a
				1229	href="#onealternative">unnamed alternatives using the generic parser</a>)
				1230	specifies that a value must be provided. This mode informs the command line
				1231	library that if an option is not provides with an equal sign, that the next
				1232	argument provided must be the value. This allows things like '<tt>-o
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1233	a.out</tt>' to work.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1234
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1235	<li><a name="cl::ValueDisallowed">The <b><tt>cl::ValueDisallowed</tt></b></a>
				1236	modifier (which is the default for <a href="#onealternative">unnamed
				1237	alternatives using the generic parser</a>) indicates that it is a runtime error
				1238	for the user to specify a value. This can be provided to disallow users from
				1239	providing options to boolean options (like '<tt>-foo=true</tt>').</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1240
				1241	</ul>
				1242
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1243	<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]	1244	want them to. As mentioned above, you can specify the <a
				1245	href="#cl::ValueDisallowed">cl::ValueDisallowed</a> modifier to a boolean
				1246	argument to restrict your command line parser. These options are mostly useful
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1247	when <a href="#extensionguide">extending the library</a>.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1248
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1249	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1250
				1251	<!-- _______________________________________________________________________ -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1252	<div class="doc_subsubsection">
				1253	<a name="formatting">Controlling other formatting options</a>
				1254	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1255
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1256	<div class="doc_text">
				1257
				1258	<p>The formatting option group is used to specify that the command line option
				1259	has special abilities and is otherwise different from other command line
				1260	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]	1261
				1262	<ul>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1263
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1264	<li><a name="cl::NormalFormatting">The <b><tt>cl::NormalFormatting</tt></b></a>
				1265	modifier (which is the default all options) specifies that this option is
				1266	"normal".</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1267
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1268	<li><a name="cl::Positional">The <b><tt>cl::Positional</tt></b></a> modifier
				1269	specifies that this is a positional argument, that does not have a command line
				1270	option associated with it. See the <a href="#positional">Positional
				1271	Arguments</a> section for more information.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1272
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1273	<li>The <b><a href="#cl::ConsumeAfter"><tt>cl::ConsumeAfter</tt></a></b> modifier
				1274	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]	1275
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1276	<li><a name="cl::Prefix">The <b><tt>cl::Prefix</tt></b></a> modifier specifies
				1277	that this option prefixes its value. With 'Prefix' options, there is no equal
				1278	sign that separates the value from the option name specified. This is useful
				1279	for processing odd arguments like '<tt>-lmalloc -L/usr/lib'</tt> in a linker
				1280	tool. Here, the '<tt>l</tt>' and '<tt>L</tt>' options are normal string (list)
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1281	options, that have the <a href="#cl::Prefix">cl::Prefix</a> modifier added to
				1282	allow the CommandLine library to recognize them. Note that <a
				1283	href="#cl::Prefix">cl::Prefix</a> options must not have the <a
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1284	href="#cl::ValueDisallowed">cl::ValueDisallowed</a> modifier specified.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1285
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1286	<li><a name="cl::Grouping">The <b><tt>cl::Grouping</tt></b></a> modifier is used
				1287	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]	1288	arguments, but only require a single dash. For example, the '<tt>ls -labF</tt>'
				1289	command actually enables four different options, all of which are single
				1290	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]	1291	values.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1292
				1293	</ul>
				1294
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1295	<p>The CommandLine library does not restrict how you use the <a
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1296	href="#cl::Prefix">cl::Prefix</a> or <a href="#cl::Grouping">cl::Grouping</a>
				1297	modifiers, but it is possible to specify ambiguous argument settings. Thus, it
				1298	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]	1299	and they will still work as designed.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1300
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1301	<p>To do this, the CommandLine library uses a greedy algorithm to parse the
				1302	input option into (potentially multiple) prefix and grouping options. The
				1303	strategy basically looks like this:</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><tt>parse(string OrigInput) {</tt>
Misha Brukman	c53aefb	2004-05-12 18:42:35 +0000	[diff] [blame]	1306
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1307	<ol>
				1308	<li><tt>string input = OrigInput;</tt>
				1309	<li><tt>if (isOption(input)) return getOption(input).parse();</tt>    <i>// Normal option</i>
				1310	<li><tt>while (!isOption(input) && !input.empty()) input.pop_back();</tt>    <i>// Remove the last letter</i>
				1311	<li><tt>if (input.empty()) return error();</tt>    <i>// No matching option</i>
				1312	<li><tt>if (getOption(input).isPrefix())<br>
				1313	return getOption(input).parse(input);</tt>
				1314	<li><tt>while (!input.empty()) {    <i>// Must be grouping options</i><br>
				1315	getOption(input).parse();<br>
				1316	OrigInput.erase(OrigInput.begin(), OrigInput.begin()+input.length());<br>
				1317	input = OrigInput;<br>
				1318	while (!isOption(input) && !input.empty()) input.pop_back();<br>
				1319	}</tt>
Misha Brukman	c53aefb	2004-05-12 18:42:35 +0000	[diff] [blame]	1320	<li><tt>if (!OrigInput.empty()) error();</tt></li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1321
				1322	</ol>
Misha Brukman	c53aefb	2004-05-12 18:42:35 +0000	[diff] [blame]	1323
				1324	<p><tt>}</tt></p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1325
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1326	</div>
Chris Lattner	32a3284	2003-05-22 20:36:06 +0000	[diff] [blame]	1327
				1328	<!-- _______________________________________________________________________ -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1329	<div class="doc_subsubsection">
				1330	<a name="misc">Miscellaneous option modifiers</a>
				1331	</div>
Chris Lattner	32a3284	2003-05-22 20:36:06 +0000	[diff] [blame]	1332
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1333	<div class="doc_text">
				1334
				1335	<p>The miscellaneous option modifiers are the only flags where you can specify
				1336	more than one flag from the set: they are not mutually exclusive. These flags
				1337	specify boolean properties that modify the option.</p>
Chris Lattner	32a3284	2003-05-22 20:36:06 +0000	[diff] [blame]	1338
				1339	<ul>
				1340
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1341	<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]	1342	indicates that any commas specified for an option's value should be used to
				1343	split the value up into multiple values for the option. For example, these two
				1344	options are equivalent when <tt>cl::CommaSeparated</tt> is specified:
				1345	"<tt>-foo=a -foo=b -foo=c</tt>" and "<tt>-foo=a,b,c</tt>". This option only
				1346	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]	1347	more values (i.e. it is a <a href="#cl::list">cl::list</a> option).</li>
				1348
Chris Lattner	be801bf	2004-05-06 22:03:59 +0000	[diff] [blame]	1349	<li><a name="cl::PositionalEatsArgs">The
				1350	<b><tt>cl::PositionalEatsArgs</tt></b></a> modifier (which only applies to
				1351	positional arguments, and only makes sense for lists) indicates that positional
				1352	argument should consume any strings after it (including strings that start with
				1353	a "-") up until another recognized positional argument. For example, if you
				1354	have two "eating" positional arguments "<tt>pos1</tt>" and "<tt>pos2</tt>" the
				1355	string "<tt>-pos1 -foo -bar baz -pos2 -bork</tt>" would cause the "<tt>-foo -bar
				1356	-baz</tt>" strings to be applied to the "<tt>-pos1</tt>" option and the
				1357	"<tt>-bork</tt>" string to be applied to the "<tt>-pos2</tt>" option.</li>
				1358
Chris Lattner	32a3284	2003-05-22 20:36:06 +0000	[diff] [blame]	1359	</ul>
				1360
Chris Lattner	be801bf	2004-05-06 22:03:59 +0000	[diff] [blame]	1361	<p>So far, these are the only two miscellaneous option modifiers.</p>
Chris Lattner	32a3284	2003-05-22 20:36:06 +0000	[diff] [blame]	1362
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1363	</div>
Chris Lattner	32a3284	2003-05-22 20:36:06 +0000	[diff] [blame]	1364
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1365	<!-- ======================================================================= -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1366	<div class="doc_subsection">
				1367	<a name="toplevel">Top-Level Classes and Functions</a>
				1368	</div>
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_text">
				1371
				1372	<p>Despite all of the built-in flexibility, the CommandLine option library
				1373	really only consists of one function (<a
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1374	href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>)
				1375	and three main classes: <a href="#cl::opt"><tt>cl::opt</tt></a>, <a
				1376	href="#cl::list"><tt>cl::list</tt></a>, and <a
				1377	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]	1378	classes in detail.</p>
				1379
				1380	</div>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1381
				1382	<!-- _______________________________________________________________________ -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1383	<div class="doc_subsubsection">
				1384	<a name="cl::ParseCommandLineOptions">The <tt>cl::ParseCommandLineOptions</tt>
				1385	function</a>
				1386	</div>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1387
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1388	<div class="doc_text">
				1389
				1390	<p>The <tt>cl::ParseCommandLineOptions</tt> function is designed to be called
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1391	directly from <tt>main</tt>, and is used to fill in the values of all of the
				1392	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]	1393	available.</p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1394
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1395	<p>The <tt>cl::ParseCommandLineOptions</tt> function requires two parameters
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1396	(<tt>argc</tt> and <tt>argv</tt>), but may also take an optional third parameter
				1397	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]	1398	<tt>--help</tt> option is invoked.</p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1399
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1400	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1401
				1402	<!-- _______________________________________________________________________ -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1403	<div class="doc_subsubsection">
				1404	<a name="cl::ParseEnvironmentOptions">The <tt>cl::ParseEnvironmentOptions</tt>
				1405	function</a>
				1406	</div>
Brian Gaeke	e584285	2003-08-19 23:11:43 +0000	[diff] [blame]	1407
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1408	<div class="doc_text">
Brian Gaeke	e584285	2003-08-19 23:11:43 +0000	[diff] [blame]	1409
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1410	<p>The <tt>cl::ParseEnvironmentOptions</tt> function has mostly the same effects
				1411	as <a
				1412	href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>,
				1413	except that it is designed to take values for options from an environment
				1414	variable, for those cases in which reading the command line is not convenient or
				1415	not desired. It fills in the values of all the command line option variables
				1416	just like <a
				1417	href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>
				1418	does.</p>
				1419
				1420	<p>It takes three parameters: first, the name of the program (since
				1421	<tt>argv</tt> may not be available, it can't just look in <tt>argv[0]</tt>),
				1422	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]	1423	<a href="#description">additional extra text</a> to emit when the
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1424	<tt>--help</tt> option is invoked.</p>
Brian Gaeke	e584285	2003-08-19 23:11:43 +0000	[diff] [blame]	1425
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1426	<p><tt>cl::ParseEnvironmentOptions</tt> will break the environment
Brian Gaeke	e584285	2003-08-19 23:11:43 +0000	[diff] [blame]	1427	variable's value up into words and then process them using
				1428	<a href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>.
				1429	<b>Note:</b> Currently <tt>cl::ParseEnvironmentOptions</tt> does not support
				1430	quoting, so an environment variable containing <tt>-option "foo bar"</tt> will
				1431	be parsed as three words, <tt>-option</tt>, <tt>"foo</tt>, and <tt>bar"</tt>,
				1432	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]	1433	input.</p>
				1434
				1435	</div>
Brian Gaeke	e584285	2003-08-19 23:11:43 +0000	[diff] [blame]	1436
				1437	<!-- _______________________________________________________________________ -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1438	<div class="doc_subsubsection">
				1439	<a name="cl::opt">The <tt>cl::opt</tt> class</a>
				1440	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1441
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1442	<div class="doc_text">
				1443
				1444	<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]	1445	options, and is the one used most of the time. It is a templated class which
				1446	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]	1447	though):</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1448
				1449	<pre>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1450	<b>namespace</b> cl {
				1451	<b>template</b> <<b>class</b> DataType, <b>bool</b> ExternalStorage = <b>false</b>,
				1452	<b>class</b> ParserClass = parser<DataType> >
				1453	<b>class</b> opt;
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1454	}
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1455	</pre>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1456
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1457	<p>The first template argument specifies what underlying data type the command
				1458	line argument is, and is used to select a default parser implementation. The
				1459	second template argument is used to specify whether the option should contain
				1460	the storage for the option (the default) or whether external storage should be
				1461	used to contain the value parsed for the option (see <a href="#storage">Internal
				1462	vs External Storage</a> for more information).</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1463
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1464	<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]	1465	selects an instantiation of the <tt>parser</tt> class based on the underlying
				1466	data type of the option. In general, this default works well for most
				1467	applications, so this option is only used when using a <a
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1468	href="#customparser">custom parser</a>.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1469
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1470	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1471
				1472	<!-- _______________________________________________________________________ -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1473	<div class="doc_subsubsection">
				1474	<a name="cl::list">The <tt>cl::list</tt> class</a>
				1475	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1476
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1477	<div class="doc_text">
				1478
				1479	<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]	1480	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]	1481	arguments:</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1482
				1483	<pre>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1484	<b>namespace</b> cl {
				1485	<b>template</b> <<b>class</b> DataType, <b>class</b> Storage = <b>bool</b>,
				1486	<b>class</b> ParserClass = parser<DataType> >
				1487	<b>class</b> list;
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1488	}
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1489	</pre>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1490
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1491	<p>This class works the exact same as the <a
				1492	href="#cl::opt"><tt>cl::opt</tt></a> class, except that the second argument is
				1493	the <b>type</b> of the external storage, not a boolean value. For this class,
				1494	the marker type '<tt>bool</tt>' is used to indicate that internal storage should
				1495	be used.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1496
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1497	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1498
				1499	<!-- _______________________________________________________________________ -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1500	<div class="doc_subsubsection">
				1501	<a name="cl::alias">The <tt>cl::alias</tt> class</a>
				1502	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1503
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1504	<div class="doc_text">
				1505
				1506	<p>The <tt>cl::alias</tt> class is a nontemplated class that is used to form
				1507	aliases for other arguments.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1508
				1509	<pre>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1510	<b>namespace</b> cl {
				1511	<b>class</b> alias;
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1512	}
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1513	</pre>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1514
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1515	<p>The <a href="#cl::aliasopt"><tt>cl::aliasopt</tt></a> attribute should be
				1516	used to specify which option this is an alias for. Alias arguments default to
				1517	being <a href="#cl::Hidden">Hidden</a>, and use the aliased options parser to do
				1518	the conversion from string to data.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1519
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1520	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1521
				1522	<!-- ======================================================================= -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1523	<div class="doc_subsection">
				1524	<a name="builtinparsers">Builtin parsers</a>
				1525	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1526
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1527	<div class="doc_text">
				1528
				1529	<p>Parsers control how the string value taken from the command line is
				1530	translated into a typed value, suitable for use in a C++ program. By default,
				1531	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]	1532	command line option specifies that it uses values of type '<tt>type</tt>'.
				1533	Because of this, custom option processing is specified with specializations of
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1534	the '<tt>parser</tt>' class.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1535
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1536	<p>The CommandLine library provides the following builtin parser
				1537	specializations, which are sufficient for most applications. It can, however,
				1538	also be extended to work with new data types and new ways of interpreting the
				1539	same data. See the <a href="#customparser">Writing a Custom Parser</a> for more
				1540	details on this type of library extension.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1541
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1542	<ul>
				1543
				1544	<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]	1545	can be used to map strings values to any data type, through the use of the <a
				1546	href="#cl::values">cl::values</a> property, which specifies the mapping
				1547	information. The most common use of this parser is for parsing enum values,
				1548	which allows you to use the CommandLine library for all of the error checking to
				1549	make sure that only valid enum values are specified (as opposed to accepting
				1550	arbitrary strings). Despite this, however, the generic parser class can be used
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1551	for any data type.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1552
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1553	<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]	1554	is used to convert boolean strings to a boolean value. Currently accepted
				1555	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]	1556	"<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]	1557
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1558	<li><a name="stringparser">The <b><tt>parser<string></tt>
				1559	specialization</b></a> simply stores the parsed string into the string value
				1560	specified. No conversion or modification of the data is performed.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1561
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1562	<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]	1563	uses the C <tt>strtol</tt> function to parse the string input. As such, it will
				1564	accept a decimal number (with an optional '+' or '-' prefix) which must start
				1565	with a non-zero digit. It accepts octal numbers, which are identified with a
				1566	'<tt>0</tt>' prefix digit, and hexadecimal numbers with a prefix of
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1567	'<tt>0x</tt>' or '<tt>0X</tt>'.</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1568
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1569	<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]	1570	<b><tt>parser<float></tt> specializations</b> use the standard C
				1571	<tt>strtod</tt> function to convert floating point strings into floating point
				1572	values. As such, a broad range of string formats is supported, including
				1573	exponential notation (ex: <tt>1.7e15</tt>) and properly supports locales.
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1574	</li>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1575
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1576	</ul>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	1577
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1578	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	1579
				1580	<!-- *********************************************************************** -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1581	<div class="doc_section">
				1582	<a name="extensionguide">Extension Guide</a>
				1583	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	1584	<!-- *********************************************************************** -->
				1585
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1586	<div class="doc_text">
				1587
				1588	<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]	1589	already (as discussed previously), one of its true strengths lie in its
				1590	extensibility. This section discusses how the CommandLine library works under
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1591	the covers and illustrates how to do some simple, common, extensions.</p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1592
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1593	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	1594
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1595	<!-- ======================================================================= -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1596	<div class="doc_subsection">
				1597	<a name="customparser">Writing a custom parser</a>
				1598	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1599
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1600	<div class="doc_text">
				1601
				1602	<p>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]	1603	As <a href="#builtinparsers">discussed previously</a>, parsers are the portion
				1604	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]	1605	particular parsed data type, validating the input in the process.</p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1606
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1607	<p>There are two ways to use a new parser:</p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1608
				1609	<ol>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1610
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1611	<li>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1612
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1613	<p>Specialize the <a href="#genericparser"><tt>cl::parser</tt></a> template for
				1614	your custom data type.<p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1615
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1616	<p>This approach has the advantage that users of your custom data type will
				1617	automatically use your custom parser whenever they define an option with a value
				1618	type of your data type. The disadvantage of this approach is that it doesn't
				1619	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]	1620
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1621	</li>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1622
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1623	<li>
				1624
				1625	<p>Write an independent class, using it explicitly from options that need
				1626	it.</p>
				1627
				1628	<p>This approach works well in situations where you would line to parse an
				1629	option using special syntax for a not-very-special data-type. The drawback of
				1630	this approach is that users of your parser have to be aware that they are using
				1631	your parser, instead of the builtin ones.</p>
				1632
				1633	</li>
				1634
				1635	</ol>
				1636
				1637	<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]	1638	sizes, specified with an optional unit after the numeric size. For example, we
				1639	would like to parse "102kb", "41M", "1G" into the appropriate integer value. In
				1640	this case, the underlying data type we want to parse into is
				1641	'<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]	1642	this the default for all <tt>unsigned</tt> options.</p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1643
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1644	<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]	1645
				1646	<pre>
				1647	<b>struct</b> FileSizeParser : <b>public</b> cl::basic_parser<<b>unsigned</b>> {
				1648	<i>// parse - Return true on error.</i>
				1649	<b>bool</b> parse(cl::Option &O, <b>const char</b> *ArgName, <b>const</b> std::string &ArgValue,
				1650	<b>unsigned</b> &Val);
				1651	};
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1652	</pre>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1653
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1654	<p>Our new class inherits from the <tt>cl::basic_parser</tt> template class to
				1655	fill in the default, boiler plate, code for us. We give it the data type that
				1656	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]	1657	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]	1658	declare that we parse into '<tt>unsigned</tt>' variables.</p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1659
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1660	<p>For most purposes, the only method that must be implemented in a custom
				1661	parser is the <tt>parse</tt> method. The <tt>parse</tt> method is called
				1662	whenever the option is invoked, passing in the option itself, the option name,
				1663	the string to parse, and a reference to a return value. If the string to parse
				1664	is not well formed, the parser should output an error message and return true.
				1665	Otherwise it should return false and set '<tt>Val</tt>' to the parsed value. In
				1666	our example, we implement <tt>parse</tt> as:</p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1667
				1668	<pre>
				1669	<b>bool</b> FileSizeParser::parse(cl::Option &O, <b>const char</b> *ArgName,
				1670	<b>const</b> std::string &Arg, <b>unsigned</b> &Val) {
				1671	<b>const char</b> *ArgStart = Arg.c_str();
				1672	<b>char</b> *End;
				1673
				1674	<i>// Parse integer part, leaving 'End' pointing to the first non-integer char</i>
				1675	Val = (unsigned)strtol(ArgStart, &End, 0);
				1676
				1677	<b>while</b> (1) {
				1678	<b>switch</b> (*End++) {
				1679	<b>case</b> 0: <b>return</b> false; <i>// No error</i>
				1680	<b>case</b> 'i': <i>// Ignore the 'i' in KiB if people use that</i>
				1681	<b>case</b> 'b': <b>case</b> 'B': <i>// Ignore B suffix</i>
				1682	<b>break</b>;
				1683
				1684	<b>case</b> 'g': <b>case</b> 'G': Val = 10241024*1024; <b>break</b>;
				1685	<b>case</b> 'm': <b>case</b> 'M': Val = 10241024; <b>break</b>;
				1686	<b>case</b> 'k': <b>case</b> 'K': Val *= 1024; <b>break</b>;
				1687
				1688	default:
				1689	<i>// Print an error message if unrecognized character!</i>
				1690	<b>return</b> O.error(": '" + Arg + "' value invalid for file size argument!");
				1691	}
				1692	}
				1693	}
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1694	</pre>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1695
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1696	<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]	1697	interested in. Although it has some holes (it allows "<tt>123KKK</tt>" for
				1698	example), it is good enough for this example. Note that we use the option
				1699	itself to print out the error message (the <tt>error</tt> method always returns
				1700	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]	1701	parser class, we can use it like this:</p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1702
				1703	<pre>
				1704	<b>static</b> <a href="#cl::opt">cl::opt</a><<b>unsigned</b>, <b>false</b>, FileSizeParser>
				1705	MFS(<i>"max-file-size"</i>, <a href="#cl::desc">cl::desc</a>(<i>"Maximum file size to accept"</i>),
				1706	<a href="#cl::value_desc">cl::value_desc</a>("<i>size</i>"));
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1707	</pre>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1708
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1709	<p>Which adds this to the output of our program:</p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1710
				1711	<pre>
				1712	OPTIONS:
				1713	-help - display available options (--help-hidden for more)
				1714	...
				1715	<b>-max-file-size=<size> - Maximum file size to accept</b>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1716	</pre>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1717
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1718	<p>And we can test that our parse works correctly now (the test program just
				1719	prints out the max-file-size argument value):</p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1720
				1721	<pre>
				1722	$ ./test
				1723	MFS: 0
				1724	$ ./test -max-file-size=123MB
				1725	MFS: 128974848
				1726	$ ./test -max-file-size=3G
				1727	MFS: 3221225472
				1728	$ ./test -max-file-size=dog
				1729	-max-file-size option: 'dog' value invalid for file size argument!
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1730	</pre>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1731
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1732	<p>It looks like it works. The error message that we get is nice and helpful,
				1733	and we seem to accept reasonable file sizes. This wraps up the "custom parser"
				1734	tutorial.</p>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1735
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1736	</div>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1737
				1738	<!-- ======================================================================= -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1739	<div class="doc_subsection">
				1740	<a name="explotingexternal">Exploiting external storage</a>
				1741	</div>
Chris Lattner	c1ae40c	2002-08-07 18:27:04 +0000	[diff] [blame]	1742
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1743	<div class="doc_text">
Reid Spencer	b993feb	2004-08-30 05:56:51 +0000	[diff] [blame]	1744	<p>Several of the LLVM libraries define static <tt>cl::opt</tt> instances that
				1745	will automatically be included in any program that links with that library.
				1746	This is a feature. However, sometimes it is necessary to know the value of the
				1747	command line option outside of the library. In these cases the library does or
				1748	should provide an external storage location that is accessible to users of the
				1749	library. Examples of this include the <tt>llvm::DebugFlag</tt> exported by the
				1750	<tt>lib/Support/Debug.cpp</tt> file and the <tt>llvm::TimePassesIsEnabled</tt>
				1751	flag exported by the <tt>lib/VMCore/Pass.cpp</tt> file.</p>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1752
Reid Spencer	b993feb	2004-08-30 05:56:51 +0000	[diff] [blame]	1753	<p>TODO: complete this section</p>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1754
				1755	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1756
				1757	<!-- ======================================================================= -->
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1758	<div class="doc_subsection">
				1759	<a name="dynamicopts">Dynamically adding command line options</a>
				1760	</div>
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1761
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1762	<div class="doc_text">
Chris Lattner	e76d4ab	2002-08-06 19:36:06 +0000	[diff] [blame]	1763
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1764	<p>TODO: fill in this section</p>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	1765
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1766	</div>
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	1767
Chris Lattner	209c7f4	2001-07-23 23:03:12 +0000	[diff] [blame]	1768	<!-- *********************************************************************** -->
				1769
				1770	<hr>
Misha Brukman	c53aefb	2004-05-12 18:42:35 +0000	[diff] [blame]	1771	<address>
				1772	<a href="http://jigsaw.w3.org/css-validator/check/referer"><img
				1773	src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
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				1775	src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!"></a>
				1776
				1777	<a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
				1778	<a href="http://llvm.cs.uiuc.edu">LLVM Compiler Infrastructure</a><br>
Misha Brukman	3c29911	2003-11-07 18:11:14 +0000	[diff] [blame]	1779	Last modified: $Date$
Misha Brukman	c53aefb	2004-05-12 18:42:35 +0000	[diff] [blame]	1780	</address>
Misha Brukman	9718e96	2003-10-24 19:59:21 +0000	[diff] [blame]	1781
				1782	</body>
				1783	</html>