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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>
Anton Korobeynikov45982a52008-02-20 12:38:31 +0000[diff] [blame]47 <li><a href="#hiding">Hiding an option from <tt>--help</tt>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]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>
Mikhail Glushenkovbeb4d822008-04-28 16:44:25 +0000[diff] [blame]55 <li><a href="#response">Response files</a></li>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]56 </ul></li>
57
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]58 <li><a href="#toplevel">Top-Level Classes and Functions</a>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]59 <ul>
Anton Korobeynikov45982a52008-02-20 12:38:31 +0000[diff] [blame]60 <li><a href="#cl::ParseCommandLineOptions">The
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]61 <tt>cl::ParseCommandLineOptions</tt> function</a></li>
Anton Korobeynikov45982a52008-02-20 12:38:31 +0000[diff] [blame]62 <li><a href="#cl::ParseEnvironmentOptions">The
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]63 <tt>cl::ParseEnvironmentOptions</tt> function</a></li>
Chris Lattnerf021f8a2007-12-19 19:48:49 +0000[diff] [blame]64 <li><a href="#cl::SetVersionPrinter">The <tt>cl::SetVersionPrinter</tt>
Reid Spencer2403b852006-06-05 17:30:16 +0000[diff] [blame]65 function</a></li>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]66 <li><a href="#cl::opt">The <tt>cl::opt</tt> class</a></li>
67 <li><a href="#cl::list">The <tt>cl::list</tt> class</a></li>
Jim Laskey1d8f6262005-08-25 22:52:43 +0000[diff] [blame]68 <li><a href="#cl::bits">The <tt>cl::bits</tt> class</a></li>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]69 <li><a href="#cl::alias">The <tt>cl::alias</tt> class</a></li>
Reid Spencer9bbba0912004-11-16 06:11:52 +0000[diff] [blame]70 <li><a href="#cl::extrahelp">The <tt>cl::extrahelp</tt> class</a></li>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]71 </ul></li>
72
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]73 <li><a href="#builtinparsers">Builtin parsers</a>
74 <ul>
75 <li><a href="#genericparser">The Generic <tt>parser&lt;t&gt;</tt>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]76 parser</a></li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]77 <li><a href="#boolparser">The <tt>parser&lt;bool&gt;</tt>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]78 specialization</a></li>
Dale Johannesen0f2c8fc2007-05-22 18:32:34 +0000[diff] [blame]79 <li><a href="#boolOrDefaultparser">The <tt>parser&lt;boolOrDefault&gt;</tt>
80 specialization</a></li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]81 <li><a href="#stringparser">The <tt>parser&lt;string&gt;</tt>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]82 specialization</a></li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]83 <li><a href="#intparser">The <tt>parser&lt;int&gt;</tt>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]84 specialization</a></li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]85 <li><a href="#doubleparser">The <tt>parser&lt;double&gt;</tt> and
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]86 <tt>parser&lt;float&gt;</tt> specializations</a></li>
87 </ul></li>
88 </ol></li>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]89 <li><a href="#extensionguide">Extension Guide</a>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]90 <ol>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]91 <li><a href="#customparser">Writing a custom parser</a></li>
92 <li><a href="#explotingexternal">Exploiting external storage</a></li>
Anton Korobeynikov45982a52008-02-20 12:38:31 +0000[diff] [blame]93 <li><a href="#dynamicopts">Dynamically adding command line
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]94 options</a></li>
95 </ol></li>
96</ol>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]97
Chris Lattner7911ce22004-05-23 21:07:27 +0000[diff] [blame]98<div class="doc_author">
99 <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a></p>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]100</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]101
102<!-- *********************************************************************** -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]103<div class="doc_section">
Misha Brukman8becd712003-11-07 19:42:44 +0000[diff] [blame]104 <a name="introduction">Introduction</a>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]105</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]106<!-- *********************************************************************** -->
107
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]108<div class="doc_text">
109
110<p>This document describes the CommandLine argument processing library. It will
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]111show you how to use it, and what it can do. The CommandLine library uses a
112declarative approach to specifying the command line options that your program
113takes. By default, these options declarations implicitly hold the value parsed
114for the option declared (of course this <a href="#storage">can be
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]115changed</a>).</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]116
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]117<p>Although there are a <b>lot</b> of command line argument parsing libraries
118out there in many different languages, none of them fit well with what I needed.
119By looking at the features and problems of other libraries, I designed the
120CommandLine library to have the following features:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]121
122<ol>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]123<li>Speed: The CommandLine library is very quick and uses little resources. The
124parsing time of the library is directly proportional to the number of arguments
125parsed, not the the number of options recognized. Additionally, command line
Chris Lattneredf351f2003-06-21 21:45:56 +0000[diff] [blame]126argument values are captured transparently into user defined global variables,
127which can be accessed like any other variable (and with the same
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]128performance).</li>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]129
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]130<li>Type Safe: As a user of CommandLine, you don't have to worry about
131remembering the type of arguments that you want (is it an int? a string? a
132bool? an enum?) and keep casting it around. Not only does this help prevent
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]133error prone constructs, it also leads to dramatically cleaner source code.</li>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]134
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]135<li>No subclasses required: To use CommandLine, you instantiate variables that
136correspond to the arguments that you would like to capture, you don't subclass a
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]137parser. This means that you don't have to write <b>any</b> boilerplate
138code.</li>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]139
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]140<li>Globally accessible: Libraries can specify command line arguments that are
141automatically enabled in any tool that links to the library. This is possible
Chris Lattner8b44b902008-01-09 19:28:50 +0000[diff] [blame]142because the application doesn't have to keep a list of arguments to pass to
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]143the parser. This also makes supporting <a href="#dynamicopts">dynamically
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]144loaded options</a> trivial.</li>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]145
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]146<li>Cleaner: CommandLine supports enum and other types directly, meaning that
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]147there is less error and more security built into the library. You don't have to
148worry about whether your integral command line argument accidentally got
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]149assigned a value that is not valid for your enum type.</li>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]150
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]151<li>Powerful: The CommandLine library supports many different types of
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]152arguments, from simple <a href="#boolparser">boolean flags</a> to <a
153href="#cl::opt">scalars arguments</a> (<a href="#stringparser">strings</a>, <a
154href="#intparser">integers</a>, <a href="#genericparser">enums</a>, <a
155href="#doubleparser">doubles</a>), to <a href="#cl::list">lists of
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]156arguments</a>. This is possible because CommandLine is...</li>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]157
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]158<li>Extensible: It is very simple to add a new argument type to CommandLine.
159Simply specify the parser that you want to use with the command line option when
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]160you declare it. <a href="#customparser">Custom parsers</a> are no problem.</li>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]161
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]162<li>Labor Saving: The CommandLine library cuts down on the amount of grunt work
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]163that you, the user, have to do. For example, it automatically provides a
164<tt>--help</tt> option that shows the available command line options for your
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]165tool. Additionally, it does most of the basic correctness checking for
166you.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]167
168<li>Capable: The CommandLine library can handle lots of different forms of
169options often found in real programs. For example, <a
170href="#positional">positional</a> arguments, <tt>ls</tt> style <a
171href="#cl::Grouping">grouping</a> options (to allow processing '<tt>ls
172-lad</tt>' naturally), <tt>ld</tt> style <a href="#cl::Prefix">prefix</a>
173options (to parse '<tt>-lmalloc -L/usr/lib</tt>'), and <a
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]174href="#cl::ConsumeAfter">interpreter style options</a>.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]175
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]176</ol>
177
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]178<p>This document will hopefully let you jump in and start using CommandLine in
179your utility quickly and painlessly. Additionally it should be a simple
180reference manual to figure out how stuff works. If it is failing in some area
181(or you want an extension to the library), nag the author, <a
182href="mailto:sabre@nondot.org">Chris Lattner</a>.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]183
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]184</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]185
186<!-- *********************************************************************** -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]187<div class="doc_section">
188 <a name="quickstart">Quick Start Guide</a>
189</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]190<!-- *********************************************************************** -->
191
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]192<div class="doc_text">
193
194<p>This section of the manual runs through a simple CommandLine'ification of a
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]195basic compiler tool. This is intended to show you how to jump into using the
196CommandLine library in your own program, and show you some of the cool things it
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]197can do.</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]198
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]199<p>To start out, you need to include the CommandLine header file into your
200program:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]201
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]202<div class="doc_code"><pre>
Andrew Lenharth94f3d1a2005-11-14 19:32:05 +0000[diff] [blame]203 #include "llvm/Support/CommandLine.h"
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]204</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]205
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]206<p>Additionally, you need to add this as the first line of your main
207program:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]208
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]209<div class="doc_code"><pre>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]210int main(int argc, char **argv) {
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]211 <a href="#cl::ParseCommandLineOptions">cl::ParseCommandLineOptions</a>(argc, argv);
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]212 ...
213}
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]214</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]215
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]216<p>... which actually parses the arguments and fills in the variable
217declarations.</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]218
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]219<p>Now that you are ready to support command line arguments, we need to tell the
Chris Lattner8b44b902008-01-09 19:28:50 +0000[diff] [blame]220system which ones we want, and what type of arguments they are. The CommandLine
Chris Lattneredf351f2003-06-21 21:45:56 +0000[diff] [blame]221library uses a declarative syntax to model command line arguments with the
222global variable declarations that capture the parsed values. This means that
223for every command line option that you would like to support, there should be a
224global variable declaration to capture the result. For example, in a compiler,
Chris Lattner8b44b902008-01-09 19:28:50 +0000[diff] [blame]225we would like to support the Unix-standard '<tt>-o &lt;filename&gt;</tt>' option
Chris Lattneredf351f2003-06-21 21:45:56 +0000[diff] [blame]226to specify where to put the output. With the CommandLine library, this is
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]227represented like this:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]228
Misha Brukmanc53aefb2004-05-12 18:42:35 +0000[diff] [blame]229<a name="value_desc_example"></a>
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]230<div class="doc_code"><pre>
Misha Brukmanc53aefb2004-05-12 18:42:35 +0000[diff] [blame]231<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]232</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]233
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]234<p>This declares a global variable "<tt>OutputFilename</tt>" that is used to
Chris Lattneredf351f2003-06-21 21:45:56 +0000[diff] [blame]235capture the result of the "<tt>o</tt>" argument (first parameter). We specify
236that this is a simple scalar option by using the "<tt><a
237href="#cl::opt">cl::opt</a></tt>" template (as opposed to the <a
238href="#list">"<tt>cl::list</tt> template</a>), and tell the CommandLine library
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]239that the data type that we are parsing is a string.</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]240
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]241<p>The second and third parameters (which are optional) are used to specify what
242to output for the "<tt>--help</tt>" option. In this case, we get a line that
243looks like this:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]244
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]245<div class="doc_code"><pre>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]246USAGE: compiler [options]
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]247
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]248OPTIONS:
249 -help - display available options (--help-hidden for more)
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]250 <b>-o &lt;filename&gt; - Specify output filename</b>
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]251</pre></div>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]252
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]253<p>Because we specified that the command line option should parse using the
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]254<tt>string</tt> data type, the variable declared is automatically usable as a
255real string in all contexts that a normal C++ string object may be used. For
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]256example:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]257
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]258<div class="doc_code"><pre>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]259 ...
Chris Lattner74ba1712008-03-30 16:59:21 +0000[diff] [blame]260 std::ofstream Output(OutputFilename.c_str());
261 if (Output.good()) ...
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]262 ...
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]263</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]264
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]265<p>There are many different options that you can use to customize the command
266line option handling library, but the above example shows the general interface
267to these options. The options can be specified in any order, and are specified
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]268with helper functions like <a href="#cl::desc"><tt>cl::desc(...)</tt></a>, so
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]269there are no positional dependencies to remember. The available options are
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]270discussed in detail in the <a href="#referenceguide">Reference Guide</a>.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]271
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]272<p>Continuing the example, we would like to have our compiler take an input
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]273filename as well as an output filename, but we do not want the input filename to
274be specified with a hyphen (ie, not <tt>-filename.c</tt>). To support this
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]275style of argument, the CommandLine library allows for <a
276href="#positional">positional</a> arguments to be specified for the program.
277These positional arguments are filled with command line parameters that are not
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]278in option form. We use this feature like this:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]279
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]280<div class="doc_code"><pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]281<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]282</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]283
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]284<p>This declaration indicates that the first positional argument should be
285treated as the input filename. Here we use the <tt><a
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]286href="#cl::init">cl::init</a></tt> option to specify an initial value for the
287command line option, which is used if the option is not specified (if you do not
288specify a <tt><a href="#cl::init">cl::init</a></tt> modifier for an option, then
289the default constructor for the data type is used to initialize the value).
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]290Command line options default to being optional, so if we would like to require
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]291that the user always specify an input filename, we would add the <tt><a
292href="#cl::Required">cl::Required</a></tt> flag, and we could eliminate the
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]293<tt><a href="#cl::init">cl::init</a></tt> modifier, like this:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]294
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]295<div class="doc_code"><pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]296<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]297</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]298
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]299<p>Again, the CommandLine library does not require the options to be specified
300in any particular order, so the above declaration is equivalent to:</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]301
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]302<div class="doc_code"><pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]303<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]304</pre></div>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]305
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]306<p>By simply adding the <tt><a href="#cl::Required">cl::Required</a></tt> flag,
307the CommandLine library will automatically issue an error if the argument is not
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]308specified, which shifts all of the command line option verification code out of
309your application into the library. This is just one example of how using flags
310can alter the default behaviour of the library, on a per-option basis. By
311adding one of the declarations above, the <tt>--help</tt> option synopsis is now
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]312extended to:</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]313
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]314<div class="doc_code"><pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]315USAGE: compiler [options] <b>&lt;input file&gt;</b>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]316
317OPTIONS:
318 -help - display available options (--help-hidden for more)
319 -o &lt;filename&gt; - Specify output filename
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]320</pre></div>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]321
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]322<p>... indicating that an input filename is expected.</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]323
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]324</div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]325
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]326<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]327<div class="doc_subsection">
328 <a name="bool">Boolean Arguments</a>
329</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]330
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]331<div class="doc_text">
332
333<p>In addition to input and output filenames, we would like the compiler example
334to support three boolean flags: "<tt>-f</tt>" to force overwriting of the output
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]335file, "<tt>--quiet</tt>" to enable quiet mode, and "<tt>-q</tt>" for backwards
336compatibility with some of our users. We can support these by declaring options
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]337of boolean type like this:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]338
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]339<div class="doc_code"><pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]340<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>"));
341<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>"));
342<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]343</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]344
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]345<p>This does what you would expect: it declares three boolean variables
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]346("<tt>Force</tt>", "<tt>Quiet</tt>", and "<tt>Quiet2</tt>") to recognize these
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]347options. Note that the "<tt>-q</tt>" option is specified with the "<a
348href="#cl::Hidden"><tt>cl::Hidden</tt></a>" flag. This modifier prevents it
349from being shown by the standard "<tt>--help</tt>" output (note that it is still
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]350shown in the "<tt>--help-hidden</tt>" output).</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]351
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]352<p>The CommandLine library uses a <a href="#builtinparsers">different parser</a>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]353for different data types. For example, in the string case, the argument passed
354to the option is copied literally into the content of the string variable... we
355obviously cannot do that in the boolean case, however, so we must use a smarter
356parser. In the case of the boolean parser, it allows no options (in which case
357it assigns the value of true to the variable), or it allows the values
358"<tt>true</tt>" or "<tt>false</tt>" to be specified, allowing any of the
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]359following inputs:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]360
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]361<div class="doc_code"><pre>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]362 compiler -f # No value, 'Force' == true
363 compiler -f=true # Value specified, 'Force' == true
364 compiler -f=TRUE # Value specified, 'Force' == true
365 compiler -f=FALSE # Value specified, 'Force' == false
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]366</pre></div>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]367
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]368<p>... you get the idea. The <a href="#boolparser">bool parser</a> just turns
369the string values into boolean values, and rejects things like '<tt>compiler
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]370-f=foo</tt>'. Similarly, the <a href="#doubleparser">float</a>, <a
371href="#doubleparser">double</a>, and <a href="#intparser">int</a> parsers work
372like you would expect, using the '<tt>strtol</tt>' and '<tt>strtod</tt>' C
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]373library calls to parse the string value into the specified data type.</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]374
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]375<p>With the declarations above, "<tt>compiler --help</tt>" emits this:</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]376
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]377<div class="doc_code"><pre>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]378USAGE: compiler [options] &lt;input file&gt;
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]379
380OPTIONS:
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]381 <b>-f - Overwrite output files</b>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]382 -o - Override output filename
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]383 <b>-quiet - Don't print informational messages</b>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]384 -help - display available options (--help-hidden for more)
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]385</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]386
Chris Lattner8b44b902008-01-09 19:28:50 +0000[diff] [blame]387<p>and "<tt>compiler --help-hidden</tt>" prints this:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]388
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]389<div class="doc_code"><pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]390USAGE: compiler [options] &lt;input file&gt;
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]391
392OPTIONS:
393 -f - Overwrite output files
394 -o - Override output filename
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]395 <b>-q - Don't print informational messages</b>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]396 -quiet - Don't print informational messages
397 -help - display available options (--help-hidden for more)
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]398</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]399
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]400<p>This brief example has shown you how to use the '<tt><a
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]401href="#cl::opt">cl::opt</a></tt>' class to parse simple scalar command line
402arguments. In addition to simple scalar arguments, the CommandLine library also
403provides primitives to support CommandLine option <a href="#alias">aliases</a>,
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]404and <a href="#list">lists</a> of options.</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]405
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]406</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]407
408<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]409<div class="doc_subsection">
410 <a name="alias">Argument Aliases</a>
411</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]412
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]413<div class="doc_text">
414
415<p>So far, the example works well, except for the fact that we need to check the
416quiet condition like this now:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]417
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]418<div class="doc_code"><pre>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]419...
420 if (!Quiet &amp;&amp; !Quiet2) printInformationalMessage(...);
421...
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]422</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]423
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]424<p>... which is a real pain! Instead of defining two values for the same
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]425condition, 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]426option an <b>alias</b> for the "<tt>-quiet</tt>" option, instead of providing
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]427a value itself:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]428
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]429<div class="doc_code"><pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]430<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>"));
431<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>"));
432<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]433</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]434
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]435<p>The third line (which is the only one we modified from above) defines a
Chris Lattner8b44b902008-01-09 19:28:50 +0000[diff] [blame]436"<tt>-q</tt>" alias that updates the "<tt>Quiet</tt>" variable (as specified by
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]437the <tt><a href="#cl::aliasopt">cl::aliasopt</a></tt> modifier) whenever it is
438specified. Because aliases do not hold state, the only thing the program has to
439query is the <tt>Quiet</tt> variable now. Another nice feature of aliases is
440that they automatically hide themselves from the <tt>-help</tt> output
441(although, again, they are still visible in the <tt>--help-hidden
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]442output</tt>).</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]443
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]444<p>Now the application code can simply use:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]445
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]446<div class="doc_code"><pre>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]447...
448 if (!Quiet) printInformationalMessage(...);
449...
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]450</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]451
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]452<p>... which is much nicer! The "<tt><a href="#cl::alias">cl::alias</a></tt>"
453can be used to specify an alternative name for any variable type, and has many
454uses.</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]455
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]456</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]457
458<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]459<div class="doc_subsection">
460 <a name="onealternative">Selecting an alternative from a set of
461 possibilities</a>
462</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]463
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]464<div class="doc_text">
465
Chris Lattner8b44b902008-01-09 19:28:50 +0000[diff] [blame]466<p>So far we have seen how the CommandLine library handles builtin types like
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]467<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]468things it doesn't know about, like enums or '<tt>int*</tt>'s?</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]469
Chris Lattner8b44b902008-01-09 19:28:50 +0000[diff] [blame]470<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]471your own parser, as described in the <a href="#extensionguide">Extension
Reid Spencerd8473372004-08-10 16:38:18 +0000[diff] [blame]472Guide</a>). This parser maps literal strings to whatever type is required, and
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]473requires you to tell it what this mapping should be.</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]474
Chris Lattner8b44b902008-01-09 19:28:50 +0000[diff] [blame]475<p>Let's say that we would like to add four optimization levels to our
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]476optimizer, using the standard flags "<tt>-g</tt>", "<tt>-O0</tt>",
477"<tt>-O1</tt>", and "<tt>-O2</tt>". We could easily implement this with boolean
478options like above, but there are several problems with this strategy:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]479
480<ol>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]481<li>A user could specify more than one of the options at a time, for example,
Chris Lattner8b44b902008-01-09 19:28:50 +0000[diff] [blame]482"<tt>compiler -O3 -O2</tt>". The CommandLine library would not be able to
483catch this erroneous input for us.</li>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]484
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]485<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]486
487<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]488see if some level &gt;= "<tt>-O1</tt>" is enabled.</li>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]489
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]490</ol>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]491
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]492<p>To cope with these problems, we can use an enum value, and have the
493CommandLine library fill it in with the appropriate level directly, which is
494used like this:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]495
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]496<div class="doc_code"><pre>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]497enum OptLevel {
498 g, O1, O2, O3
499};
500
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]501<a href="#cl::opt">cl::opt</a>&lt;OptLevel&gt; OptimizationLevel(<a href="#cl::desc">cl::desc</a>("<i>Choose optimization level:</i>"),
502 <a href="#cl::values">cl::values</a>(
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]503 clEnumVal(g , "<i>No optimizations, enable debugging</i>"),
504 clEnumVal(O1, "<i>Enable trivial optimizations</i>"),
505 clEnumVal(O2, "<i>Enable default optimizations</i>"),
506 clEnumVal(O3, "<i>Enable expensive optimizations</i>"),
Chris Lattnerb406ead2004-07-16 00:10:54 +0000[diff] [blame]507 clEnumValEnd));
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]508
509...
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]510 if (OptimizationLevel &gt;= O2) doPartialRedundancyElimination(...);
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]511...
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]512</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]513
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]514<p>This declaration defines a variable "<tt>OptimizationLevel</tt>" of the
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]515"<tt>OptLevel</tt>" enum type. This variable can be assigned any of the values
516that are listed in the declaration (Note that the declaration list must be
Anton Korobeynikov45982a52008-02-20 12:38:31 +0000[diff] [blame]517terminated with the "<tt>clEnumValEnd</tt>" argument!). The CommandLine
Chris Lattnerb406ead2004-07-16 00:10:54 +0000[diff] [blame]518library enforces
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]519that the user can only specify one of the options, and it ensure that only valid
520enum values can be specified. The "<tt>clEnumVal</tt>" macros ensure that the
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]521command line arguments matched the enum values. With this option added, our
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]522help output now is:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]523
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]524<div class="doc_code"><pre>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]525USAGE: compiler [options] &lt;input file&gt;
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]526
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]527OPTIONS:
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]528 <b>Choose optimization level:
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]529 -g - No optimizations, enable debugging
530 -O1 - Enable trivial optimizations
531 -O2 - Enable default optimizations
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]532 -O3 - Enable expensive optimizations</b>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]533 -f - Overwrite output files
534 -help - display available options (--help-hidden for more)
535 -o &lt;filename&gt; - Specify output filename
536 -quiet - Don't print informational messages
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]537</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]538
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]539<p>In this case, it is sort of awkward that flag names correspond directly to
540enum names, because we probably don't want a enum definition named "<tt>g</tt>"
541in our program. Because of this, we can alternatively write this example like
542this:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]543
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]544<div class="doc_code"><pre>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]545enum OptLevel {
546 Debug, O1, O2, O3
547};
548
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]549<a href="#cl::opt">cl::opt</a>&lt;OptLevel&gt; OptimizationLevel(<a href="#cl::desc">cl::desc</a>("<i>Choose optimization level:</i>"),
550 <a href="#cl::values">cl::values</a>(
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]551 clEnumValN(Debug, "g", "<i>No optimizations, enable debugging</i>"),
552 clEnumVal(O1 , "<i>Enable trivial optimizations</i>"),
553 clEnumVal(O2 , "<i>Enable default optimizations</i>"),
554 clEnumVal(O3 , "<i>Enable expensive optimizations</i>"),
Chris Lattnerb406ead2004-07-16 00:10:54 +0000[diff] [blame]555 clEnumValEnd));
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]556
557...
558 if (OptimizationLevel == Debug) outputDebugInfo(...);
559...
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]560</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]561
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]562<p>By using the "<tt>clEnumValN</tt>" macro instead of "<tt>clEnumVal</tt>", we
563can directly specify the name that the flag should get. In general a direct
564mapping is nice, but sometimes you can't or don't want to preserve the mapping,
565which is when you would use it.</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]566
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]567</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]568
569<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]570<div class="doc_subsection">
571 <a name="namedalternatives">Named Alternatives</a>
572</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]573
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]574<div class="doc_text">
575
576<p>Another useful argument form is a named alternative style. We shall use this
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]577style in our compiler to specify different debug levels that can be used.
578Instead of each debug level being its own switch, we want to support the
579following options, of which only one can be specified at a time:
580"<tt>--debug-level=none</tt>", "<tt>--debug-level=quick</tt>",
581"<tt>--debug-level=detailed</tt>". To do this, we use the exact same format as
582our optimization level flags, but we also specify an option name. For this
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]583case, the code looks like this:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]584
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]585<div class="doc_code"><pre>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]586enum DebugLev {
587 nodebuginfo, quick, detailed
588};
589
590// Enable Debug Options to be specified on the command line
Chris Lattnerdc844fa2003-06-03 04:40:06 +0000[diff] [blame]591<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]592 <a href="#cl::values">cl::values</a>(
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]593 clEnumValN(nodebuginfo, "none", "<i>disable debug information</i>"),
594 clEnumVal(quick, "<i>enable quick debug information</i>"),
595 clEnumVal(detailed, "<i>enable detailed debug information</i>"),
Chris Lattnerb406ead2004-07-16 00:10:54 +0000[diff] [blame]596 clEnumValEnd));
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]597</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]598
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]599<p>This definition defines an enumerated command line variable of type "<tt>enum
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]600DebugLev</tt>", which works exactly the same way as before. The difference here
601is 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]602the "<tt>--help</tt>" option:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]603
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]604<div class="doc_code"><pre>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]605USAGE: compiler [options] &lt;input file&gt;
606
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]607OPTIONS:
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]608 Choose optimization level:
609 -g - No optimizations, enable debugging
610 -O1 - Enable trivial optimizations
611 -O2 - Enable default optimizations
612 -O3 - Enable expensive optimizations
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]613 <b>-debug_level - Set the debugging level:
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]614 =none - disable debug information
615 =quick - enable quick debug information
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]616 =detailed - enable detailed debug information</b>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]617 -f - Overwrite output files
618 -help - display available options (--help-hidden for more)
619 -o &lt;filename&gt; - Specify output filename
620 -quiet - Don't print informational messages
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]621</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]622
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]623<p>Again, the only structural difference between the debug level declaration and
John Criswellc24d4822004-11-21 14:34:34 +0000[diff] [blame]624the optimization level declaration is that the debug level declaration includes
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]625an option name (<tt>"debug_level"</tt>), which automatically changes how the
626library processes the argument. The CommandLine library supports both forms so
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]627that you can choose the form most appropriate for your application.</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]628
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]629</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]630
631<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]632<div class="doc_subsection">
633 <a name="list">Parsing a list of options</a>
634</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]635
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]636<div class="doc_text">
637
Chris Lattner8b44b902008-01-09 19:28:50 +0000[diff] [blame]638<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]639lets get a little wild and crazy. Lets say that we want our optimizer to accept
640a <b>list</b> of optimizations to perform, allowing duplicates. For example, we
641might want to run: "<tt>compiler -dce -constprop -inline -dce -strip</tt>". In
642this case, the order of the arguments and the number of appearances is very
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]643important. This is what the "<tt><a href="#cl::list">cl::list</a></tt>"
644template is for. First, start by defining an enum of the optimizations that you
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]645would like to perform:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]646
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]647<div class="doc_code"><pre>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]648enum Opts {
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]649 // 'inline' is a C++ keyword, so name it 'inlining'
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]650 dce, constprop, inlining, strip
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]651};
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]652</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]653
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]654<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]655
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]656<div class="doc_code"><pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]657<a href="#cl::list">cl::list</a>&lt;Opts&gt; OptimizationList(<a href="#cl::desc">cl::desc</a>("<i>Available Optimizations:</i>"),
658 <a href="#cl::values">cl::values</a>(
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]659 clEnumVal(dce , "<i>Dead Code Elimination</i>"),
Misha Brukman82c89b92003-05-20 21:01:22 +0000[diff] [blame]660 clEnumVal(constprop , "<i>Constant Propagation</i>"),
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]661 clEnumValN(inlining, "<i>inline</i>", "<i>Procedure Integration</i>"),
662 clEnumVal(strip , "<i>Strip Symbols</i>"),
Chris Lattnerb406ead2004-07-16 00:10:54 +0000[diff] [blame]663 clEnumValEnd));
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]664</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]665
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]666<p>This defines a variable that is conceptually of the type
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]667"<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]668vector methods:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]669
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]670<div class="doc_code"><pre>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]671 for (unsigned i = 0; i != OptimizationList.size(); ++i)
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]672 switch (OptimizationList[i])
673 ...
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]674</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]675
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]676<p>... to iterate through the list of options specified.</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]677
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]678<p>Note that the "<tt><a href="#cl::list">cl::list</a></tt>" template is
679completely general and may be used with any data types or other arguments that
680you can use with the "<tt><a href="#cl::opt">cl::opt</a></tt>" template. One
681especially useful way to use a list is to capture all of the positional
682arguments together if there may be more than one specified. In the case of a
683linker, for example, the linker takes several '<tt>.o</tt>' files, and needs to
684capture them into a list. This is naturally specified as:</p>
Chris Lattner3e5fe172002-04-13 18:35:59 +0000[diff] [blame]685
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]686<div class="doc_code"><pre>
Chris Lattner3e5fe172002-04-13 18:35:59 +0000[diff] [blame]687...
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]688<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]689...
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]690</pre></div>
Chris Lattner3e5fe172002-04-13 18:35:59 +0000[diff] [blame]691
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]692<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]693such, accessing the list is simple, just like above. In this example, we used
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]694the <tt><a href="#cl::OneOrMore">cl::OneOrMore</a></tt> modifier to inform the
695CommandLine library that it is an error if the user does not specify any
696<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]697checking we have to do.</p>
Chris Lattner3e5fe172002-04-13 18:35:59 +0000[diff] [blame]698
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]699</div>
Chris Lattner3e5fe172002-04-13 18:35:59 +0000[diff] [blame]700
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]701<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]702<div class="doc_subsection">
Jim Laskey1d8f6262005-08-25 22:52:43 +0000[diff] [blame]703 <a name="bits">Collecting options as a set of flags</a>
704</div>
705
706<div class="doc_text">
707
708<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]709gather information for enum values in a <b>bit vector</b>. The represention used by
710the <a href="#bits"><tt>cl::bits</tt></a> class is an <tt>unsigned</tt>
Jim Laskey1d8f6262005-08-25 22:52:43 +0000[diff] [blame]711integer. An enum value is represented by a 0/1 in the enum's ordinal value bit
712position. 1 indicating that the enum was specified, 0 otherwise. As each
713specified value is parsed, the resulting enum's bit is set in the option's bit
714vector:</p>
715
716<div class="doc_code"><pre>
717 <i>bits</i> |= 1 << (unsigned)<i>enum</i>;
718</pre></div>
719
Jim Laskey26029222005-08-25 23:01:25 +0000[diff] [blame]720<p>Options that are specified multiple times are redundant. Any instances after
721the first are discarded.</p>
Jim Laskey1d8f6262005-08-25 22:52:43 +0000[diff] [blame]722
723<p>Reworking the above list example, we could replace <a href="#list">
724<tt>cl::list</tt></a> with <a href="#bits"><tt>cl::bits</tt></a>:</p>
725
726<div class="doc_code"><pre>
727<a href="#cl::bits">cl::bits</a>&lt;Opts&gt; OptimizationBits(<a href="#cl::desc">cl::desc</a>("<i>Available Optimizations:</i>"),
728 <a href="#cl::values">cl::values</a>(
729 clEnumVal(dce , "<i>Dead Code Elimination</i>"),
730 clEnumVal(constprop , "<i>Constant Propagation</i>"),
731 clEnumValN(inlining, "<i>inline</i>", "<i>Procedure Integration</i>"),
732 clEnumVal(strip , "<i>Strip Symbols</i>"),
733 clEnumValEnd));
734</pre></div>
735
736<p>To test to see if <tt>constprop</tt> was specified, we can use the
737<tt>cl:bits::isSet</tt> function:</p>
738
739<div class="doc_code"><pre>
740 if (OptimizationBits.isSet(constprop)) {
741 ...
742 }
743</pre></div>
744
745<p>It's also possible to get the raw bit vector using the
746<tt>cl::bits::getBits</tt> function:</p>
747
748<div class="doc_code"><pre>
Jim Laskey22b7dfa2005-08-26 09:25:54 +0000[diff] [blame]749 unsigned bits = OptimizationBits.getBits();
Jim Laskey1d8f6262005-08-25 22:52:43 +0000[diff] [blame]750</pre></div>
751
752<p>Finally, if external storage is used, then the location specified must be of
Jim Laskey22b7dfa2005-08-26 09:25:54 +0000[diff] [blame]753<b>type</b> <tt>unsigned</tt>. In all other ways a <a
Chris Lattner8b44b902008-01-09 19:28:50 +0000[diff] [blame]754href="#bits"><tt>cl::bits</tt></a> option is equivalent to a <a
Jim Laskey22b7dfa2005-08-26 09:25:54 +0000[diff] [blame]755href="#list"> <tt>cl::list</tt></a> option.</p>
Jim Laskey1d8f6262005-08-25 22:52:43 +0000[diff] [blame]756
757</div>
758
759
760<!-- ======================================================================= -->
761<div class="doc_subsection">
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]762 <a name="description">Adding freeform text to help output</a>
763</div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]764
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]765<div class="doc_text">
766
767<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]768information about what it does into the help output. The help output is styled
769to look similar to a Unix <tt>man</tt> page, providing concise information about
770a program. Unix <tt>man</tt> pages, however often have a description about what
771the program does. To add this to your CommandLine program, simply pass a third
772argument to the <a
773href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>
774call in main. This additional argument is then printed as the overview
775information for your program, allowing you to include any additional information
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]776that you want. For example:</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]777
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]778<div class="doc_code"><pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]779int main(int argc, char **argv) {
780 <a href="#cl::ParseCommandLineOptions">cl::ParseCommandLineOptions</a>(argc, argv, " CommandLine compiler example\n\n"
781 " This program blah blah blah...\n");
782 ...
783}
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]784</pre></div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]785
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]786<p>would yield the help output:</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]787
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]788<div class="doc_code"><pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]789<b>OVERVIEW: CommandLine compiler example
790
791 This program blah blah blah...</b>
792
793USAGE: compiler [options] &lt;input file&gt;
794
795OPTIONS:
796 ...
797 -help - display available options (--help-hidden for more)
798 -o &lt;filename&gt; - Specify output filename
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]799</pre></div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]800
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]801</div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]802
803
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]804<!-- *********************************************************************** -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]805<div class="doc_section">
806 <a name="referenceguide">Reference Guide</a>
807</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]808<!-- *********************************************************************** -->
809
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]810<div class="doc_text">
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]811
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]812<p>Now that you know the basics of how to use the CommandLine library, this
813section will give you the detailed information you need to tune how command line
814options work, as well as information on more "advanced" command line option
815processing capabilities.</p>
816
817</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]818
819<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]820<div class="doc_subsection">
821 <a name="positional">Positional Arguments</a>
822</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]823
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]824<div class="doc_text">
825
826<p>Positional arguments are those arguments that are not named, and are not
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]827specified with a hyphen. Positional arguments should be used when an option is
828specified by its position alone. For example, the standard Unix <tt>grep</tt>
829tool takes a regular expression argument, and an optional filename to search
830through (which defaults to standard input if a filename is not specified).
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]831Using the CommandLine library, this would be specified as:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]832
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]833<div class="doc_code"><pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]834<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>);
835<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]836</pre></div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]837
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]838<p>Given these two option declarations, the <tt>--help</tt> output for our grep
839replacement would look like this:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]840
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]841<div class="doc_code"><pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]842USAGE: spiffygrep [options] <b>&lt;regular expression&gt; &lt;input file&gt;</b>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]843
844OPTIONS:
845 -help - display available options (--help-hidden for more)
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]846</pre></div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]847
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]848<p>... and the resultant program could be used just like the standard
849<tt>grep</tt> tool.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]850
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]851<p>Positional arguments are sorted by their order of construction. This means
852that command line options will be ordered according to how they are listed in a
Reid Spencer2c8ab582004-08-13 20:19:14 +0000[diff] [blame]853.cpp file, but will not have an ordering defined if the positional arguments
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]854are defined in multiple .cpp files. The fix for this problem is simply to
855define all of your positional arguments in one .cpp file.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]856
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]857</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]858
859
860<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]861<div class="doc_subsubsection">
862 <a name="--">Specifying positional options with hyphens</a>
863</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]864
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]865<div class="doc_text">
866
867<p>Sometimes you may want to specify a value to your positional argument that
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]868starts with a hyphen (for example, searching for '<tt>-foo</tt>' in a file). At
869first, you will have trouble doing this, because it will try to find an argument
870named '<tt>-foo</tt>', and will fail (and single quotes will not save you).
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]871Note that the system <tt>grep</tt> has the same problem:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]872
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]873<div class="doc_code"><pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]874 $ spiffygrep '-foo' test.txt
875 Unknown command line argument '-foo'. Try: spiffygrep --help'
876
877 $ grep '-foo' test.txt
878 grep: illegal option -- f
879 grep: illegal option -- o
880 grep: illegal option -- o
881 Usage: grep -hblcnsviw pattern file . . .
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]882</pre></div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]883
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]884<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]885version: use the '<tt>--</tt>' marker. When the user specifies '<tt>--</tt>' on
886the command line, it is telling the program that all options after the
887'<tt>--</tt>' should be treated as positional arguments, not options. Thus, we
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]888can use it like this:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]889
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]890<div class="doc_code"><pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]891 $ spiffygrep -- -foo test.txt
892 ...output...
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]893</pre></div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]894
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]895</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]896
897<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]898<div class="doc_subsubsection">
Reid Spencer2c8ab582004-08-13 20:19:14 +0000[diff] [blame]899 <a name="getPosition">Determining absolute position with getPosition()</a>
900</div>
901<div class="doc_text">
902 <p>Sometimes an option can affect or modify the meaning of another option. For
903 example, consider <tt>gcc</tt>'s <tt>-x LANG</tt> option. This tells
904 <tt>gcc</tt> to ignore the suffix of subsequent positional arguments and force
905 the file to be interpreted as if it contained source code in language
Chris Lattner8eedc9e2008-04-01 18:02:36 +0000[diff] [blame]906 <tt>LANG</tt>. In order to handle this properly, you need to know the
Anton Korobeynikov45982a52008-02-20 12:38:31 +0000[diff] [blame]907 absolute position of each argument, especially those in lists, so their
908 interaction(s) can be applied correctly. This is also useful for options like
909 <tt>-llibname</tt> which is actually a positional argument that starts with
Reid Spencer2c8ab582004-08-13 20:19:14 +0000[diff] [blame]910 a dash.</p>
911 <p>So, generally, the problem is that you have two <tt>cl::list</tt> variables
912 that interact in some way. To ensure the correct interaction, you can use the
913 <tt>cl::list::getPosition(optnum)</tt> method. This method returns the
914 absolute position (as found on the command line) of the <tt>optnum</tt>
915 item in the <tt>cl::list</tt>.</p>
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]916 <p>The idiom for usage is like this:</p>
Anton Korobeynikov45982a52008-02-20 12:38:31 +0000[diff] [blame]917
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]918 <div class="doc_code"><pre>
Reid Spencer2c8ab582004-08-13 20:19:14 +0000[diff] [blame]919 static cl::list&lt;std::string&gt; Files(cl::Positional, cl::OneOrMore);
Chris Lattner8b44b902008-01-09 19:28:50 +0000[diff] [blame]920 static cl::list&lt;std::string&gt; Libraries("l", cl::ZeroOrMore);
Reid Spencer2c8ab582004-08-13 20:19:14 +0000[diff] [blame]921
922 int main(int argc, char**argv) {
923 // ...
924 std::vector&lt;std::string&gt;::iterator fileIt = Files.begin();
925 std::vector&lt;std::string&gt;::iterator libIt = Libraries.begin();
926 unsigned libPos = 0, filePos = 0;
927 while ( 1 ) {
928 if ( libIt != Libraries.end() )
929 libPos = Libraries.getPosition( libIt - Libraries.begin() );
930 else
931 libPos = 0;
932 if ( fileIt != Files.end() )
933 filePos = Files.getPosition( fileIt - Files.begin() );
934 else
935 filePos = 0;
936
937 if ( filePos != 0 &amp;&amp; (libPos == 0 || filePos &lt; libPos) ) {
938 // Source File Is next
939 ++fileIt;
940 }
941 else if ( libPos != 0 &amp;&amp; (filePos == 0 || libPos &lt; filePos) ) {
942 // Library is next
943 ++libIt;
944 }
945 else
946 break; // we're done with the list
947 }
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]948 }</pre></div>
949
Reid Spencer2c8ab582004-08-13 20:19:14 +0000[diff] [blame]950 <p>Note that, for compatibility reasons, the <tt>cl::opt</tt> also supports an
951 <tt>unsigned getPosition()</tt> option that will provide the absolute position
Anton Korobeynikov45982a52008-02-20 12:38:31 +0000[diff] [blame]952 of that option. You can apply the same approach as above with a
Reid Spencer2c8ab582004-08-13 20:19:14 +0000[diff] [blame]953 <tt>cl::opt</tt> and a <tt>cl::list</tt> option as you can with two lists.</p>
954</div>
955
956<!-- _______________________________________________________________________ -->
957<div class="doc_subsubsection">
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]958 <a name="cl::ConsumeAfter">The <tt>cl::ConsumeAfter</tt> modifier</a>
959</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]960
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]961<div class="doc_text">
962
963<p>The <tt>cl::ConsumeAfter</tt> <a href="#formatting">formatting option</a> is
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]964used to construct programs that use "interpreter style" option processing. With
965this style of option processing, all arguments specified after the last
966positional argument are treated as special interpreter arguments that are not
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]967interpreted by the command line argument.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]968
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]969<p>As a concrete example, lets say we are developing a replacement for the
970standard Unix Bourne shell (<tt>/bin/sh</tt>). To run <tt>/bin/sh</tt>, first
971you specify options to the shell itself (like <tt>-x</tt> which turns on trace
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]972output), then you specify the name of the script to run, then you specify
Chris Lattner8b44b902008-01-09 19:28:50 +0000[diff] [blame]973arguments to the script. These arguments to the script are parsed by the Bourne
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]974shell command line option processor, but are not interpreted as options to the
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]975shell itself. Using the CommandLine library, we would specify this as:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]976
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]977<div class="doc_code"><pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]978<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>("-"));
979<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>"));
980<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]981</pre></div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]982
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]983<p>which automatically provides the help output:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]984
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]985<div class="doc_code"><pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]986USAGE: spiffysh [options] <b>&lt;input script&gt; &lt;program arguments&gt;...</b>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]987
988OPTIONS:
989 -help - display available options (--help-hidden for more)
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]990 <b>-x - Enable trace output</b>
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]991</pre></div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]992
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]993<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]994-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]995<tt>Script</tt> variable will be set to "<tt>test.sh</tt>", and the
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]996<tt>Argv</tt> list will contain <tt>["-a", "-x", "-y", "bar"]</tt>, because they
997were specified after the last positional argument (which is the script
998name).</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]999
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1000<p>There are several limitations to when <tt>cl::ConsumeAfter</tt> options can
1001be specified. For example, only one <tt>cl::ConsumeAfter</tt> can be specified
1002per program, there must be at least one <a href="#positional">positional
Chris Lattnerbe801bf2004-05-06 22:03:59 +0000[diff] [blame]1003argument</a> specified, there must not be any <a href="#cl::list">cl::list</a>
1004positional arguments, and the <tt>cl::ConsumeAfter</tt> option should be a <a
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1005href="#cl::list">cl::list</a> option.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1006
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1007</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1008
1009<!-- ======================================================================= -->
Chris Lattnerbe801bf2004-05-06 22:03:59 +0000[diff] [blame]1010<div class="doc_subsection">
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1011 <a name="storage">Internal vs External Storage</a>
1012</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1013
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1014<div class="doc_text">
1015
1016<p>By default, all command line options automatically hold the value that they
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1017parse from the command line. This is very convenient in the common case,
1018especially when combined with the ability to define command line options in the
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1019files that use them. This is called the internal storage model.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1020
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1021<p>Sometimes, however, it is nice to separate the command line option processing
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1022code from the storage of the value parsed. For example, lets say that we have a
1023'<tt>-debug</tt>' option that we would like to use to enable debug information
1024across the entire body of our program. In this case, the boolean value
1025controlling the debug code should be globally accessable (in a header file, for
1026example) yet the command line option processing code should not be exposed to
1027all of these clients (requiring lots of .cpp files to #include
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1028<tt>CommandLine.h</tt>).</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1029
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1030<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]1031
Misha Brukman1fc9f8e2005-02-09 22:49:05 +0000[diff] [blame]1032<div class="doc_code">
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1033<pre>
1034<i>// DebugFlag.h - Get access to the '-debug' command line option
1035//
1036
1037// DebugFlag - This boolean is set to true if the '-debug' command line option
1038// is specified. This should probably not be referenced directly, instead, use
1039// the DEBUG macro below.
1040//</i>
1041extern bool DebugFlag;
1042
1043<i>// DEBUG macro - This macro should be used by code to emit debug information.
1044// In the '-debug' option is specified on the command line, and if this is a
1045// debug build, then the code specified as the option to the macro will be
Chris Lattner8b44b902008-01-09 19:28:50 +0000[diff] [blame]1046// executed. Otherwise it will not be.</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
Chris Lattner8b44b902008-01-09 19:28:50 +0000[diff] [blame]1058an additional 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
Anton Korobeynikov45982a52008-02-20 12:38:31 +0000[diff] [blame]1130<b>clEnumValEnd terminated</b> list of (option, value, description) triplets
Chris Lattnerb406ead2004-07-16 00:10:54 +0000[diff] [blame]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
Mikhail Glushenkov7059d472009-01-16 22:54:19 +0000[diff] [blame]1149<li><a name="cl::multi_val">The <b><tt>cl::multi_val</tt></b></a>
1150attribute specifies that this option takes has multiple values
1151(example: <tt>-sectalign segname sectname sectvalue</tt>). This
1152attribute takes one unsigned argument - the number of values for the
1153option. This attribute is valid only on <tt>cl::list</tt> options (and
1154will fail with compile error if you try to use it with other option
1155types). It is allowed to use all of the usual modifiers on
1156multi-valued options (besides <tt>cl::ValueDisallowed</tt>,
1157obviously).</li>
1158
1159
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1160</ol>
1161
1162You 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]1163that does not support it.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1164
1165</ul>
1166
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1167</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1168
1169<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1170<div class="doc_subsection">
1171 <a name="modifiers">Option Modifiers</a>
1172</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1173
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1174<div class="doc_text">
1175
1176<p>Option modifiers are the flags and expressions that you pass into the
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1177constructors for <tt><a href="#cl::opt">cl::opt</a></tt> and <tt><a
1178href="#cl::list">cl::list</a></tt>. These modifiers give you the ability to
1179tweak how options are parsed and how <tt>--help</tt> output is generated to fit
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1180your application well.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1181
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1182<p>These options fall into five main catagories:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1183
1184<ol>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1185<li><a href="#hiding">Hiding an option from <tt>--help</tt> output</a></li>
1186<li><a href="#numoccurrences">Controlling the number of occurrences
1187 required and allowed</a></li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1188<li><a href="#valrequired">Controlling whether or not a value must be
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1189 specified</a></li>
1190<li><a href="#formatting">Controlling other formatting options</a></li>
1191<li><a href="#misc">Miscellaneous option modifiers</a></li>
1192</ol>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1193
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1194<p>It is not possible to specify two options from the same catagory (you'll get
1195a runtime error) to a single option, except for options in the miscellaneous
Chris Lattner32a32842003-05-22 20:36:06 +0000[diff] [blame]1196catagory. The CommandLine library specifies defaults for all of these settings
1197that are the most useful in practice and the most common, which mean that you
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1198usually shouldn't have to worry about these.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1199
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1200</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1201
1202<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1203<div class="doc_subsubsection">
1204 <a name="hiding">Hiding an option from <tt>--help</tt> output</a>
1205</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1206
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1207<div class="doc_text">
1208
1209<p>The <tt>cl::NotHidden</tt>, <tt>cl::Hidden</tt>, and
1210<tt>cl::ReallyHidden</tt> modifiers are used to control whether or not an option
1211appears in the <tt>--help</tt> and <tt>--help-hidden</tt> output for the
1212compiled program:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1213
1214<ul>
1215
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1216<li><a name="cl::NotHidden">The <b><tt>cl::NotHidden</tt></b></a> modifier
1217(which is the default for <tt><a href="#cl::opt">cl::opt</a></tt> and <tt><a
Chris Lattner8b44b902008-01-09 19:28:50 +0000[diff] [blame]1218href="#cl::list">cl::list</a></tt> options) indicates the option is to appear
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1219in both help listings.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1220
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1221<li><a name="cl::Hidden">The <b><tt>cl::Hidden</tt></b></a> modifier (which is the
Chris Lattner8b44b902008-01-09 19:28:50 +0000[diff] [blame]1222default for <tt><a href="#cl::alias">cl::alias</a></tt> options) indicates that
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1223the option should not appear in the <tt>--help</tt> output, but should appear in
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1224the <tt>--help-hidden</tt> output.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1225
Chris Lattner8b44b902008-01-09 19:28:50 +0000[diff] [blame]1226<li><a name="cl::ReallyHidden">The <b><tt>cl::ReallyHidden</tt></b></a> modifier
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1227indicates that the option should not appear in any help output.</li>
1228
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1229</ul>
1230
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1231</div>
1232
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1233<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1234<div class="doc_subsubsection">
1235 <a name="numoccurrences">Controlling the number of occurrences required and
1236 allowed</a>
1237</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1238
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1239<div class="doc_text">
1240
1241<p>This group of options is used to control how many time an option is allowed
1242(or required) to be specified on the command line of your program. Specifying a
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1243value for this setting allows the CommandLine library to do error checking for
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1244you.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1245
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1246<p>The allowed values for this option group are:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1247
1248<ul>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1249
1250<li><a name="cl::Optional">The <b><tt>cl::Optional</tt></b></a> modifier (which
1251is 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]1252href="#cl::alias">cl::alias</a></tt> classes) indicates that your program will
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1253allow either zero or one occurrence of the option to be specified.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1254
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1255<li><a name="cl::ZeroOrMore">The <b><tt>cl::ZeroOrMore</tt></b></a> modifier
1256(which is the default for the <tt><a href="#cl::list">cl::list</a></tt> class)
1257indicates that your program will allow the option to be specified zero or more
1258times.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1259
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1260<li><a name="cl::Required">The <b><tt>cl::Required</tt></b></a> modifier
1261indicates that the specified option must be specified exactly one time.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1262
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1263<li><a name="cl::OneOrMore">The <b><tt>cl::OneOrMore</tt></b></a> modifier
1264indicates that the option must be specified at least one time.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1265
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1266<li>The <b><tt>cl::ConsumeAfter</tt></b> modifier is described in the <a
Chris Lattner8b44b902008-01-09 19:28:50 +0000[diff] [blame]1267href="#positional">Positional arguments section</a>.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1268
1269</ul>
1270
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1271<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]1272value specified by the <tt><a href="#cl::init">cl::init</a></tt> attribute. If
1273the <tt><a href="#cl::init">cl::init</a></tt> attribute is not specified, the
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1274option value is initialized with the default constructor for the data type.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1275
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1276<p>If an option is specified multiple times for an option of the <tt><a
1277href="#cl::opt">cl::opt</a></tt> class, only the last value will be
1278retained.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1279
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1280</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1281
1282<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1283<div class="doc_subsubsection">
1284 <a name="valrequired">Controlling whether or not a value must be specified</a>
1285</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1286
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1287<div class="doc_text">
1288
1289<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]1290value to be present. In the case of the CommandLine library, a value is either
1291specified 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]1292string (e.g. '<tt>-o a.out</tt>').</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1293
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1294<p>The allowed values for this option group are:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1295
1296<ul>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1297
1298<li><a name="cl::ValueOptional">The <b><tt>cl::ValueOptional</tt></b></a> modifier
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1299(which is the default for <tt>bool</tt> typed options) specifies that it is
1300acceptable to have a value, or not. A boolean argument can be enabled just by
1301appearing on the command line, or it can have an explicit '<tt>-foo=true</tt>'.
1302If an option is specified with this mode, it is illegal for the value to be
1303provided without the equal sign. Therefore '<tt>-foo true</tt>' is illegal. To
1304get this behavior, you must use the <a
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1305href="#cl::ValueRequired">cl::ValueRequired</a> modifier.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1306
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1307<li><a name="cl::ValueRequired">The <b><tt>cl::ValueRequired</tt></b></a> modifier
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1308(which is the default for all other types except for <a
1309href="#onealternative">unnamed alternatives using the generic parser</a>)
1310specifies that a value must be provided. This mode informs the command line
1311library that if an option is not provides with an equal sign, that the next
1312argument provided must be the value. This allows things like '<tt>-o
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1313a.out</tt>' to work.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1314
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1315<li><a name="cl::ValueDisallowed">The <b><tt>cl::ValueDisallowed</tt></b></a>
1316modifier (which is the default for <a href="#onealternative">unnamed
1317alternatives using the generic parser</a>) indicates that it is a runtime error
1318for the user to specify a value. This can be provided to disallow users from
1319providing options to boolean options (like '<tt>-foo=true</tt>').</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1320
1321</ul>
1322
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1323<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]1324want them to. As mentioned above, you can specify the <a
1325href="#cl::ValueDisallowed">cl::ValueDisallowed</a> modifier to a boolean
1326argument to restrict your command line parser. These options are mostly useful
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1327when <a href="#extensionguide">extending the library</a>.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1328
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1329</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1330
1331<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1332<div class="doc_subsubsection">
1333 <a name="formatting">Controlling other formatting options</a>
1334</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1335
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1336<div class="doc_text">
1337
1338<p>The formatting option group is used to specify that the command line option
1339has special abilities and is otherwise different from other command line
Chris Lattner8b44b902008-01-09 19:28:50 +0000[diff] [blame]1340arguments. As usual, you can only specify one of these arguments at most.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1341
1342<ul>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1343
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1344<li><a name="cl::NormalFormatting">The <b><tt>cl::NormalFormatting</tt></b></a>
1345modifier (which is the default all options) specifies that this option is
1346"normal".</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1347
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1348<li><a name="cl::Positional">The <b><tt>cl::Positional</tt></b></a> modifier
Chris Lattner8b44b902008-01-09 19:28:50 +0000[diff] [blame]1349specifies that this is a positional argument that does not have a command line
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1350option associated with it. See the <a href="#positional">Positional
1351Arguments</a> section for more information.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1352
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1353<li>The <b><a href="#cl::ConsumeAfter"><tt>cl::ConsumeAfter</tt></a></b> modifier
1354specifies 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]1355
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1356<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]1357that this option prefixes its value. With 'Prefix' options, the equal sign does
1358not separate the value from the option name specified. Instead, the value is
1359everything after the prefix, including any equal sign if present. This is useful
1360for 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]1361linker tool or <tt>-DNAME=value</tt> in a compiler tool. Here, the
Reid Spencer5f8448f2004-11-24 06:13:42 +0000[diff] [blame]1362'<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]1363options, that have the <b><tt><a href="#cl::Prefix">cl::Prefix</a></tt></b>
1364modifier added to allow the CommandLine library to recognize them. Note that
1365<b><tt><a href="#cl::Prefix">cl::Prefix</a></tt></b> options must not have the
1366<b><tt><a href="#cl::ValueDisallowed">cl::ValueDisallowed</a></tt></b> modifier
1367specified.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1368
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1369<li><a name="cl::Grouping">The <b><tt>cl::Grouping</tt></b></a> modifier is used
Chris Lattner8b44b902008-01-09 19:28:50 +0000[diff] [blame]1370to implement Unix-style tools (like <tt>ls</tt>) that have lots of single letter
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1371arguments, but only require a single dash. For example, the '<tt>ls -labF</tt>'
1372command actually enables four different options, all of which are single
Misha Brukmanc43d9142005-05-10 22:05:27 +0000[diff] [blame]1373letters. Note that <b><tt><a href="#cl::Grouping">cl::Grouping</a></tt></b>
1374options cannot have values.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1375
1376</ul>
1377
Misha Brukmanc43d9142005-05-10 22:05:27 +0000[diff] [blame]1378<p>The CommandLine library does not restrict how you use the <b><tt><a
1379href="#cl::Prefix">cl::Prefix</a></tt></b> or <b><tt><a
1380href="#cl::Grouping">cl::Grouping</a></tt></b> modifiers, but it is possible to
1381specify ambiguous argument settings. Thus, it is possible to have multiple
1382letter options that are prefix or grouping options, and they will still work as
1383designed.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1384
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1385<p>To do this, the CommandLine library uses a greedy algorithm to parse the
1386input option into (potentially multiple) prefix and grouping options. The
1387strategy basically looks like this:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1388
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1389<div class="doc_code"><tt>parse(string OrigInput) {</tt>
Misha Brukmanc53aefb2004-05-12 18:42:35 +0000[diff] [blame]1390
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1391<ol>
1392<li><tt>string input = OrigInput;</tt>
1393<li><tt>if (isOption(input)) return getOption(input).parse();</tt>&nbsp;&nbsp;&nbsp;&nbsp;<i>// Normal option</i>
1394<li><tt>while (!isOption(input) &amp;&amp; !input.empty()) input.pop_back();</tt>&nbsp;&nbsp;&nbsp;&nbsp;<i>// Remove the last letter</i>
1395<li><tt>if (input.empty()) return error();</tt>&nbsp;&nbsp;&nbsp;&nbsp;<i>// No matching option</i>
1396<li><tt>if (getOption(input).isPrefix())<br>
1397&nbsp;&nbsp;return getOption(input).parse(input);</tt>
1398<li><tt>while (!input.empty()) {&nbsp;&nbsp;&nbsp;&nbsp;<i>// Must be grouping options</i><br>
1399&nbsp;&nbsp;getOption(input).parse();<br>
1400&nbsp;&nbsp;OrigInput.erase(OrigInput.begin(), OrigInput.begin()+input.length());<br>
1401&nbsp;&nbsp;input = OrigInput;<br>
1402&nbsp;&nbsp;while (!isOption(input) &amp;&amp; !input.empty()) input.pop_back();<br>
1403}</tt>
Misha Brukmanc53aefb2004-05-12 18:42:35 +0000[diff] [blame]1404<li><tt>if (!OrigInput.empty()) error();</tt></li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1405</ol>
Misha Brukmanc53aefb2004-05-12 18:42:35 +0000[diff] [blame]1406
1407<p><tt>}</tt></p>
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1408</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1409
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1410</div>
Chris Lattner32a32842003-05-22 20:36:06 +0000[diff] [blame]1411
1412<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1413<div class="doc_subsubsection">
1414 <a name="misc">Miscellaneous option modifiers</a>
1415</div>
Chris Lattner32a32842003-05-22 20:36:06 +0000[diff] [blame]1416
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1417<div class="doc_text">
1418
1419<p>The miscellaneous option modifiers are the only flags where you can specify
1420more than one flag from the set: they are not mutually exclusive. These flags
1421specify boolean properties that modify the option.</p>
Chris Lattner32a32842003-05-22 20:36:06 +0000[diff] [blame]1422
1423<ul>
1424
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1425<li><a name="cl::CommaSeparated">The <b><tt>cl::CommaSeparated</tt></b></a> modifier
Chris Lattner32a32842003-05-22 20:36:06 +0000[diff] [blame]1426indicates that any commas specified for an option's value should be used to
1427split the value up into multiple values for the option. For example, these two
1428options are equivalent when <tt>cl::CommaSeparated</tt> is specified:
1429"<tt>-foo=a -foo=b -foo=c</tt>" and "<tt>-foo=a,b,c</tt>". This option only
1430makes 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]1431more values (i.e. it is a <a href="#cl::list">cl::list</a> option).</li>
1432
Chris Lattnerbe801bf2004-05-06 22:03:59 +0000[diff] [blame]1433<li><a name="cl::PositionalEatsArgs">The
1434<b><tt>cl::PositionalEatsArgs</tt></b></a> modifier (which only applies to
1435positional arguments, and only makes sense for lists) indicates that positional
1436argument should consume any strings after it (including strings that start with
1437a "-") up until another recognized positional argument. For example, if you
Chris Lattner8b44b902008-01-09 19:28:50 +0000[diff] [blame]1438have two "eating" positional arguments, "<tt>pos1</tt>" and "<tt>pos2</tt>", the
Chris Lattnerbe801bf2004-05-06 22:03:59 +0000[diff] [blame]1439string "<tt>-pos1 -foo -bar baz -pos2 -bork</tt>" would cause the "<tt>-foo -bar
1440-baz</tt>" strings to be applied to the "<tt>-pos1</tt>" option and the
1441"<tt>-bork</tt>" string to be applied to the "<tt>-pos2</tt>" option.</li>
1442
Anton Korobeynikov45982a52008-02-20 12:38:31 +0000[diff] [blame]1443<li><a name="cl::Sink">The <b><tt>cl::Sink</tt></b></a> modifier is
1444used to handle unknown options. If there is at least one option with
1445<b><tt>cl::Sink</tt></b></a> modifier specified, the parser passes
1446unrecognized option strings to it as values instead of signaling an
1447error. As with <b><tt>cl::CommaSeparated</tt></b></a>, this modifier
1448only makes sense with a <a href="#cl::list">cl::list</a> option.</li>
1449
Mike Stumpd64e0eb2009-02-02 22:48:49 +0000[diff] [blame]1450<li><a name="cl::AllowInverse">The <b><tt>cl::AllowInverse</tt></b></a>
1451modifier can be used on options that have the form <tt>-fopt</tt> to
1452automatically create a corresponding
1453<tt>-fno-opt</tt> option. The <tt>f</tt> can be any single
1454character, and the <tt>opt</tt> can be any one or more characters.
1455The value of the created option is the logical complement of the value
1456that would have been used if the base form of the option was used.
1457This modifier only makes sense with an option that uses
1458a <a href="#boolparser">bool parser</a>.</li>
1459
Anton Korobeynikov45982a52008-02-20 12:38:31 +0000[diff] [blame]1460
Chris Lattner32a32842003-05-22 20:36:06 +0000[diff] [blame]1461</ul>
1462
Anton Korobeynikov45982a52008-02-20 12:38:31 +0000[diff] [blame]1463<p>So far, these are the only three miscellaneous option modifiers.</p>
Chris Lattner32a32842003-05-22 20:36:06 +0000[diff] [blame]1464
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1465</div>
Chris Lattner32a32842003-05-22 20:36:06 +0000[diff] [blame]1466
Mikhail Glushenkovbeb4d822008-04-28 16:44:25 +0000[diff] [blame]1467<!-- _______________________________________________________________________ -->
1468<div class="doc_subsubsection">
1469 <a name="response">Response files</a>
1470</div>
1471
1472<div class="doc_text">
1473
1474<p>Some systems, such as certain variants of Microsoft Windows and
1475some older Unices have a relatively low limit on command-line
1476length. It is therefore customary to use the so-called 'response
1477files' to circumvent this restriction. These files are mentioned on
1478the command-line (using the "@file") syntax. The program reads these
1479files and inserts the contents into argv, thereby working around the
1480command-line length limits. Response files are enabled by an optional
1481fourth argument to
1482<a href="#cl::ParseEnvironmentOptions"><tt>cl::ParseEnvironmentOptions</tt></a>
1483and
1484<a href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>.
1485</p>
1486
1487</div>
1488
1489
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1490<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1491<div class="doc_subsection">
1492 <a name="toplevel">Top-Level Classes and Functions</a>
1493</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1494
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1495<div class="doc_text">
1496
1497<p>Despite all of the built-in flexibility, the CommandLine option library
1498really only consists of one function (<a
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1499href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>)
1500and three main classes: <a href="#cl::opt"><tt>cl::opt</tt></a>, <a
1501href="#cl::list"><tt>cl::list</tt></a>, and <a
1502href="#cl::alias"><tt>cl::alias</tt></a>. This section describes these three
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1503classes in detail.</p>
1504
1505</div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1506
1507<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1508<div class="doc_subsubsection">
1509 <a name="cl::ParseCommandLineOptions">The <tt>cl::ParseCommandLineOptions</tt>
1510 function</a>
1511</div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1512
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1513<div class="doc_text">
1514
1515<p>The <tt>cl::ParseCommandLineOptions</tt> function is designed to be called
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1516directly from <tt>main</tt>, and is used to fill in the values of all of the
1517command line option variables once <tt>argc</tt> and <tt>argv</tt> are
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1518available.</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1519
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1520<p>The <tt>cl::ParseCommandLineOptions</tt> function requires two parameters
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1521(<tt>argc</tt> and <tt>argv</tt>), but may also take an optional third parameter
1522which holds <a href="#description">additional extra text</a> to emit when the
Mikhail Glushenkovbeb4d822008-04-28 16:44:25 +0000[diff] [blame]1523<tt>--help</tt> option is invoked, and a fourth boolean parameter that enables
1524<a href="#response">response files</a>.</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1525
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1526</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1527
1528<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1529<div class="doc_subsubsection">
1530 <a name="cl::ParseEnvironmentOptions">The <tt>cl::ParseEnvironmentOptions</tt>
1531 function</a>
1532</div>
Brian Gaekee5842852003-08-19 23:11:43 +0000[diff] [blame]1533
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1534<div class="doc_text">
Brian Gaekee5842852003-08-19 23:11:43 +0000[diff] [blame]1535
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1536<p>The <tt>cl::ParseEnvironmentOptions</tt> function has mostly the same effects
1537as <a
1538href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>,
1539except that it is designed to take values for options from an environment
1540variable, for those cases in which reading the command line is not convenient or
Chris Lattner8b44b902008-01-09 19:28:50 +0000[diff] [blame]1541desired. It fills in the values of all the command line option variables just
1542like <a
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1543href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>
1544does.</p>
1545
Mikhail Glushenkovbeb4d822008-04-28 16:44:25 +0000[diff] [blame]1546<p>It takes four parameters: the name of the program (since <tt>argv</tt> may
Chris Lattner8b44b902008-01-09 19:28:50 +0000[diff] [blame]1547not be available, it can't just look in <tt>argv[0]</tt>), the name of the
Mikhail Glushenkovbeb4d822008-04-28 16:44:25 +0000[diff] [blame]1548environment variable to examine, the optional
Brian Gaekee5842852003-08-19 23:11:43 +0000[diff] [blame]1549<a href="#description">additional extra text</a> to emit when the
Mikhail Glushenkovbeb4d822008-04-28 16:44:25 +0000[diff] [blame]1550<tt>--help</tt> option is invoked, and the boolean
1551switch that controls whether <a href="#response">reponse files</a>
1552should be read.</p>
Brian Gaekee5842852003-08-19 23:11:43 +0000[diff] [blame]1553
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1554<p><tt>cl::ParseEnvironmentOptions</tt> will break the environment
Brian Gaekee5842852003-08-19 23:11:43 +0000[diff] [blame]1555variable's value up into words and then process them using
1556<a href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>.
1557<b>Note:</b> Currently <tt>cl::ParseEnvironmentOptions</tt> does not support
1558quoting, so an environment variable containing <tt>-option "foo bar"</tt> will
1559be parsed as three words, <tt>-option</tt>, <tt>"foo</tt>, and <tt>bar"</tt>,
1560which is different from what you would get from the shell with the same
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1561input.</p>
1562
1563</div>
Brian Gaekee5842852003-08-19 23:11:43 +0000[diff] [blame]1564
1565<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1566<div class="doc_subsubsection">
Reid Spencer2403b852006-06-05 17:30:16 +0000[diff] [blame]1567 <a name="cl::SetVersionPrinter">The <tt>cl::SetVersionPrinter</tt>
1568 function</a>
1569</div>
1570
1571<div class="doc_text">
1572
1573<p>The <tt>cl::SetVersionPrinter</tt> function is designed to be called
Chris Lattner8b44b902008-01-09 19:28:50 +0000[diff] [blame]1574directly from <tt>main</tt> and <i>before</i>
Reid Spencer2403b852006-06-05 17:30:16 +0000[diff] [blame]1575<tt>cl::ParseCommandLineOptions</tt>. Its use is optional. It simply arranges
1576for a function to be called in response to the <tt>--version</tt> option instead
1577of having the <tt>CommandLine</tt> library print out the usual version string
1578for LLVM. This is useful for programs that are not part of LLVM but wish to use
1579the <tt>CommandLine</tt> facilities. Such programs should just define a small
1580function that takes no arguments and returns <tt>void</tt> and that prints out
1581whatever version information is appropriate for the program. Pass the address
1582of that function to <tt>cl::SetVersionPrinter</tt> to arrange for it to be
1583called when the <tt>--version</tt> option is given by the user.</p>
1584
1585</div>
1586<!-- _______________________________________________________________________ -->
1587<div class="doc_subsubsection">
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1588 <a name="cl::opt">The <tt>cl::opt</tt> class</a>
1589</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1590
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1591<div class="doc_text">
1592
1593<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]1594options, and is the one used most of the time. It is a templated class which
1595can take up to three arguments (all except for the first have default values
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1596though):</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1597
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1598<div class="doc_code"><pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1599<b>namespace</b> cl {
1600 <b>template</b> &lt;<b>class</b> DataType, <b>bool</b> ExternalStorage = <b>false</b>,
1601 <b>class</b> ParserClass = parser&lt;DataType&gt; &gt;
1602 <b>class</b> opt;
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1603}
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1604</pre></div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1605
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1606<p>The first template argument specifies what underlying data type the command
1607line argument is, and is used to select a default parser implementation. The
1608second template argument is used to specify whether the option should contain
1609the storage for the option (the default) or whether external storage should be
1610used to contain the value parsed for the option (see <a href="#storage">Internal
1611vs External Storage</a> for more information).</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1612
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1613<p>The third template argument specifies which parser to use. The default value
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1614selects an instantiation of the <tt>parser</tt> class based on the underlying
1615data type of the option. In general, this default works well for most
1616applications, so this option is only used when using a <a
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1617href="#customparser">custom parser</a>.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1618
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1619</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1620
1621<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1622<div class="doc_subsubsection">
1623 <a name="cl::list">The <tt>cl::list</tt> class</a>
1624</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1625
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1626<div class="doc_text">
1627
1628<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]1629line options. It too is a templated class which can take up to three
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1630arguments:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1631
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1632<div class="doc_code"><pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1633<b>namespace</b> cl {
1634 <b>template</b> &lt;<b>class</b> DataType, <b>class</b> Storage = <b>bool</b>,
1635 <b>class</b> ParserClass = parser&lt;DataType&gt; &gt;
1636 <b>class</b> list;
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1637}
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1638</pre></div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1639
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1640<p>This class works the exact same as the <a
1641href="#cl::opt"><tt>cl::opt</tt></a> class, except that the second argument is
1642the <b>type</b> of the external storage, not a boolean value. For this class,
1643the marker type '<tt>bool</tt>' is used to indicate that internal storage should
1644be used.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1645
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1646</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1647
1648<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1649<div class="doc_subsubsection">
Jim Laskey1d8f6262005-08-25 22:52:43 +0000[diff] [blame]1650 <a name="cl::bits">The <tt>cl::bits</tt> class</a>
1651</div>
1652
1653<div class="doc_text">
1654
1655<p>The <tt>cl::bits</tt> class is the class used to represent a list of command
1656line options in the form of a bit vector. It is also a templated class which
1657can take up to three arguments:</p>
1658
1659<div class="doc_code"><pre>
1660<b>namespace</b> cl {
1661 <b>template</b> &lt;<b>class</b> DataType, <b>class</b> Storage = <b>bool</b>,
1662 <b>class</b> ParserClass = parser&lt;DataType&gt; &gt;
1663 <b>class</b> bits;
1664}
1665</pre></div>
1666
1667<p>This class works the exact same as the <a
1668href="#cl::opt"><tt>cl::lists</tt></a> class, except that the second argument
Jim Laskey22b7dfa2005-08-26 09:25:54 +0000[diff] [blame]1669must be of <b>type</b> <tt>unsigned</tt> if external storage is used.</p>
Jim Laskey1d8f6262005-08-25 22:52:43 +0000[diff] [blame]1670
1671</div>
1672
1673<!-- _______________________________________________________________________ -->
1674<div class="doc_subsubsection">
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1675 <a name="cl::alias">The <tt>cl::alias</tt> class</a>
1676</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1677
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1678<div class="doc_text">
1679
1680<p>The <tt>cl::alias</tt> class is a nontemplated class that is used to form
1681aliases for other arguments.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1682
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1683<div class="doc_code"><pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1684<b>namespace</b> cl {
1685 <b>class</b> alias;
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1686}
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1687</pre></div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1688
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1689<p>The <a href="#cl::aliasopt"><tt>cl::aliasopt</tt></a> attribute should be
1690used to specify which option this is an alias for. Alias arguments default to
1691being <a href="#cl::Hidden">Hidden</a>, and use the aliased options parser to do
1692the conversion from string to data.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1693
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1694</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1695
Reid Spencer9bbba0912004-11-16 06:11:52 +0000[diff] [blame]1696<!-- _______________________________________________________________________ -->
1697<div class="doc_subsubsection">
1698 <a name="cl::extrahelp">The <tt>cl::extrahelp</tt> class</a>
1699</div>
1700
1701<div class="doc_text">
1702
1703<p>The <tt>cl::extrahelp</tt> class is a nontemplated class that allows extra
1704help text to be printed out for the <tt>--help</tt> option.</p>
1705
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1706<div class="doc_code"><pre>
Reid Spencer9bbba0912004-11-16 06:11:52 +0000[diff] [blame]1707<b>namespace</b> cl {
1708 <b>struct</b> extrahelp;
1709}
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1710</pre></div>
Reid Spencer9bbba0912004-11-16 06:11:52 +0000[diff] [blame]1711
Anton Korobeynikov45982a52008-02-20 12:38:31 +0000[diff] [blame]1712<p>To use the extrahelp, simply construct one with a <tt>const char*</tt>
Reid Spencer9bbba0912004-11-16 06:11:52 +0000[diff] [blame]1713parameter to the constructor. The text passed to the constructor will be printed
1714at the bottom of the help message, verbatim. Note that multiple
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1715<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]1716your tool needs to print additional help information, put all that help into a
1717single <tt>cl::extrahelp</tt> instance.</p>
1718<p>For example:</p>
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1719<div class="doc_code"><pre>
Reid Spencer9bbba0912004-11-16 06:11:52 +0000[diff] [blame]1720 cl::extrahelp("\nADDITIONAL HELP:\n\n This is the extra help\n");
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1721</pre></div>
Reid Spencer9bbba0912004-11-16 06:11:52 +0000[diff] [blame]1722</div>
1723
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1724<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1725<div class="doc_subsection">
1726 <a name="builtinparsers">Builtin parsers</a>
1727</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1728
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1729<div class="doc_text">
1730
1731<p>Parsers control how the string value taken from the command line is
1732translated into a typed value, suitable for use in a C++ program. By default,
1733the CommandLine library uses an instance of <tt>parser&lt;type&gt;</tt> if the
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1734command line option specifies that it uses values of type '<tt>type</tt>'.
1735Because of this, custom option processing is specified with specializations of
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1736the '<tt>parser</tt>' class.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1737
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1738<p>The CommandLine library provides the following builtin parser
1739specializations, which are sufficient for most applications. It can, however,
1740also be extended to work with new data types and new ways of interpreting the
1741same data. See the <a href="#customparser">Writing a Custom Parser</a> for more
1742details on this type of library extension.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1743
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1744<ul>
1745
1746<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]1747can be used to map strings values to any data type, through the use of the <a
1748href="#cl::values">cl::values</a> property, which specifies the mapping
1749information. The most common use of this parser is for parsing enum values,
1750which allows you to use the CommandLine library for all of the error checking to
1751make sure that only valid enum values are specified (as opposed to accepting
1752arbitrary strings). Despite this, however, the generic parser class can be used
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1753for any data type.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1754
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1755<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]1756is used to convert boolean strings to a boolean value. Currently accepted
1757strings are "<tt>true</tt>", "<tt>TRUE</tt>", "<tt>True</tt>", "<tt>1</tt>",
Mike Stumpd64e0eb2009-02-02 22:48:49 +0000[diff] [blame]1758"<tt>false</tt>", "<tt>FALSE</tt>", "<tt>False</tt>", and "<tt>0</tt>". The
1759<b><tt>cl::AllowInverse</tt></b> modifier can be used on an option of the form
1760<tt>-fopt</tt> that uses the <tt>parser&lt;bool&gt;</tt> specialization
1761to create a corresponding option with the form <tt>-fno-opt</tt>. See
1762<a href="#cl::AllowInverse"><tt>cl::AllowInverse</tt></a> for details.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1763
Dale Johannesen0f2c8fc2007-05-22 18:32:34 +0000[diff] [blame]1764<li><a name="boolOrDefaultparser">The <b><tt>parser&lt;boolOrDefault&gt;</tt>
1765 specialization</b></a> is used for cases where the value is boolean,
1766but we also need to know whether the option was specified at all. boolOrDefault
1767is an enum with 3 values, BOU_UNSET, BOU_TRUE and BOU_FALSE. This parser accepts
1768the same strings as <b><tt>parser&lt;bool&gt;</tt></b>.</li>
1769
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1770<li><a name="stringparser">The <b><tt>parser&lt;string&gt;</tt>
1771specialization</b></a> simply stores the parsed string into the string value
1772specified. No conversion or modification of the data is performed.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1773
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1774<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]1775uses the C <tt>strtol</tt> function to parse the string input. As such, it will
1776accept a decimal number (with an optional '+' or '-' prefix) which must start
1777with a non-zero digit. It accepts octal numbers, which are identified with a
1778'<tt>0</tt>' prefix digit, and hexadecimal numbers with a prefix of
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1779'<tt>0x</tt>' or '<tt>0X</tt>'.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1780
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1781<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]1782<b><tt>parser&lt;float&gt;</tt> specializations</b> use the standard C
1783<tt>strtod</tt> function to convert floating point strings into floating point
1784values. As such, a broad range of string formats is supported, including
1785exponential notation (ex: <tt>1.7e15</tt>) and properly supports locales.
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1786</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1787
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1788</ul>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]1789
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1790</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]1791
1792<!-- *********************************************************************** -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1793<div class="doc_section">
1794 <a name="extensionguide">Extension Guide</a>
1795</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]1796<!-- *********************************************************************** -->
1797
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1798<div class="doc_text">
1799
1800<p>Although the CommandLine library has a lot of functionality built into it
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1801already (as discussed previously), one of its true strengths lie in its
1802extensibility. This section discusses how the CommandLine library works under
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1803the covers and illustrates how to do some simple, common, extensions.</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1804
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1805</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]1806
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1807<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1808<div class="doc_subsection">
1809 <a name="customparser">Writing a custom parser</a>
1810</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1811
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1812<div class="doc_text">
1813
1814<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]1815As <a href="#builtinparsers">discussed previously</a>, parsers are the portion
1816of the CommandLine library that turns string input from the user into a
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1817particular parsed data type, validating the input in the process.</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1818
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1819<p>There are two ways to use a new parser:</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1820
1821<ol>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1822
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1823<li>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1824
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1825<p>Specialize the <a href="#genericparser"><tt>cl::parser</tt></a> template for
1826your custom data type.<p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1827
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1828<p>This approach has the advantage that users of your custom data type will
1829automatically use your custom parser whenever they define an option with a value
1830type of your data type. The disadvantage of this approach is that it doesn't
Jim Laskeyf55914a2006-07-31 20:18:49 +0000[diff] [blame]1831work if your fundamental data type is something that is already supported.</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1832
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1833</li>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1834
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1835<li>
1836
1837<p>Write an independent class, using it explicitly from options that need
1838it.</p>
1839
1840<p>This approach works well in situations where you would line to parse an
1841option using special syntax for a not-very-special data-type. The drawback of
1842this approach is that users of your parser have to be aware that they are using
Chris Lattner8b44b902008-01-09 19:28:50 +0000[diff] [blame]1843your parser instead of the builtin ones.</p>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1844
1845</li>
1846
1847</ol>
1848
1849<p>To guide the discussion, we will discuss a custom parser that accepts file
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1850sizes, specified with an optional unit after the numeric size. For example, we
1851would like to parse "102kb", "41M", "1G" into the appropriate integer value. In
1852this case, the underlying data type we want to parse into is
1853'<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]1854this the default for all <tt>unsigned</tt> options.</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1855
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1856<p>To start out, we declare our new <tt>FileSizeParser</tt> class:</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]1859<b>struct</b> FileSizeParser : <b>public</b> cl::basic_parser&lt;<b>unsigned</b>&gt; {
1860 <i>// parse - Return true on error.</i>
1861 <b>bool</b> parse(cl::Option &amp;O, <b>const char</b> *ArgName, <b>const</b> std::string &amp;ArgValue,
1862 <b>unsigned</b> &amp;Val);
1863};
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1864</pre></div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1865
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1866<p>Our new class inherits from the <tt>cl::basic_parser</tt> template class to
Chris Lattner8b44b902008-01-09 19:28:50 +0000[diff] [blame]1867fill in the default, boiler plate code for us. We give it the data type that
1868we parse into, the last argument to the <tt>parse</tt> method, so that clients of
1869our custom parser know what object type to pass in to the parse method. (Here we
1870declare that we parse into '<tt>unsigned</tt>' variables.)</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1871
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1872<p>For most purposes, the only method that must be implemented in a custom
1873parser is the <tt>parse</tt> method. The <tt>parse</tt> method is called
1874whenever the option is invoked, passing in the option itself, the option name,
1875the string to parse, and a reference to a return value. If the string to parse
Chris Lattner8b44b902008-01-09 19:28:50 +0000[diff] [blame]1876is not well-formed, the parser should output an error message and return true.
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1877Otherwise it should return false and set '<tt>Val</tt>' to the parsed value. In
1878our example, we implement <tt>parse</tt> as:</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1879
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1880<div class="doc_code"><pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1881<b>bool</b> FileSizeParser::parse(cl::Option &amp;O, <b>const char</b> *ArgName,
1882 <b>const</b> std::string &amp;Arg, <b>unsigned</b> &amp;Val) {
1883 <b>const char</b> *ArgStart = Arg.c_str();
1884 <b>char</b> *End;
Anton Korobeynikov45982a52008-02-20 12:38:31 +0000[diff] [blame]1885
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1886 <i>// Parse integer part, leaving 'End' pointing to the first non-integer char</i>
1887 Val = (unsigned)strtol(ArgStart, &amp;End, 0);
1888
1889 <b>while</b> (1) {
1890 <b>switch</b> (*End++) {
Chris Lattnerce5fcc32005-08-22 16:24:25 +0000[diff] [blame]1891 <b>case</b> 0: <b>return</b> false; <i>// No error</i>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1892 <b>case</b> 'i': <i>// Ignore the 'i' in KiB if people use that</i>
1893 <b>case</b> 'b': <b>case</b> 'B': <i>// Ignore B suffix</i>
1894 <b>break</b>;
1895
1896 <b>case</b> 'g': <b>case</b> 'G': Val *= 1024*1024*1024; <b>break</b>;
1897 <b>case</b> 'm': <b>case</b> 'M': Val *= 1024*1024; <b>break</b>;
1898 <b>case</b> 'k': <b>case</b> 'K': Val *= 1024; <b>break</b>;
1899
1900 default:
1901 <i>// Print an error message if unrecognized character!</i>
1902 <b>return</b> O.error(": '" + Arg + "' value invalid for file size argument!");
1903 }
1904 }
1905}
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1906</pre></div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1907
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1908<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]1909interested in. Although it has some holes (it allows "<tt>123KKK</tt>" for
1910example), it is good enough for this example. Note that we use the option
1911itself to print out the error message (the <tt>error</tt> method always returns
1912true) 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]1913parser class, we can use it like this:</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1914
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1915<div class="doc_code"><pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1916<b>static</b> <a href="#cl::opt">cl::opt</a>&lt;<b>unsigned</b>, <b>false</b>, FileSizeParser&gt;
1917MFS(<i>"max-file-size"</i>, <a href="#cl::desc">cl::desc</a>(<i>"Maximum file size to accept"</i>),
1918 <a href="#cl::value_desc">cl::value_desc</a>("<i>size</i>"));
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1919</pre></div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1920
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1921<p>Which adds this to the output of our program:</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1922
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1923<div class="doc_code"><pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1924OPTIONS:
1925 -help - display available options (--help-hidden for more)
1926 ...
1927 <b>-max-file-size=&lt;size&gt; - Maximum file size to accept</b>
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1928</pre></div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1929
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1930<p>And we can test that our parse works correctly now (the test program just
1931prints out the max-file-size argument value):</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1932
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1933<div class="doc_code"><pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1934$ ./test
1935MFS: 0
1936$ ./test -max-file-size=123MB
1937MFS: 128974848
1938$ ./test -max-file-size=3G
1939MFS: 3221225472
1940$ ./test -max-file-size=dog
1941-max-file-size option: 'dog' value invalid for file size argument!
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1942</pre></div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1943
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1944<p>It looks like it works. The error message that we get is nice and helpful,
1945and we seem to accept reasonable file sizes. This wraps up the "custom parser"
1946tutorial.</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1947
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1948</div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1949
1950<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1951<div class="doc_subsection">
1952 <a name="explotingexternal">Exploiting external storage</a>
1953</div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1954
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1955<div class="doc_text">
Reid Spencerb993feb2004-08-30 05:56:51 +0000[diff] [blame]1956 <p>Several of the LLVM libraries define static <tt>cl::opt</tt> instances that
1957 will automatically be included in any program that links with that library.
1958 This is a feature. However, sometimes it is necessary to know the value of the
1959 command line option outside of the library. In these cases the library does or
1960 should provide an external storage location that is accessible to users of the
1961 library. Examples of this include the <tt>llvm::DebugFlag</tt> exported by the
1962 <tt>lib/Support/Debug.cpp</tt> file and the <tt>llvm::TimePassesIsEnabled</tt>
1963 flag exported by the <tt>lib/VMCore/Pass.cpp</tt> file.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1964
Reid Spencerb993feb2004-08-30 05:56:51 +0000[diff] [blame]1965<p>TODO: complete this section</p>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1966
1967</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1968
1969<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1970<div class="doc_subsection">
1971 <a name="dynamicopts">Dynamically adding command line options</a>
1972</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1973
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1974<div class="doc_text">
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1975
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1976<p>TODO: fill in this section</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]1977
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1978</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]1979
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]1980<!-- *********************************************************************** -->
1981
1982<hr>
Misha Brukmanc53aefb2004-05-12 18:42:35 +0000[diff] [blame]1983<address>
1984 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
Misha Brukman44408702008-12-11 17:34:48 +0000[diff] [blame]1985 src="http://jigsaw.w3.org/css-validator/images/vcss-blue" alt="Valid CSS"></a>
Misha Brukmanc53aefb2004-05-12 18:42:35 +0000[diff] [blame]1986 <a href="http://validator.w3.org/check/referer"><img
Misha Brukman44408702008-12-11 17:34:48 +0000[diff] [blame]1987 src="http://www.w3.org/Icons/valid-html401-blue" alt="Valid HTML 4.01"></a>
Misha Brukmanc53aefb2004-05-12 18:42:35 +0000[diff] [blame]1988
1989 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
Reid Spencer05fe4b02006-03-14 05:39:39 +0000[diff] [blame]1990 <a href="http://llvm.org">LLVM Compiler Infrastructure</a><br>
Misha Brukman3c299112003-11-07 18:11:14 +0000[diff] [blame]1991 Last modified: $Date$
Misha Brukmanc53aefb2004-05-12 18:42:35 +0000[diff] [blame]1992</address>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1993
1994</body>
1995</html>