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Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
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4<head>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]5 <title>CommandLine 2.0 Library Manual</title>
Misha Brukman3c299112003-11-07 18:11:14 +0000[diff] [blame]6 <link rel="stylesheet" href="llvm.css" type="text/css">
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]7</head>
8<body>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]9
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]10<div class="doc_title">
11 CommandLine 2.0 Library Manual
12</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]13
14<ol>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]15 <li><a href="#introduction">Introduction</a></li>
16
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]17 <li><a href="#quickstart">Quick Start Guide</a>
18 <ol>
Misha Brukman9718e962003-10-24 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 Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]21 <li><a href="#onealternative">Selecting an alternative from a
Misha Brukman9718e962003-10-24 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 Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]28 <li><a href="#referenceguide">Reference Guide</a>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]29 <ol>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]30 <li><a href="#positional">Positional Arguments</a>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]31 <ul>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]32 <li><a href="#--">Specifying positional options with hyphens</a></li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]33 <li><a href="#cl::ConsumeAfter">The <tt>cl::ConsumeAfter</tt>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]34 modifier</a></li>
35 </ul></li>
36
37 <li><a href="#storage">Internal vs External Storage</a></li>
38
39 <li><a href="#attributes">Option Attributes</a></li>
40
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]41 <li><a href="#modifiers">Option Modifiers</a>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]42 <ul>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]43 <li><a href="#hiding">Hiding an option from <tt>--help</tt>
44 output</a></li>
45 <li><a href="#numoccurrences">Controlling the number of occurrences
46 required and allowed</a></li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]47 <li><a href="#valrequired">Controlling whether or not a value must be
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]48 specified</a></li>
49 <li><a href="#formatting">Controlling other formatting options</a></li>
50 <li><a href="#misc">Miscellaneous option modifiers</a></li>
51 </ul></li>
52
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]53 <li><a href="#toplevel">Top-Level Classes and Functions</a>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]54 <ul>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]55 <li><a href="#cl::ParseCommandLineOptions">The
56 <tt>cl::ParseCommandLineOptions</tt> function</a></li>
57 <li><a href="#cl::ParseEnvironmentOptions">The
58 <tt>cl::ParseEnvironmentOptions</tt> function</a></li>
59 <li><a href="#cl::opt">The <tt>cl::opt</tt> class</a></li>
60 <li><a href="#cl::list">The <tt>cl::list</tt> class</a></li>
61 <li><a href="#cl::alias">The <tt>cl::alias</tt> class</a></li>
62 </ul></li>
63
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]64 <li><a href="#builtinparsers">Builtin parsers</a>
65 <ul>
66 <li><a href="#genericparser">The Generic <tt>parser&lt;t&gt;</tt>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]67 parser</a></li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]68 <li><a href="#boolparser">The <tt>parser&lt;bool&gt;</tt>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]69 specialization</a></li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]70 <li><a href="#stringparser">The <tt>parser&lt;string&gt;</tt>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]71 specialization</a></li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]72 <li><a href="#intparser">The <tt>parser&lt;int&gt;</tt>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]73 specialization</a></li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]74 <li><a href="#doubleparser">The <tt>parser&lt;double&gt;</tt> and
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]75 <tt>parser&lt;float&gt;</tt> specializations</a></li>
76 </ul></li>
77 </ol></li>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]78 <li><a href="#extensionguide">Extension Guide</a>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]79 <ol>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]80 <li><a href="#customparser">Writing a custom parser</a></li>
81 <li><a href="#explotingexternal">Exploiting external storage</a></li>
82 <li><a href="#dynamicopts">Dynamically adding command line
83 options</a></li>
84 </ol></li>
85</ol>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]86
Chris Lattner7911ce22004-05-23 21:07:27 +0000[diff] [blame^]87<div class="doc_author">
88 <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a></p>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]89</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]90
91<!-- *********************************************************************** -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]92<div class="doc_section">
Misha Brukman8becd712003-11-07 19:42:44 +0000[diff] [blame]93 <a name="introduction">Introduction</a>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]94</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]95<!-- *********************************************************************** -->
96
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]97<div class="doc_text">
98
99<p>This document describes the CommandLine argument processing library. It will
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]100show you how to use it, and what it can do. The CommandLine library uses a
101declarative approach to specifying the command line options that your program
102takes. By default, these options declarations implicitly hold the value parsed
103for the option declared (of course this <a href="#storage">can be
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]104changed</a>).</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]105
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]106<p>Although there are a <b>lot</b> of command line argument parsing libraries
107out there in many different languages, none of them fit well with what I needed.
108By looking at the features and problems of other libraries, I designed the
109CommandLine library to have the following features:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]110
111<ol>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]112<li>Speed: The CommandLine library is very quick and uses little resources. The
113parsing time of the library is directly proportional to the number of arguments
114parsed, not the the number of options recognized. Additionally, command line
Chris Lattneredf351f2003-06-21 21:45:56 +0000[diff] [blame]115argument values are captured transparently into user defined global variables,
116which can be accessed like any other variable (and with the same
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]117performance).</li>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]118
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]119<li>Type Safe: As a user of CommandLine, you don't have to worry about
120remembering the type of arguments that you want (is it an int? a string? a
121bool? an enum?) and keep casting it around. Not only does this help prevent
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]122error prone constructs, it also leads to dramatically cleaner source code.</li>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]123
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]124<li>No subclasses required: To use CommandLine, you instantiate variables that
125correspond to the arguments that you would like to capture, you don't subclass a
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]126parser. This means that you don't have to write <b>any</b> boilerplate
127code.</li>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]128
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]129<li>Globally accessible: Libraries can specify command line arguments that are
130automatically enabled in any tool that links to the library. This is possible
131because the application doesn't have to keep a "list" of arguments to pass to
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]132the parser. This also makes supporting <a href="#dynamicopts">dynamically
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]133loaded options</a> trivial.</li>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]134
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]135<li>Cleaner: CommandLine supports enum and other types directly, meaning that
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]136there is less error and more security built into the library. You don't have to
137worry about whether your integral command line argument accidentally got
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]138assigned a value that is not valid for your enum type.</li>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]139
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]140<li>Powerful: The CommandLine library supports many different types of
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]141arguments, from simple <a href="#boolparser">boolean flags</a> to <a
142href="#cl::opt">scalars arguments</a> (<a href="#stringparser">strings</a>, <a
143href="#intparser">integers</a>, <a href="#genericparser">enums</a>, <a
144href="#doubleparser">doubles</a>), to <a href="#cl::list">lists of
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]145arguments</a>. This is possible because CommandLine is...</li>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]146
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]147<li>Extensible: It is very simple to add a new argument type to CommandLine.
148Simply specify the parser that you want to use with the command line option when
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]149you declare it. <a href="#customparser">Custom parsers</a> are no problem.</li>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]150
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]151<li>Labor Saving: The CommandLine library cuts down on the amount of grunt work
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]152that you, the user, have to do. For example, it automatically provides a
153<tt>--help</tt> option that shows the available command line options for your
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]154tool. Additionally, it does most of the basic correctness checking for
155you.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]156
157<li>Capable: The CommandLine library can handle lots of different forms of
158options often found in real programs. For example, <a
159href="#positional">positional</a> arguments, <tt>ls</tt> style <a
160href="#cl::Grouping">grouping</a> options (to allow processing '<tt>ls
161-lad</tt>' naturally), <tt>ld</tt> style <a href="#cl::Prefix">prefix</a>
162options (to parse '<tt>-lmalloc -L/usr/lib</tt>'), and <a
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]163href="#cl::ConsumeAfter">interpreter style options</a>.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]164
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]165</ol>
166
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]167<p>This document will hopefully let you jump in and start using CommandLine in
168your utility quickly and painlessly. Additionally it should be a simple
169reference manual to figure out how stuff works. If it is failing in some area
170(or you want an extension to the library), nag the author, <a
171href="mailto:sabre@nondot.org">Chris Lattner</a>.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]172
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]173</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]174
175<!-- *********************************************************************** -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]176<div class="doc_section">
177 <a name="quickstart">Quick Start Guide</a>
178</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]179<!-- *********************************************************************** -->
180
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]181<div class="doc_text">
182
183<p>This section of the manual runs through a simple CommandLine'ification of a
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]184basic compiler tool. This is intended to show you how to jump into using the
185CommandLine library in your own program, and show you some of the cool things it
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]186can do.</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]187
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]188<p>To start out, you need to include the CommandLine header file into your
189program:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]190
191<pre>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]192 #include "Support/CommandLine.h"
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]193</pre>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]194
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]195<p>Additionally, you need to add this as the first line of your main
196program:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]197
198<pre>
199int main(int argc, char **argv) {
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]200 <a href="#cl::ParseCommandLineOptions">cl::ParseCommandLineOptions</a>(argc, argv);
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]201 ...
202}
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]203</pre>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]204
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]205<p>... which actually parses the arguments and fills in the variable
206declarations.</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]207
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]208<p>Now that you are ready to support command line arguments, we need to tell the
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]209system which ones we want, and what type of argument they are. The CommandLine
Chris Lattneredf351f2003-06-21 21:45:56 +0000[diff] [blame]210library uses a declarative syntax to model command line arguments with the
211global variable declarations that capture the parsed values. This means that
212for every command line option that you would like to support, there should be a
213global variable declaration to capture the result. For example, in a compiler,
214we would like to support the unix standard '<tt>-o &lt;filename&gt;</tt>' option
215to specify where to put the output. With the CommandLine library, this is
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]216represented like this:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]217
Misha Brukmanc53aefb2004-05-12 18:42:35 +0000[diff] [blame]218<a name="value_desc_example"></a>
219<pre>
220<a href="#cl::opt">cl::opt</a>&lt;string&gt; 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>"));
221</pre>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]222
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]223<p>This declares a global variable "<tt>OutputFilename</tt>" that is used to
Chris Lattneredf351f2003-06-21 21:45:56 +0000[diff] [blame]224capture the result of the "<tt>o</tt>" argument (first parameter). We specify
225that this is a simple scalar option by using the "<tt><a
226href="#cl::opt">cl::opt</a></tt>" template (as opposed to the <a
227href="#list">"<tt>cl::list</tt> template</a>), and tell the CommandLine library
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]228that the data type that we are parsing is a string.</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]229
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]230<p>The second and third parameters (which are optional) are used to specify what
231to output for the "<tt>--help</tt>" option. In this case, we get a line that
232looks like this:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]233
234<pre>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]235USAGE: compiler [options]
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]236
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]237OPTIONS:
238 -help - display available options (--help-hidden for more)
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]239 <b>-o &lt;filename&gt; - Specify output filename</b>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]240</pre>
241
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]242<p>Because we specified that the command line option should parse using the
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]243<tt>string</tt> data type, the variable declared is automatically usable as a
244real string in all contexts that a normal C++ string object may be used. For
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]245example:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]246
247<pre>
248 ...
249 ofstream Output(OutputFilename.c_str());
250 if (Out.good()) ...
251 ...
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]252</pre>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]253
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]254<p>There are many different options that you can use to customize the command
255line option handling library, but the above example shows the general interface
256to these options. The options can be specified in any order, and are specified
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]257with helper functions like <a href="#cl::desc"><tt>cl::desc(...)</tt></a>, so
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]258there are no positional dependencies to remember. The available options are
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]259discussed in detail in the <a href="#referenceguide">Reference Guide</a>.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]260
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]261<p>Continuing the example, we would like to have our compiler take an input
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]262filename as well as an output filename, but we do not want the input filename to
263be specified with a hyphen (ie, not <tt>-filename.c</tt>). To support this
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]264style of argument, the CommandLine library allows for <a
265href="#positional">positional</a> arguments to be specified for the program.
266These positional arguments are filled with command line parameters that are not
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]267in option form. We use this feature like this:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]268
269<pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]270<a href="#cl::opt">cl::opt</a>&lt;string&gt; InputFilename(<a href="#cl::Positional">cl::Positional</a>, <a href="#cl::desc">cl::desc</a>("<i>&lt;input file&gt;</i>"), <a href="#cl::init">cl::init</a>("<i>-</i>"));
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]271</pre>
272
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]273<p>This declaration indicates that the first positional argument should be
274treated as the input filename. Here we use the <tt><a
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]275href="#cl::init">cl::init</a></tt> option to specify an initial value for the
276command line option, which is used if the option is not specified (if you do not
277specify a <tt><a href="#cl::init">cl::init</a></tt> modifier for an option, then
278the default constructor for the data type is used to initialize the value).
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]279Command line options default to being optional, so if we would like to require
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]280that the user always specify an input filename, we would add the <tt><a
281href="#cl::Required">cl::Required</a></tt> flag, and we could eliminate the
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]282<tt><a href="#cl::init">cl::init</a></tt> modifier, like this:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]283
284<pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]285<a href="#cl::opt">cl::opt</a>&lt;string&gt; InputFilename(<a href="#cl::Positional">cl::Positional</a>, <a href="#cl::desc">cl::desc</a>("<i>&lt;input file&gt;</i>"), <b><a href="#cl::Required">cl::Required</a></b>);
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]286</pre>
287
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]288<p>Again, the CommandLine library does not require the options to be specified
289in any particular order, so the above declaration is equivalent to:</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]290
291<pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]292<a href="#cl::opt">cl::opt</a>&lt;string&gt; InputFilename(<a href="#cl::Positional">cl::Positional</a>, <a href="#cl::Required">cl::Required</a>, <a href="#cl::desc">cl::desc</a>("<i>&lt;input file&gt;</i>"));
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]293</pre>
294
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]295<p>By simply adding the <tt><a href="#cl::Required">cl::Required</a></tt> flag,
296the CommandLine library will automatically issue an error if the argument is not
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]297specified, which shifts all of the command line option verification code out of
298your application into the library. This is just one example of how using flags
299can alter the default behaviour of the library, on a per-option basis. By
300adding one of the declarations above, the <tt>--help</tt> option synopsis is now
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]301extended to:</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]302
303<pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]304USAGE: compiler [options] <b>&lt;input file&gt;</b>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]305
306OPTIONS:
307 -help - display available options (--help-hidden for more)
308 -o &lt;filename&gt; - Specify output filename
309</pre>
310
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]311<p>... indicating that an input filename is expected.</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]312
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]313</div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]314
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]315<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]316<div class="doc_subsection">
317 <a name="bool">Boolean Arguments</a>
318</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]319
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]320<div class="doc_text">
321
322<p>In addition to input and output filenames, we would like the compiler example
323to support three boolean flags: "<tt>-f</tt>" to force overwriting of the output
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]324file, "<tt>--quiet</tt>" to enable quiet mode, and "<tt>-q</tt>" for backwards
325compatibility with some of our users. We can support these by declaring options
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]326of boolean type like this:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]327
328<pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]329<a href="#cl::opt">cl::opt</a>&lt;bool&gt; Force ("<i>f</i>", <a href="#cl::desc">cl::desc</a>("<i>Overwrite output files</i>"));
330<a href="#cl::opt">cl::opt</a>&lt;bool&gt; Quiet ("<i>quiet</i>", <a href="#cl::desc">cl::desc</a>("<i>Don't print informational messages</i>"));
331<a href="#cl::opt">cl::opt</a>&lt;bool&gt; 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 Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]332</pre>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]333
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]334<p>This does what you would expect: it declares three boolean variables
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]335("<tt>Force</tt>", "<tt>Quiet</tt>", and "<tt>Quiet2</tt>") to recognize these
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]336options. Note that the "<tt>-q</tt>" option is specified with the "<a
337href="#cl::Hidden"><tt>cl::Hidden</tt></a>" flag. This modifier prevents it
338from being shown by the standard "<tt>--help</tt>" output (note that it is still
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]339shown in the "<tt>--help-hidden</tt>" output).</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]340
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]341<p>The CommandLine library uses a <a href="#builtinparsers">different parser</a>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]342for different data types. For example, in the string case, the argument passed
343to the option is copied literally into the content of the string variable... we
344obviously cannot do that in the boolean case, however, so we must use a smarter
345parser. In the case of the boolean parser, it allows no options (in which case
346it assigns the value of true to the variable), or it allows the values
347"<tt>true</tt>" or "<tt>false</tt>" to be specified, allowing any of the
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]348following inputs:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]349
350<pre>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]351 compiler -f # No value, 'Force' == true
352 compiler -f=true # Value specified, 'Force' == true
353 compiler -f=TRUE # Value specified, 'Force' == true
354 compiler -f=FALSE # Value specified, 'Force' == false
355</pre>
356
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]357<p>... you get the idea. The <a href="#boolparser">bool parser</a> just turns
358the string values into boolean values, and rejects things like '<tt>compiler
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]359-f=foo</tt>'. Similarly, the <a href="#doubleparser">float</a>, <a
360href="#doubleparser">double</a>, and <a href="#intparser">int</a> parsers work
361like you would expect, using the '<tt>strtol</tt>' and '<tt>strtod</tt>' C
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]362library calls to parse the string value into the specified data type.</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]363
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]364<p>With the declarations above, "<tt>compiler --help</tt>" emits this:</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]365
366<pre>
367USAGE: compiler [options] &lt;input file&gt;
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]368
369OPTIONS:
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]370 <b>-f - Overwrite output files</b>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]371 -o - Override output filename
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]372 <b>-quiet - Don't print informational messages</b>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]373 -help - display available options (--help-hidden for more)
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]374</pre>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]375
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]376<p>and "<tt>opt --help-hidden</tt>" prints this:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]377
378<pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]379USAGE: compiler [options] &lt;input file&gt;
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]380
381OPTIONS:
382 -f - Overwrite output files
383 -o - Override output filename
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]384 <b>-q - Don't print informational messages</b>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]385 -quiet - Don't print informational messages
386 -help - display available options (--help-hidden for more)
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]387</pre>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]388
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]389<p>This brief example has shown you how to use the '<tt><a
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]390href="#cl::opt">cl::opt</a></tt>' class to parse simple scalar command line
391arguments. In addition to simple scalar arguments, the CommandLine library also
392provides primitives to support CommandLine option <a href="#alias">aliases</a>,
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]393and <a href="#list">lists</a> of options.</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]394
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]395</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]396
397<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]398<div class="doc_subsection">
399 <a name="alias">Argument Aliases</a>
400</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]401
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]402<div class="doc_text">
403
404<p>So far, the example works well, except for the fact that we need to check the
405quiet condition like this now:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]406
407<pre>
408...
409 if (!Quiet &amp;&amp; !Quiet2) printInformationalMessage(...);
410...
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]411</pre>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]412
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]413<p>... which is a real pain! Instead of defining two values for the same
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]414condition, we can use the "<tt><a href="#cl::alias">cl::alias</a></tt>" class to make the "<tt>-q</tt>"
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]415option an <b>alias</b> for the "<tt>-quiet</tt>" option, instead of providing
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]416a value itself:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]417
418<pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]419<a href="#cl::opt">cl::opt</a>&lt;bool&gt; Force ("<i>f</i>", <a href="#cl::desc">cl::desc</a>("<i>Overwrite output files</i>"));
420<a href="#cl::opt">cl::opt</a>&lt;bool&gt; Quiet ("<i>quiet</i>", <a href="#cl::desc">cl::desc</a>("<i>Don't print informational messages</i>"));
421<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 Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]422</pre>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]423
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]424<p>The third line (which is the only one we modified from above) defines a
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]425"<tt>-q</tt> alias that updates the "<tt>Quiet</tt>" variable (as specified by
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]426the <tt><a href="#cl::aliasopt">cl::aliasopt</a></tt> modifier) whenever it is
427specified. Because aliases do not hold state, the only thing the program has to
428query is the <tt>Quiet</tt> variable now. Another nice feature of aliases is
429that they automatically hide themselves from the <tt>-help</tt> output
430(although, again, they are still visible in the <tt>--help-hidden
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]431output</tt>).</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]432
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]433<p>Now the application code can simply use:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]434
435<pre>
436...
437 if (!Quiet) printInformationalMessage(...);
438...
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]439</pre>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]440
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]441<p>... which is much nicer! The "<tt><a href="#cl::alias">cl::alias</a></tt>"
442can be used to specify an alternative name for any variable type, and has many
443uses.</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]444
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]445</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]446
447<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]448<div class="doc_subsection">
449 <a name="onealternative">Selecting an alternative from a set of
450 possibilities</a>
451</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]452
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]453<div class="doc_text">
454
455<p>So far, we have seen how the CommandLine library handles builtin types like
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]456<tt>std::string</tt>, <tt>bool</tt> and <tt>int</tt>, but how does it handle
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]457things it doesn't know about, like enums or '<tt>int*</tt>'s?</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]458
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]459<p>The answer is that it uses a table driven generic parser (unless you specify
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]460your own parser, as described in the <a href="#extensionguide">Extension
461Guide</a>). This parser maps literal strings to whatever type is required, are
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]462requires you to tell it what this mapping should be.</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]463
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]464<p>Lets say that we would like to add four optimizations levels to our
465optimizer, using the standard flags "<tt>-g</tt>", "<tt>-O0</tt>",
466"<tt>-O1</tt>", and "<tt>-O2</tt>". We could easily implement this with boolean
467options like above, but there are several problems with this strategy:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]468
469<ol>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]470<li>A user could specify more than one of the options at a time, for example,
471"<tt>opt -O3 -O2</tt>". The CommandLine library would not be able to catch this
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]472erroneous input for us.</li>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]473
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]474<li>We would have to test 4 different variables to see which ones are set.</li>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]475
476<li>This doesn't map to the numeric levels that we want... so we cannot easily
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]477see if some level &gt;= "<tt>-O1</tt>" is enabled.</li>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]478
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]479</ol>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]480
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]481<p>To cope with these problems, we can use an enum value, and have the
482CommandLine library fill it in with the appropriate level directly, which is
483used like this:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]484
485<pre>
486enum OptLevel {
487 g, O1, O2, O3
488};
489
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]490<a href="#cl::opt">cl::opt</a>&lt;OptLevel&gt; OptimizationLevel(<a href="#cl::desc">cl::desc</a>("<i>Choose optimization level:</i>"),
491 <a href="#cl::values">cl::values</a>(
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]492 clEnumVal(g , "<i>No optimizations, enable debugging</i>"),
493 clEnumVal(O1, "<i>Enable trivial optimizations</i>"),
494 clEnumVal(O2, "<i>Enable default optimizations</i>"),
495 clEnumVal(O3, "<i>Enable expensive optimizations</i>"),
496 0));
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]497
498...
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]499 if (OptimizationLevel &gt;= O2) doPartialRedundancyElimination(...);
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]500...
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]501</pre>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]502
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]503<p>This declaration defines a variable "<tt>OptimizationLevel</tt>" of the
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]504"<tt>OptLevel</tt>" enum type. This variable can be assigned any of the values
505that are listed in the declaration (Note that the declaration list must be
506terminated with the "<tt>0</tt>" argument!). The CommandLine library enforces
507that the user can only specify one of the options, and it ensure that only valid
508enum values can be specified. The "<tt>clEnumVal</tt>" macros ensure that the
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]509command line arguments matched the enum values. With this option added, our
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]510help output now is:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]511
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]512<pre>
513USAGE: compiler [options] &lt;input file&gt;
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]514
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]515OPTIONS:
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]516 <b>Choose optimization level:
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]517 -g - No optimizations, enable debugging
518 -O1 - Enable trivial optimizations
519 -O2 - Enable default optimizations
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]520 -O3 - Enable expensive optimizations</b>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]521 -f - Overwrite output files
522 -help - display available options (--help-hidden for more)
523 -o &lt;filename&gt; - Specify output filename
524 -quiet - Don't print informational messages
525</pre>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]526
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]527<p>In this case, it is sort of awkward that flag names correspond directly to
528enum names, because we probably don't want a enum definition named "<tt>g</tt>"
529in our program. Because of this, we can alternatively write this example like
530this:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]531
532<pre>
533enum OptLevel {
534 Debug, O1, O2, O3
535};
536
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]537<a href="#cl::opt">cl::opt</a>&lt;OptLevel&gt; OptimizationLevel(<a href="#cl::desc">cl::desc</a>("<i>Choose optimization level:</i>"),
538 <a href="#cl::values">cl::values</a>(
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]539 clEnumValN(Debug, "g", "<i>No optimizations, enable debugging</i>"),
540 clEnumVal(O1 , "<i>Enable trivial optimizations</i>"),
541 clEnumVal(O2 , "<i>Enable default optimizations</i>"),
542 clEnumVal(O3 , "<i>Enable expensive optimizations</i>"),
543 0));
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]544
545...
546 if (OptimizationLevel == Debug) outputDebugInfo(...);
547...
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]548</pre>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]549
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]550<p>By using the "<tt>clEnumValN</tt>" macro instead of "<tt>clEnumVal</tt>", we
551can directly specify the name that the flag should get. In general a direct
552mapping is nice, but sometimes you can't or don't want to preserve the mapping,
553which is when you would use it.</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]554
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]555</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]556
557<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]558<div class="doc_subsection">
559 <a name="namedalternatives">Named Alternatives</a>
560</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]561
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]562<div class="doc_text">
563
564<p>Another useful argument form is a named alternative style. We shall use this
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]565style in our compiler to specify different debug levels that can be used.
566Instead of each debug level being its own switch, we want to support the
567following options, of which only one can be specified at a time:
568"<tt>--debug-level=none</tt>", "<tt>--debug-level=quick</tt>",
569"<tt>--debug-level=detailed</tt>". To do this, we use the exact same format as
570our optimization level flags, but we also specify an option name. For this
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]571case, the code looks like this:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]572
573<pre>
574enum DebugLev {
575 nodebuginfo, quick, detailed
576};
577
578// Enable Debug Options to be specified on the command line
Chris Lattnerdc844fa2003-06-03 04:40:06 +0000[diff] [blame]579<a href="#cl::opt">cl::opt</a>&lt;DebugLev&gt; DebugLevel("<i>debug_level</i>", <a href="#cl::desc">cl::desc</a>("<i>Set the debugging level:</i>"),
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]580 <a href="#cl::values">cl::values</a>(
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]581 clEnumValN(nodebuginfo, "none", "<i>disable debug information</i>"),
582 clEnumVal(quick, "<i>enable quick debug information</i>"),
583 clEnumVal(detailed, "<i>enable detailed debug information</i>"),
584 0));
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]585</pre>
586
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]587<p>This definition defines an enumerated command line variable of type "<tt>enum
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]588DebugLev</tt>", which works exactly the same way as before. The difference here
589is just the interface exposed to the user of your program and the help output by
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]590the "<tt>--help</tt>" option:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]591
592<pre>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]593USAGE: compiler [options] &lt;input file&gt;
594
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]595OPTIONS:
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]596 Choose optimization level:
597 -g - No optimizations, enable debugging
598 -O1 - Enable trivial optimizations
599 -O2 - Enable default optimizations
600 -O3 - Enable expensive optimizations
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]601 <b>-debug_level - Set the debugging level:
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]602 =none - disable debug information
603 =quick - enable quick debug information
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]604 =detailed - enable detailed debug information</b>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]605 -f - Overwrite output files
606 -help - display available options (--help-hidden for more)
607 -o &lt;filename&gt; - Specify output filename
608 -quiet - Don't print informational messages
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]609</pre>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]610
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]611<p>Again, the only structural difference between the debug level declaration and
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]612the optimiation level declaration is that the debug level declaration includes
613an option name (<tt>"debug_level"</tt>), which automatically changes how the
614library processes the argument. The CommandLine library supports both forms so
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]615that you can choose the form most appropriate for your application.</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]616
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]617</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]618
619<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]620<div class="doc_subsection">
621 <a name="list">Parsing a list of options</a>
622</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]623
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]624<div class="doc_text">
625
626<p>Now that we have the standard run of the mill argument types out of the way,
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]627lets get a little wild and crazy. Lets say that we want our optimizer to accept
628a <b>list</b> of optimizations to perform, allowing duplicates. For example, we
629might want to run: "<tt>compiler -dce -constprop -inline -dce -strip</tt>". In
630this case, the order of the arguments and the number of appearances is very
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]631important. This is what the "<tt><a href="#cl::list">cl::list</a></tt>"
632template is for. First, start by defining an enum of the optimizations that you
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]633would like to perform:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]634
635<pre>
636enum Opts {
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]637 // 'inline' is a C++ keyword, so name it 'inlining'
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]638 dce, constprop, inlining, strip
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]639};
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]640</pre>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]641
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]642<p>Then define your "<tt><a href="#cl::list">cl::list</a></tt>" variable:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]643
644<pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]645<a href="#cl::list">cl::list</a>&lt;Opts&gt; OptimizationList(<a href="#cl::desc">cl::desc</a>("<i>Available Optimizations:</i>"),
646 <a href="#cl::values">cl::values</a>(
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]647 clEnumVal(dce , "<i>Dead Code Elimination</i>"),
Misha Brukman82c89b92003-05-20 21:01:22 +0000[diff] [blame]648 clEnumVal(constprop , "<i>Constant Propagation</i>"),
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]649 clEnumValN(inlining, "<i>inline</i>", "<i>Procedure Integration</i>"),
650 clEnumVal(strip , "<i>Strip Symbols</i>"),
651 0));
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]652</pre>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]653
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]654<p>This defines a variable that is conceptually of the type
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]655"<tt>std::vector&lt;enum Opts&gt;</tt>". Thus, you can access it with standard
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]656vector methods:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]657
658<pre>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]659 for (unsigned i = 0; i != OptimizationList.size(); ++i)
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]660 switch (OptimizationList[i])
661 ...
662</pre>
663
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]664<p>... to iterate through the list of options specified.</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]665
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]666<p>Note that the "<tt><a href="#cl::list">cl::list</a></tt>" template is
667completely general and may be used with any data types or other arguments that
668you can use with the "<tt><a href="#cl::opt">cl::opt</a></tt>" template. One
669especially useful way to use a list is to capture all of the positional
670arguments together if there may be more than one specified. In the case of a
671linker, for example, the linker takes several '<tt>.o</tt>' files, and needs to
672capture them into a list. This is naturally specified as:</p>
Chris Lattner3e5fe172002-04-13 18:35:59 +0000[diff] [blame]673
674<pre>
675...
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]676<a href="#cl::list">cl::list</a>&lt;std::string&gt; InputFilenames(<a href="#cl::Positional">cl::Positional</a>, <a href="#cl::desc">cl::desc</a>("&lt;Input files&gt;"), <a href="#cl::OneOrMore">cl::OneOrMore</a>);
Chris Lattner3e5fe172002-04-13 18:35:59 +0000[diff] [blame]677...
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]678</pre>
Chris Lattner3e5fe172002-04-13 18:35:59 +0000[diff] [blame]679
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]680<p>This variable works just like a "<tt>vector&lt;string&gt;</tt>" object. As
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]681such, accessing the list is simple, just like above. In this example, we used
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]682the <tt><a href="#cl::OneOrMore">cl::OneOrMore</a></tt> modifier to inform the
683CommandLine library that it is an error if the user does not specify any
684<tt>.o</tt> files on our command line. Again, this just reduces the amount of
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]685checking we have to do.</p>
Chris Lattner3e5fe172002-04-13 18:35:59 +0000[diff] [blame]686
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]687</div>
Chris Lattner3e5fe172002-04-13 18:35:59 +0000[diff] [blame]688
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]689<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]690<div class="doc_subsection">
691 <a name="description">Adding freeform text to help output</a>
692</div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]693
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]694<div class="doc_text">
695
696<p>As our program grows and becomes more mature, we may decide to put summary
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]697information about what it does into the help output. The help output is styled
698to look similar to a Unix <tt>man</tt> page, providing concise information about
699a program. Unix <tt>man</tt> pages, however often have a description about what
700the program does. To add this to your CommandLine program, simply pass a third
701argument to the <a
702href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>
703call in main. This additional argument is then printed as the overview
704information for your program, allowing you to include any additional information
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]705that you want. For example:</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]706
707<pre>
708int main(int argc, char **argv) {
709 <a href="#cl::ParseCommandLineOptions">cl::ParseCommandLineOptions</a>(argc, argv, " CommandLine compiler example\n\n"
710 " This program blah blah blah...\n");
711 ...
712}
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]713</pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]714
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]715<p>Would yield the help output:</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]716
717<pre>
718<b>OVERVIEW: CommandLine compiler example
719
720 This program blah blah blah...</b>
721
722USAGE: compiler [options] &lt;input file&gt;
723
724OPTIONS:
725 ...
726 -help - display available options (--help-hidden for more)
727 -o &lt;filename&gt; - Specify output filename
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]728</pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]729
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]730</div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]731
732
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]733<!-- *********************************************************************** -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]734<div class="doc_section">
735 <a name="referenceguide">Reference Guide</a>
736</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]737<!-- *********************************************************************** -->
738
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]739<div class="doc_text">
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]740
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]741<p>Now that you know the basics of how to use the CommandLine library, this
742section will give you the detailed information you need to tune how command line
743options work, as well as information on more "advanced" command line option
744processing capabilities.</p>
745
746</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]747
748<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]749<div class="doc_subsection">
750 <a name="positional">Positional Arguments</a>
751</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]752
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]753<div class="doc_text">
754
755<p>Positional arguments are those arguments that are not named, and are not
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]756specified with a hyphen. Positional arguments should be used when an option is
757specified by its position alone. For example, the standard Unix <tt>grep</tt>
758tool takes a regular expression argument, and an optional filename to search
759through (which defaults to standard input if a filename is not specified).
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]760Using the CommandLine library, this would be specified as:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]761
762<pre>
763<a href="#cl::opt">cl::opt</a>&lt;string&gt; Regex (<a href="#cl::Positional">cl::Positional</a>, <a href="#cl::desc">cl::desc</a>("<i>&lt;regular expression&gt;</i>"), <a href="#cl::Required">cl::Required</a>);
764<a href="#cl::opt">cl::opt</a>&lt;string&gt; Filename(<a href="#cl::Positional">cl::Positional</a>, <a href="#cl::desc">cl::desc</a>("<i>&lt;input file&gt;</i>"), <a href="#cl::init">cl::init</a>("<i>-</i>"));
765</pre>
766
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]767<p>Given these two option declarations, the <tt>--help</tt> output for our grep
768replacement would look like this:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]769
770<pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]771USAGE: spiffygrep [options] <b>&lt;regular expression&gt; &lt;input file&gt;</b>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]772
773OPTIONS:
774 -help - display available options (--help-hidden for more)
775</pre>
776
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]777<p>... and the resultant program could be used just like the standard
778<tt>grep</tt> tool.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]779
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]780<p>Positional arguments are sorted by their order of construction. This means
781that command line options will be ordered according to how they are listed in a
782.cpp file, but will not have an ordering defined if they positional arguments
783are defined in multiple .cpp files. The fix for this problem is simply to
784define all of your positional arguments in one .cpp file.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]785
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]786</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]787
788
789<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]790<div class="doc_subsubsection">
791 <a name="--">Specifying positional options with hyphens</a>
792</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]793
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]794<div class="doc_text">
795
796<p>Sometimes you may want to specify a value to your positional argument that
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]797starts with a hyphen (for example, searching for '<tt>-foo</tt>' in a file). At
798first, you will have trouble doing this, because it will try to find an argument
799named '<tt>-foo</tt>', and will fail (and single quotes will not save you).
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]800Note that the system <tt>grep</tt> has the same problem:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]801
802<pre>
803 $ spiffygrep '-foo' test.txt
804 Unknown command line argument '-foo'. Try: spiffygrep --help'
805
806 $ grep '-foo' test.txt
807 grep: illegal option -- f
808 grep: illegal option -- o
809 grep: illegal option -- o
810 Usage: grep -hblcnsviw pattern file . . .
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]811</pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]812
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]813<p>The solution for this problem is the same for both your tool and the system
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]814version: use the '<tt>--</tt>' marker. When the user specifies '<tt>--</tt>' on
815the command line, it is telling the program that all options after the
816'<tt>--</tt>' should be treated as positional arguments, not options. Thus, we
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]817can use it like this:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]818
819<pre>
820 $ spiffygrep -- -foo test.txt
821 ...output...
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]822</pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]823
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]824</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]825
826<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]827<div class="doc_subsubsection">
828 <a name="cl::ConsumeAfter">The <tt>cl::ConsumeAfter</tt> modifier</a>
829</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]830
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]831<div class="doc_text">
832
833<p>The <tt>cl::ConsumeAfter</tt> <a href="#formatting">formatting option</a> is
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]834used to construct programs that use "interpreter style" option processing. With
835this style of option processing, all arguments specified after the last
836positional argument are treated as special interpreter arguments that are not
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]837interpreted by the command line argument.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]838
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]839<p>As a concrete example, lets say we are developing a replacement for the
840standard Unix Bourne shell (<tt>/bin/sh</tt>). To run <tt>/bin/sh</tt>, first
841you specify options to the shell itself (like <tt>-x</tt> which turns on trace
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]842output), then you specify the name of the script to run, then you specify
843arguments to the script. These arguments to the script are parsed by the bourne
844shell command line option processor, but are not interpreted as options to the
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]845shell itself. Using the CommandLine library, we would specify this as:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]846
847<pre>
848<a href="#cl::opt">cl::opt</a>&lt;string&gt; Script(<a href="#cl::Positional">cl::Positional</a>, <a href="#cl::desc">cl::desc</a>("<i>&lt;input script&gt;</i>"), <a href="#cl::init">cl::init</a>("-"));
849<a href="#cl::list">cl::list</a>&lt;string&gt; Argv(<a href="#cl::ConsumeAfter">cl::ConsumeAfter</a>, <a href="#cl::desc">cl::desc</a>("<i>&lt;program arguments&gt;...</i>"));
850<a href="#cl::opt">cl::opt</a>&lt;bool&gt; Trace("<i>x</i>", <a href="#cl::desc">cl::desc</a>("<i>Enable trace output</i>"));
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]851</pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]852
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]853<p>which automatically provides the help output:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]854
855<pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]856USAGE: spiffysh [options] <b>&lt;input script&gt; &lt;program arguments&gt;...</b>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]857
858OPTIONS:
859 -help - display available options (--help-hidden for more)
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]860 <b>-x - Enable trace output</b>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]861</pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]862
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]863<p>At runtime, if we run our new shell replacement as '<tt>spiffysh -x test.sh
864-a -x -y bar</tt>', the <tt>Trace</tt> variable will be set to true, the
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]865<tt>Script</tt> variable will be set to "<tt>test.sh</tt>", and the
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]866<tt>Argv</tt> list will contain <tt>["-a", "-x", "-y", "bar"]</tt>, because they
867were specified after the last positional argument (which is the script
868name).</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]869
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]870<p>There are several limitations to when <tt>cl::ConsumeAfter</tt> options can
871be specified. For example, only one <tt>cl::ConsumeAfter</tt> can be specified
872per program, there must be at least one <a href="#positional">positional
Chris Lattnerbe801bf2004-05-06 22:03:59 +0000[diff] [blame]873argument</a> specified, there must not be any <a href="#cl::list">cl::list</a>
874positional arguments, and the <tt>cl::ConsumeAfter</tt> option should be a <a
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]875href="#cl::list">cl::list</a> option.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]876
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]877</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]878
879<!-- ======================================================================= -->
Chris Lattnerbe801bf2004-05-06 22:03:59 +0000[diff] [blame]880<div class="doc_subsection">
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]881 <a name="storage">Internal vs External Storage</a>
882</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]883
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]884<div class="doc_text">
885
886<p>By default, all command line options automatically hold the value that they
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]887parse from the command line. This is very convenient in the common case,
888especially when combined with the ability to define command line options in the
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]889files that use them. This is called the internal storage model.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]890
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]891<p>Sometimes, however, it is nice to separate the command line option processing
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]892code from the storage of the value parsed. For example, lets say that we have a
893'<tt>-debug</tt>' option that we would like to use to enable debug information
894across the entire body of our program. In this case, the boolean value
895controlling the debug code should be globally accessable (in a header file, for
896example) yet the command line option processing code should not be exposed to
897all of these clients (requiring lots of .cpp files to #include
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]898<tt>CommandLine.h</tt>).</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]899
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]900<p>To do this, set up your .h file with your option, like this for example:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]901
902<pre>
903<i>// DebugFlag.h - Get access to the '-debug' command line option
904//
905
906// DebugFlag - This boolean is set to true if the '-debug' command line option
907// is specified. This should probably not be referenced directly, instead, use
908// the DEBUG macro below.
909//</i>
910extern bool DebugFlag;
911
912<i>// DEBUG macro - This macro should be used by code to emit debug information.
913// In the '-debug' option is specified on the command line, and if this is a
914// debug build, then the code specified as the option to the macro will be
915// executed. Otherwise it will not be. Example:
916//
917// DEBUG(cerr << "Bitset contains: " << Bitset << "\n");
918//</i>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]919<span class="doc_red">#ifdef NDEBUG
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]920#define DEBUG(X)
921#else
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]922#define DEBUG(X)</span> \
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]923 do { if (DebugFlag) { X; } } while (0)
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]924<span class="doc_red">#endif</span>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]925</pre>
926
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]927<p>This allows clients to blissfully use the <tt>DEBUG()</tt> macro, or the
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]928<tt>DebugFlag</tt> explicitly if they want to. Now we just need to be able to
929set the <tt>DebugFlag</tt> boolean when the option is set. To do this, we pass
930an additial argument to our command line argument processor, and we specify
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]931where to fill in with the <a href="#cl::location">cl::location</a>
932attribute:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]933
934<pre>
935bool DebugFlag; <i>// the actual value</i>
Chris Lattner589a4cc2003-08-01 21:30:37 +0000[diff] [blame]936static <a href="#cl::opt">cl::opt</a>&lt;bool, true&gt; <i>// The parser</i>
Misha Brukmanc53aefb2004-05-12 18:42:35 +0000[diff] [blame]937Debug("<i>debug</i>", <a href="#cl::desc">cl::desc</a>("<i>Enable debug output</i>"), <a href="#cl::Hidden">cl::Hidden</a>,
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]938 <a href="#cl::location">cl::location</a>(DebugFlag));
939</pre>
940
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]941<p>In the above example, we specify "<tt>true</tt>" as the second argument to
942the <a href="#cl::opt">cl::opt</a> template, indicating that the template should
943not maintain a copy of the value itself. In addition to this, we specify the <a
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]944href="#cl::location">cl::location</a> attribute, so that <tt>DebugFlag</tt> is
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]945automatically set.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]946
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]947</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]948
949<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]950<div class="doc_subsection">
951 <a name="attributes">Option Attributes</a>
952</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]953
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]954<div class="doc_text">
955
956<p>This section describes the basic attributes that you can specify on
957options.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]958
959<ul>
960
961<li>The option name attribute (which is required for all options, except <a
962href="#positional">positional options</a>) specifies what the option name is.
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]963This option is specified in simple double quotes:
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]964
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]965<pre>
966<a href="#cl::opt">cl::opt</a>&lt;<b>bool</b>&gt; Quiet("<i>quiet</i>");
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]967</pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]968
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]969</li>
970
971<li><a name="cl::desc">The <b><tt>cl::desc</tt></b></a> attribute specifies a
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]972description for the option to be shown in the <tt>--help</tt> output for the
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]973program.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]974
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]975<li><a name="cl::value_desc">The <b><tt>cl::value_desc</tt></b></a> attribute
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]976specifies a string that can be used to fine tune the <tt>--help</tt> output for
977a command line option. Look <a href="#value_desc_example">here</a> for an
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]978example.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]979
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]980<li><a name="cl::init">The <b><tt>cl::init</tt></b></a> attribute specifies an
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]981inital value for a <a href="#cl::opt">scalar</a> option. If this attribute is
982not specified then the command line option value defaults to the value created
Brian Gaeke9d292ff2003-08-19 22:56:22 +0000[diff] [blame]983by the default constructor for the type. <b>Warning</b>: If you specify both
984<b><tt>cl::init</tt></b> and <b><tt>cl::location</tt></b> for an option,
985you must specify <b><tt>cl::location</tt></b> first, so that when the
986command-line parser sees <b><tt>cl::init</tt></b>, it knows where to put the
987initial value. (You will get an error at runtime if you don't put them in
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]988the right order.)</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]989
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]990<li><a name="cl::location">The <b><tt>cl::location</tt></b></a> attribute where to
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]991store the value for a parsed command line option if using external storage. See
992the section on <a href="#storage">Internal vs External Storage</a> for more
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]993information.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]994
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]995<li><a name="cl::aliasopt">The <b><tt>cl::aliasopt</tt></b></a> attribute
996specifies which option a <a href="#cl::alias">cl::alias</a> option is an alias
997for.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]998
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]999<li><a name="cl::values">The <b><tt>cl::values</tt></b></a> attribute specifies
1000the string-to-value mapping to be used by the generic parser. It takes a
1001<b>null terminated</b> list of (option, value, description) triplets that
1002specify the option name, the value mapped to, and the description shown in the
1003<tt>--help</tt> for the tool. Because the generic parser is used most
1004frequently with enum values, two macros are often useful:
1005
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1006<ol>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1007
1008<li><a name="clEnumVal">The <b><tt>clEnumVal</tt></b></a> macro is used as a
1009nice simple way to specify a triplet for an enum. This macro automatically
1010makes the option name be the same as the enum name. The first option to the
1011macro is the enum, the second is the description for the command line
1012option.</li>
1013
1014<li><a name="clEnumValN">The <b><tt>clEnumValN</tt></b></a> macro is used to
1015specify macro options where the option name doesn't equal the enum name. For
1016this macro, the first argument is the enum value, the second is the flag name,
1017and the second is the description.</li>
1018
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1019</ol>
1020
1021You will get a compile time error if you try to use cl::values with a parser
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1022that does not support it.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1023
1024</ul>
1025
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1026</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1027
1028<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1029<div class="doc_subsection">
1030 <a name="modifiers">Option Modifiers</a>
1031</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1032
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1033<div class="doc_text">
1034
1035<p>Option modifiers are the flags and expressions that you pass into the
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1036constructors for <tt><a href="#cl::opt">cl::opt</a></tt> and <tt><a
1037href="#cl::list">cl::list</a></tt>. These modifiers give you the ability to
1038tweak how options are parsed and how <tt>--help</tt> output is generated to fit
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1039your application well.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1040
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1041<p>These options fall into five main catagories:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1042
1043<ol>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1044<li><a href="#hiding">Hiding an option from <tt>--help</tt> output</a></li>
1045<li><a href="#numoccurrences">Controlling the number of occurrences
1046 required and allowed</a></li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1047<li><a href="#valrequired">Controlling whether or not a value must be
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1048 specified</a></li>
1049<li><a href="#formatting">Controlling other formatting options</a></li>
1050<li><a href="#misc">Miscellaneous option modifiers</a></li>
1051</ol>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1052
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1053<p>It is not possible to specify two options from the same catagory (you'll get
1054a runtime error) to a single option, except for options in the miscellaneous
Chris Lattner32a32842003-05-22 20:36:06 +0000[diff] [blame]1055catagory. The CommandLine library specifies defaults for all of these settings
1056that are the most useful in practice and the most common, which mean that you
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1057usually shouldn't have to worry about these.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1058
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1059</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1060
1061<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1062<div class="doc_subsubsection">
1063 <a name="hiding">Hiding an option from <tt>--help</tt> output</a>
1064</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1065
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1066<div class="doc_text">
1067
1068<p>The <tt>cl::NotHidden</tt>, <tt>cl::Hidden</tt>, and
1069<tt>cl::ReallyHidden</tt> modifiers are used to control whether or not an option
1070appears in the <tt>--help</tt> and <tt>--help-hidden</tt> output for the
1071compiled program:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1072
1073<ul>
1074
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1075<li><a name="cl::NotHidden">The <b><tt>cl::NotHidden</tt></b></a> modifier
1076(which is the default for <tt><a href="#cl::opt">cl::opt</a></tt> and <tt><a
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1077href="#cl::list">cl::list</a></tt> options), indicates the option is to appear
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1078in both help listings.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1079
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1080<li><a name="cl::Hidden">The <b><tt>cl::Hidden</tt></b></a> modifier (which is the
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1081default for <tt><a href="#cl::alias">cl::alias</a></tt> options), indicates that
1082the option should not appear in the <tt>--help</tt> output, but should appear in
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1083the <tt>--help-hidden</tt> output.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1084
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1085<li><a name="cl::ReallyHidden">The <b><tt>cl::ReallyHidden</tt></b></a> modifier,
1086indicates that the option should not appear in any help output.</li>
1087
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1088</ul>
1089
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1090</div>
1091
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1092<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1093<div class="doc_subsubsection">
1094 <a name="numoccurrences">Controlling the number of occurrences required and
1095 allowed</a>
1096</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1097
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1098<div class="doc_text">
1099
1100<p>This group of options is used to control how many time an option is allowed
1101(or required) to be specified on the command line of your program. Specifying a
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1102value for this setting allows the CommandLine library to do error checking for
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1103you.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1104
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1105<p>The allowed values for this option group are:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1106
1107<ul>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1108
1109<li><a name="cl::Optional">The <b><tt>cl::Optional</tt></b></a> modifier (which
1110is the default for the <tt><a href="#cl::opt">cl::opt</a></tt> and <tt><a
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1111href="#cl::alias">cl::alias</a></tt> classes) indicates that your program will
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1112allow either zero or one occurrence of the option to be specified.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1113
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1114<li><a name="cl::ZeroOrMore">The <b><tt>cl::ZeroOrMore</tt></b></a> modifier
1115(which is the default for the <tt><a href="#cl::list">cl::list</a></tt> class)
1116indicates that your program will allow the option to be specified zero or more
1117times.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1118
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1119<li><a name="cl::Required">The <b><tt>cl::Required</tt></b></a> modifier
1120indicates that the specified option must be specified exactly one time.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1121
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1122<li><a name="cl::OneOrMore">The <b><tt>cl::OneOrMore</tt></b></a> modifier
1123indicates that the option must be specified at least one time.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1124
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1125<li>The <b><tt>cl::ConsumeAfter</tt></b> modifier is described in the <a
1126href="#positional">Positional arguments section</a></li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1127
1128</ul>
1129
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1130<p>If an option is not specified, then the value of the option is equal to the
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1131value specified by the <tt><a href="#cl::init">cl::init</a></tt> attribute. If
1132the <tt><a href="#cl::init">cl::init</a></tt> attribute is not specified, the
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1133option value is initialized with the default constructor for the data type.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1134
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1135<p>If an option is specified multiple times for an option of the <tt><a
1136href="#cl::opt">cl::opt</a></tt> class, only the last value will be
1137retained.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1138
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1139</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1140
1141<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1142<div class="doc_subsubsection">
1143 <a name="valrequired">Controlling whether or not a value must be specified</a>
1144</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1145
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1146<div class="doc_text">
1147
1148<p>This group of options is used to control whether or not the option allows a
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1149value to be present. In the case of the CommandLine library, a value is either
1150specified with an equal sign (e.g. '<tt>-index-depth=17</tt>') or as a trailing
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1151string (e.g. '<tt>-o a.out</tt>').</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1152
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1153<p>The allowed values for this option group are:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1154
1155<ul>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1156
1157<li><a name="cl::ValueOptional">The <b><tt>cl::ValueOptional</tt></b></a> modifier
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1158(which is the default for <tt>bool</tt> typed options) specifies that it is
1159acceptable to have a value, or not. A boolean argument can be enabled just by
1160appearing on the command line, or it can have an explicit '<tt>-foo=true</tt>'.
1161If an option is specified with this mode, it is illegal for the value to be
1162provided without the equal sign. Therefore '<tt>-foo true</tt>' is illegal. To
1163get this behavior, you must use the <a
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1164href="#cl::ValueRequired">cl::ValueRequired</a> modifier.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1165
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1166<li><a name="cl::ValueRequired">The <b><tt>cl::ValueRequired</tt></b></a> modifier
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1167(which is the default for all other types except for <a
1168href="#onealternative">unnamed alternatives using the generic parser</a>)
1169specifies that a value must be provided. This mode informs the command line
1170library that if an option is not provides with an equal sign, that the next
1171argument provided must be the value. This allows things like '<tt>-o
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1172a.out</tt>' to work.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1173
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1174<li><a name="cl::ValueDisallowed">The <b><tt>cl::ValueDisallowed</tt></b></a>
1175modifier (which is the default for <a href="#onealternative">unnamed
1176alternatives using the generic parser</a>) indicates that it is a runtime error
1177for the user to specify a value. This can be provided to disallow users from
1178providing options to boolean options (like '<tt>-foo=true</tt>').</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1179
1180</ul>
1181
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1182<p>In general, the default values for this option group work just like you would
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1183want them to. As mentioned above, you can specify the <a
1184href="#cl::ValueDisallowed">cl::ValueDisallowed</a> modifier to a boolean
1185argument to restrict your command line parser. These options are mostly useful
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1186when <a href="#extensionguide">extending the library</a>.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1187
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1188</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1189
1190<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1191<div class="doc_subsubsection">
1192 <a name="formatting">Controlling other formatting options</a>
1193</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1194
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1195<div class="doc_text">
1196
1197<p>The formatting option group is used to specify that the command line option
1198has special abilities and is otherwise different from other command line
1199arguments. As usual, you can only specify at most one of these arguments.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1200
1201<ul>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1202
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1203<li><a name="cl::NormalFormatting">The <b><tt>cl::NormalFormatting</tt></b></a>
1204modifier (which is the default all options) specifies that this option is
1205"normal".</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1206
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1207<li><a name="cl::Positional">The <b><tt>cl::Positional</tt></b></a> modifier
1208specifies that this is a positional argument, that does not have a command line
1209option associated with it. See the <a href="#positional">Positional
1210Arguments</a> section for more information.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1211
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1212<li>The <b><a href="#cl::ConsumeAfter"><tt>cl::ConsumeAfter</tt></a></b> modifier
1213specifies that this option is used to capture "interpreter style" arguments. See <a href="#cl::ConsumeAfter">this section for more information</a>.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1214
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1215<li><a name="cl::Prefix">The <b><tt>cl::Prefix</tt></b></a> modifier specifies
1216that this option prefixes its value. With 'Prefix' options, there is no equal
1217sign that separates the value from the option name specified. This is useful
1218for processing odd arguments like '<tt>-lmalloc -L/usr/lib'</tt> in a linker
1219tool. Here, the '<tt>l</tt>' and '<tt>L</tt>' options are normal string (list)
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1220options, that have the <a href="#cl::Prefix">cl::Prefix</a> modifier added to
1221allow the CommandLine library to recognize them. Note that <a
1222href="#cl::Prefix">cl::Prefix</a> options must not have the <a
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1223href="#cl::ValueDisallowed">cl::ValueDisallowed</a> modifier specified.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1224
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1225<li><a name="cl::Grouping">The <b><tt>cl::Grouping</tt></b></a> modifier is used
1226to implement unix style tools (like <tt>ls</tt>) that have lots of single letter
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1227arguments, but only require a single dash. For example, the '<tt>ls -labF</tt>'
1228command actually enables four different options, all of which are single
1229letters. Note that <a href="#cl::Grouping">cl::Grouping</a> options cannot have
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1230values.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1231
1232</ul>
1233
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1234<p>The CommandLine library does not restrict how you use the <a
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1235href="#cl::Prefix">cl::Prefix</a> or <a href="#cl::Grouping">cl::Grouping</a>
1236modifiers, but it is possible to specify ambiguous argument settings. Thus, it
1237is possible to have multiple letter options that are prefix or grouping options,
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1238and they will still work as designed.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1239
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1240<p>To do this, the CommandLine library uses a greedy algorithm to parse the
1241input option into (potentially multiple) prefix and grouping options. The
1242strategy basically looks like this:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1243
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1244<p><tt>parse(string OrigInput) {</tt>
Misha Brukmanc53aefb2004-05-12 18:42:35 +0000[diff] [blame]1245
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1246<ol>
1247<li><tt>string input = OrigInput;</tt>
1248<li><tt>if (isOption(input)) return getOption(input).parse();</tt>&nbsp;&nbsp;&nbsp;&nbsp;<i>// Normal option</i>
1249<li><tt>while (!isOption(input) &amp;&amp; !input.empty()) input.pop_back();</tt>&nbsp;&nbsp;&nbsp;&nbsp;<i>// Remove the last letter</i>
1250<li><tt>if (input.empty()) return error();</tt>&nbsp;&nbsp;&nbsp;&nbsp;<i>// No matching option</i>
1251<li><tt>if (getOption(input).isPrefix())<br>
1252&nbsp;&nbsp;return getOption(input).parse(input);</tt>
1253<li><tt>while (!input.empty()) {&nbsp;&nbsp;&nbsp;&nbsp;<i>// Must be grouping options</i><br>
1254&nbsp;&nbsp;getOption(input).parse();<br>
1255&nbsp;&nbsp;OrigInput.erase(OrigInput.begin(), OrigInput.begin()+input.length());<br>
1256&nbsp;&nbsp;input = OrigInput;<br>
1257&nbsp;&nbsp;while (!isOption(input) &amp;&amp; !input.empty()) input.pop_back();<br>
1258}</tt>
Misha Brukmanc53aefb2004-05-12 18:42:35 +0000[diff] [blame]1259<li><tt>if (!OrigInput.empty()) error();</tt></li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1260
1261</ol>
Misha Brukmanc53aefb2004-05-12 18:42:35 +0000[diff] [blame]1262
1263<p><tt>}</tt></p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1264
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1265</div>
Chris Lattner32a32842003-05-22 20:36:06 +0000[diff] [blame]1266
1267<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1268<div class="doc_subsubsection">
1269 <a name="misc">Miscellaneous option modifiers</a>
1270</div>
Chris Lattner32a32842003-05-22 20:36:06 +0000[diff] [blame]1271
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1272<div class="doc_text">
1273
1274<p>The miscellaneous option modifiers are the only flags where you can specify
1275more than one flag from the set: they are not mutually exclusive. These flags
1276specify boolean properties that modify the option.</p>
Chris Lattner32a32842003-05-22 20:36:06 +0000[diff] [blame]1277
1278<ul>
1279
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1280<li><a name="cl::CommaSeparated">The <b><tt>cl::CommaSeparated</tt></b></a> modifier
Chris Lattner32a32842003-05-22 20:36:06 +0000[diff] [blame]1281indicates that any commas specified for an option's value should be used to
1282split the value up into multiple values for the option. For example, these two
1283options are equivalent when <tt>cl::CommaSeparated</tt> is specified:
1284"<tt>-foo=a -foo=b -foo=c</tt>" and "<tt>-foo=a,b,c</tt>". This option only
1285makes sense to be used in a case where the option is allowed to accept one or
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1286more values (i.e. it is a <a href="#cl::list">cl::list</a> option).</li>
1287
Chris Lattnerbe801bf2004-05-06 22:03:59 +0000[diff] [blame]1288<li><a name="cl::PositionalEatsArgs">The
1289<b><tt>cl::PositionalEatsArgs</tt></b></a> modifier (which only applies to
1290positional arguments, and only makes sense for lists) indicates that positional
1291argument should consume any strings after it (including strings that start with
1292a "-") up until another recognized positional argument. For example, if you
1293have two "eating" positional arguments "<tt>pos1</tt>" and "<tt>pos2</tt>" the
1294string "<tt>-pos1 -foo -bar baz -pos2 -bork</tt>" would cause the "<tt>-foo -bar
1295-baz</tt>" strings to be applied to the "<tt>-pos1</tt>" option and the
1296"<tt>-bork</tt>" string to be applied to the "<tt>-pos2</tt>" option.</li>
1297
Chris Lattner32a32842003-05-22 20:36:06 +0000[diff] [blame]1298</ul>
1299
Chris Lattnerbe801bf2004-05-06 22:03:59 +0000[diff] [blame]1300<p>So far, these are the only two miscellaneous option modifiers.</p>
Chris Lattner32a32842003-05-22 20:36:06 +0000[diff] [blame]1301
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1302</div>
Chris Lattner32a32842003-05-22 20:36:06 +0000[diff] [blame]1303
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1304<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1305<div class="doc_subsection">
1306 <a name="toplevel">Top-Level Classes and Functions</a>
1307</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1308
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1309<div class="doc_text">
1310
1311<p>Despite all of the built-in flexibility, the CommandLine option library
1312really only consists of one function (<a
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1313href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>)
1314and three main classes: <a href="#cl::opt"><tt>cl::opt</tt></a>, <a
1315href="#cl::list"><tt>cl::list</tt></a>, and <a
1316href="#cl::alias"><tt>cl::alias</tt></a>. This section describes these three
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1317classes in detail.</p>
1318
1319</div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1320
1321<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1322<div class="doc_subsubsection">
1323 <a name="cl::ParseCommandLineOptions">The <tt>cl::ParseCommandLineOptions</tt>
1324 function</a>
1325</div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1326
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1327<div class="doc_text">
1328
1329<p>The <tt>cl::ParseCommandLineOptions</tt> function is designed to be called
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1330directly from <tt>main</tt>, and is used to fill in the values of all of the
1331command line option variables once <tt>argc</tt> and <tt>argv</tt> are
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1332available.</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1333
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1334<p>The <tt>cl::ParseCommandLineOptions</tt> function requires two parameters
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1335(<tt>argc</tt> and <tt>argv</tt>), but may also take an optional third parameter
1336which holds <a href="#description">additional extra text</a> to emit when the
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1337<tt>--help</tt> option is invoked.</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1338
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1339</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1340
1341<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1342<div class="doc_subsubsection">
1343 <a name="cl::ParseEnvironmentOptions">The <tt>cl::ParseEnvironmentOptions</tt>
1344 function</a>
1345</div>
Brian Gaekee5842852003-08-19 23:11:43 +0000[diff] [blame]1346
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1347<div class="doc_text">
Brian Gaekee5842852003-08-19 23:11:43 +0000[diff] [blame]1348
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1349<p>The <tt>cl::ParseEnvironmentOptions</tt> function has mostly the same effects
1350as <a
1351href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>,
1352except that it is designed to take values for options from an environment
1353variable, for those cases in which reading the command line is not convenient or
1354not desired. It fills in the values of all the command line option variables
1355just like <a
1356href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>
1357does.</p>
1358
1359<p>It takes three parameters: first, the name of the program (since
1360<tt>argv</tt> may not be available, it can't just look in <tt>argv[0]</tt>),
1361second, the name of the environment variable to examine, and third, the optional
Brian Gaekee5842852003-08-19 23:11:43 +0000[diff] [blame]1362<a href="#description">additional extra text</a> to emit when the
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1363<tt>--help</tt> option is invoked.</p>
Brian Gaekee5842852003-08-19 23:11:43 +0000[diff] [blame]1364
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1365<p><tt>cl::ParseEnvironmentOptions</tt> will break the environment
Brian Gaekee5842852003-08-19 23:11:43 +0000[diff] [blame]1366variable's value up into words and then process them using
1367<a href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>.
1368<b>Note:</b> Currently <tt>cl::ParseEnvironmentOptions</tt> does not support
1369quoting, so an environment variable containing <tt>-option "foo bar"</tt> will
1370be parsed as three words, <tt>-option</tt>, <tt>"foo</tt>, and <tt>bar"</tt>,
1371which is different from what you would get from the shell with the same
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1372input.</p>
1373
1374</div>
Brian Gaekee5842852003-08-19 23:11:43 +0000[diff] [blame]1375
1376<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1377<div class="doc_subsubsection">
1378 <a name="cl::opt">The <tt>cl::opt</tt> class</a>
1379</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1380
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1381<div class="doc_text">
1382
1383<p>The <tt>cl::opt</tt> class is the class used to represent scalar command line
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1384options, and is the one used most of the time. It is a templated class which
1385can take up to three arguments (all except for the first have default values
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1386though):</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1387
1388<pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1389<b>namespace</b> cl {
1390 <b>template</b> &lt;<b>class</b> DataType, <b>bool</b> ExternalStorage = <b>false</b>,
1391 <b>class</b> ParserClass = parser&lt;DataType&gt; &gt;
1392 <b>class</b> opt;
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1393}
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1394</pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1395
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1396<p>The first template argument specifies what underlying data type the command
1397line argument is, and is used to select a default parser implementation. The
1398second template argument is used to specify whether the option should contain
1399the storage for the option (the default) or whether external storage should be
1400used to contain the value parsed for the option (see <a href="#storage">Internal
1401vs External Storage</a> for more information).</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1402
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1403<p>The third template argument specifies which parser to use. The default value
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1404selects an instantiation of the <tt>parser</tt> class based on the underlying
1405data type of the option. In general, this default works well for most
1406applications, so this option is only used when using a <a
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1407href="#customparser">custom parser</a>.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1408
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1409</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1410
1411<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1412<div class="doc_subsubsection">
1413 <a name="cl::list">The <tt>cl::list</tt> class</a>
1414</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1415
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1416<div class="doc_text">
1417
1418<p>The <tt>cl::list</tt> class is the class used to represent a list of command
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1419line options. It too is a templated class which can take up to three
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1420arguments:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1421
1422<pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1423<b>namespace</b> cl {
1424 <b>template</b> &lt;<b>class</b> DataType, <b>class</b> Storage = <b>bool</b>,
1425 <b>class</b> ParserClass = parser&lt;DataType&gt; &gt;
1426 <b>class</b> list;
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1427}
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1428</pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1429
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1430<p>This class works the exact same as the <a
1431href="#cl::opt"><tt>cl::opt</tt></a> class, except that the second argument is
1432the <b>type</b> of the external storage, not a boolean value. For this class,
1433the marker type '<tt>bool</tt>' is used to indicate that internal storage should
1434be used.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1435
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1436</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1437
1438<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1439<div class="doc_subsubsection">
1440 <a name="cl::alias">The <tt>cl::alias</tt> class</a>
1441</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1442
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1443<div class="doc_text">
1444
1445<p>The <tt>cl::alias</tt> class is a nontemplated class that is used to form
1446aliases for other arguments.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1447
1448<pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1449<b>namespace</b> cl {
1450 <b>class</b> alias;
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1451}
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1452</pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1453
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1454<p>The <a href="#cl::aliasopt"><tt>cl::aliasopt</tt></a> attribute should be
1455used to specify which option this is an alias for. Alias arguments default to
1456being <a href="#cl::Hidden">Hidden</a>, and use the aliased options parser to do
1457the conversion from string to data.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1458
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1459</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1460
1461<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1462<div class="doc_subsection">
1463 <a name="builtinparsers">Builtin parsers</a>
1464</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1465
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1466<div class="doc_text">
1467
1468<p>Parsers control how the string value taken from the command line is
1469translated into a typed value, suitable for use in a C++ program. By default,
1470the CommandLine library uses an instance of <tt>parser&lt;type&gt;</tt> if the
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1471command line option specifies that it uses values of type '<tt>type</tt>'.
1472Because of this, custom option processing is specified with specializations of
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1473the '<tt>parser</tt>' class.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1474
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1475<p>The CommandLine library provides the following builtin parser
1476specializations, which are sufficient for most applications. It can, however,
1477also be extended to work with new data types and new ways of interpreting the
1478same data. See the <a href="#customparser">Writing a Custom Parser</a> for more
1479details on this type of library extension.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1480
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1481<ul>
1482
1483<li><a name="genericparser">The <b>generic <tt>parser&lt;t&gt;</tt> parser</b></a>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1484can be used to map strings values to any data type, through the use of the <a
1485href="#cl::values">cl::values</a> property, which specifies the mapping
1486information. The most common use of this parser is for parsing enum values,
1487which allows you to use the CommandLine library for all of the error checking to
1488make sure that only valid enum values are specified (as opposed to accepting
1489arbitrary strings). Despite this, however, the generic parser class can be used
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1490for any data type.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1491
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1492<li><a name="boolparser">The <b><tt>parser&lt;bool&gt;</tt> specialization</b></a>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1493is used to convert boolean strings to a boolean value. Currently accepted
1494strings are "<tt>true</tt>", "<tt>TRUE</tt>", "<tt>True</tt>", "<tt>1</tt>",
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1495"<tt>false</tt>", "<tt>FALSE</tt>", "<tt>False</tt>", and "<tt>0</tt>".</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1496
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1497<li><a name="stringparser">The <b><tt>parser&lt;string&gt;</tt>
1498specialization</b></a> simply stores the parsed string into the string value
1499specified. No conversion or modification of the data is performed.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1500
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1501<li><a name="intparser">The <b><tt>parser&lt;int&gt;</tt> specialization</b></a>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1502uses the C <tt>strtol</tt> function to parse the string input. As such, it will
1503accept a decimal number (with an optional '+' or '-' prefix) which must start
1504with a non-zero digit. It accepts octal numbers, which are identified with a
1505'<tt>0</tt>' prefix digit, and hexadecimal numbers with a prefix of
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1506'<tt>0x</tt>' or '<tt>0X</tt>'.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1507
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1508<li><a name="doubleparser">The <b><tt>parser&lt;double&gt;</tt></b></a> and
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1509<b><tt>parser&lt;float&gt;</tt> specializations</b> use the standard C
1510<tt>strtod</tt> function to convert floating point strings into floating point
1511values. As such, a broad range of string formats is supported, including
1512exponential notation (ex: <tt>1.7e15</tt>) and properly supports locales.
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1513</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1514
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1515</ul>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]1516
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1517</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]1518
1519<!-- *********************************************************************** -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1520<div class="doc_section">
1521 <a name="extensionguide">Extension Guide</a>
1522</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]1523<!-- *********************************************************************** -->
1524
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1525<div class="doc_text">
1526
1527<p>Although the CommandLine library has a lot of functionality built into it
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1528already (as discussed previously), one of its true strengths lie in its
1529extensibility. This section discusses how the CommandLine library works under
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1530the covers and illustrates how to do some simple, common, extensions.</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1531
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1532</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]1533
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1534<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1535<div class="doc_subsection">
1536 <a name="customparser">Writing a custom parser</a>
1537</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1538
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1539<div class="doc_text">
1540
1541<p>One of the simplest and most common extensions is the use of a custom parser.
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1542As <a href="#builtinparsers">discussed previously</a>, parsers are the portion
1543of the CommandLine library that turns string input from the user into a
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1544particular parsed data type, validating the input in the process.</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1545
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1546<p>There are two ways to use a new parser:</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1547
1548<ol>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1549
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1550<li>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1551
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1552<p>Specialize the <a href="#genericparser"><tt>cl::parser</tt></a> template for
1553your custom data type.<p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1554
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1555<p>This approach has the advantage that users of your custom data type will
1556automatically use your custom parser whenever they define an option with a value
1557type of your data type. The disadvantage of this approach is that it doesn't
1558work if your fundemental data type is something that is already supported.</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1559
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1560</li>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1561
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1562<li>
1563
1564<p>Write an independent class, using it explicitly from options that need
1565it.</p>
1566
1567<p>This approach works well in situations where you would line to parse an
1568option using special syntax for a not-very-special data-type. The drawback of
1569this approach is that users of your parser have to be aware that they are using
1570your parser, instead of the builtin ones.</p>
1571
1572</li>
1573
1574</ol>
1575
1576<p>To guide the discussion, we will discuss a custom parser that accepts file
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1577sizes, specified with an optional unit after the numeric size. For example, we
1578would like to parse "102kb", "41M", "1G" into the appropriate integer value. In
1579this case, the underlying data type we want to parse into is
1580'<tt>unsigned</tt>'. We choose approach #2 above because we don't want to make
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1581this the default for all <tt>unsigned</tt> options.</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1582
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1583<p>To start out, we declare our new <tt>FileSizeParser</tt> class:</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1584
1585<pre>
1586<b>struct</b> FileSizeParser : <b>public</b> cl::basic_parser&lt;<b>unsigned</b>&gt; {
1587 <i>// parse - Return true on error.</i>
1588 <b>bool</b> parse(cl::Option &amp;O, <b>const char</b> *ArgName, <b>const</b> std::string &amp;ArgValue,
1589 <b>unsigned</b> &amp;Val);
1590};
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1591</pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1592
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1593<p>Our new class inherits from the <tt>cl::basic_parser</tt> template class to
1594fill in the default, boiler plate, code for us. We give it the data type that
1595we parse into (the last argument to the <tt>parse</tt> method so that clients of
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1596our custom parser know what object type to pass in to the parse method (here we
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1597declare that we parse into '<tt>unsigned</tt>' variables.</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1598
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1599<p>For most purposes, the only method that must be implemented in a custom
1600parser is the <tt>parse</tt> method. The <tt>parse</tt> method is called
1601whenever the option is invoked, passing in the option itself, the option name,
1602the string to parse, and a reference to a return value. If the string to parse
1603is not well formed, the parser should output an error message and return true.
1604Otherwise it should return false and set '<tt>Val</tt>' to the parsed value. In
1605our example, we implement <tt>parse</tt> as:</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1606
1607<pre>
1608<b>bool</b> FileSizeParser::parse(cl::Option &amp;O, <b>const char</b> *ArgName,
1609 <b>const</b> std::string &amp;Arg, <b>unsigned</b> &amp;Val) {
1610 <b>const char</b> *ArgStart = Arg.c_str();
1611 <b>char</b> *End;
1612
1613 <i>// Parse integer part, leaving 'End' pointing to the first non-integer char</i>
1614 Val = (unsigned)strtol(ArgStart, &amp;End, 0);
1615
1616 <b>while</b> (1) {
1617 <b>switch</b> (*End++) {
1618 <b>case</b> 0: <b>return</b> false; <i>// No error</i>
1619 <b>case</b> 'i': <i>// Ignore the 'i' in KiB if people use that</i>
1620 <b>case</b> 'b': <b>case</b> 'B': <i>// Ignore B suffix</i>
1621 <b>break</b>;
1622
1623 <b>case</b> 'g': <b>case</b> 'G': Val *= 1024*1024*1024; <b>break</b>;
1624 <b>case</b> 'm': <b>case</b> 'M': Val *= 1024*1024; <b>break</b>;
1625 <b>case</b> 'k': <b>case</b> 'K': Val *= 1024; <b>break</b>;
1626
1627 default:
1628 <i>// Print an error message if unrecognized character!</i>
1629 <b>return</b> O.error(": '" + Arg + "' value invalid for file size argument!");
1630 }
1631 }
1632}
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1633</pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1634
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1635<p>This function implements a very simple parser for the kinds of strings we are
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1636interested in. Although it has some holes (it allows "<tt>123KKK</tt>" for
1637example), it is good enough for this example. Note that we use the option
1638itself to print out the error message (the <tt>error</tt> method always returns
1639true) in order to get a nice error message (shown below). Now that we have our
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1640parser class, we can use it like this:</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1641
1642<pre>
1643<b>static</b> <a href="#cl::opt">cl::opt</a>&lt;<b>unsigned</b>, <b>false</b>, FileSizeParser&gt;
1644MFS(<i>"max-file-size"</i>, <a href="#cl::desc">cl::desc</a>(<i>"Maximum file size to accept"</i>),
1645 <a href="#cl::value_desc">cl::value_desc</a>("<i>size</i>"));
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1646</pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1647
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1648<p>Which adds this to the output of our program:</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1649
1650<pre>
1651OPTIONS:
1652 -help - display available options (--help-hidden for more)
1653 ...
1654 <b>-max-file-size=&lt;size&gt; - Maximum file size to accept</b>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1655</pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1656
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1657<p>And we can test that our parse works correctly now (the test program just
1658prints out the max-file-size argument value):</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1659
1660<pre>
1661$ ./test
1662MFS: 0
1663$ ./test -max-file-size=123MB
1664MFS: 128974848
1665$ ./test -max-file-size=3G
1666MFS: 3221225472
1667$ ./test -max-file-size=dog
1668-max-file-size option: 'dog' value invalid for file size argument!
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1669</pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1670
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1671<p>It looks like it works. The error message that we get is nice and helpful,
1672and we seem to accept reasonable file sizes. This wraps up the "custom parser"
1673tutorial.</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1674
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1675</div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1676
1677<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1678<div class="doc_subsection">
1679 <a name="explotingexternal">Exploiting external storage</a>
1680</div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1681
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1682<div class="doc_text">
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1683
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1684<p>TODO: fill in this section</p>
1685
1686</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1687
1688<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1689<div class="doc_subsection">
1690 <a name="dynamicopts">Dynamically adding command line options</a>
1691</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1692
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1693<div class="doc_text">
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1694
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1695<p>TODO: fill in this section</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]1696
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1697</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]1698
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]1699<!-- *********************************************************************** -->
1700
1701<hr>
Misha Brukmanc53aefb2004-05-12 18:42:35 +0000[diff] [blame]1702<address>
1703 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
1704 src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
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1706 src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!"></a>
1707
1708 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
1709 <a href="http://llvm.cs.uiuc.edu">LLVM Compiler Infrastructure</a><br>
Misha Brukman3c299112003-11-07 18:11:14 +0000[diff] [blame]1710 Last modified: $Date$
Misha Brukmanc53aefb2004-05-12 18:42:35 +0000[diff] [blame]1711</address>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1712
1713</body>
1714</html>