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Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
2 "http://www.w3.org/TR/html4/strict.dtd">
3<html>
4<head>
5 <link rel="stylesheet" href="llvm.css" type="text/css">
6 <title>CommandLine 2.0 Library Manual</title>
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
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]87<div class="doc_text">
88 <p><b>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a></b></p>
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">
93 Introduction
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 Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]218<p><tt>
219<a name="value_desc_example">
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>"));</a>
221</tt></p>
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 Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]873argument</a> specified, and the <tt>cl::ConsumeAfter</tt> option should be a <a
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]874href="#cl::list">cl::list</a> option.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]875
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]876</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]877
878<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]879<div class="subsection">
880 <a name="storage">Internal vs External Storage</a>
881</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]882
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]883<div class="doc_text">
884
885<p>By default, all command line options automatically hold the value that they
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]886parse from the command line. This is very convenient in the common case,
887especially when combined with the ability to define command line options in the
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]888files that use them. This is called the internal storage model.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]889
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]890<p>Sometimes, however, it is nice to separate the command line option processing
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]891code from the storage of the value parsed. For example, lets say that we have a
892'<tt>-debug</tt>' option that we would like to use to enable debug information
893across the entire body of our program. In this case, the boolean value
894controlling the debug code should be globally accessable (in a header file, for
895example) yet the command line option processing code should not be exposed to
896all of these clients (requiring lots of .cpp files to #include
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]897<tt>CommandLine.h</tt>).</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]898
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]899<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]900
901<pre>
902<i>// DebugFlag.h - Get access to the '-debug' command line option
903//
904
905// DebugFlag - This boolean is set to true if the '-debug' command line option
906// is specified. This should probably not be referenced directly, instead, use
907// the DEBUG macro below.
908//</i>
909extern bool DebugFlag;
910
911<i>// DEBUG macro - This macro should be used by code to emit debug information.
912// In the '-debug' option is specified on the command line, and if this is a
913// debug build, then the code specified as the option to the macro will be
914// executed. Otherwise it will not be. Example:
915//
916// DEBUG(cerr << "Bitset contains: " << Bitset << "\n");
917//</i>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]918<span class="doc_red">#ifdef NDEBUG
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]919#define DEBUG(X)
920#else
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]921#define DEBUG(X)</span> \
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]922 do { if (DebugFlag) { X; } } while (0)
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]923<span class="doc_red">#endif</span>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]924</pre>
925
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]926<p>This allows clients to blissfully use the <tt>DEBUG()</tt> macro, or the
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]927<tt>DebugFlag</tt> explicitly if they want to. Now we just need to be able to
928set the <tt>DebugFlag</tt> boolean when the option is set. To do this, we pass
929an additial argument to our command line argument processor, and we specify
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]930where to fill in with the <a href="#cl::location">cl::location</a>
931attribute:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]932
933<pre>
934bool DebugFlag; <i>// the actual value</i>
Chris Lattner589a4cc2003-08-01 21:30:37 +0000[diff] [blame]935static <a href="#cl::opt">cl::opt</a>&lt;bool, true&gt; <i>// The parser</i>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]936Debug("<i>debug</i>", <a href="#cl::desc">cl::desc</a>("<i>Enable debug output</i>")</a>, <a href="#cl::Hidden">cl::Hidden</a>,
937 <a href="#cl::location">cl::location</a>(DebugFlag));
938</pre>
939
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]940<p>In the above example, we specify "<tt>true</tt>" as the second argument to
941the <a href="#cl::opt">cl::opt</a> template, indicating that the template should
942not 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]943href="#cl::location">cl::location</a> attribute, so that <tt>DebugFlag</tt> is
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]944automatically set.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]945
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]946</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]947
948<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]949<div class="doc_subsection">
950 <a name="attributes">Option Attributes</a>
951</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]952
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]953<div class="doc_text">
954
955<p>This section describes the basic attributes that you can specify on
956options.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]957
958<ul>
959
960<li>The option name attribute (which is required for all options, except <a
961href="#positional">positional options</a>) specifies what the option name is.
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]962This option is specified in simple double quotes:
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]963
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]964<pre>
965<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^]966</pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]967
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]968</li>
969
970<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]971description for the option to be shown in the <tt>--help</tt> output for the
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]972program.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]973
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]974<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]975specifies a string that can be used to fine tune the <tt>--help</tt> output for
976a command line option. Look <a href="#value_desc_example">here</a> for an
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]977example.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]978
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]979<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]980inital value for a <a href="#cl::opt">scalar</a> option. If this attribute is
981not specified then the command line option value defaults to the value created
Brian Gaeke9d292ff2003-08-19 22:56:22 +0000[diff] [blame]982by the default constructor for the type. <b>Warning</b>: If you specify both
983<b><tt>cl::init</tt></b> and <b><tt>cl::location</tt></b> for an option,
984you must specify <b><tt>cl::location</tt></b> first, so that when the
985command-line parser sees <b><tt>cl::init</tt></b>, it knows where to put the
986initial 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^]987the right order.)</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]988
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]989<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]990store the value for a parsed command line option if using external storage. See
991the section on <a href="#storage">Internal vs External Storage</a> for more
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]992information.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]993
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]994<li><a name="cl::aliasopt">The <b><tt>cl::aliasopt</tt></b></a> attribute
995specifies which option a <a href="#cl::alias">cl::alias</a> option is an alias
996for.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]997
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]998<li><a name="cl::values">The <b><tt>cl::values</tt></b></a> attribute specifies
999the string-to-value mapping to be used by the generic parser. It takes a
1000<b>null terminated</b> list of (option, value, description) triplets that
1001specify the option name, the value mapped to, and the description shown in the
1002<tt>--help</tt> for the tool. Because the generic parser is used most
1003frequently with enum values, two macros are often useful:
1004
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1005<ol>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1006
1007<li><a name="clEnumVal">The <b><tt>clEnumVal</tt></b></a> macro is used as a
1008nice simple way to specify a triplet for an enum. This macro automatically
1009makes the option name be the same as the enum name. The first option to the
1010macro is the enum, the second is the description for the command line
1011option.</li>
1012
1013<li><a name="clEnumValN">The <b><tt>clEnumValN</tt></b></a> macro is used to
1014specify macro options where the option name doesn't equal the enum name. For
1015this macro, the first argument is the enum value, the second is the flag name,
1016and the second is the description.</li>
1017
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1018</ol>
1019
1020You 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^]1021that does not support it.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1022
1023</ul>
1024
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1025</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1026
1027<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1028<div class="doc_subsection">
1029 <a name="modifiers">Option Modifiers</a>
1030</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1031
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1032<div class="doc_text">
1033
1034<p>Option modifiers are the flags and expressions that you pass into the
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1035constructors for <tt><a href="#cl::opt">cl::opt</a></tt> and <tt><a
1036href="#cl::list">cl::list</a></tt>. These modifiers give you the ability to
1037tweak how options are parsed and how <tt>--help</tt> output is generated to fit
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1038your application well.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1039
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1040<p>These options fall into five main catagories:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1041
1042<ol>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1043<li><a href="#hiding">Hiding an option from <tt>--help</tt> output</a></li>
1044<li><a href="#numoccurrences">Controlling the number of occurrences
1045 required and allowed</a></li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1046<li><a href="#valrequired">Controlling whether or not a value must be
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1047 specified</a></li>
1048<li><a href="#formatting">Controlling other formatting options</a></li>
1049<li><a href="#misc">Miscellaneous option modifiers</a></li>
1050</ol>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1051
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1052<p>It is not possible to specify two options from the same catagory (you'll get
1053a runtime error) to a single option, except for options in the miscellaneous
Chris Lattner32a32842003-05-22 20:36:06 +0000[diff] [blame]1054catagory. The CommandLine library specifies defaults for all of these settings
1055that are the most useful in practice and the most common, which mean that you
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1056usually shouldn't have to worry about these.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1057
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1058</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1059
1060<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1061<div class="doc_subsubsection">
1062 <a name="hiding">Hiding an option from <tt>--help</tt> output</a>
1063</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1064
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1065<div class="doc_text">
1066
1067<p>The <tt>cl::NotHidden</tt>, <tt>cl::Hidden</tt>, and
1068<tt>cl::ReallyHidden</tt> modifiers are used to control whether or not an option
1069appears in the <tt>--help</tt> and <tt>--help-hidden</tt> output for the
1070compiled program:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1071
1072<ul>
1073
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1074<li><a name="cl::NotHidden">The <b><tt>cl::NotHidden</tt></b></a> modifier
1075(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]1076href="#cl::list">cl::list</a></tt> options), indicates the option is to appear
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1077in both help listings.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1078
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1079<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]1080default for <tt><a href="#cl::alias">cl::alias</a></tt> options), indicates that
1081the option should not appear in the <tt>--help</tt> output, but should appear in
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1082the <tt>--help-hidden</tt> output.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1083
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1084<li><a name="cl::ReallyHidden">The <b><tt>cl::ReallyHidden</tt></b></a> modifier,
1085indicates that the option should not appear in any help output.</li>
1086
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1087</ul>
1088
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1089</div>
1090
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1091<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1092<div class="doc_subsubsection">
1093 <a name="numoccurrences">Controlling the number of occurrences required and
1094 allowed</a>
1095</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1096
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1097<div class="doc_text">
1098
1099<p>This group of options is used to control how many time an option is allowed
1100(or required) to be specified on the command line of your program. Specifying a
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1101value for this setting allows the CommandLine library to do error checking for
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1102you.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1103
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1104<p>The allowed values for this option group are:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1105
1106<ul>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1107
1108<li><a name="cl::Optional">The <b><tt>cl::Optional</tt></b></a> modifier (which
1109is 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]1110href="#cl::alias">cl::alias</a></tt> classes) indicates that your program will
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1111allow either zero or one occurrence of the option to be specified.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1112
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1113<li><a name="cl::ZeroOrMore">The <b><tt>cl::ZeroOrMore</tt></b></a> modifier
1114(which is the default for the <tt><a href="#cl::list">cl::list</a></tt> class)
1115indicates that your program will allow the option to be specified zero or more
1116times.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1117
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1118<li><a name="cl::Required">The <b><tt>cl::Required</tt></b></a> modifier
1119indicates that the specified option must be specified exactly one time.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1120
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1121<li><a name="cl::OneOrMore">The <b><tt>cl::OneOrMore</tt></b></a> modifier
1122indicates that the option must be specified at least one time.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1123
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1124<li>The <b><tt>cl::ConsumeAfter</tt></b> modifier is described in the <a
1125href="#positional">Positional arguments section</a></li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1126
1127</ul>
1128
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1129<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]1130value specified by the <tt><a href="#cl::init">cl::init</a></tt> attribute. If
1131the <tt><a href="#cl::init">cl::init</a></tt> attribute is not specified, the
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1132option value is initialized with the default constructor for the data type.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1133
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1134<p>If an option is specified multiple times for an option of the <tt><a
1135href="#cl::opt">cl::opt</a></tt> class, only the last value will be
1136retained.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1137
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1138</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1139
1140<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1141<div class="doc_subsubsection">
1142 <a name="valrequired">Controlling whether or not a value must be specified</a>
1143</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1144
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1145<div class="doc_text">
1146
1147<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]1148value to be present. In the case of the CommandLine library, a value is either
1149specified 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^]1150string (e.g. '<tt>-o a.out</tt>').</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1151
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1152<p>The allowed values for this option group are:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1153
1154<ul>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1155
1156<li><a name="cl::ValueOptional">The <b><tt>cl::ValueOptional</tt></b></a> modifier
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1157(which is the default for <tt>bool</tt> typed options) specifies that it is
1158acceptable to have a value, or not. A boolean argument can be enabled just by
1159appearing on the command line, or it can have an explicit '<tt>-foo=true</tt>'.
1160If an option is specified with this mode, it is illegal for the value to be
1161provided without the equal sign. Therefore '<tt>-foo true</tt>' is illegal. To
1162get this behavior, you must use the <a
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1163href="#cl::ValueRequired">cl::ValueRequired</a> modifier.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1164
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1165<li><a name="cl::ValueRequired">The <b><tt>cl::ValueRequired</tt></b></a> modifier
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1166(which is the default for all other types except for <a
1167href="#onealternative">unnamed alternatives using the generic parser</a>)
1168specifies that a value must be provided. This mode informs the command line
1169library that if an option is not provides with an equal sign, that the next
1170argument provided must be the value. This allows things like '<tt>-o
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1171a.out</tt>' to work.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1172
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1173<li><a name="cl::ValueDisallowed">The <b><tt>cl::ValueDisallowed</tt></b></a>
1174modifier (which is the default for <a href="#onealternative">unnamed
1175alternatives using the generic parser</a>) indicates that it is a runtime error
1176for the user to specify a value. This can be provided to disallow users from
1177providing options to boolean options (like '<tt>-foo=true</tt>').</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1178
1179</ul>
1180
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1181<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]1182want them to. As mentioned above, you can specify the <a
1183href="#cl::ValueDisallowed">cl::ValueDisallowed</a> modifier to a boolean
1184argument to restrict your command line parser. These options are mostly useful
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1185when <a href="#extensionguide">extending the library</a>.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1186
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1187</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1188
1189<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1190<div class="doc_subsubsection">
1191 <a name="formatting">Controlling other formatting options</a>
1192</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1193
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1194<div class="doc_text">
1195
1196<p>The formatting option group is used to specify that the command line option
1197has special abilities and is otherwise different from other command line
1198arguments. As usual, you can only specify at most one of these arguments.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1199
1200<ul>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1201
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1202<li><a name="cl::NormalFormatting">The <b><tt>cl::NormalFormatting</tt></b></a>
1203modifier (which is the default all options) specifies that this option is
1204"normal".</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1205
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1206<li><a name="cl::Positional">The <b><tt>cl::Positional</tt></b></a> modifier
1207specifies that this is a positional argument, that does not have a command line
1208option associated with it. See the <a href="#positional">Positional
1209Arguments</a> section for more information.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1210
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1211<li>The <b><a href="#cl::ConsumeAfter"><tt>cl::ConsumeAfter</tt></a></b> modifier
1212specifies 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]1213
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1214<li><a name="cl::Prefix">The <b><tt>cl::Prefix</tt></b></a> modifier specifies
1215that this option prefixes its value. With 'Prefix' options, there is no equal
1216sign that separates the value from the option name specified. This is useful
1217for processing odd arguments like '<tt>-lmalloc -L/usr/lib'</tt> in a linker
1218tool. Here, the '<tt>l</tt>' and '<tt>L</tt>' options are normal string (list)
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1219options, that have the <a href="#cl::Prefix">cl::Prefix</a> modifier added to
1220allow the CommandLine library to recognize them. Note that <a
1221href="#cl::Prefix">cl::Prefix</a> options must not have the <a
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1222href="#cl::ValueDisallowed">cl::ValueDisallowed</a> modifier specified.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1223
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1224<li><a name="cl::Grouping">The <b><tt>cl::Grouping</tt></b></a> modifier is used
1225to implement unix style tools (like <tt>ls</tt>) that have lots of single letter
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1226arguments, but only require a single dash. For example, the '<tt>ls -labF</tt>'
1227command actually enables four different options, all of which are single
1228letters. Note that <a href="#cl::Grouping">cl::Grouping</a> options cannot have
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1229values.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1230
1231</ul>
1232
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1233<p>The CommandLine library does not restrict how you use the <a
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1234href="#cl::Prefix">cl::Prefix</a> or <a href="#cl::Grouping">cl::Grouping</a>
1235modifiers, but it is possible to specify ambiguous argument settings. Thus, it
1236is possible to have multiple letter options that are prefix or grouping options,
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1237and they will still work as designed.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1238
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1239<p>To do this, the CommandLine library uses a greedy algorithm to parse the
1240input option into (potentially multiple) prefix and grouping options. The
1241strategy basically looks like this:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1242
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1243<p><tt>parse(string OrigInput) {</tt>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1244<ol>
1245<li><tt>string input = OrigInput;</tt>
1246<li><tt>if (isOption(input)) return getOption(input).parse();</tt>&nbsp;&nbsp;&nbsp;&nbsp;<i>// Normal option</i>
1247<li><tt>while (!isOption(input) &amp;&amp; !input.empty()) input.pop_back();</tt>&nbsp;&nbsp;&nbsp;&nbsp;<i>// Remove the last letter</i>
1248<li><tt>if (input.empty()) return error();</tt>&nbsp;&nbsp;&nbsp;&nbsp;<i>// No matching option</i>
1249<li><tt>if (getOption(input).isPrefix())<br>
1250&nbsp;&nbsp;return getOption(input).parse(input);</tt>
1251<li><tt>while (!input.empty()) {&nbsp;&nbsp;&nbsp;&nbsp;<i>// Must be grouping options</i><br>
1252&nbsp;&nbsp;getOption(input).parse();<br>
1253&nbsp;&nbsp;OrigInput.erase(OrigInput.begin(), OrigInput.begin()+input.length());<br>
1254&nbsp;&nbsp;input = OrigInput;<br>
1255&nbsp;&nbsp;while (!isOption(input) &amp;&amp; !input.empty()) input.pop_back();<br>
1256}</tt>
1257<li><tt>if (!OrigInput.empty()) error();</tt>
1258</tt>
1259
1260</ol>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1261<tt>}</tt></p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1262
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1263</div>
Chris Lattner32a32842003-05-22 20:36:06 +0000[diff] [blame]1264
1265<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1266<div class="doc_subsubsection">
1267 <a name="misc">Miscellaneous option modifiers</a>
1268</div>
Chris Lattner32a32842003-05-22 20:36:06 +0000[diff] [blame]1269
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1270<div class="doc_text">
1271
1272<p>The miscellaneous option modifiers are the only flags where you can specify
1273more than one flag from the set: they are not mutually exclusive. These flags
1274specify boolean properties that modify the option.</p>
Chris Lattner32a32842003-05-22 20:36:06 +0000[diff] [blame]1275
1276<ul>
1277
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1278<li><a name="cl::CommaSeparated">The <b><tt>cl::CommaSeparated</tt></b></a> modifier
Chris Lattner32a32842003-05-22 20:36:06 +0000[diff] [blame]1279indicates that any commas specified for an option's value should be used to
1280split the value up into multiple values for the option. For example, these two
1281options are equivalent when <tt>cl::CommaSeparated</tt> is specified:
1282"<tt>-foo=a -foo=b -foo=c</tt>" and "<tt>-foo=a,b,c</tt>". This option only
1283makes 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^]1284more values (i.e. it is a <a href="#cl::list">cl::list</a> option).</li>
1285
Chris Lattner32a32842003-05-22 20:36:06 +0000[diff] [blame]1286</ul>
1287
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1288<p>So far, the only miscellaneous option modifier is the
1289<tt>cl::CommaSeparated</tt> modifier.</p>
Chris Lattner32a32842003-05-22 20:36:06 +0000[diff] [blame]1290
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1291</div>
Chris Lattner32a32842003-05-22 20:36:06 +0000[diff] [blame]1292
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1293<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1294<div class="doc_subsection">
1295 <a name="toplevel">Top-Level Classes and Functions</a>
1296</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1297
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1298<div class="doc_text">
1299
1300<p>Despite all of the built-in flexibility, the CommandLine option library
1301really only consists of one function (<a
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1302href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>)
1303and three main classes: <a href="#cl::opt"><tt>cl::opt</tt></a>, <a
1304href="#cl::list"><tt>cl::list</tt></a>, and <a
1305href="#cl::alias"><tt>cl::alias</tt></a>. This section describes these three
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1306classes in detail.</p>
1307
1308</div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1309
1310<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1311<div class="doc_subsubsection">
1312 <a name="cl::ParseCommandLineOptions">The <tt>cl::ParseCommandLineOptions</tt>
1313 function</a>
1314</div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1315
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1316<div class="doc_text">
1317
1318<p>The <tt>cl::ParseCommandLineOptions</tt> function is designed to be called
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1319directly from <tt>main</tt>, and is used to fill in the values of all of the
1320command line option variables once <tt>argc</tt> and <tt>argv</tt> are
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1321available.</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1322
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1323<p>The <tt>cl::ParseCommandLineOptions</tt> function requires two parameters
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1324(<tt>argc</tt> and <tt>argv</tt>), but may also take an optional third parameter
1325which holds <a href="#description">additional extra text</a> to emit when the
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1326<tt>--help</tt> option is invoked.</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1327
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1328</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1329
1330<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1331<div class="doc_subsubsection">
1332 <a name="cl::ParseEnvironmentOptions">The <tt>cl::ParseEnvironmentOptions</tt>
1333 function</a>
1334</div>
Brian Gaekee5842852003-08-19 23:11:43 +0000[diff] [blame]1335
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1336<div class="doc_text">
Brian Gaekee5842852003-08-19 23:11:43 +0000[diff] [blame]1337
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1338<p>The <tt>cl::ParseEnvironmentOptions</tt> function has mostly the same effects
1339as <a
1340href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>,
1341except that it is designed to take values for options from an environment
1342variable, for those cases in which reading the command line is not convenient or
1343not desired. It fills in the values of all the command line option variables
1344just like <a
1345href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>
1346does.</p>
1347
1348<p>It takes three parameters: first, the name of the program (since
1349<tt>argv</tt> may not be available, it can't just look in <tt>argv[0]</tt>),
1350second, the name of the environment variable to examine, and third, the optional
Brian Gaekee5842852003-08-19 23:11:43 +0000[diff] [blame]1351<a href="#description">additional extra text</a> to emit when the
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1352<tt>--help</tt> option is invoked.</p>
Brian Gaekee5842852003-08-19 23:11:43 +0000[diff] [blame]1353
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1354<p><tt>cl::ParseEnvironmentOptions</tt> will break the environment
Brian Gaekee5842852003-08-19 23:11:43 +0000[diff] [blame]1355variable's value up into words and then process them using
1356<a href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>.
1357<b>Note:</b> Currently <tt>cl::ParseEnvironmentOptions</tt> does not support
1358quoting, so an environment variable containing <tt>-option "foo bar"</tt> will
1359be parsed as three words, <tt>-option</tt>, <tt>"foo</tt>, and <tt>bar"</tt>,
1360which is different from what you would get from the shell with the same
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1361input.</p>
1362
1363</div>
Brian Gaekee5842852003-08-19 23:11:43 +0000[diff] [blame]1364
1365<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1366<div class="doc_subsubsection">
1367 <a name="cl::opt">The <tt>cl::opt</tt> class</a>
1368</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1369
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1370<div class="doc_text">
1371
1372<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]1373options, and is the one used most of the time. It is a templated class which
1374can take up to three arguments (all except for the first have default values
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1375though):</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1376
1377<pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1378<b>namespace</b> cl {
1379 <b>template</b> &lt;<b>class</b> DataType, <b>bool</b> ExternalStorage = <b>false</b>,
1380 <b>class</b> ParserClass = parser&lt;DataType&gt; &gt;
1381 <b>class</b> opt;
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1382}
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1383</pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1384
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1385<p>The first template argument specifies what underlying data type the command
1386line argument is, and is used to select a default parser implementation. The
1387second template argument is used to specify whether the option should contain
1388the storage for the option (the default) or whether external storage should be
1389used to contain the value parsed for the option (see <a href="#storage">Internal
1390vs External Storage</a> for more information).</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1391
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1392<p>The third template argument specifies which parser to use. The default value
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1393selects an instantiation of the <tt>parser</tt> class based on the underlying
1394data type of the option. In general, this default works well for most
1395applications, so this option is only used when using a <a
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1396href="#customparser">custom parser</a>.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1397
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1398</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1399
1400<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1401<div class="doc_subsubsection">
1402 <a name="cl::list">The <tt>cl::list</tt> class</a>
1403</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1404
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1405<div class="doc_text">
1406
1407<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]1408line options. It too is a templated class which can take up to three
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1409arguments:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1410
1411<pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1412<b>namespace</b> cl {
1413 <b>template</b> &lt;<b>class</b> DataType, <b>class</b> Storage = <b>bool</b>,
1414 <b>class</b> ParserClass = parser&lt;DataType&gt; &gt;
1415 <b>class</b> list;
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1416}
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1417</pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1418
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1419<p>This class works the exact same as the <a
1420href="#cl::opt"><tt>cl::opt</tt></a> class, except that the second argument is
1421the <b>type</b> of the external storage, not a boolean value. For this class,
1422the marker type '<tt>bool</tt>' is used to indicate that internal storage should
1423be used.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1424
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1425</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1426
1427<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1428<div class="doc_subsubsection">
1429 <a name="cl::alias">The <tt>cl::alias</tt> class</a>
1430</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1431
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1432<div class="doc_text">
1433
1434<p>The <tt>cl::alias</tt> class is a nontemplated class that is used to form
1435aliases for other arguments.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1436
1437<pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1438<b>namespace</b> cl {
1439 <b>class</b> alias;
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1440}
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1441</pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1442
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1443<p>The <a href="#cl::aliasopt"><tt>cl::aliasopt</tt></a> attribute should be
1444used to specify which option this is an alias for. Alias arguments default to
1445being <a href="#cl::Hidden">Hidden</a>, and use the aliased options parser to do
1446the conversion from string to data.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1447
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1448</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1449
1450<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1451<div class="doc_subsection">
1452 <a name="builtinparsers">Builtin parsers</a>
1453</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1454
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1455<div class="doc_text">
1456
1457<p>Parsers control how the string value taken from the command line is
1458translated into a typed value, suitable for use in a C++ program. By default,
1459the CommandLine library uses an instance of <tt>parser&lt;type&gt;</tt> if the
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1460command line option specifies that it uses values of type '<tt>type</tt>'.
1461Because of this, custom option processing is specified with specializations of
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1462the '<tt>parser</tt>' class.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1463
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1464<p>The CommandLine library provides the following builtin parser
1465specializations, which are sufficient for most applications. It can, however,
1466also be extended to work with new data types and new ways of interpreting the
1467same data. See the <a href="#customparser">Writing a Custom Parser</a> for more
1468details on this type of library extension.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1469
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1470<ul>
1471
1472<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]1473can be used to map strings values to any data type, through the use of the <a
1474href="#cl::values">cl::values</a> property, which specifies the mapping
1475information. The most common use of this parser is for parsing enum values,
1476which allows you to use the CommandLine library for all of the error checking to
1477make sure that only valid enum values are specified (as opposed to accepting
1478arbitrary strings). Despite this, however, the generic parser class can be used
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1479for any data type.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1480
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1481<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]1482is used to convert boolean strings to a boolean value. Currently accepted
1483strings are "<tt>true</tt>", "<tt>TRUE</tt>", "<tt>True</tt>", "<tt>1</tt>",
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1484"<tt>false</tt>", "<tt>FALSE</tt>", "<tt>False</tt>", and "<tt>0</tt>".</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1485
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1486<li><a name="stringparser">The <b><tt>parser&lt;string&gt;</tt>
1487specialization</b></a> simply stores the parsed string into the string value
1488specified. No conversion or modification of the data is performed.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1489
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1490<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]1491uses the C <tt>strtol</tt> function to parse the string input. As such, it will
1492accept a decimal number (with an optional '+' or '-' prefix) which must start
1493with a non-zero digit. It accepts octal numbers, which are identified with a
1494'<tt>0</tt>' prefix digit, and hexadecimal numbers with a prefix of
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1495'<tt>0x</tt>' or '<tt>0X</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="doubleparser">The <b><tt>parser&lt;double&gt;</tt></b></a> and
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1498<b><tt>parser&lt;float&gt;</tt> specializations</b> use the standard C
1499<tt>strtod</tt> function to convert floating point strings into floating point
1500values. As such, a broad range of string formats is supported, including
1501exponential notation (ex: <tt>1.7e15</tt>) and properly supports locales.
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1502</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1503
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1504</ul>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]1505
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1506</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]1507
1508<!-- *********************************************************************** -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1509<div class="doc_section">
1510 <a name="extensionguide">Extension Guide</a>
1511</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]1512<!-- *********************************************************************** -->
1513
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1514<div class="doc_text">
1515
1516<p>Although the CommandLine library has a lot of functionality built into it
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1517already (as discussed previously), one of its true strengths lie in its
1518extensibility. This section discusses how the CommandLine library works under
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1519the covers and illustrates how to do some simple, common, extensions.</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1520
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1521</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]1522
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1523<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1524<div class="doc_subsection">
1525 <a name="customparser">Writing a custom parser</a>
1526</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1527
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1528<div class="doc_text">
1529
1530<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]1531As <a href="#builtinparsers">discussed previously</a>, parsers are the portion
1532of the CommandLine library that turns string input from the user into a
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1533particular parsed data type, validating the input in the process.</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1534
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1535<p>There are two ways to use a new parser:</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1536
1537<ol>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1538
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1539<li>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1540
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1541<p>Specialize the <a href="#genericparser"><tt>cl::parser</tt></a> template for
1542your custom data type.<p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1543
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1544<p>This approach has the advantage that users of your custom data type will
1545automatically use your custom parser whenever they define an option with a value
1546type of your data type. The disadvantage of this approach is that it doesn't
1547work if your fundemental data type is something that is already supported.</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1548
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1549</li>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1550
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1551<li>
1552
1553<p>Write an independent class, using it explicitly from options that need
1554it.</p>
1555
1556<p>This approach works well in situations where you would line to parse an
1557option using special syntax for a not-very-special data-type. The drawback of
1558this approach is that users of your parser have to be aware that they are using
1559your parser, instead of the builtin ones.</p>
1560
1561</li>
1562
1563</ol>
1564
1565<p>To guide the discussion, we will discuss a custom parser that accepts file
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1566sizes, specified with an optional unit after the numeric size. For example, we
1567would like to parse "102kb", "41M", "1G" into the appropriate integer value. In
1568this case, the underlying data type we want to parse into is
1569'<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^]1570this the default for all <tt>unsigned</tt> options.</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1571
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1572<p>To start out, we declare our new <tt>FileSizeParser</tt> class:</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1573
1574<pre>
1575<b>struct</b> FileSizeParser : <b>public</b> cl::basic_parser&lt;<b>unsigned</b>&gt; {
1576 <i>// parse - Return true on error.</i>
1577 <b>bool</b> parse(cl::Option &amp;O, <b>const char</b> *ArgName, <b>const</b> std::string &amp;ArgValue,
1578 <b>unsigned</b> &amp;Val);
1579};
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1580</pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1581
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1582<p>Our new class inherits from the <tt>cl::basic_parser</tt> template class to
1583fill in the default, boiler plate, code for us. We give it the data type that
1584we 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]1585our 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^]1586declare that we parse into '<tt>unsigned</tt>' variables.</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1587
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1588<p>For most purposes, the only method that must be implemented in a custom
1589parser is the <tt>parse</tt> method. The <tt>parse</tt> method is called
1590whenever the option is invoked, passing in the option itself, the option name,
1591the string to parse, and a reference to a return value. If the string to parse
1592is not well formed, the parser should output an error message and return true.
1593Otherwise it should return false and set '<tt>Val</tt>' to the parsed value. In
1594our example, we implement <tt>parse</tt> as:</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1595
1596<pre>
1597<b>bool</b> FileSizeParser::parse(cl::Option &amp;O, <b>const char</b> *ArgName,
1598 <b>const</b> std::string &amp;Arg, <b>unsigned</b> &amp;Val) {
1599 <b>const char</b> *ArgStart = Arg.c_str();
1600 <b>char</b> *End;
1601
1602 <i>// Parse integer part, leaving 'End' pointing to the first non-integer char</i>
1603 Val = (unsigned)strtol(ArgStart, &amp;End, 0);
1604
1605 <b>while</b> (1) {
1606 <b>switch</b> (*End++) {
1607 <b>case</b> 0: <b>return</b> false; <i>// No error</i>
1608 <b>case</b> 'i': <i>// Ignore the 'i' in KiB if people use that</i>
1609 <b>case</b> 'b': <b>case</b> 'B': <i>// Ignore B suffix</i>
1610 <b>break</b>;
1611
1612 <b>case</b> 'g': <b>case</b> 'G': Val *= 1024*1024*1024; <b>break</b>;
1613 <b>case</b> 'm': <b>case</b> 'M': Val *= 1024*1024; <b>break</b>;
1614 <b>case</b> 'k': <b>case</b> 'K': Val *= 1024; <b>break</b>;
1615
1616 default:
1617 <i>// Print an error message if unrecognized character!</i>
1618 <b>return</b> O.error(": '" + Arg + "' value invalid for file size argument!");
1619 }
1620 }
1621}
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1622</pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1623
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1624<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]1625interested in. Although it has some holes (it allows "<tt>123KKK</tt>" for
1626example), it is good enough for this example. Note that we use the option
1627itself to print out the error message (the <tt>error</tt> method always returns
1628true) 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^]1629parser class, we can use it like this:</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1630
1631<pre>
1632<b>static</b> <a href="#cl::opt">cl::opt</a>&lt;<b>unsigned</b>, <b>false</b>, FileSizeParser&gt;
1633MFS(<i>"max-file-size"</i>, <a href="#cl::desc">cl::desc</a>(<i>"Maximum file size to accept"</i>),
1634 <a href="#cl::value_desc">cl::value_desc</a>("<i>size</i>"));
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1635</pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1636
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1637<p>Which adds this to the output of our program:</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1638
1639<pre>
1640OPTIONS:
1641 -help - display available options (--help-hidden for more)
1642 ...
1643 <b>-max-file-size=&lt;size&gt; - Maximum file size to accept</b>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1644</pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1645
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1646<p>And we can test that our parse works correctly now (the test program just
1647prints out the max-file-size argument value):</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1648
1649<pre>
1650$ ./test
1651MFS: 0
1652$ ./test -max-file-size=123MB
1653MFS: 128974848
1654$ ./test -max-file-size=3G
1655MFS: 3221225472
1656$ ./test -max-file-size=dog
1657-max-file-size option: 'dog' value invalid for file size argument!
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1658</pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1659
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1660<p>It looks like it works. The error message that we get is nice and helpful,
1661and we seem to accept reasonable file sizes. This wraps up the "custom parser"
1662tutorial.</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1663
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1664</div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1665
1666<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1667<div class="doc_subsection">
1668 <a name="explotingexternal">Exploiting external storage</a>
1669</div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1670
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1671<div class="doc_text">
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1672
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1673<p>TODO: fill in this section</p>
1674
1675</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1676
1677<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1678<div class="doc_subsection">
1679 <a name="dynamicopts">Dynamically adding command line options</a>
1680</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +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>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]1685
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1686</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]1687
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]1688<!-- *********************************************************************** -->
1689
1690<hr>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1691<div class="doc_footer">
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]1692<address><a href="mailto:sabre@nondot.org">Chris Lattner</a></address>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame^]1693Last modified: $Date$
1694</div>
1695
1696</body>
1697</html>