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gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / ba4733d901b1c2b994f66707657342b8c81c92bc / . / docs / CommandLine.html
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Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
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3<html>
4<head>
Reid Spencer9bbba0912004-11-16 06:11:52 +0000[diff] [blame]5 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]6 <title>CommandLine 2.0 Library Manual</title>
Misha Brukman3c299112003-11-07 18:11:14 +0000[diff] [blame]7 <link rel="stylesheet" href="llvm.css" type="text/css">
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]8</head>
9<body>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]10
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]11<div class="doc_title">
12 CommandLine 2.0 Library Manual
13</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]14
15<ol>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]16 <li><a href="#introduction">Introduction</a></li>
17
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]18 <li><a href="#quickstart">Quick Start Guide</a>
19 <ol>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]20 <li><a href="#bool">Boolean Arguments</a></li>
21 <li><a href="#alias">Argument Aliases</a></li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]22 <li><a href="#onealternative">Selecting an alternative from a
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]23 set of possibilities</a></li>
24 <li><a href="#namedalternatives">Named alternatives</a></li>
25 <li><a href="#list">Parsing a list of options</a></li>
Jim Laskey1d8f6262005-08-25 22:52:43 +0000[diff] [blame]26 <li><a href="#bits">Collecting options as a set of flags</a></li>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]27 <li><a href="#description">Adding freeform text to help output</a></li>
28 </ol></li>
29
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]30 <li><a href="#referenceguide">Reference Guide</a>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]31 <ol>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]32 <li><a href="#positional">Positional Arguments</a>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]33 <ul>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]34 <li><a href="#--">Specifying positional options with hyphens</a></li>
Reid Spencer2c8ab582004-08-13 20:19:14 +0000[diff] [blame]35 <li><a href="#getPosition">Determining absolute position with
36 getPosition</a></li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]37 <li><a href="#cl::ConsumeAfter">The <tt>cl::ConsumeAfter</tt>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]38 modifier</a></li>
39 </ul></li>
40
41 <li><a href="#storage">Internal vs External Storage</a></li>
42
43 <li><a href="#attributes">Option Attributes</a></li>
44
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]45 <li><a href="#modifiers">Option Modifiers</a>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]46 <ul>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]47 <li><a href="#hiding">Hiding an option from <tt>--help</tt>
48 output</a></li>
49 <li><a href="#numoccurrences">Controlling the number of occurrences
50 required and allowed</a></li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]51 <li><a href="#valrequired">Controlling whether or not a value must be
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]52 specified</a></li>
53 <li><a href="#formatting">Controlling other formatting options</a></li>
54 <li><a href="#misc">Miscellaneous option modifiers</a></li>
55 </ul></li>
56
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]57 <li><a href="#toplevel">Top-Level Classes and Functions</a>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]58 <ul>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]59 <li><a href="#cl::ParseCommandLineOptions">The
60 <tt>cl::ParseCommandLineOptions</tt> function</a></li>
61 <li><a href="#cl::ParseEnvironmentOptions">The
62 <tt>cl::ParseEnvironmentOptions</tt> function</a></li>
Reid Spencer2403b852006-06-05 17:30:16 +0000[diff] [blame]63 <li><a href="#cl::SetVersionPrinter">The cl::SetVersionPrinter
64 function</a></li>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]65 <li><a href="#cl::opt">The <tt>cl::opt</tt> class</a></li>
66 <li><a href="#cl::list">The <tt>cl::list</tt> class</a></li>
Jim Laskey1d8f6262005-08-25 22:52:43 +0000[diff] [blame]67 <li><a href="#cl::bits">The <tt>cl::bits</tt> class</a></li>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]68 <li><a href="#cl::alias">The <tt>cl::alias</tt> class</a></li>
Reid Spencer9bbba0912004-11-16 06:11:52 +0000[diff] [blame]69 <li><a href="#cl::extrahelp">The <tt>cl::extrahelp</tt> class</a></li>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]70 </ul></li>
71
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]72 <li><a href="#builtinparsers">Builtin parsers</a>
73 <ul>
74 <li><a href="#genericparser">The Generic <tt>parser&lt;t&gt;</tt>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]75 parser</a></li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]76 <li><a href="#boolparser">The <tt>parser&lt;bool&gt;</tt>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]77 specialization</a></li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]78 <li><a href="#stringparser">The <tt>parser&lt;string&gt;</tt>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]79 specialization</a></li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]80 <li><a href="#intparser">The <tt>parser&lt;int&gt;</tt>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]81 specialization</a></li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]82 <li><a href="#doubleparser">The <tt>parser&lt;double&gt;</tt> and
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]83 <tt>parser&lt;float&gt;</tt> specializations</a></li>
84 </ul></li>
85 </ol></li>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]86 <li><a href="#extensionguide">Extension Guide</a>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]87 <ol>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]88 <li><a href="#customparser">Writing a custom parser</a></li>
89 <li><a href="#explotingexternal">Exploiting external storage</a></li>
90 <li><a href="#dynamicopts">Dynamically adding command line
91 options</a></li>
92 </ol></li>
93</ol>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]94
Chris Lattner7911ce22004-05-23 21:07:27 +0000[diff] [blame]95<div class="doc_author">
96 <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a></p>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]97</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]98
99<!-- *********************************************************************** -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]100<div class="doc_section">
Misha Brukman8becd712003-11-07 19:42:44 +0000[diff] [blame]101 <a name="introduction">Introduction</a>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]102</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]103<!-- *********************************************************************** -->
104
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]105<div class="doc_text">
106
107<p>This document describes the CommandLine argument processing library. It will
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]108show you how to use it, and what it can do. The CommandLine library uses a
109declarative approach to specifying the command line options that your program
110takes. By default, these options declarations implicitly hold the value parsed
111for the option declared (of course this <a href="#storage">can be
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]112changed</a>).</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]113
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]114<p>Although there are a <b>lot</b> of command line argument parsing libraries
115out there in many different languages, none of them fit well with what I needed.
116By looking at the features and problems of other libraries, I designed the
117CommandLine library to have the following features:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]118
119<ol>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]120<li>Speed: The CommandLine library is very quick and uses little resources. The
121parsing time of the library is directly proportional to the number of arguments
122parsed, not the the number of options recognized. Additionally, command line
Chris Lattneredf351f2003-06-21 21:45:56 +0000[diff] [blame]123argument values are captured transparently into user defined global variables,
124which can be accessed like any other variable (and with the same
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]125performance).</li>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]126
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]127<li>Type Safe: As a user of CommandLine, you don't have to worry about
128remembering the type of arguments that you want (is it an int? a string? a
129bool? an enum?) and keep casting it around. Not only does this help prevent
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]130error prone constructs, it also leads to dramatically cleaner source code.</li>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]131
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]132<li>No subclasses required: To use CommandLine, you instantiate variables that
133correspond to the arguments that you would like to capture, you don't subclass a
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]134parser. This means that you don't have to write <b>any</b> boilerplate
135code.</li>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]136
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]137<li>Globally accessible: Libraries can specify command line arguments that are
138automatically enabled in any tool that links to the library. This is possible
139because the application doesn't have to keep a "list" of arguments to pass to
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]140the parser. This also makes supporting <a href="#dynamicopts">dynamically
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]141loaded options</a> trivial.</li>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]142
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]143<li>Cleaner: CommandLine supports enum and other types directly, meaning that
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]144there is less error and more security built into the library. You don't have to
145worry about whether your integral command line argument accidentally got
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]146assigned a value that is not valid for your enum type.</li>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]147
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]148<li>Powerful: The CommandLine library supports many different types of
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]149arguments, from simple <a href="#boolparser">boolean flags</a> to <a
150href="#cl::opt">scalars arguments</a> (<a href="#stringparser">strings</a>, <a
151href="#intparser">integers</a>, <a href="#genericparser">enums</a>, <a
152href="#doubleparser">doubles</a>), to <a href="#cl::list">lists of
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]153arguments</a>. This is possible because CommandLine is...</li>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]154
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]155<li>Extensible: It is very simple to add a new argument type to CommandLine.
156Simply specify the parser that you want to use with the command line option when
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]157you declare it. <a href="#customparser">Custom parsers</a> are no problem.</li>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]158
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]159<li>Labor Saving: The CommandLine library cuts down on the amount of grunt work
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]160that you, the user, have to do. For example, it automatically provides a
161<tt>--help</tt> option that shows the available command line options for your
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]162tool. Additionally, it does most of the basic correctness checking for
163you.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]164
165<li>Capable: The CommandLine library can handle lots of different forms of
166options often found in real programs. For example, <a
167href="#positional">positional</a> arguments, <tt>ls</tt> style <a
168href="#cl::Grouping">grouping</a> options (to allow processing '<tt>ls
169-lad</tt>' naturally), <tt>ld</tt> style <a href="#cl::Prefix">prefix</a>
170options (to parse '<tt>-lmalloc -L/usr/lib</tt>'), and <a
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]171href="#cl::ConsumeAfter">interpreter style options</a>.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]172
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]173</ol>
174
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]175<p>This document will hopefully let you jump in and start using CommandLine in
176your utility quickly and painlessly. Additionally it should be a simple
177reference manual to figure out how stuff works. If it is failing in some area
178(or you want an extension to the library), nag the author, <a
179href="mailto:sabre@nondot.org">Chris Lattner</a>.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]180
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]181</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]182
183<!-- *********************************************************************** -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]184<div class="doc_section">
185 <a name="quickstart">Quick Start Guide</a>
186</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]187<!-- *********************************************************************** -->
188
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]189<div class="doc_text">
190
191<p>This section of the manual runs through a simple CommandLine'ification of a
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]192basic compiler tool. This is intended to show you how to jump into using the
193CommandLine library in your own program, and show you some of the cool things it
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]194can do.</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]195
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]196<p>To start out, you need to include the CommandLine header file into your
197program:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]198
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]199<div class="doc_code"><pre>
Andrew Lenharth94f3d1a2005-11-14 19:32:05 +0000[diff] [blame]200 #include "llvm/Support/CommandLine.h"
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]201</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]202
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]203<p>Additionally, you need to add this as the first line of your main
204program:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]205
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]206<div class="doc_code"><pre>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]207int main(int argc, char **argv) {
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]208 <a href="#cl::ParseCommandLineOptions">cl::ParseCommandLineOptions</a>(argc, argv);
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]209 ...
210}
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]211</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]212
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]213<p>... which actually parses the arguments and fills in the variable
214declarations.</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]215
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]216<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]217system which ones we want, and what type of argument they are. The CommandLine
Chris Lattneredf351f2003-06-21 21:45:56 +0000[diff] [blame]218library uses a declarative syntax to model command line arguments with the
219global variable declarations that capture the parsed values. This means that
220for every command line option that you would like to support, there should be a
221global variable declaration to capture the result. For example, in a compiler,
222we would like to support the unix standard '<tt>-o &lt;filename&gt;</tt>' option
223to specify where to put the output. With the CommandLine library, this is
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]224represented like this:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]225
Misha Brukmanc53aefb2004-05-12 18:42:35 +0000[diff] [blame]226<a name="value_desc_example"></a>
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]227<div class="doc_code"><pre>
Misha Brukmanc53aefb2004-05-12 18:42:35 +0000[diff] [blame]228<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>"));
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]229</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]230
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]231<p>This declares a global variable "<tt>OutputFilename</tt>" that is used to
Chris Lattneredf351f2003-06-21 21:45:56 +0000[diff] [blame]232capture the result of the "<tt>o</tt>" argument (first parameter). We specify
233that this is a simple scalar option by using the "<tt><a
234href="#cl::opt">cl::opt</a></tt>" template (as opposed to the <a
235href="#list">"<tt>cl::list</tt> template</a>), and tell the CommandLine library
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]236that the data type that we are parsing is a string.</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]237
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]238<p>The second and third parameters (which are optional) are used to specify what
239to output for the "<tt>--help</tt>" option. In this case, we get a line that
240looks like this:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]241
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]242<div class="doc_code"><pre>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]243USAGE: compiler [options]
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]244
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]245OPTIONS:
246 -help - display available options (--help-hidden for more)
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]247 <b>-o &lt;filename&gt; - Specify output filename</b>
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]248</pre></div>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]249
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]250<p>Because we specified that the command line option should parse using the
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]251<tt>string</tt> data type, the variable declared is automatically usable as a
252real string in all contexts that a normal C++ string object may be used. For
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]253example:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]254
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]255<div class="doc_code"><pre>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]256 ...
257 ofstream Output(OutputFilename.c_str());
258 if (Out.good()) ...
259 ...
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]260</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]261
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]262<p>There are many different options that you can use to customize the command
263line option handling library, but the above example shows the general interface
264to these options. The options can be specified in any order, and are specified
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]265with helper functions like <a href="#cl::desc"><tt>cl::desc(...)</tt></a>, so
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]266there are no positional dependencies to remember. The available options are
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]267discussed in detail in the <a href="#referenceguide">Reference Guide</a>.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]268
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]269<p>Continuing the example, we would like to have our compiler take an input
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]270filename as well as an output filename, but we do not want the input filename to
271be specified with a hyphen (ie, not <tt>-filename.c</tt>). To support this
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]272style of argument, the CommandLine library allows for <a
273href="#positional">positional</a> arguments to be specified for the program.
274These positional arguments are filled with command line parameters that are not
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]275in option form. We use this feature like this:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]276
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]277<div class="doc_code"><pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]278<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>"));
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]279</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]280
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]281<p>This declaration indicates that the first positional argument should be
282treated as the input filename. Here we use the <tt><a
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]283href="#cl::init">cl::init</a></tt> option to specify an initial value for the
284command line option, which is used if the option is not specified (if you do not
285specify a <tt><a href="#cl::init">cl::init</a></tt> modifier for an option, then
286the default constructor for the data type is used to initialize the value).
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]287Command line options default to being optional, so if we would like to require
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]288that the user always specify an input filename, we would add the <tt><a
289href="#cl::Required">cl::Required</a></tt> flag, and we could eliminate the
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]290<tt><a href="#cl::init">cl::init</a></tt> modifier, like this:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]291
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]292<div class="doc_code"><pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]293<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>);
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]294</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]295
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]296<p>Again, the CommandLine library does not require the options to be specified
297in any particular order, so the above declaration is equivalent to:</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]298
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]299<div class="doc_code"><pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]300<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>"));
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]301</pre></div>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]302
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]303<p>By simply adding the <tt><a href="#cl::Required">cl::Required</a></tt> flag,
304the CommandLine library will automatically issue an error if the argument is not
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]305specified, which shifts all of the command line option verification code out of
306your application into the library. This is just one example of how using flags
307can alter the default behaviour of the library, on a per-option basis. By
308adding one of the declarations above, the <tt>--help</tt> option synopsis is now
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]309extended to:</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]310
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]311<div class="doc_code"><pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]312USAGE: compiler [options] <b>&lt;input file&gt;</b>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]313
314OPTIONS:
315 -help - display available options (--help-hidden for more)
316 -o &lt;filename&gt; - Specify output filename
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]317</pre></div>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]318
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]319<p>... indicating that an input filename is expected.</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]320
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]321</div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]322
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]323<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]324<div class="doc_subsection">
325 <a name="bool">Boolean Arguments</a>
326</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]327
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]328<div class="doc_text">
329
330<p>In addition to input and output filenames, we would like the compiler example
331to support three boolean flags: "<tt>-f</tt>" to force overwriting of the output
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]332file, "<tt>--quiet</tt>" to enable quiet mode, and "<tt>-q</tt>" for backwards
333compatibility with some of our users. We can support these by declaring options
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]334of boolean type like this:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]335
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]336<div class="doc_code"><pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]337<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>"));
338<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>"));
339<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 Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]340</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]341
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]342<p>This does what you would expect: it declares three boolean variables
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]343("<tt>Force</tt>", "<tt>Quiet</tt>", and "<tt>Quiet2</tt>") to recognize these
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]344options. Note that the "<tt>-q</tt>" option is specified with the "<a
345href="#cl::Hidden"><tt>cl::Hidden</tt></a>" flag. This modifier prevents it
346from being shown by the standard "<tt>--help</tt>" output (note that it is still
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]347shown in the "<tt>--help-hidden</tt>" output).</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]348
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]349<p>The CommandLine library uses a <a href="#builtinparsers">different parser</a>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]350for different data types. For example, in the string case, the argument passed
351to the option is copied literally into the content of the string variable... we
352obviously cannot do that in the boolean case, however, so we must use a smarter
353parser. In the case of the boolean parser, it allows no options (in which case
354it assigns the value of true to the variable), or it allows the values
355"<tt>true</tt>" or "<tt>false</tt>" to be specified, allowing any of the
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]356following inputs:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]357
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]358<div class="doc_code"><pre>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]359 compiler -f # No value, 'Force' == true
360 compiler -f=true # Value specified, 'Force' == true
361 compiler -f=TRUE # Value specified, 'Force' == true
362 compiler -f=FALSE # Value specified, 'Force' == false
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]363</pre></div>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]364
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]365<p>... you get the idea. The <a href="#boolparser">bool parser</a> just turns
366the string values into boolean values, and rejects things like '<tt>compiler
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]367-f=foo</tt>'. Similarly, the <a href="#doubleparser">float</a>, <a
368href="#doubleparser">double</a>, and <a href="#intparser">int</a> parsers work
369like you would expect, using the '<tt>strtol</tt>' and '<tt>strtod</tt>' C
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]370library calls to parse the string value into the specified data type.</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]371
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]372<p>With the declarations above, "<tt>compiler --help</tt>" emits this:</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]373
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]374<div class="doc_code"><pre>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]375USAGE: compiler [options] &lt;input file&gt;
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]376
377OPTIONS:
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]378 <b>-f - Overwrite output files</b>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]379 -o - Override output filename
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]380 <b>-quiet - Don't print informational messages</b>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]381 -help - display available options (--help-hidden for more)
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]382</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]383
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]384<p>and "<tt>opt --help-hidden</tt>" prints this:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]385
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]386<div class="doc_code"><pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]387USAGE: compiler [options] &lt;input file&gt;
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]388
389OPTIONS:
390 -f - Overwrite output files
391 -o - Override output filename
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]392 <b>-q - Don't print informational messages</b>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]393 -quiet - Don't print informational messages
394 -help - display available options (--help-hidden for more)
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]395</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]396
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]397<p>This brief example has shown you how to use the '<tt><a
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]398href="#cl::opt">cl::opt</a></tt>' class to parse simple scalar command line
399arguments. In addition to simple scalar arguments, the CommandLine library also
400provides primitives to support CommandLine option <a href="#alias">aliases</a>,
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]401and <a href="#list">lists</a> of options.</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]402
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]403</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]404
405<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]406<div class="doc_subsection">
407 <a name="alias">Argument Aliases</a>
408</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]409
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]410<div class="doc_text">
411
412<p>So far, the example works well, except for the fact that we need to check the
413quiet condition like this now:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]414
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]415<div class="doc_code"><pre>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]416...
417 if (!Quiet &amp;&amp; !Quiet2) printInformationalMessage(...);
418...
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]419</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]420
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]421<p>... which is a real pain! Instead of defining two values for the same
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]422condition, 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]423option an <b>alias</b> for the "<tt>-quiet</tt>" option, instead of providing
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]424a value itself:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]425
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]426<div class="doc_code"><pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]427<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>"));
428<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>"));
429<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 Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]430</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]431
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]432<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]433"<tt>-q</tt> alias that updates the "<tt>Quiet</tt>" variable (as specified by
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]434the <tt><a href="#cl::aliasopt">cl::aliasopt</a></tt> modifier) whenever it is
435specified. Because aliases do not hold state, the only thing the program has to
436query is the <tt>Quiet</tt> variable now. Another nice feature of aliases is
437that they automatically hide themselves from the <tt>-help</tt> output
438(although, again, they are still visible in the <tt>--help-hidden
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]439output</tt>).</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]440
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]441<p>Now the application code can simply use:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]442
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]443<div class="doc_code"><pre>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]444...
445 if (!Quiet) printInformationalMessage(...);
446...
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]447</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]448
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]449<p>... which is much nicer! The "<tt><a href="#cl::alias">cl::alias</a></tt>"
450can be used to specify an alternative name for any variable type, and has many
451uses.</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]452
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]453</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]454
455<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]456<div class="doc_subsection">
457 <a name="onealternative">Selecting an alternative from a set of
458 possibilities</a>
459</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]460
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]461<div class="doc_text">
462
463<p>So far, we have seen how the CommandLine library handles builtin types like
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]464<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]465things it doesn't know about, like enums or '<tt>int*</tt>'s?</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]466
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]467<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]468your own parser, as described in the <a href="#extensionguide">Extension
Reid Spencerd8473372004-08-10 16:38:18 +0000[diff] [blame]469Guide</a>). This parser maps literal strings to whatever type is required, and
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]470requires you to tell it what this mapping should be.</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]471
Reid Spencerd8473372004-08-10 16:38:18 +0000[diff] [blame]472<p>Lets say that we would like to add four optimization levels to our
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]473optimizer, using the standard flags "<tt>-g</tt>", "<tt>-O0</tt>",
474"<tt>-O1</tt>", and "<tt>-O2</tt>". We could easily implement this with boolean
475options like above, but there are several problems with this strategy:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]476
477<ol>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]478<li>A user could specify more than one of the options at a time, for example,
479"<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]480erroneous input for us.</li>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]481
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]482<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]483
484<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]485see if some level &gt;= "<tt>-O1</tt>" is enabled.</li>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]486
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]487</ol>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]488
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]489<p>To cope with these problems, we can use an enum value, and have the
490CommandLine library fill it in with the appropriate level directly, which is
491used like this:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]492
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]493<div class="doc_code"><pre>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]494enum OptLevel {
495 g, O1, O2, O3
496};
497
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]498<a href="#cl::opt">cl::opt</a>&lt;OptLevel&gt; OptimizationLevel(<a href="#cl::desc">cl::desc</a>("<i>Choose optimization level:</i>"),
499 <a href="#cl::values">cl::values</a>(
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]500 clEnumVal(g , "<i>No optimizations, enable debugging</i>"),
501 clEnumVal(O1, "<i>Enable trivial optimizations</i>"),
502 clEnumVal(O2, "<i>Enable default optimizations</i>"),
503 clEnumVal(O3, "<i>Enable expensive optimizations</i>"),
Chris Lattnerb406ead2004-07-16 00:10:54 +0000[diff] [blame]504 clEnumValEnd));
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]505
506...
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]507 if (OptimizationLevel &gt;= O2) doPartialRedundancyElimination(...);
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]508...
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]509</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]510
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]511<p>This declaration defines a variable "<tt>OptimizationLevel</tt>" of the
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]512"<tt>OptLevel</tt>" enum type. This variable can be assigned any of the values
513that are listed in the declaration (Note that the declaration list must be
Chris Lattnerb406ead2004-07-16 00:10:54 +0000[diff] [blame]514terminated with the "<tt>clEnumValEnd</tt>" argument!). The CommandLine
515library enforces
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]516that the user can only specify one of the options, and it ensure that only valid
517enum values can be specified. The "<tt>clEnumVal</tt>" macros ensure that the
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]518command line arguments matched the enum values. With this option added, our
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]519help output now is:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]520
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]521<div class="doc_code"><pre>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]522USAGE: compiler [options] &lt;input file&gt;
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]523
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]524OPTIONS:
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]525 <b>Choose optimization level:
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]526 -g - No optimizations, enable debugging
527 -O1 - Enable trivial optimizations
528 -O2 - Enable default optimizations
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]529 -O3 - Enable expensive optimizations</b>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]530 -f - Overwrite output files
531 -help - display available options (--help-hidden for more)
532 -o &lt;filename&gt; - Specify output filename
533 -quiet - Don't print informational messages
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]534</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]535
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]536<p>In this case, it is sort of awkward that flag names correspond directly to
537enum names, because we probably don't want a enum definition named "<tt>g</tt>"
538in our program. Because of this, we can alternatively write this example like
539this:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]540
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]541<div class="doc_code"><pre>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]542enum OptLevel {
543 Debug, O1, O2, O3
544};
545
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]546<a href="#cl::opt">cl::opt</a>&lt;OptLevel&gt; OptimizationLevel(<a href="#cl::desc">cl::desc</a>("<i>Choose optimization level:</i>"),
547 <a href="#cl::values">cl::values</a>(
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]548 clEnumValN(Debug, "g", "<i>No optimizations, enable debugging</i>"),
549 clEnumVal(O1 , "<i>Enable trivial optimizations</i>"),
550 clEnumVal(O2 , "<i>Enable default optimizations</i>"),
551 clEnumVal(O3 , "<i>Enable expensive optimizations</i>"),
Chris Lattnerb406ead2004-07-16 00:10:54 +0000[diff] [blame]552 clEnumValEnd));
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]553
554...
555 if (OptimizationLevel == Debug) outputDebugInfo(...);
556...
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]557</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]558
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]559<p>By using the "<tt>clEnumValN</tt>" macro instead of "<tt>clEnumVal</tt>", we
560can directly specify the name that the flag should get. In general a direct
561mapping is nice, but sometimes you can't or don't want to preserve the mapping,
562which is when you would use it.</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]563
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]564</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]565
566<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]567<div class="doc_subsection">
568 <a name="namedalternatives">Named Alternatives</a>
569</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]570
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]571<div class="doc_text">
572
573<p>Another useful argument form is a named alternative style. We shall use this
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]574style in our compiler to specify different debug levels that can be used.
575Instead of each debug level being its own switch, we want to support the
576following options, of which only one can be specified at a time:
577"<tt>--debug-level=none</tt>", "<tt>--debug-level=quick</tt>",
578"<tt>--debug-level=detailed</tt>". To do this, we use the exact same format as
579our optimization level flags, but we also specify an option name. For this
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]580case, the code looks like this:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]581
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]582<div class="doc_code"><pre>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]583enum DebugLev {
584 nodebuginfo, quick, detailed
585};
586
587// Enable Debug Options to be specified on the command line
Chris Lattnerdc844fa2003-06-03 04:40:06 +0000[diff] [blame]588<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]589 <a href="#cl::values">cl::values</a>(
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]590 clEnumValN(nodebuginfo, "none", "<i>disable debug information</i>"),
591 clEnumVal(quick, "<i>enable quick debug information</i>"),
592 clEnumVal(detailed, "<i>enable detailed debug information</i>"),
Chris Lattnerb406ead2004-07-16 00:10:54 +0000[diff] [blame]593 clEnumValEnd));
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]594</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]595
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]596<p>This definition defines an enumerated command line variable of type "<tt>enum
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]597DebugLev</tt>", which works exactly the same way as before. The difference here
598is 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]599the "<tt>--help</tt>" option:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]600
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]601<div class="doc_code"><pre>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]602USAGE: compiler [options] &lt;input file&gt;
603
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]604OPTIONS:
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]605 Choose optimization level:
606 -g - No optimizations, enable debugging
607 -O1 - Enable trivial optimizations
608 -O2 - Enable default optimizations
609 -O3 - Enable expensive optimizations
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]610 <b>-debug_level - Set the debugging level:
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]611 =none - disable debug information
612 =quick - enable quick debug information
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]613 =detailed - enable detailed debug information</b>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]614 -f - Overwrite output files
615 -help - display available options (--help-hidden for more)
616 -o &lt;filename&gt; - Specify output filename
617 -quiet - Don't print informational messages
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]618</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]619
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]620<p>Again, the only structural difference between the debug level declaration and
John Criswellc24d4822004-11-21 14:34:34 +0000[diff] [blame]621the optimization level declaration is that the debug level declaration includes
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]622an option name (<tt>"debug_level"</tt>), which automatically changes how the
623library processes the argument. The CommandLine library supports both forms so
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]624that you can choose the form most appropriate for your application.</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]625
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]626</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]627
628<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]629<div class="doc_subsection">
630 <a name="list">Parsing a list of options</a>
631</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]632
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]633<div class="doc_text">
634
635<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]636lets get a little wild and crazy. Lets say that we want our optimizer to accept
637a <b>list</b> of optimizations to perform, allowing duplicates. For example, we
638might want to run: "<tt>compiler -dce -constprop -inline -dce -strip</tt>". In
639this case, the order of the arguments and the number of appearances is very
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]640important. This is what the "<tt><a href="#cl::list">cl::list</a></tt>"
641template is for. First, start by defining an enum of the optimizations that you
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]642would like to perform:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]643
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]644<div class="doc_code"><pre>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]645enum Opts {
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]646 // 'inline' is a C++ keyword, so name it 'inlining'
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]647 dce, constprop, inlining, strip
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]648};
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]649</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]650
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]651<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]652
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]653<div class="doc_code"><pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]654<a href="#cl::list">cl::list</a>&lt;Opts&gt; OptimizationList(<a href="#cl::desc">cl::desc</a>("<i>Available Optimizations:</i>"),
655 <a href="#cl::values">cl::values</a>(
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]656 clEnumVal(dce , "<i>Dead Code Elimination</i>"),
Misha Brukman82c89b92003-05-20 21:01:22 +0000[diff] [blame]657 clEnumVal(constprop , "<i>Constant Propagation</i>"),
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]658 clEnumValN(inlining, "<i>inline</i>", "<i>Procedure Integration</i>"),
659 clEnumVal(strip , "<i>Strip Symbols</i>"),
Chris Lattnerb406ead2004-07-16 00:10:54 +0000[diff] [blame]660 clEnumValEnd));
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]661</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]662
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]663<p>This defines a variable that is conceptually of the type
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]664"<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]665vector methods:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]666
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]667<div class="doc_code"><pre>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]668 for (unsigned i = 0; i != OptimizationList.size(); ++i)
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]669 switch (OptimizationList[i])
670 ...
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]671</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]672
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]673<p>... to iterate through the list of options specified.</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]674
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]675<p>Note that the "<tt><a href="#cl::list">cl::list</a></tt>" template is
676completely general and may be used with any data types or other arguments that
677you can use with the "<tt><a href="#cl::opt">cl::opt</a></tt>" template. One
678especially useful way to use a list is to capture all of the positional
679arguments together if there may be more than one specified. In the case of a
680linker, for example, the linker takes several '<tt>.o</tt>' files, and needs to
681capture them into a list. This is naturally specified as:</p>
Chris Lattner3e5fe172002-04-13 18:35:59 +0000[diff] [blame]682
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]683<div class="doc_code"><pre>
Chris Lattner3e5fe172002-04-13 18:35:59 +0000[diff] [blame]684...
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]685<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]686...
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]687</pre></div>
Chris Lattner3e5fe172002-04-13 18:35:59 +0000[diff] [blame]688
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]689<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]690such, accessing the list is simple, just like above. In this example, we used
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]691the <tt><a href="#cl::OneOrMore">cl::OneOrMore</a></tt> modifier to inform the
692CommandLine library that it is an error if the user does not specify any
693<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]694checking we have to do.</p>
Chris Lattner3e5fe172002-04-13 18:35:59 +0000[diff] [blame]695
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]696</div>
Chris Lattner3e5fe172002-04-13 18:35:59 +0000[diff] [blame]697
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]698<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]699<div class="doc_subsection">
Jim Laskey1d8f6262005-08-25 22:52:43 +0000[diff] [blame]700 <a name="bits">Collecting options as a set of flags</a>
701</div>
702
703<div class="doc_text">
704
705<p>Instead of collecting sets of options in a list, it is also possible to
Jim Laskey22b7dfa2005-08-26 09:25:54 +0000[diff] [blame]706gather information for enum values in a <b>bit vector</b>. The represention used by
707the <a href="#bits"><tt>cl::bits</tt></a> class is an <tt>unsigned</tt>
Jim Laskey1d8f6262005-08-25 22:52:43 +0000[diff] [blame]708integer. An enum value is represented by a 0/1 in the enum's ordinal value bit
709position. 1 indicating that the enum was specified, 0 otherwise. As each
710specified value is parsed, the resulting enum's bit is set in the option's bit
711vector:</p>
712
713<div class="doc_code"><pre>
714 <i>bits</i> |= 1 << (unsigned)<i>enum</i>;
715</pre></div>
716
Jim Laskey26029222005-08-25 23:01:25 +0000[diff] [blame]717<p>Options that are specified multiple times are redundant. Any instances after
718the first are discarded.</p>
Jim Laskey1d8f6262005-08-25 22:52:43 +0000[diff] [blame]719
720<p>Reworking the above list example, we could replace <a href="#list">
721<tt>cl::list</tt></a> with <a href="#bits"><tt>cl::bits</tt></a>:</p>
722
723<div class="doc_code"><pre>
724<a href="#cl::bits">cl::bits</a>&lt;Opts&gt; OptimizationBits(<a href="#cl::desc">cl::desc</a>("<i>Available Optimizations:</i>"),
725 <a href="#cl::values">cl::values</a>(
726 clEnumVal(dce , "<i>Dead Code Elimination</i>"),
727 clEnumVal(constprop , "<i>Constant Propagation</i>"),
728 clEnumValN(inlining, "<i>inline</i>", "<i>Procedure Integration</i>"),
729 clEnumVal(strip , "<i>Strip Symbols</i>"),
730 clEnumValEnd));
731</pre></div>
732
733<p>To test to see if <tt>constprop</tt> was specified, we can use the
734<tt>cl:bits::isSet</tt> function:</p>
735
736<div class="doc_code"><pre>
737 if (OptimizationBits.isSet(constprop)) {
738 ...
739 }
740</pre></div>
741
742<p>It's also possible to get the raw bit vector using the
743<tt>cl::bits::getBits</tt> function:</p>
744
745<div class="doc_code"><pre>
Jim Laskey22b7dfa2005-08-26 09:25:54 +0000[diff] [blame]746 unsigned bits = OptimizationBits.getBits();
Jim Laskey1d8f6262005-08-25 22:52:43 +0000[diff] [blame]747</pre></div>
748
749<p>Finally, if external storage is used, then the location specified must be of
Jim Laskey22b7dfa2005-08-26 09:25:54 +0000[diff] [blame]750<b>type</b> <tt>unsigned</tt>. In all other ways a <a
Jim Laskey1d8f6262005-08-25 22:52:43 +0000[diff] [blame]751href="#bits"><tt>cl::bits</tt></a> option is morally equivalent to a <a
Jim Laskey22b7dfa2005-08-26 09:25:54 +0000[diff] [blame]752href="#list"> <tt>cl::list</tt></a> option.</p>
Jim Laskey1d8f6262005-08-25 22:52:43 +0000[diff] [blame]753
754</div>
755
756
757<!-- ======================================================================= -->
758<div class="doc_subsection">
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]759 <a name="description">Adding freeform text to help output</a>
760</div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]761
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]762<div class="doc_text">
763
764<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]765information about what it does into the help output. The help output is styled
766to look similar to a Unix <tt>man</tt> page, providing concise information about
767a program. Unix <tt>man</tt> pages, however often have a description about what
768the program does. To add this to your CommandLine program, simply pass a third
769argument to the <a
770href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>
771call in main. This additional argument is then printed as the overview
772information for your program, allowing you to include any additional information
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]773that you want. For example:</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]774
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]775<div class="doc_code"><pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]776int main(int argc, char **argv) {
777 <a href="#cl::ParseCommandLineOptions">cl::ParseCommandLineOptions</a>(argc, argv, " CommandLine compiler example\n\n"
778 " This program blah blah blah...\n");
779 ...
780}
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]781</pre></div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]782
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]783<p>would yield the help output:</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]784
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]785<div class="doc_code"><pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]786<b>OVERVIEW: CommandLine compiler example
787
788 This program blah blah blah...</b>
789
790USAGE: compiler [options] &lt;input file&gt;
791
792OPTIONS:
793 ...
794 -help - display available options (--help-hidden for more)
795 -o &lt;filename&gt; - Specify output filename
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]796</pre></div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]797
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]798</div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]799
800
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]801<!-- *********************************************************************** -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]802<div class="doc_section">
803 <a name="referenceguide">Reference Guide</a>
804</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]805<!-- *********************************************************************** -->
806
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]807<div class="doc_text">
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]808
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]809<p>Now that you know the basics of how to use the CommandLine library, this
810section will give you the detailed information you need to tune how command line
811options work, as well as information on more "advanced" command line option
812processing capabilities.</p>
813
814</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]815
816<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]817<div class="doc_subsection">
818 <a name="positional">Positional Arguments</a>
819</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]820
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]821<div class="doc_text">
822
823<p>Positional arguments are those arguments that are not named, and are not
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]824specified with a hyphen. Positional arguments should be used when an option is
825specified by its position alone. For example, the standard Unix <tt>grep</tt>
826tool takes a regular expression argument, and an optional filename to search
827through (which defaults to standard input if a filename is not specified).
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]828Using the CommandLine library, this would be specified as:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]829
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]830<div class="doc_code"><pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]831<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>);
832<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>"));
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]833</pre></div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]834
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]835<p>Given these two option declarations, the <tt>--help</tt> output for our grep
836replacement would look like this:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]837
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]838<div class="doc_code"><pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]839USAGE: spiffygrep [options] <b>&lt;regular expression&gt; &lt;input file&gt;</b>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]840
841OPTIONS:
842 -help - display available options (--help-hidden for more)
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]843</pre></div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]844
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]845<p>... and the resultant program could be used just like the standard
846<tt>grep</tt> tool.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]847
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]848<p>Positional arguments are sorted by their order of construction. This means
849that command line options will be ordered according to how they are listed in a
Reid Spencer2c8ab582004-08-13 20:19:14 +0000[diff] [blame]850.cpp file, but will not have an ordering defined if the positional arguments
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]851are defined in multiple .cpp files. The fix for this problem is simply to
852define all of your positional arguments in one .cpp file.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]853
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]854</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]855
856
857<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]858<div class="doc_subsubsection">
859 <a name="--">Specifying positional options with hyphens</a>
860</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]861
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]862<div class="doc_text">
863
864<p>Sometimes you may want to specify a value to your positional argument that
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]865starts with a hyphen (for example, searching for '<tt>-foo</tt>' in a file). At
866first, you will have trouble doing this, because it will try to find an argument
867named '<tt>-foo</tt>', and will fail (and single quotes will not save you).
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]868Note that the system <tt>grep</tt> has the same problem:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]869
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]870<div class="doc_code"><pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]871 $ spiffygrep '-foo' test.txt
872 Unknown command line argument '-foo'. Try: spiffygrep --help'
873
874 $ grep '-foo' test.txt
875 grep: illegal option -- f
876 grep: illegal option -- o
877 grep: illegal option -- o
878 Usage: grep -hblcnsviw pattern file . . .
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]879</pre></div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]880
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]881<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]882version: use the '<tt>--</tt>' marker. When the user specifies '<tt>--</tt>' on
883the command line, it is telling the program that all options after the
884'<tt>--</tt>' should be treated as positional arguments, not options. Thus, we
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]885can use it like this:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]886
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]887<div class="doc_code"><pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]888 $ spiffygrep -- -foo test.txt
889 ...output...
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]890</pre></div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]891
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]892</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]893
894<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]895<div class="doc_subsubsection">
Reid Spencer2c8ab582004-08-13 20:19:14 +0000[diff] [blame]896 <a name="getPosition">Determining absolute position with getPosition()</a>
897</div>
898<div class="doc_text">
899 <p>Sometimes an option can affect or modify the meaning of another option. For
900 example, consider <tt>gcc</tt>'s <tt>-x LANG</tt> option. This tells
901 <tt>gcc</tt> to ignore the suffix of subsequent positional arguments and force
902 the file to be interpreted as if it contained source code in language
903 <tt>LANG</tt>. In order to handle this properly , you need to know the
904 absolute position of each argument, especially those in lists, so their
905 interaction(s) can be applied correctly. This is also useful for options like
906 <tt>-llibname</tt> which is actually a positional argument that starts with
907 a dash.</p>
908 <p>So, generally, the problem is that you have two <tt>cl::list</tt> variables
909 that interact in some way. To ensure the correct interaction, you can use the
910 <tt>cl::list::getPosition(optnum)</tt> method. This method returns the
911 absolute position (as found on the command line) of the <tt>optnum</tt>
912 item in the <tt>cl::list</tt>.</p>
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]913 <p>The idiom for usage is like this:</p>
914
915 <div class="doc_code"><pre>
Reid Spencer2c8ab582004-08-13 20:19:14 +0000[diff] [blame]916 static cl::list&lt;std::string&gt; Files(cl::Positional, cl::OneOrMore);
917 static cl::listlt;std::string&gt; Libraries("l", cl::ZeroOrMore);
918
919 int main(int argc, char**argv) {
920 // ...
921 std::vector&lt;std::string&gt;::iterator fileIt = Files.begin();
922 std::vector&lt;std::string&gt;::iterator libIt = Libraries.begin();
923 unsigned libPos = 0, filePos = 0;
924 while ( 1 ) {
925 if ( libIt != Libraries.end() )
926 libPos = Libraries.getPosition( libIt - Libraries.begin() );
927 else
928 libPos = 0;
929 if ( fileIt != Files.end() )
930 filePos = Files.getPosition( fileIt - Files.begin() );
931 else
932 filePos = 0;
933
934 if ( filePos != 0 &amp;&amp; (libPos == 0 || filePos &lt; libPos) ) {
935 // Source File Is next
936 ++fileIt;
937 }
938 else if ( libPos != 0 &amp;&amp; (filePos == 0 || libPos &lt; filePos) ) {
939 // Library is next
940 ++libIt;
941 }
942 else
943 break; // we're done with the list
944 }
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]945 }</pre></div>
946
Reid Spencer2c8ab582004-08-13 20:19:14 +0000[diff] [blame]947 <p>Note that, for compatibility reasons, the <tt>cl::opt</tt> also supports an
948 <tt>unsigned getPosition()</tt> option that will provide the absolute position
949 of that option. You can apply the same approach as above with a
950 <tt>cl::opt</tt> and a <tt>cl::list</tt> option as you can with two lists.</p>
951</div>
952
953<!-- _______________________________________________________________________ -->
954<div class="doc_subsubsection">
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]955 <a name="cl::ConsumeAfter">The <tt>cl::ConsumeAfter</tt> modifier</a>
956</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]957
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]958<div class="doc_text">
959
960<p>The <tt>cl::ConsumeAfter</tt> <a href="#formatting">formatting option</a> is
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]961used to construct programs that use "interpreter style" option processing. With
962this style of option processing, all arguments specified after the last
963positional argument are treated as special interpreter arguments that are not
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]964interpreted by the command line argument.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]965
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]966<p>As a concrete example, lets say we are developing a replacement for the
967standard Unix Bourne shell (<tt>/bin/sh</tt>). To run <tt>/bin/sh</tt>, first
968you specify options to the shell itself (like <tt>-x</tt> which turns on trace
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]969output), then you specify the name of the script to run, then you specify
970arguments to the script. These arguments to the script are parsed by the bourne
971shell command line option processor, but are not interpreted as options to the
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]972shell itself. Using the CommandLine library, we would specify this as:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]973
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]974<div class="doc_code"><pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]975<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>("-"));
976<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>"));
977<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 Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]978</pre></div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]979
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]980<p>which automatically provides the help output:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]981
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]982<div class="doc_code"><pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]983USAGE: spiffysh [options] <b>&lt;input script&gt; &lt;program arguments&gt;...</b>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]984
985OPTIONS:
986 -help - display available options (--help-hidden for more)
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]987 <b>-x - Enable trace output</b>
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]988</pre></div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]989
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]990<p>At runtime, if we run our new shell replacement as `<tt>spiffysh -x test.sh
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]991-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]992<tt>Script</tt> variable will be set to "<tt>test.sh</tt>", and the
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]993<tt>Argv</tt> list will contain <tt>["-a", "-x", "-y", "bar"]</tt>, because they
994were specified after the last positional argument (which is the script
995name).</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]996
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]997<p>There are several limitations to when <tt>cl::ConsumeAfter</tt> options can
998be specified. For example, only one <tt>cl::ConsumeAfter</tt> can be specified
999per program, there must be at least one <a href="#positional">positional
Chris Lattnerbe801bf2004-05-06 22:03:59 +0000[diff] [blame]1000argument</a> specified, there must not be any <a href="#cl::list">cl::list</a>
1001positional arguments, and the <tt>cl::ConsumeAfter</tt> option should be a <a
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1002href="#cl::list">cl::list</a> option.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1003
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1004</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1005
1006<!-- ======================================================================= -->
Chris Lattnerbe801bf2004-05-06 22:03:59 +0000[diff] [blame]1007<div class="doc_subsection">
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1008 <a name="storage">Internal vs External Storage</a>
1009</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1010
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1011<div class="doc_text">
1012
1013<p>By default, all command line options automatically hold the value that they
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1014parse from the command line. This is very convenient in the common case,
1015especially when combined with the ability to define command line options in the
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1016files that use them. This is called the internal storage model.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1017
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1018<p>Sometimes, however, it is nice to separate the command line option processing
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1019code from the storage of the value parsed. For example, lets say that we have a
1020'<tt>-debug</tt>' option that we would like to use to enable debug information
1021across the entire body of our program. In this case, the boolean value
1022controlling the debug code should be globally accessable (in a header file, for
1023example) yet the command line option processing code should not be exposed to
1024all of these clients (requiring lots of .cpp files to #include
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1025<tt>CommandLine.h</tt>).</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1026
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1027<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]1028
Misha Brukman1fc9f8e2005-02-09 22:49:05 +0000[diff] [blame]1029<div class="doc_code">
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1030<pre>
1031<i>// DebugFlag.h - Get access to the '-debug' command line option
1032//
1033
1034// DebugFlag - This boolean is set to true if the '-debug' command line option
1035// is specified. This should probably not be referenced directly, instead, use
1036// the DEBUG macro below.
1037//</i>
1038extern bool DebugFlag;
1039
1040<i>// DEBUG macro - This macro should be used by code to emit debug information.
1041// In the '-debug' option is specified on the command line, and if this is a
1042// debug build, then the code specified as the option to the macro will be
1043// executed. Otherwise it will not be. Example:
1044//
Misha Brukman1fc9f8e2005-02-09 22:49:05 +0000[diff] [blame]1045// DEBUG(std::cerr &lt;&lt; "Bitset contains: " &lt;&lt; Bitset &lt;&lt; "\n");
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1046//</i>
Misha Brukman1fc9f8e2005-02-09 22:49:05 +0000[diff] [blame]1047<span class="doc_hilite">#ifdef NDEBUG
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1048#define DEBUG(X)
1049#else
Misha Brukman1fc9f8e2005-02-09 22:49:05 +0000[diff] [blame]1050#define DEBUG(X)</span> do { if (DebugFlag) { X; } } while (0)
1051<span class="doc_hilite">#endif</span>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1052</pre>
Misha Brukman1fc9f8e2005-02-09 22:49:05 +0000[diff] [blame]1053</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1054
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1055<p>This allows clients to blissfully use the <tt>DEBUG()</tt> macro, or the
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1056<tt>DebugFlag</tt> explicitly if they want to. Now we just need to be able to
1057set the <tt>DebugFlag</tt> boolean when the option is set. To do this, we pass
1058an additial argument to our command line argument processor, and we specify
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1059where to fill in with the <a href="#cl::location">cl::location</a>
1060attribute:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1061
Misha Brukman1fc9f8e2005-02-09 22:49:05 +0000[diff] [blame]1062<div class="doc_code">
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1063<pre>
Misha Brukman1fc9f8e2005-02-09 22:49:05 +0000[diff] [blame]1064bool DebugFlag; <i>// the actual value</i>
Chris Lattner589a4cc2003-08-01 21:30:37 +0000[diff] [blame]1065static <a href="#cl::opt">cl::opt</a>&lt;bool, true&gt; <i>// The parser</i>
Misha Brukman1fc9f8e2005-02-09 22:49:05 +0000[diff] [blame]1066Debug("<i>debug</i>", <a href="#cl::desc">cl::desc</a>("<i>Enable debug output</i>"), <a href="#cl::Hidden">cl::Hidden</a>, <a href="#cl::location">cl::location</a>(DebugFlag));
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1067</pre>
Misha Brukman1fc9f8e2005-02-09 22:49:05 +0000[diff] [blame]1068</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1069
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1070<p>In the above example, we specify "<tt>true</tt>" as the second argument to
Misha Brukman1fc9f8e2005-02-09 22:49:05 +0000[diff] [blame]1071the <tt><a href="#cl::opt">cl::opt</a></tt> template, indicating that the
1072template should not maintain a copy of the value itself. In addition to this,
1073we specify the <tt><a href="#cl::location">cl::location</a></tt> attribute, so
1074that <tt>DebugFlag</tt> is automatically set.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1075
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1076</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1077
1078<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1079<div class="doc_subsection">
1080 <a name="attributes">Option Attributes</a>
1081</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1082
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1083<div class="doc_text">
1084
1085<p>This section describes the basic attributes that you can specify on
1086options.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1087
1088<ul>
1089
1090<li>The option name attribute (which is required for all options, except <a
1091href="#positional">positional options</a>) specifies what the option name is.
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1092This option is specified in simple double quotes:
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1093
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1094<pre>
1095<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]1096</pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1097
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1098</li>
1099
1100<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]1101description for the option to be shown in the <tt>--help</tt> output for the
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1102program.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1103
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1104<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]1105specifies a string that can be used to fine tune the <tt>--help</tt> output for
1106a command line option. Look <a href="#value_desc_example">here</a> for an
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1107example.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1108
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1109<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]1110inital value for a <a href="#cl::opt">scalar</a> option. If this attribute is
1111not specified then the command line option value defaults to the value created
Brian Gaeke9d292ff2003-08-19 22:56:22 +0000[diff] [blame]1112by the default constructor for the type. <b>Warning</b>: If you specify both
1113<b><tt>cl::init</tt></b> and <b><tt>cl::location</tt></b> for an option,
1114you must specify <b><tt>cl::location</tt></b> first, so that when the
1115command-line parser sees <b><tt>cl::init</tt></b>, it knows where to put the
1116initial 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]1117the right order.)</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1118
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1119<li><a name="cl::location">The <b><tt>cl::location</tt></b></a> attribute where to
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1120store the value for a parsed command line option if using external storage. See
1121the section on <a href="#storage">Internal vs External Storage</a> for more
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1122information.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1123
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1124<li><a name="cl::aliasopt">The <b><tt>cl::aliasopt</tt></b></a> attribute
Misha Brukman1fc9f8e2005-02-09 22:49:05 +0000[diff] [blame]1125specifies which option a <tt><a href="#cl::alias">cl::alias</a></tt> option is
1126an alias for.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1127
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1128<li><a name="cl::values">The <b><tt>cl::values</tt></b></a> attribute specifies
1129the string-to-value mapping to be used by the generic parser. It takes a
Chris Lattnerb406ead2004-07-16 00:10:54 +0000[diff] [blame]1130<b>clEnumValEnd terminated</b> list of (option, value, description) triplets
1131that
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1132specify the option name, the value mapped to, and the description shown in the
1133<tt>--help</tt> for the tool. Because the generic parser is used most
1134frequently with enum values, two macros are often useful:
1135
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1136<ol>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1137
1138<li><a name="clEnumVal">The <b><tt>clEnumVal</tt></b></a> macro is used as a
1139nice simple way to specify a triplet for an enum. This macro automatically
1140makes the option name be the same as the enum name. The first option to the
1141macro is the enum, the second is the description for the command line
1142option.</li>
1143
1144<li><a name="clEnumValN">The <b><tt>clEnumValN</tt></b></a> macro is used to
1145specify macro options where the option name doesn't equal the enum name. For
1146this macro, the first argument is the enum value, the second is the flag name,
1147and the second is the description.</li>
1148
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1149</ol>
1150
1151You 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]1152that does not support it.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1153
1154</ul>
1155
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1156</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1157
1158<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1159<div class="doc_subsection">
1160 <a name="modifiers">Option Modifiers</a>
1161</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1162
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1163<div class="doc_text">
1164
1165<p>Option modifiers are the flags and expressions that you pass into the
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1166constructors for <tt><a href="#cl::opt">cl::opt</a></tt> and <tt><a
1167href="#cl::list">cl::list</a></tt>. These modifiers give you the ability to
1168tweak how options are parsed and how <tt>--help</tt> output is generated to fit
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1169your application well.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1170
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1171<p>These options fall into five main catagories:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1172
1173<ol>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1174<li><a href="#hiding">Hiding an option from <tt>--help</tt> output</a></li>
1175<li><a href="#numoccurrences">Controlling the number of occurrences
1176 required and allowed</a></li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1177<li><a href="#valrequired">Controlling whether or not a value must be
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1178 specified</a></li>
1179<li><a href="#formatting">Controlling other formatting options</a></li>
1180<li><a href="#misc">Miscellaneous option modifiers</a></li>
1181</ol>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1182
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1183<p>It is not possible to specify two options from the same catagory (you'll get
1184a runtime error) to a single option, except for options in the miscellaneous
Chris Lattner32a32842003-05-22 20:36:06 +0000[diff] [blame]1185catagory. The CommandLine library specifies defaults for all of these settings
1186that are the most useful in practice and the most common, which mean that you
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1187usually shouldn't have to worry about these.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1188
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1189</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1190
1191<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1192<div class="doc_subsubsection">
1193 <a name="hiding">Hiding an option from <tt>--help</tt> output</a>
1194</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1195
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1196<div class="doc_text">
1197
1198<p>The <tt>cl::NotHidden</tt>, <tt>cl::Hidden</tt>, and
1199<tt>cl::ReallyHidden</tt> modifiers are used to control whether or not an option
1200appears in the <tt>--help</tt> and <tt>--help-hidden</tt> output for the
1201compiled program:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1202
1203<ul>
1204
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1205<li><a name="cl::NotHidden">The <b><tt>cl::NotHidden</tt></b></a> modifier
1206(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]1207href="#cl::list">cl::list</a></tt> options), indicates the option is to appear
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1208in both help listings.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1209
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1210<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]1211default for <tt><a href="#cl::alias">cl::alias</a></tt> options), indicates that
1212the option should not appear in the <tt>--help</tt> output, but should appear in
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1213the <tt>--help-hidden</tt> output.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1214
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1215<li><a name="cl::ReallyHidden">The <b><tt>cl::ReallyHidden</tt></b></a> modifier,
1216indicates that the option should not appear in any help output.</li>
1217
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1218</ul>
1219
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1220</div>
1221
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1222<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1223<div class="doc_subsubsection">
1224 <a name="numoccurrences">Controlling the number of occurrences required and
1225 allowed</a>
1226</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1227
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1228<div class="doc_text">
1229
1230<p>This group of options is used to control how many time an option is allowed
1231(or required) to be specified on the command line of your program. Specifying a
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1232value for this setting allows the CommandLine library to do error checking for
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1233you.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1234
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1235<p>The allowed values for this option group are:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1236
1237<ul>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1238
1239<li><a name="cl::Optional">The <b><tt>cl::Optional</tt></b></a> modifier (which
1240is 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]1241href="#cl::alias">cl::alias</a></tt> classes) indicates that your program will
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1242allow either zero or one occurrence of the option to be specified.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1243
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1244<li><a name="cl::ZeroOrMore">The <b><tt>cl::ZeroOrMore</tt></b></a> modifier
1245(which is the default for the <tt><a href="#cl::list">cl::list</a></tt> class)
1246indicates that your program will allow the option to be specified zero or more
1247times.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1248
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1249<li><a name="cl::Required">The <b><tt>cl::Required</tt></b></a> modifier
1250indicates that the specified option must be specified exactly one time.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1251
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1252<li><a name="cl::OneOrMore">The <b><tt>cl::OneOrMore</tt></b></a> modifier
1253indicates that the option must be specified at least one time.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1254
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1255<li>The <b><tt>cl::ConsumeAfter</tt></b> modifier is described in the <a
1256href="#positional">Positional arguments section</a></li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1257
1258</ul>
1259
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1260<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]1261value specified by the <tt><a href="#cl::init">cl::init</a></tt> attribute. If
1262the <tt><a href="#cl::init">cl::init</a></tt> attribute is not specified, the
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1263option value is initialized with the default constructor for the data type.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1264
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1265<p>If an option is specified multiple times for an option of the <tt><a
1266href="#cl::opt">cl::opt</a></tt> class, only the last value will be
1267retained.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1268
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1269</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1270
1271<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1272<div class="doc_subsubsection">
1273 <a name="valrequired">Controlling whether or not a value must be specified</a>
1274</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1275
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1276<div class="doc_text">
1277
1278<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]1279value to be present. In the case of the CommandLine library, a value is either
1280specified 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]1281string (e.g. '<tt>-o a.out</tt>').</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1282
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1283<p>The allowed values for this option group are:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1284
1285<ul>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1286
1287<li><a name="cl::ValueOptional">The <b><tt>cl::ValueOptional</tt></b></a> modifier
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1288(which is the default for <tt>bool</tt> typed options) specifies that it is
1289acceptable to have a value, or not. A boolean argument can be enabled just by
1290appearing on the command line, or it can have an explicit '<tt>-foo=true</tt>'.
1291If an option is specified with this mode, it is illegal for the value to be
1292provided without the equal sign. Therefore '<tt>-foo true</tt>' is illegal. To
1293get this behavior, you must use the <a
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1294href="#cl::ValueRequired">cl::ValueRequired</a> modifier.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1295
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1296<li><a name="cl::ValueRequired">The <b><tt>cl::ValueRequired</tt></b></a> modifier
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1297(which is the default for all other types except for <a
1298href="#onealternative">unnamed alternatives using the generic parser</a>)
1299specifies that a value must be provided. This mode informs the command line
1300library that if an option is not provides with an equal sign, that the next
1301argument provided must be the value. This allows things like '<tt>-o
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1302a.out</tt>' to work.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1303
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1304<li><a name="cl::ValueDisallowed">The <b><tt>cl::ValueDisallowed</tt></b></a>
1305modifier (which is the default for <a href="#onealternative">unnamed
1306alternatives using the generic parser</a>) indicates that it is a runtime error
1307for the user to specify a value. This can be provided to disallow users from
1308providing options to boolean options (like '<tt>-foo=true</tt>').</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1309
1310</ul>
1311
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1312<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]1313want them to. As mentioned above, you can specify the <a
1314href="#cl::ValueDisallowed">cl::ValueDisallowed</a> modifier to a boolean
1315argument to restrict your command line parser. These options are mostly useful
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1316when <a href="#extensionguide">extending the library</a>.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1317
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1318</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1319
1320<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1321<div class="doc_subsubsection">
1322 <a name="formatting">Controlling other formatting options</a>
1323</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1324
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1325<div class="doc_text">
1326
1327<p>The formatting option group is used to specify that the command line option
1328has special abilities and is otherwise different from other command line
1329arguments. As usual, you can only specify at most one of these arguments.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1330
1331<ul>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1332
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1333<li><a name="cl::NormalFormatting">The <b><tt>cl::NormalFormatting</tt></b></a>
1334modifier (which is the default all options) specifies that this option is
1335"normal".</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1336
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1337<li><a name="cl::Positional">The <b><tt>cl::Positional</tt></b></a> modifier
1338specifies that this is a positional argument, that does not have a command line
1339option associated with it. See the <a href="#positional">Positional
1340Arguments</a> section for more information.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1341
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1342<li>The <b><a href="#cl::ConsumeAfter"><tt>cl::ConsumeAfter</tt></a></b> modifier
1343specifies 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]1344
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1345<li><a name="cl::Prefix">The <b><tt>cl::Prefix</tt></b></a> modifier specifies
Reid Spencer5f8448f2004-11-24 06:13:42 +0000[diff] [blame]1346that this option prefixes its value. With 'Prefix' options, the equal sign does
1347not separate the value from the option name specified. Instead, the value is
1348everything after the prefix, including any equal sign if present. This is useful
1349for processing odd arguments like <tt>-lmalloc</tt> and <tt>-L/usr/lib</tt> in a
Misha Brukmanc43d9142005-05-10 22:05:27 +0000[diff] [blame]1350linker tool or <tt>-DNAME=value</tt> in a compiler tool. Here, the
Reid Spencer5f8448f2004-11-24 06:13:42 +0000[diff] [blame]1351'<tt>l</tt>', '<tt>D</tt>' and '<tt>L</tt>' options are normal string (or list)
Misha Brukmanc43d9142005-05-10 22:05:27 +0000[diff] [blame]1352options, that have the <b><tt><a href="#cl::Prefix">cl::Prefix</a></tt></b>
1353modifier added to allow the CommandLine library to recognize them. Note that
1354<b><tt><a href="#cl::Prefix">cl::Prefix</a></tt></b> options must not have the
1355<b><tt><a href="#cl::ValueDisallowed">cl::ValueDisallowed</a></tt></b> modifier
1356specified.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1357
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1358<li><a name="cl::Grouping">The <b><tt>cl::Grouping</tt></b></a> modifier is used
1359to implement unix style tools (like <tt>ls</tt>) that have lots of single letter
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1360arguments, but only require a single dash. For example, the '<tt>ls -labF</tt>'
1361command actually enables four different options, all of which are single
Misha Brukmanc43d9142005-05-10 22:05:27 +0000[diff] [blame]1362letters. Note that <b><tt><a href="#cl::Grouping">cl::Grouping</a></tt></b>
1363options cannot have values.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1364
1365</ul>
1366
Misha Brukmanc43d9142005-05-10 22:05:27 +0000[diff] [blame]1367<p>The CommandLine library does not restrict how you use the <b><tt><a
1368href="#cl::Prefix">cl::Prefix</a></tt></b> or <b><tt><a
1369href="#cl::Grouping">cl::Grouping</a></tt></b> modifiers, but it is possible to
1370specify ambiguous argument settings. Thus, it is possible to have multiple
1371letter options that are prefix or grouping options, and they will still work as
1372designed.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1373
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1374<p>To do this, the CommandLine library uses a greedy algorithm to parse the
1375input option into (potentially multiple) prefix and grouping options. The
1376strategy basically looks like this:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1377
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1378<div class="doc_code"><tt>parse(string OrigInput) {</tt>
Misha Brukmanc53aefb2004-05-12 18:42:35 +0000[diff] [blame]1379
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1380<ol>
1381<li><tt>string input = OrigInput;</tt>
1382<li><tt>if (isOption(input)) return getOption(input).parse();</tt>&nbsp;&nbsp;&nbsp;&nbsp;<i>// Normal option</i>
1383<li><tt>while (!isOption(input) &amp;&amp; !input.empty()) input.pop_back();</tt>&nbsp;&nbsp;&nbsp;&nbsp;<i>// Remove the last letter</i>
1384<li><tt>if (input.empty()) return error();</tt>&nbsp;&nbsp;&nbsp;&nbsp;<i>// No matching option</i>
1385<li><tt>if (getOption(input).isPrefix())<br>
1386&nbsp;&nbsp;return getOption(input).parse(input);</tt>
1387<li><tt>while (!input.empty()) {&nbsp;&nbsp;&nbsp;&nbsp;<i>// Must be grouping options</i><br>
1388&nbsp;&nbsp;getOption(input).parse();<br>
1389&nbsp;&nbsp;OrigInput.erase(OrigInput.begin(), OrigInput.begin()+input.length());<br>
1390&nbsp;&nbsp;input = OrigInput;<br>
1391&nbsp;&nbsp;while (!isOption(input) &amp;&amp; !input.empty()) input.pop_back();<br>
1392}</tt>
Misha Brukmanc53aefb2004-05-12 18:42:35 +0000[diff] [blame]1393<li><tt>if (!OrigInput.empty()) error();</tt></li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1394</ol>
Misha Brukmanc53aefb2004-05-12 18:42:35 +0000[diff] [blame]1395
1396<p><tt>}</tt></p>
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1397</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1398
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1399</div>
Chris Lattner32a32842003-05-22 20:36:06 +0000[diff] [blame]1400
1401<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1402<div class="doc_subsubsection">
1403 <a name="misc">Miscellaneous option modifiers</a>
1404</div>
Chris Lattner32a32842003-05-22 20:36:06 +0000[diff] [blame]1405
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1406<div class="doc_text">
1407
1408<p>The miscellaneous option modifiers are the only flags where you can specify
1409more than one flag from the set: they are not mutually exclusive. These flags
1410specify boolean properties that modify the option.</p>
Chris Lattner32a32842003-05-22 20:36:06 +0000[diff] [blame]1411
1412<ul>
1413
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1414<li><a name="cl::CommaSeparated">The <b><tt>cl::CommaSeparated</tt></b></a> modifier
Chris Lattner32a32842003-05-22 20:36:06 +0000[diff] [blame]1415indicates that any commas specified for an option's value should be used to
1416split the value up into multiple values for the option. For example, these two
1417options are equivalent when <tt>cl::CommaSeparated</tt> is specified:
1418"<tt>-foo=a -foo=b -foo=c</tt>" and "<tt>-foo=a,b,c</tt>". This option only
1419makes 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]1420more values (i.e. it is a <a href="#cl::list">cl::list</a> option).</li>
1421
Chris Lattnerbe801bf2004-05-06 22:03:59 +0000[diff] [blame]1422<li><a name="cl::PositionalEatsArgs">The
1423<b><tt>cl::PositionalEatsArgs</tt></b></a> modifier (which only applies to
1424positional arguments, and only makes sense for lists) indicates that positional
1425argument should consume any strings after it (including strings that start with
1426a "-") up until another recognized positional argument. For example, if you
1427have two "eating" positional arguments "<tt>pos1</tt>" and "<tt>pos2</tt>" the
1428string "<tt>-pos1 -foo -bar baz -pos2 -bork</tt>" would cause the "<tt>-foo -bar
1429-baz</tt>" strings to be applied to the "<tt>-pos1</tt>" option and the
1430"<tt>-bork</tt>" string to be applied to the "<tt>-pos2</tt>" option.</li>
1431
Chris Lattner32a32842003-05-22 20:36:06 +0000[diff] [blame]1432</ul>
1433
Chris Lattnerbe801bf2004-05-06 22:03:59 +0000[diff] [blame]1434<p>So far, these are the only two miscellaneous option modifiers.</p>
Chris Lattner32a32842003-05-22 20:36:06 +0000[diff] [blame]1435
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1436</div>
Chris Lattner32a32842003-05-22 20:36:06 +0000[diff] [blame]1437
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1438<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1439<div class="doc_subsection">
1440 <a name="toplevel">Top-Level Classes and Functions</a>
1441</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1442
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1443<div class="doc_text">
1444
1445<p>Despite all of the built-in flexibility, the CommandLine option library
1446really only consists of one function (<a
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1447href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>)
1448and three main classes: <a href="#cl::opt"><tt>cl::opt</tt></a>, <a
1449href="#cl::list"><tt>cl::list</tt></a>, and <a
1450href="#cl::alias"><tt>cl::alias</tt></a>. This section describes these three
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1451classes in detail.</p>
1452
1453</div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1454
1455<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1456<div class="doc_subsubsection">
1457 <a name="cl::ParseCommandLineOptions">The <tt>cl::ParseCommandLineOptions</tt>
1458 function</a>
1459</div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1460
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1461<div class="doc_text">
1462
1463<p>The <tt>cl::ParseCommandLineOptions</tt> function is designed to be called
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1464directly from <tt>main</tt>, and is used to fill in the values of all of the
1465command line option variables once <tt>argc</tt> and <tt>argv</tt> are
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1466available.</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1467
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1468<p>The <tt>cl::ParseCommandLineOptions</tt> function requires two parameters
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1469(<tt>argc</tt> and <tt>argv</tt>), but may also take an optional third parameter
1470which holds <a href="#description">additional extra text</a> to emit when the
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1471<tt>--help</tt> option is invoked.</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1472
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1473</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1474
1475<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1476<div class="doc_subsubsection">
1477 <a name="cl::ParseEnvironmentOptions">The <tt>cl::ParseEnvironmentOptions</tt>
1478 function</a>
1479</div>
Brian Gaekee5842852003-08-19 23:11:43 +0000[diff] [blame]1480
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1481<div class="doc_text">
Brian Gaekee5842852003-08-19 23:11:43 +0000[diff] [blame]1482
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1483<p>The <tt>cl::ParseEnvironmentOptions</tt> function has mostly the same effects
1484as <a
1485href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>,
1486except that it is designed to take values for options from an environment
1487variable, for those cases in which reading the command line is not convenient or
1488not desired. It fills in the values of all the command line option variables
1489just like <a
1490href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>
1491does.</p>
1492
1493<p>It takes three parameters: first, the name of the program (since
1494<tt>argv</tt> may not be available, it can't just look in <tt>argv[0]</tt>),
1495second, the name of the environment variable to examine, and third, the optional
Brian Gaekee5842852003-08-19 23:11:43 +0000[diff] [blame]1496<a href="#description">additional extra text</a> to emit when the
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1497<tt>--help</tt> option is invoked.</p>
Brian Gaekee5842852003-08-19 23:11:43 +0000[diff] [blame]1498
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1499<p><tt>cl::ParseEnvironmentOptions</tt> will break the environment
Brian Gaekee5842852003-08-19 23:11:43 +0000[diff] [blame]1500variable's value up into words and then process them using
1501<a href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>.
1502<b>Note:</b> Currently <tt>cl::ParseEnvironmentOptions</tt> does not support
1503quoting, so an environment variable containing <tt>-option "foo bar"</tt> will
1504be parsed as three words, <tt>-option</tt>, <tt>"foo</tt>, and <tt>bar"</tt>,
1505which is different from what you would get from the shell with the same
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1506input.</p>
1507
1508</div>
Brian Gaekee5842852003-08-19 23:11:43 +0000[diff] [blame]1509
1510<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1511<div class="doc_subsubsection">
Reid Spencer2403b852006-06-05 17:30:16 +0000[diff] [blame]1512 <a name="cl::SetVersionPrinter">The <tt>cl::SetVersionPrinter</tt>
1513 function</a>
1514</div>
1515
1516<div class="doc_text">
1517
1518<p>The <tt>cl::SetVersionPrinter</tt> function is designed to be called
1519directly from <tt>main</tt>, and <i>before</i>
1520<tt>cl::ParseCommandLineOptions</tt>. Its use is optional. It simply arranges
1521for a function to be called in response to the <tt>--version</tt> option instead
1522of having the <tt>CommandLine</tt> library print out the usual version string
1523for LLVM. This is useful for programs that are not part of LLVM but wish to use
1524the <tt>CommandLine</tt> facilities. Such programs should just define a small
1525function that takes no arguments and returns <tt>void</tt> and that prints out
1526whatever version information is appropriate for the program. Pass the address
1527of that function to <tt>cl::SetVersionPrinter</tt> to arrange for it to be
1528called when the <tt>--version</tt> option is given by the user.</p>
1529
1530</div>
1531<!-- _______________________________________________________________________ -->
1532<div class="doc_subsubsection">
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1533 <a name="cl::opt">The <tt>cl::opt</tt> class</a>
1534</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1535
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1536<div class="doc_text">
1537
1538<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]1539options, and is the one used most of the time. It is a templated class which
1540can take up to three arguments (all except for the first have default values
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1541though):</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1542
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1543<div class="doc_code"><pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1544<b>namespace</b> cl {
1545 <b>template</b> &lt;<b>class</b> DataType, <b>bool</b> ExternalStorage = <b>false</b>,
1546 <b>class</b> ParserClass = parser&lt;DataType&gt; &gt;
1547 <b>class</b> opt;
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1548}
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1549</pre></div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1550
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1551<p>The first template argument specifies what underlying data type the command
1552line argument is, and is used to select a default parser implementation. The
1553second template argument is used to specify whether the option should contain
1554the storage for the option (the default) or whether external storage should be
1555used to contain the value parsed for the option (see <a href="#storage">Internal
1556vs External Storage</a> for more information).</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1557
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1558<p>The third template argument specifies which parser to use. The default value
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1559selects an instantiation of the <tt>parser</tt> class based on the underlying
1560data type of the option. In general, this default works well for most
1561applications, so this option is only used when using a <a
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1562href="#customparser">custom parser</a>.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1563
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1564</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1565
1566<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1567<div class="doc_subsubsection">
1568 <a name="cl::list">The <tt>cl::list</tt> class</a>
1569</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1570
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1571<div class="doc_text">
1572
1573<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]1574line options. It too is a templated class which can take up to three
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1575arguments:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1576
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1577<div class="doc_code"><pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1578<b>namespace</b> cl {
1579 <b>template</b> &lt;<b>class</b> DataType, <b>class</b> Storage = <b>bool</b>,
1580 <b>class</b> ParserClass = parser&lt;DataType&gt; &gt;
1581 <b>class</b> list;
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1582}
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1583</pre></div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1584
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1585<p>This class works the exact same as the <a
1586href="#cl::opt"><tt>cl::opt</tt></a> class, except that the second argument is
1587the <b>type</b> of the external storage, not a boolean value. For this class,
1588the marker type '<tt>bool</tt>' is used to indicate that internal storage should
1589be used.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1590
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1591</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1592
1593<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1594<div class="doc_subsubsection">
Jim Laskey1d8f6262005-08-25 22:52:43 +0000[diff] [blame]1595 <a name="cl::bits">The <tt>cl::bits</tt> class</a>
1596</div>
1597
1598<div class="doc_text">
1599
1600<p>The <tt>cl::bits</tt> class is the class used to represent a list of command
1601line options in the form of a bit vector. It is also a templated class which
1602can take up to three arguments:</p>
1603
1604<div class="doc_code"><pre>
1605<b>namespace</b> cl {
1606 <b>template</b> &lt;<b>class</b> DataType, <b>class</b> Storage = <b>bool</b>,
1607 <b>class</b> ParserClass = parser&lt;DataType&gt; &gt;
1608 <b>class</b> bits;
1609}
1610</pre></div>
1611
1612<p>This class works the exact same as the <a
1613href="#cl::opt"><tt>cl::lists</tt></a> class, except that the second argument
Jim Laskey22b7dfa2005-08-26 09:25:54 +0000[diff] [blame]1614must be of <b>type</b> <tt>unsigned</tt> if external storage is used.</p>
Jim Laskey1d8f6262005-08-25 22:52:43 +0000[diff] [blame]1615
1616</div>
1617
1618<!-- _______________________________________________________________________ -->
1619<div class="doc_subsubsection">
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1620 <a name="cl::alias">The <tt>cl::alias</tt> class</a>
1621</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1622
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1623<div class="doc_text">
1624
1625<p>The <tt>cl::alias</tt> class is a nontemplated class that is used to form
1626aliases for other arguments.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1627
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1628<div class="doc_code"><pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1629<b>namespace</b> cl {
1630 <b>class</b> alias;
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1631}
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1632</pre></div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1633
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1634<p>The <a href="#cl::aliasopt"><tt>cl::aliasopt</tt></a> attribute should be
1635used to specify which option this is an alias for. Alias arguments default to
1636being <a href="#cl::Hidden">Hidden</a>, and use the aliased options parser to do
1637the conversion from string to data.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1638
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1639</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1640
Reid Spencer9bbba0912004-11-16 06:11:52 +0000[diff] [blame]1641<!-- _______________________________________________________________________ -->
1642<div class="doc_subsubsection">
1643 <a name="cl::extrahelp">The <tt>cl::extrahelp</tt> class</a>
1644</div>
1645
1646<div class="doc_text">
1647
1648<p>The <tt>cl::extrahelp</tt> class is a nontemplated class that allows extra
1649help text to be printed out for the <tt>--help</tt> option.</p>
1650
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1651<div class="doc_code"><pre>
Reid Spencer9bbba0912004-11-16 06:11:52 +0000[diff] [blame]1652<b>namespace</b> cl {
1653 <b>struct</b> extrahelp;
1654}
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1655</pre></div>
Reid Spencer9bbba0912004-11-16 06:11:52 +0000[diff] [blame]1656
1657<p>To use the extrahelp, simply construct one with a <tt>const char*</tt>
1658parameter to the constructor. The text passed to the constructor will be printed
1659at the bottom of the help message, verbatim. Note that multiple
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1660<tt>cl::extrahelp</tt> <b>can</b> be used, but this practice is discouraged. If
Reid Spencer9bbba0912004-11-16 06:11:52 +0000[diff] [blame]1661your tool needs to print additional help information, put all that help into a
1662single <tt>cl::extrahelp</tt> instance.</p>
1663<p>For example:</p>
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1664<div class="doc_code"><pre>
Reid Spencer9bbba0912004-11-16 06:11:52 +0000[diff] [blame]1665 cl::extrahelp("\nADDITIONAL HELP:\n\n This is the extra help\n");
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1666</pre></div>
Reid Spencer9bbba0912004-11-16 06:11:52 +0000[diff] [blame]1667</div>
1668
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1669<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1670<div class="doc_subsection">
1671 <a name="builtinparsers">Builtin parsers</a>
1672</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1673
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1674<div class="doc_text">
1675
1676<p>Parsers control how the string value taken from the command line is
1677translated into a typed value, suitable for use in a C++ program. By default,
1678the CommandLine library uses an instance of <tt>parser&lt;type&gt;</tt> if the
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1679command line option specifies that it uses values of type '<tt>type</tt>'.
1680Because of this, custom option processing is specified with specializations of
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1681the '<tt>parser</tt>' class.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1682
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1683<p>The CommandLine library provides the following builtin parser
1684specializations, which are sufficient for most applications. It can, however,
1685also be extended to work with new data types and new ways of interpreting the
1686same data. See the <a href="#customparser">Writing a Custom Parser</a> for more
1687details on this type of library extension.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1688
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1689<ul>
1690
1691<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]1692can be used to map strings values to any data type, through the use of the <a
1693href="#cl::values">cl::values</a> property, which specifies the mapping
1694information. The most common use of this parser is for parsing enum values,
1695which allows you to use the CommandLine library for all of the error checking to
1696make sure that only valid enum values are specified (as opposed to accepting
1697arbitrary strings). Despite this, however, the generic parser class can be used
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1698for any data type.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1699
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1700<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]1701is used to convert boolean strings to a boolean value. Currently accepted
1702strings are "<tt>true</tt>", "<tt>TRUE</tt>", "<tt>True</tt>", "<tt>1</tt>",
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1703"<tt>false</tt>", "<tt>FALSE</tt>", "<tt>False</tt>", and "<tt>0</tt>".</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1704
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1705<li><a name="stringparser">The <b><tt>parser&lt;string&gt;</tt>
1706specialization</b></a> simply stores the parsed string into the string value
1707specified. No conversion or modification of the data is performed.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1708
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1709<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]1710uses the C <tt>strtol</tt> function to parse the string input. As such, it will
1711accept a decimal number (with an optional '+' or '-' prefix) which must start
1712with a non-zero digit. It accepts octal numbers, which are identified with a
1713'<tt>0</tt>' prefix digit, and hexadecimal numbers with a prefix of
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1714'<tt>0x</tt>' or '<tt>0X</tt>'.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1715
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1716<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]1717<b><tt>parser&lt;float&gt;</tt> specializations</b> use the standard C
1718<tt>strtod</tt> function to convert floating point strings into floating point
1719values. As such, a broad range of string formats is supported, including
1720exponential notation (ex: <tt>1.7e15</tt>) and properly supports locales.
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1721</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1722
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1723</ul>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]1724
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1725</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]1726
1727<!-- *********************************************************************** -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1728<div class="doc_section">
1729 <a name="extensionguide">Extension Guide</a>
1730</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]1731<!-- *********************************************************************** -->
1732
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1733<div class="doc_text">
1734
1735<p>Although the CommandLine library has a lot of functionality built into it
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1736already (as discussed previously), one of its true strengths lie in its
1737extensibility. This section discusses how the CommandLine library works under
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1738the covers and illustrates how to do some simple, common, extensions.</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1739
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1740</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]1741
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1742<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1743<div class="doc_subsection">
1744 <a name="customparser">Writing a custom parser</a>
1745</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1746
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1747<div class="doc_text">
1748
1749<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]1750As <a href="#builtinparsers">discussed previously</a>, parsers are the portion
1751of the CommandLine library that turns string input from the user into a
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1752particular parsed data type, validating the input in the process.</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1753
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1754<p>There are two ways to use a new parser:</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1755
1756<ol>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1757
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1758<li>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1759
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1760<p>Specialize the <a href="#genericparser"><tt>cl::parser</tt></a> template for
1761your custom data type.<p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1762
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1763<p>This approach has the advantage that users of your custom data type will
1764automatically use your custom parser whenever they define an option with a value
1765type of your data type. The disadvantage of this approach is that it doesn't
1766work if your fundemental data type is something that is already supported.</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1767
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1768</li>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1769
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1770<li>
1771
1772<p>Write an independent class, using it explicitly from options that need
1773it.</p>
1774
1775<p>This approach works well in situations where you would line to parse an
1776option using special syntax for a not-very-special data-type. The drawback of
1777this approach is that users of your parser have to be aware that they are using
1778your parser, instead of the builtin ones.</p>
1779
1780</li>
1781
1782</ol>
1783
1784<p>To guide the discussion, we will discuss a custom parser that accepts file
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1785sizes, specified with an optional unit after the numeric size. For example, we
1786would like to parse "102kb", "41M", "1G" into the appropriate integer value. In
1787this case, the underlying data type we want to parse into is
1788'<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]1789this the default for all <tt>unsigned</tt> options.</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1790
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1791<p>To start out, we declare our new <tt>FileSizeParser</tt> class:</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1792
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1793<div class="doc_code"><pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1794<b>struct</b> FileSizeParser : <b>public</b> cl::basic_parser&lt;<b>unsigned</b>&gt; {
1795 <i>// parse - Return true on error.</i>
1796 <b>bool</b> parse(cl::Option &amp;O, <b>const char</b> *ArgName, <b>const</b> std::string &amp;ArgValue,
1797 <b>unsigned</b> &amp;Val);
1798};
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1799</pre></div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1800
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1801<p>Our new class inherits from the <tt>cl::basic_parser</tt> template class to
1802fill in the default, boiler plate, code for us. We give it the data type that
1803we 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]1804our 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]1805declare that we parse into '<tt>unsigned</tt>' variables.</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1806
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1807<p>For most purposes, the only method that must be implemented in a custom
1808parser is the <tt>parse</tt> method. The <tt>parse</tt> method is called
1809whenever the option is invoked, passing in the option itself, the option name,
1810the string to parse, and a reference to a return value. If the string to parse
1811is not well formed, the parser should output an error message and return true.
1812Otherwise it should return false and set '<tt>Val</tt>' to the parsed value. In
1813our example, we implement <tt>parse</tt> as:</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1814
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1815<div class="doc_code"><pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1816<b>bool</b> FileSizeParser::parse(cl::Option &amp;O, <b>const char</b> *ArgName,
1817 <b>const</b> std::string &amp;Arg, <b>unsigned</b> &amp;Val) {
1818 <b>const char</b> *ArgStart = Arg.c_str();
1819 <b>char</b> *End;
1820
1821 <i>// Parse integer part, leaving 'End' pointing to the first non-integer char</i>
1822 Val = (unsigned)strtol(ArgStart, &amp;End, 0);
1823
1824 <b>while</b> (1) {
1825 <b>switch</b> (*End++) {
Chris Lattnerce5fcc32005-08-22 16:24:25 +0000[diff] [blame]1826 <b>case</b> 0: <b>return</b> false; <i>// No error</i>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1827 <b>case</b> 'i': <i>// Ignore the 'i' in KiB if people use that</i>
1828 <b>case</b> 'b': <b>case</b> 'B': <i>// Ignore B suffix</i>
1829 <b>break</b>;
1830
1831 <b>case</b> 'g': <b>case</b> 'G': Val *= 1024*1024*1024; <b>break</b>;
1832 <b>case</b> 'm': <b>case</b> 'M': Val *= 1024*1024; <b>break</b>;
1833 <b>case</b> 'k': <b>case</b> 'K': Val *= 1024; <b>break</b>;
1834
1835 default:
1836 <i>// Print an error message if unrecognized character!</i>
1837 <b>return</b> O.error(": '" + Arg + "' value invalid for file size argument!");
1838 }
1839 }
1840}
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1841</pre></div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1842
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1843<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]1844interested in. Although it has some holes (it allows "<tt>123KKK</tt>" for
1845example), it is good enough for this example. Note that we use the option
1846itself to print out the error message (the <tt>error</tt> method always returns
1847true) 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]1848parser class, we can use it like this:</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1849
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1850<div class="doc_code"><pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1851<b>static</b> <a href="#cl::opt">cl::opt</a>&lt;<b>unsigned</b>, <b>false</b>, FileSizeParser&gt;
1852MFS(<i>"max-file-size"</i>, <a href="#cl::desc">cl::desc</a>(<i>"Maximum file size to accept"</i>),
1853 <a href="#cl::value_desc">cl::value_desc</a>("<i>size</i>"));
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1854</pre></div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1855
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1856<p>Which adds this to the output of our program:</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1857
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1858<div class="doc_code"><pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1859OPTIONS:
1860 -help - display available options (--help-hidden for more)
1861 ...
1862 <b>-max-file-size=&lt;size&gt; - Maximum file size to accept</b>
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1863</pre></div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1864
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1865<p>And we can test that our parse works correctly now (the test program just
1866prints out the max-file-size argument value):</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1867
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1868<div class="doc_code"><pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1869$ ./test
1870MFS: 0
1871$ ./test -max-file-size=123MB
1872MFS: 128974848
1873$ ./test -max-file-size=3G
1874MFS: 3221225472
1875$ ./test -max-file-size=dog
1876-max-file-size option: 'dog' value invalid for file size argument!
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1877</pre></div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1878
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1879<p>It looks like it works. The error message that we get is nice and helpful,
1880and we seem to accept reasonable file sizes. This wraps up the "custom parser"
1881tutorial.</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1882
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1883</div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1884
1885<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1886<div class="doc_subsection">
1887 <a name="explotingexternal">Exploiting external storage</a>
1888</div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1889
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1890<div class="doc_text">
Reid Spencerb993feb2004-08-30 05:56:51 +0000[diff] [blame]1891 <p>Several of the LLVM libraries define static <tt>cl::opt</tt> instances that
1892 will automatically be included in any program that links with that library.
1893 This is a feature. However, sometimes it is necessary to know the value of the
1894 command line option outside of the library. In these cases the library does or
1895 should provide an external storage location that is accessible to users of the
1896 library. Examples of this include the <tt>llvm::DebugFlag</tt> exported by the
1897 <tt>lib/Support/Debug.cpp</tt> file and the <tt>llvm::TimePassesIsEnabled</tt>
1898 flag exported by the <tt>lib/VMCore/Pass.cpp</tt> file.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1899
Reid Spencerb993feb2004-08-30 05:56:51 +0000[diff] [blame]1900<p>TODO: complete this section</p>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1901
1902</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1903
1904<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1905<div class="doc_subsection">
1906 <a name="dynamicopts">Dynamically adding command line options</a>
1907</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1908
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1909<div class="doc_text">
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1910
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1911<p>TODO: fill in this section</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]1912
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1913</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]1914
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]1915<!-- *********************************************************************** -->
1916
1917<hr>
Misha Brukmanc53aefb2004-05-12 18:42:35 +0000[diff] [blame]1918<address>
1919 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
1920 src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
1921 <a href="http://validator.w3.org/check/referer"><img
1922 src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!"></a>
1923
1924 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
Reid Spencer05fe4b02006-03-14 05:39:39 +0000[diff] [blame]1925 <a href="http://llvm.org">LLVM Compiler Infrastructure</a><br>
Misha Brukman3c299112003-11-07 18:11:14 +0000[diff] [blame]1926 Last modified: $Date$
Misha Brukmanc53aefb2004-05-12 18:42:35 +0000[diff] [blame]1927</address>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1928
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