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gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / ce5fcc30ae71ee965dbde2da31e47e05b47ff248 / . / docs / CommandLine.html
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Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
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3<html>
4<head>
Reid Spencer9bbba0912004-11-16 06:11:52 +0000[diff] [blame]5 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]6 <title>CommandLine 2.0 Library Manual</title>
Misha Brukman3c299112003-11-07 18:11:14 +0000[diff] [blame]7 <link rel="stylesheet" href="llvm.css" type="text/css">
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]8</head>
9<body>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]10
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]11<div class="doc_title">
12 CommandLine 2.0 Library Manual
13</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]14
15<ol>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]16 <li><a href="#introduction">Introduction</a></li>
17
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]18 <li><a href="#quickstart">Quick Start Guide</a>
19 <ol>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]20 <li><a href="#bool">Boolean Arguments</a></li>
21 <li><a href="#alias">Argument Aliases</a></li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]22 <li><a href="#onealternative">Selecting an alternative from a
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]23 set of possibilities</a></li>
24 <li><a href="#namedalternatives">Named alternatives</a></li>
25 <li><a href="#list">Parsing a list of options</a></li>
26 <li><a href="#description">Adding freeform text to help output</a></li>
27 </ol></li>
28
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]29 <li><a href="#referenceguide">Reference Guide</a>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]30 <ol>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]31 <li><a href="#positional">Positional Arguments</a>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]32 <ul>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]33 <li><a href="#--">Specifying positional options with hyphens</a></li>
Reid Spencer2c8ab582004-08-13 20:19:14 +0000[diff] [blame]34 <li><a href="#getPosition">Determining absolute position with
35 getPosition</a></li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]36 <li><a href="#cl::ConsumeAfter">The <tt>cl::ConsumeAfter</tt>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]37 modifier</a></li>
38 </ul></li>
39
40 <li><a href="#storage">Internal vs External Storage</a></li>
41
42 <li><a href="#attributes">Option Attributes</a></li>
43
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]44 <li><a href="#modifiers">Option Modifiers</a>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]45 <ul>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]46 <li><a href="#hiding">Hiding an option from <tt>--help</tt>
47 output</a></li>
48 <li><a href="#numoccurrences">Controlling the number of occurrences
49 required and allowed</a></li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]50 <li><a href="#valrequired">Controlling whether or not a value must be
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]51 specified</a></li>
52 <li><a href="#formatting">Controlling other formatting options</a></li>
53 <li><a href="#misc">Miscellaneous option modifiers</a></li>
54 </ul></li>
55
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]56 <li><a href="#toplevel">Top-Level Classes and Functions</a>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]57 <ul>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]58 <li><a href="#cl::ParseCommandLineOptions">The
59 <tt>cl::ParseCommandLineOptions</tt> function</a></li>
60 <li><a href="#cl::ParseEnvironmentOptions">The
61 <tt>cl::ParseEnvironmentOptions</tt> function</a></li>
62 <li><a href="#cl::opt">The <tt>cl::opt</tt> class</a></li>
63 <li><a href="#cl::list">The <tt>cl::list</tt> class</a></li>
64 <li><a href="#cl::alias">The <tt>cl::alias</tt> class</a></li>
Reid Spencer9bbba0912004-11-16 06:11:52 +0000[diff] [blame]65 <li><a href="#cl::extrahelp">The <tt>cl::extrahelp</tt> class</a></li>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]66 </ul></li>
67
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]68 <li><a href="#builtinparsers">Builtin parsers</a>
69 <ul>
70 <li><a href="#genericparser">The Generic <tt>parser&lt;t&gt;</tt>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]71 parser</a></li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]72 <li><a href="#boolparser">The <tt>parser&lt;bool&gt;</tt>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]73 specialization</a></li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]74 <li><a href="#stringparser">The <tt>parser&lt;string&gt;</tt>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]75 specialization</a></li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]76 <li><a href="#intparser">The <tt>parser&lt;int&gt;</tt>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]77 specialization</a></li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]78 <li><a href="#doubleparser">The <tt>parser&lt;double&gt;</tt> and
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]79 <tt>parser&lt;float&gt;</tt> specializations</a></li>
80 </ul></li>
81 </ol></li>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]82 <li><a href="#extensionguide">Extension Guide</a>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]83 <ol>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]84 <li><a href="#customparser">Writing a custom parser</a></li>
85 <li><a href="#explotingexternal">Exploiting external storage</a></li>
86 <li><a href="#dynamicopts">Dynamically adding command line
87 options</a></li>
88 </ol></li>
89</ol>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]90
Chris Lattner7911ce22004-05-23 21:07:27 +0000[diff] [blame]91<div class="doc_author">
92 <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a></p>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]93</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]94
95<!-- *********************************************************************** -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]96<div class="doc_section">
Misha Brukman8becd712003-11-07 19:42:44 +0000[diff] [blame]97 <a name="introduction">Introduction</a>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]98</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]99<!-- *********************************************************************** -->
100
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]101<div class="doc_text">
102
103<p>This document describes the CommandLine argument processing library. It will
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]104show you how to use it, and what it can do. The CommandLine library uses a
105declarative approach to specifying the command line options that your program
106takes. By default, these options declarations implicitly hold the value parsed
107for the option declared (of course this <a href="#storage">can be
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]108changed</a>).</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]109
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]110<p>Although there are a <b>lot</b> of command line argument parsing libraries
111out there in many different languages, none of them fit well with what I needed.
112By looking at the features and problems of other libraries, I designed the
113CommandLine library to have the following features:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]114
115<ol>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]116<li>Speed: The CommandLine library is very quick and uses little resources. The
117parsing time of the library is directly proportional to the number of arguments
118parsed, not the the number of options recognized. Additionally, command line
Chris Lattneredf351f2003-06-21 21:45:56 +0000[diff] [blame]119argument values are captured transparently into user defined global variables,
120which can be accessed like any other variable (and with the same
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]121performance).</li>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]122
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]123<li>Type Safe: As a user of CommandLine, you don't have to worry about
124remembering the type of arguments that you want (is it an int? a string? a
125bool? an enum?) and keep casting it around. Not only does this help prevent
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]126error prone constructs, it also leads to dramatically cleaner source code.</li>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]127
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]128<li>No subclasses required: To use CommandLine, you instantiate variables that
129correspond to the arguments that you would like to capture, you don't subclass a
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]130parser. This means that you don't have to write <b>any</b> boilerplate
131code.</li>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]132
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]133<li>Globally accessible: Libraries can specify command line arguments that are
134automatically enabled in any tool that links to the library. This is possible
135because the application doesn't have to keep a "list" of arguments to pass to
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]136the parser. This also makes supporting <a href="#dynamicopts">dynamically
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]137loaded options</a> trivial.</li>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]138
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]139<li>Cleaner: CommandLine supports enum and other types directly, meaning that
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]140there is less error and more security built into the library. You don't have to
141worry about whether your integral command line argument accidentally got
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]142assigned a value that is not valid for your enum type.</li>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]143
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]144<li>Powerful: The CommandLine library supports many different types of
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]145arguments, from simple <a href="#boolparser">boolean flags</a> to <a
146href="#cl::opt">scalars arguments</a> (<a href="#stringparser">strings</a>, <a
147href="#intparser">integers</a>, <a href="#genericparser">enums</a>, <a
148href="#doubleparser">doubles</a>), to <a href="#cl::list">lists of
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]149arguments</a>. This is possible because CommandLine is...</li>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]150
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]151<li>Extensible: It is very simple to add a new argument type to CommandLine.
152Simply specify the parser that you want to use with the command line option when
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]153you declare it. <a href="#customparser">Custom parsers</a> are no problem.</li>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]154
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]155<li>Labor Saving: The CommandLine library cuts down on the amount of grunt work
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]156that you, the user, have to do. For example, it automatically provides a
157<tt>--help</tt> option that shows the available command line options for your
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]158tool. Additionally, it does most of the basic correctness checking for
159you.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]160
161<li>Capable: The CommandLine library can handle lots of different forms of
162options often found in real programs. For example, <a
163href="#positional">positional</a> arguments, <tt>ls</tt> style <a
164href="#cl::Grouping">grouping</a> options (to allow processing '<tt>ls
165-lad</tt>' naturally), <tt>ld</tt> style <a href="#cl::Prefix">prefix</a>
166options (to parse '<tt>-lmalloc -L/usr/lib</tt>'), and <a
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]167href="#cl::ConsumeAfter">interpreter style options</a>.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]168
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]169</ol>
170
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]171<p>This document will hopefully let you jump in and start using CommandLine in
172your utility quickly and painlessly. Additionally it should be a simple
173reference manual to figure out how stuff works. If it is failing in some area
174(or you want an extension to the library), nag the author, <a
175href="mailto:sabre@nondot.org">Chris Lattner</a>.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]176
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]177</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]178
179<!-- *********************************************************************** -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]180<div class="doc_section">
181 <a name="quickstart">Quick Start Guide</a>
182</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]183<!-- *********************************************************************** -->
184
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]185<div class="doc_text">
186
187<p>This section of the manual runs through a simple CommandLine'ification of a
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]188basic compiler tool. This is intended to show you how to jump into using the
189CommandLine library in your own program, and show you some of the cool things it
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]190can do.</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]191
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]192<p>To start out, you need to include the CommandLine header file into your
193program:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]194
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]195<div class="doc_code"><pre>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]196 #include "Support/CommandLine.h"
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]197</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]198
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]199<p>Additionally, you need to add this as the first line of your main
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>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]203int main(int argc, char **argv) {
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]204 <a href="#cl::ParseCommandLineOptions">cl::ParseCommandLineOptions</a>(argc, argv);
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]205 ...
206}
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]207</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]208
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]209<p>... which actually parses the arguments and fills in the variable
210declarations.</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]211
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]212<p>Now that you are ready to support command line arguments, we need to tell the
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]213system which ones we want, and what type of argument they are. The CommandLine
Chris Lattneredf351f2003-06-21 21:45:56 +0000[diff] [blame]214library uses a declarative syntax to model command line arguments with the
215global variable declarations that capture the parsed values. This means that
216for every command line option that you would like to support, there should be a
217global variable declaration to capture the result. For example, in a compiler,
218we would like to support the unix standard '<tt>-o &lt;filename&gt;</tt>' option
219to specify where to put the output. With the CommandLine library, this is
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]220represented like this:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]221
Misha Brukmanc53aefb2004-05-12 18:42:35 +0000[diff] [blame]222<a name="value_desc_example"></a>
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]223<div class="doc_code"><pre>
Misha Brukmanc53aefb2004-05-12 18:42:35 +0000[diff] [blame]224<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]225</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]226
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]227<p>This declares a global variable "<tt>OutputFilename</tt>" that is used to
Chris Lattneredf351f2003-06-21 21:45:56 +0000[diff] [blame]228capture the result of the "<tt>o</tt>" argument (first parameter). We specify
229that this is a simple scalar option by using the "<tt><a
230href="#cl::opt">cl::opt</a></tt>" template (as opposed to the <a
231href="#list">"<tt>cl::list</tt> template</a>), and tell the CommandLine library
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]232that the data type that we are parsing is a string.</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]233
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]234<p>The second and third parameters (which are optional) are used to specify what
235to output for the "<tt>--help</tt>" option. In this case, we get a line that
236looks like this:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]237
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]238<div class="doc_code"><pre>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]239USAGE: compiler [options]
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]240
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]241OPTIONS:
242 -help - display available options (--help-hidden for more)
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]243 <b>-o &lt;filename&gt; - Specify output filename</b>
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]244</pre></div>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]245
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]246<p>Because we specified that the command line option should parse using the
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]247<tt>string</tt> data type, the variable declared is automatically usable as a
248real string in all contexts that a normal C++ string object may be used. For
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]249example:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]250
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]251<div class="doc_code"><pre>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]252 ...
253 ofstream Output(OutputFilename.c_str());
254 if (Out.good()) ...
255 ...
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]256</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]257
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]258<p>There are many different options that you can use to customize the command
259line option handling library, but the above example shows the general interface
260to these options. The options can be specified in any order, and are specified
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]261with helper functions like <a href="#cl::desc"><tt>cl::desc(...)</tt></a>, so
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]262there are no positional dependencies to remember. The available options are
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]263discussed in detail in the <a href="#referenceguide">Reference Guide</a>.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]264
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]265<p>Continuing the example, we would like to have our compiler take an input
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]266filename as well as an output filename, but we do not want the input filename to
267be specified with a hyphen (ie, not <tt>-filename.c</tt>). To support this
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]268style of argument, the CommandLine library allows for <a
269href="#positional">positional</a> arguments to be specified for the program.
270These positional arguments are filled with command line parameters that are not
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]271in option form. We use this feature like this:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]272
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]273<div class="doc_code"><pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]274<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]275</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]276
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]277<p>This declaration indicates that the first positional argument should be
278treated as the input filename. Here we use the <tt><a
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]279href="#cl::init">cl::init</a></tt> option to specify an initial value for the
280command line option, which is used if the option is not specified (if you do not
281specify a <tt><a href="#cl::init">cl::init</a></tt> modifier for an option, then
282the default constructor for the data type is used to initialize the value).
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]283Command line options default to being optional, so if we would like to require
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]284that the user always specify an input filename, we would add the <tt><a
285href="#cl::Required">cl::Required</a></tt> flag, and we could eliminate the
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]286<tt><a href="#cl::init">cl::init</a></tt> modifier, like this:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]287
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]288<div class="doc_code"><pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]289<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]290</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]291
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]292<p>Again, the CommandLine library does not require the options to be specified
293in any particular order, so the above declaration is equivalent to:</p>
Chris Lattnerae853632002-07-25 19:27:01 +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::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]297</pre></div>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]298
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]299<p>By simply adding the <tt><a href="#cl::Required">cl::Required</a></tt> flag,
300the CommandLine library will automatically issue an error if the argument is not
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]301specified, which shifts all of the command line option verification code out of
302your application into the library. This is just one example of how using flags
303can alter the default behaviour of the library, on a per-option basis. By
304adding one of the declarations above, the <tt>--help</tt> option synopsis is now
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]305extended to:</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]306
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]307<div class="doc_code"><pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]308USAGE: compiler [options] <b>&lt;input file&gt;</b>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]309
310OPTIONS:
311 -help - display available options (--help-hidden for more)
312 -o &lt;filename&gt; - Specify output filename
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]313</pre></div>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]314
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]315<p>... indicating that an input filename is expected.</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]316
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]317</div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]318
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]319<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]320<div class="doc_subsection">
321 <a name="bool">Boolean Arguments</a>
322</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]323
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]324<div class="doc_text">
325
326<p>In addition to input and output filenames, we would like the compiler example
327to support three boolean flags: "<tt>-f</tt>" to force overwriting of the output
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]328file, "<tt>--quiet</tt>" to enable quiet mode, and "<tt>-q</tt>" for backwards
329compatibility with some of our users. We can support these by declaring options
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]330of boolean type like this:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]331
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]332<div class="doc_code"><pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]333<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>"));
334<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>"));
335<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]336</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]337
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]338<p>This does what you would expect: it declares three boolean variables
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]339("<tt>Force</tt>", "<tt>Quiet</tt>", and "<tt>Quiet2</tt>") to recognize these
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]340options. Note that the "<tt>-q</tt>" option is specified with the "<a
341href="#cl::Hidden"><tt>cl::Hidden</tt></a>" flag. This modifier prevents it
342from being shown by the standard "<tt>--help</tt>" output (note that it is still
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]343shown in the "<tt>--help-hidden</tt>" output).</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]344
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]345<p>The CommandLine library uses a <a href="#builtinparsers">different parser</a>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]346for different data types. For example, in the string case, the argument passed
347to the option is copied literally into the content of the string variable... we
348obviously cannot do that in the boolean case, however, so we must use a smarter
349parser. In the case of the boolean parser, it allows no options (in which case
350it assigns the value of true to the variable), or it allows the values
351"<tt>true</tt>" or "<tt>false</tt>" to be specified, allowing any of the
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]352following inputs:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]353
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]354<div class="doc_code"><pre>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]355 compiler -f # No value, 'Force' == true
356 compiler -f=true # Value specified, 'Force' == true
357 compiler -f=TRUE # Value specified, 'Force' == true
358 compiler -f=FALSE # Value specified, 'Force' == false
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]359</pre></div>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]360
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]361<p>... you get the idea. The <a href="#boolparser">bool parser</a> just turns
362the string values into boolean values, and rejects things like '<tt>compiler
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]363-f=foo</tt>'. Similarly, the <a href="#doubleparser">float</a>, <a
364href="#doubleparser">double</a>, and <a href="#intparser">int</a> parsers work
365like you would expect, using the '<tt>strtol</tt>' and '<tt>strtod</tt>' C
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]366library calls to parse the string value into the specified data type.</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]367
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]368<p>With the declarations above, "<tt>compiler --help</tt>" emits this:</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]369
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]370<div class="doc_code"><pre>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]371USAGE: compiler [options] &lt;input file&gt;
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]372
373OPTIONS:
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]374 <b>-f - Overwrite output files</b>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]375 -o - Override output filename
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]376 <b>-quiet - Don't print informational messages</b>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]377 -help - display available options (--help-hidden for more)
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]378</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]379
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]380<p>and "<tt>opt --help-hidden</tt>" prints this:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]381
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]382<div class="doc_code"><pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]383USAGE: compiler [options] &lt;input file&gt;
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]384
385OPTIONS:
386 -f - Overwrite output files
387 -o - Override output filename
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]388 <b>-q - Don't print informational messages</b>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]389 -quiet - Don't print informational messages
390 -help - display available options (--help-hidden for more)
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]391</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]392
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]393<p>This brief example has shown you how to use the '<tt><a
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]394href="#cl::opt">cl::opt</a></tt>' class to parse simple scalar command line
395arguments. In addition to simple scalar arguments, the CommandLine library also
396provides primitives to support CommandLine option <a href="#alias">aliases</a>,
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]397and <a href="#list">lists</a> of options.</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]398
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]399</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]400
401<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]402<div class="doc_subsection">
403 <a name="alias">Argument Aliases</a>
404</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]405
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]406<div class="doc_text">
407
408<p>So far, the example works well, except for the fact that we need to check the
409quiet condition like this now:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]410
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]411<div class="doc_code"><pre>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]412...
413 if (!Quiet &amp;&amp; !Quiet2) printInformationalMessage(...);
414...
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]415</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]416
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]417<p>... which is a real pain! Instead of defining two values for the same
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]418condition, 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]419option an <b>alias</b> for the "<tt>-quiet</tt>" option, instead of providing
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]420a value itself:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]421
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]422<div class="doc_code"><pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]423<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>"));
424<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>"));
425<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]426</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]427
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]428<p>The third line (which is the only one we modified from above) defines a
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]429"<tt>-q</tt> alias that updates the "<tt>Quiet</tt>" variable (as specified by
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]430the <tt><a href="#cl::aliasopt">cl::aliasopt</a></tt> modifier) whenever it is
431specified. Because aliases do not hold state, the only thing the program has to
432query is the <tt>Quiet</tt> variable now. Another nice feature of aliases is
433that they automatically hide themselves from the <tt>-help</tt> output
434(although, again, they are still visible in the <tt>--help-hidden
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]435output</tt>).</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]436
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]437<p>Now the application code can simply use:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]438
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]439<div class="doc_code"><pre>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]440...
441 if (!Quiet) printInformationalMessage(...);
442...
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]443</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]444
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]445<p>... which is much nicer! The "<tt><a href="#cl::alias">cl::alias</a></tt>"
446can be used to specify an alternative name for any variable type, and has many
447uses.</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]448
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]449</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]450
451<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]452<div class="doc_subsection">
453 <a name="onealternative">Selecting an alternative from a set of
454 possibilities</a>
455</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]456
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]457<div class="doc_text">
458
459<p>So far, we have seen how the CommandLine library handles builtin types like
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]460<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]461things it doesn't know about, like enums or '<tt>int*</tt>'s?</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]462
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]463<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]464your own parser, as described in the <a href="#extensionguide">Extension
Reid Spencerd8473372004-08-10 16:38:18 +0000[diff] [blame]465Guide</a>). This parser maps literal strings to whatever type is required, and
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]466requires you to tell it what this mapping should be.</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]467
Reid Spencerd8473372004-08-10 16:38:18 +0000[diff] [blame]468<p>Lets say that we would like to add four optimization levels to our
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]469optimizer, using the standard flags "<tt>-g</tt>", "<tt>-O0</tt>",
470"<tt>-O1</tt>", and "<tt>-O2</tt>". We could easily implement this with boolean
471options like above, but there are several problems with this strategy:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]472
473<ol>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]474<li>A user could specify more than one of the options at a time, for example,
475"<tt>opt -O3 -O2</tt>". The CommandLine library would not be able to catch this
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]476erroneous input for us.</li>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]477
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]478<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]479
480<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]481see if some level &gt;= "<tt>-O1</tt>" is enabled.</li>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]482
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]483</ol>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]484
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]485<p>To cope with these problems, we can use an enum value, and have the
486CommandLine library fill it in with the appropriate level directly, which is
487used like this:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]488
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]489<div class="doc_code"><pre>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]490enum OptLevel {
491 g, O1, O2, O3
492};
493
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]494<a href="#cl::opt">cl::opt</a>&lt;OptLevel&gt; OptimizationLevel(<a href="#cl::desc">cl::desc</a>("<i>Choose optimization level:</i>"),
495 <a href="#cl::values">cl::values</a>(
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]496 clEnumVal(g , "<i>No optimizations, enable debugging</i>"),
497 clEnumVal(O1, "<i>Enable trivial optimizations</i>"),
498 clEnumVal(O2, "<i>Enable default optimizations</i>"),
499 clEnumVal(O3, "<i>Enable expensive optimizations</i>"),
Chris Lattnerb406ead2004-07-16 00:10:54 +0000[diff] [blame]500 clEnumValEnd));
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]501
502...
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]503 if (OptimizationLevel &gt;= O2) doPartialRedundancyElimination(...);
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]504...
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]505</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]506
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]507<p>This declaration defines a variable "<tt>OptimizationLevel</tt>" of the
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]508"<tt>OptLevel</tt>" enum type. This variable can be assigned any of the values
509that are listed in the declaration (Note that the declaration list must be
Chris Lattnerb406ead2004-07-16 00:10:54 +0000[diff] [blame]510terminated with the "<tt>clEnumValEnd</tt>" argument!). The CommandLine
511library enforces
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]512that the user can only specify one of the options, and it ensure that only valid
513enum values can be specified. The "<tt>clEnumVal</tt>" macros ensure that the
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]514command line arguments matched the enum values. With this option added, our
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]515help output now is:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]516
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]517<div class="doc_code"><pre>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]518USAGE: compiler [options] &lt;input file&gt;
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]519
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]520OPTIONS:
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]521 <b>Choose optimization level:
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]522 -g - No optimizations, enable debugging
523 -O1 - Enable trivial optimizations
524 -O2 - Enable default optimizations
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]525 -O3 - Enable expensive optimizations</b>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]526 -f - Overwrite output files
527 -help - display available options (--help-hidden for more)
528 -o &lt;filename&gt; - Specify output filename
529 -quiet - Don't print informational messages
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]530</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]531
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]532<p>In this case, it is sort of awkward that flag names correspond directly to
533enum names, because we probably don't want a enum definition named "<tt>g</tt>"
534in our program. Because of this, we can alternatively write this example like
535this:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]536
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]537<div class="doc_code"><pre>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]538enum OptLevel {
539 Debug, O1, O2, O3
540};
541
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]542<a href="#cl::opt">cl::opt</a>&lt;OptLevel&gt; OptimizationLevel(<a href="#cl::desc">cl::desc</a>("<i>Choose optimization level:</i>"),
543 <a href="#cl::values">cl::values</a>(
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]544 clEnumValN(Debug, "g", "<i>No optimizations, enable debugging</i>"),
545 clEnumVal(O1 , "<i>Enable trivial optimizations</i>"),
546 clEnumVal(O2 , "<i>Enable default optimizations</i>"),
547 clEnumVal(O3 , "<i>Enable expensive optimizations</i>"),
Chris Lattnerb406ead2004-07-16 00:10:54 +0000[diff] [blame]548 clEnumValEnd));
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]549
550...
551 if (OptimizationLevel == Debug) outputDebugInfo(...);
552...
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]553</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]554
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]555<p>By using the "<tt>clEnumValN</tt>" macro instead of "<tt>clEnumVal</tt>", we
556can directly specify the name that the flag should get. In general a direct
557mapping is nice, but sometimes you can't or don't want to preserve the mapping,
558which is when you would use it.</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]559
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]560</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]561
562<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]563<div class="doc_subsection">
564 <a name="namedalternatives">Named Alternatives</a>
565</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]566
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]567<div class="doc_text">
568
569<p>Another useful argument form is a named alternative style. We shall use this
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]570style in our compiler to specify different debug levels that can be used.
571Instead of each debug level being its own switch, we want to support the
572following options, of which only one can be specified at a time:
573"<tt>--debug-level=none</tt>", "<tt>--debug-level=quick</tt>",
574"<tt>--debug-level=detailed</tt>". To do this, we use the exact same format as
575our optimization level flags, but we also specify an option name. For this
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]576case, the code looks like this:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]577
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]578<div class="doc_code"><pre>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]579enum DebugLev {
580 nodebuginfo, quick, detailed
581};
582
583// Enable Debug Options to be specified on the command line
Chris Lattnerdc844fa2003-06-03 04:40:06 +0000[diff] [blame]584<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]585 <a href="#cl::values">cl::values</a>(
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]586 clEnumValN(nodebuginfo, "none", "<i>disable debug information</i>"),
587 clEnumVal(quick, "<i>enable quick debug information</i>"),
588 clEnumVal(detailed, "<i>enable detailed debug information</i>"),
Chris Lattnerb406ead2004-07-16 00:10:54 +0000[diff] [blame]589 clEnumValEnd));
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]590</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]591
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]592<p>This definition defines an enumerated command line variable of type "<tt>enum
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]593DebugLev</tt>", which works exactly the same way as before. The difference here
594is 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]595the "<tt>--help</tt>" option:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]596
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]597<div class="doc_code"><pre>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]598USAGE: compiler [options] &lt;input file&gt;
599
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]600OPTIONS:
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]601 Choose optimization level:
602 -g - No optimizations, enable debugging
603 -O1 - Enable trivial optimizations
604 -O2 - Enable default optimizations
605 -O3 - Enable expensive optimizations
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]606 <b>-debug_level - Set the debugging level:
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]607 =none - disable debug information
608 =quick - enable quick debug information
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]609 =detailed - enable detailed debug information</b>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]610 -f - Overwrite output files
611 -help - display available options (--help-hidden for more)
612 -o &lt;filename&gt; - Specify output filename
613 -quiet - Don't print informational messages
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]614</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]615
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]616<p>Again, the only structural difference between the debug level declaration and
John Criswellc24d4822004-11-21 14:34:34 +0000[diff] [blame]617the optimization level declaration is that the debug level declaration includes
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]618an option name (<tt>"debug_level"</tt>), which automatically changes how the
619library processes the argument. The CommandLine library supports both forms so
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]620that you can choose the form most appropriate for your application.</p>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]621
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]622</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]623
624<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]625<div class="doc_subsection">
626 <a name="list">Parsing a list of options</a>
627</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]628
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]629<div class="doc_text">
630
631<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]632lets get a little wild and crazy. Lets say that we want our optimizer to accept
633a <b>list</b> of optimizations to perform, allowing duplicates. For example, we
634might want to run: "<tt>compiler -dce -constprop -inline -dce -strip</tt>". In
635this case, the order of the arguments and the number of appearances is very
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]636important. This is what the "<tt><a href="#cl::list">cl::list</a></tt>"
637template is for. First, start by defining an enum of the optimizations that you
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]638would like to perform:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]639
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]640<div class="doc_code"><pre>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]641enum Opts {
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]642 // 'inline' is a C++ keyword, so name it 'inlining'
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]643 dce, constprop, inlining, strip
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]644};
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]645</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]646
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]647<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]648
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]649<div class="doc_code"><pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]650<a href="#cl::list">cl::list</a>&lt;Opts&gt; OptimizationList(<a href="#cl::desc">cl::desc</a>("<i>Available Optimizations:</i>"),
651 <a href="#cl::values">cl::values</a>(
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]652 clEnumVal(dce , "<i>Dead Code Elimination</i>"),
Misha Brukman82c89b92003-05-20 21:01:22 +0000[diff] [blame]653 clEnumVal(constprop , "<i>Constant Propagation</i>"),
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]654 clEnumValN(inlining, "<i>inline</i>", "<i>Procedure Integration</i>"),
655 clEnumVal(strip , "<i>Strip Symbols</i>"),
Chris Lattnerb406ead2004-07-16 00:10:54 +0000[diff] [blame]656 clEnumValEnd));
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]657</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]658
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]659<p>This defines a variable that is conceptually of the type
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]660"<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]661vector methods:</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]662
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]663<div class="doc_code"><pre>
Chris Lattnerae853632002-07-25 19:27:01 +0000[diff] [blame]664 for (unsigned i = 0; i != OptimizationList.size(); ++i)
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]665 switch (OptimizationList[i])
666 ...
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]667</pre></div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]668
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]669<p>... to iterate through the list of options specified.</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]670
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]671<p>Note that the "<tt><a href="#cl::list">cl::list</a></tt>" template is
672completely general and may be used with any data types or other arguments that
673you can use with the "<tt><a href="#cl::opt">cl::opt</a></tt>" template. One
674especially useful way to use a list is to capture all of the positional
675arguments together if there may be more than one specified. In the case of a
676linker, for example, the linker takes several '<tt>.o</tt>' files, and needs to
677capture them into a list. This is naturally specified as:</p>
Chris Lattner3e5fe172002-04-13 18:35:59 +0000[diff] [blame]678
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]679<div class="doc_code"><pre>
Chris Lattner3e5fe172002-04-13 18:35:59 +0000[diff] [blame]680...
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]681<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]682...
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]683</pre></div>
Chris Lattner3e5fe172002-04-13 18:35:59 +0000[diff] [blame]684
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]685<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]686such, accessing the list is simple, just like above. In this example, we used
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]687the <tt><a href="#cl::OneOrMore">cl::OneOrMore</a></tt> modifier to inform the
688CommandLine library that it is an error if the user does not specify any
689<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]690checking we have to do.</p>
Chris Lattner3e5fe172002-04-13 18:35:59 +0000[diff] [blame]691
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]692</div>
Chris Lattner3e5fe172002-04-13 18:35:59 +0000[diff] [blame]693
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]694<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]695<div class="doc_subsection">
696 <a name="description">Adding freeform text to help output</a>
697</div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]698
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]699<div class="doc_text">
700
701<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]702information about what it does into the help output. The help output is styled
703to look similar to a Unix <tt>man</tt> page, providing concise information about
704a program. Unix <tt>man</tt> pages, however often have a description about what
705the program does. To add this to your CommandLine program, simply pass a third
706argument to the <a
707href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>
708call in main. This additional argument is then printed as the overview
709information for your program, allowing you to include any additional information
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]710that you want. For example:</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]711
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]712<div class="doc_code"><pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]713int main(int argc, char **argv) {
714 <a href="#cl::ParseCommandLineOptions">cl::ParseCommandLineOptions</a>(argc, argv, " CommandLine compiler example\n\n"
715 " This program blah blah blah...\n");
716 ...
717}
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]718</pre></div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]719
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]720<p>would yield the help output:</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]721
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]722<div class="doc_code"><pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]723<b>OVERVIEW: CommandLine compiler example
724
725 This program blah blah blah...</b>
726
727USAGE: compiler [options] &lt;input file&gt;
728
729OPTIONS:
730 ...
731 -help - display available options (--help-hidden for more)
732 -o &lt;filename&gt; - Specify output filename
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]733</pre></div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]734
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]735</div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]736
737
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]738<!-- *********************************************************************** -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]739<div class="doc_section">
740 <a name="referenceguide">Reference Guide</a>
741</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]742<!-- *********************************************************************** -->
743
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]744<div class="doc_text">
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]745
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]746<p>Now that you know the basics of how to use the CommandLine library, this
747section will give you the detailed information you need to tune how command line
748options work, as well as information on more "advanced" command line option
749processing capabilities.</p>
750
751</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]752
753<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]754<div class="doc_subsection">
755 <a name="positional">Positional Arguments</a>
756</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]757
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]758<div class="doc_text">
759
760<p>Positional arguments are those arguments that are not named, and are not
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]761specified with a hyphen. Positional arguments should be used when an option is
762specified by its position alone. For example, the standard Unix <tt>grep</tt>
763tool takes a regular expression argument, and an optional filename to search
764through (which defaults to standard input if a filename is not specified).
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]765Using the CommandLine library, this would be specified as:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]766
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]767<div class="doc_code"><pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]768<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>);
769<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]770</pre></div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]771
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]772<p>Given these two option declarations, the <tt>--help</tt> output for our grep
773replacement would look like this:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]774
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]775<div class="doc_code"><pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]776USAGE: spiffygrep [options] <b>&lt;regular expression&gt; &lt;input file&gt;</b>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]777
778OPTIONS:
779 -help - display available options (--help-hidden for more)
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]780</pre></div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]781
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]782<p>... and the resultant program could be used just like the standard
783<tt>grep</tt> tool.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]784
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]785<p>Positional arguments are sorted by their order of construction. This means
786that command line options will be ordered according to how they are listed in a
Reid Spencer2c8ab582004-08-13 20:19:14 +0000[diff] [blame]787.cpp file, but will not have an ordering defined if the positional arguments
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]788are defined in multiple .cpp files. The fix for this problem is simply to
789define all of your positional arguments in one .cpp file.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]790
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]791</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]792
793
794<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]795<div class="doc_subsubsection">
796 <a name="--">Specifying positional options with hyphens</a>
797</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]798
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]799<div class="doc_text">
800
801<p>Sometimes you may want to specify a value to your positional argument that
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]802starts with a hyphen (for example, searching for '<tt>-foo</tt>' in a file). At
803first, you will have trouble doing this, because it will try to find an argument
804named '<tt>-foo</tt>', and will fail (and single quotes will not save you).
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]805Note that the system <tt>grep</tt> has the same problem:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]806
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]807<div class="doc_code"><pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]808 $ spiffygrep '-foo' test.txt
809 Unknown command line argument '-foo'. Try: spiffygrep --help'
810
811 $ grep '-foo' test.txt
812 grep: illegal option -- f
813 grep: illegal option -- o
814 grep: illegal option -- o
815 Usage: grep -hblcnsviw pattern file . . .
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]816</pre></div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]817
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]818<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]819version: use the '<tt>--</tt>' marker. When the user specifies '<tt>--</tt>' on
820the command line, it is telling the program that all options after the
821'<tt>--</tt>' should be treated as positional arguments, not options. Thus, we
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]822can use it like this:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]823
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]824<div class="doc_code"><pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]825 $ spiffygrep -- -foo test.txt
826 ...output...
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]827</pre></div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]828
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]829</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]830
831<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]832<div class="doc_subsubsection">
Reid Spencer2c8ab582004-08-13 20:19:14 +0000[diff] [blame]833 <a name="getPosition">Determining absolute position with getPosition()</a>
834</div>
835<div class="doc_text">
836 <p>Sometimes an option can affect or modify the meaning of another option. For
837 example, consider <tt>gcc</tt>'s <tt>-x LANG</tt> option. This tells
838 <tt>gcc</tt> to ignore the suffix of subsequent positional arguments and force
839 the file to be interpreted as if it contained source code in language
840 <tt>LANG</tt>. In order to handle this properly , you need to know the
841 absolute position of each argument, especially those in lists, so their
842 interaction(s) can be applied correctly. This is also useful for options like
843 <tt>-llibname</tt> which is actually a positional argument that starts with
844 a dash.</p>
845 <p>So, generally, the problem is that you have two <tt>cl::list</tt> variables
846 that interact in some way. To ensure the correct interaction, you can use the
847 <tt>cl::list::getPosition(optnum)</tt> method. This method returns the
848 absolute position (as found on the command line) of the <tt>optnum</tt>
849 item in the <tt>cl::list</tt>.</p>
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]850 <p>The idiom for usage is like this:</p>
851
852 <div class="doc_code"><pre>
Reid Spencer2c8ab582004-08-13 20:19:14 +0000[diff] [blame]853 static cl::list&lt;std::string&gt; Files(cl::Positional, cl::OneOrMore);
854 static cl::listlt;std::string&gt; Libraries("l", cl::ZeroOrMore);
855
856 int main(int argc, char**argv) {
857 // ...
858 std::vector&lt;std::string&gt;::iterator fileIt = Files.begin();
859 std::vector&lt;std::string&gt;::iterator libIt = Libraries.begin();
860 unsigned libPos = 0, filePos = 0;
861 while ( 1 ) {
862 if ( libIt != Libraries.end() )
863 libPos = Libraries.getPosition( libIt - Libraries.begin() );
864 else
865 libPos = 0;
866 if ( fileIt != Files.end() )
867 filePos = Files.getPosition( fileIt - Files.begin() );
868 else
869 filePos = 0;
870
871 if ( filePos != 0 &amp;&amp; (libPos == 0 || filePos &lt; libPos) ) {
872 // Source File Is next
873 ++fileIt;
874 }
875 else if ( libPos != 0 &amp;&amp; (filePos == 0 || libPos &lt; filePos) ) {
876 // Library is next
877 ++libIt;
878 }
879 else
880 break; // we're done with the list
881 }
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]882 }</pre></div>
883
Reid Spencer2c8ab582004-08-13 20:19:14 +0000[diff] [blame]884 <p>Note that, for compatibility reasons, the <tt>cl::opt</tt> also supports an
885 <tt>unsigned getPosition()</tt> option that will provide the absolute position
886 of that option. You can apply the same approach as above with a
887 <tt>cl::opt</tt> and a <tt>cl::list</tt> option as you can with two lists.</p>
888</div>
889
890<!-- _______________________________________________________________________ -->
891<div class="doc_subsubsection">
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]892 <a name="cl::ConsumeAfter">The <tt>cl::ConsumeAfter</tt> modifier</a>
893</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]894
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]895<div class="doc_text">
896
897<p>The <tt>cl::ConsumeAfter</tt> <a href="#formatting">formatting option</a> is
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]898used to construct programs that use "interpreter style" option processing. With
899this style of option processing, all arguments specified after the last
900positional argument are treated as special interpreter arguments that are not
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]901interpreted by the command line argument.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]902
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]903<p>As a concrete example, lets say we are developing a replacement for the
904standard Unix Bourne shell (<tt>/bin/sh</tt>). To run <tt>/bin/sh</tt>, first
905you specify options to the shell itself (like <tt>-x</tt> which turns on trace
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]906output), then you specify the name of the script to run, then you specify
907arguments to the script. These arguments to the script are parsed by the bourne
908shell command line option processor, but are not interpreted as options to the
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]909shell itself. Using the CommandLine library, we would specify this as:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]910
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]911<div class="doc_code"><pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]912<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>("-"));
913<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>"));
914<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]915</pre></div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]916
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]917<p>which automatically provides the help output:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]918
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]919<div class="doc_code"><pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]920USAGE: spiffysh [options] <b>&lt;input script&gt; &lt;program arguments&gt;...</b>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]921
922OPTIONS:
923 -help - display available options (--help-hidden for more)
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]924 <b>-x - Enable trace output</b>
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]925</pre></div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]926
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]927<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]928-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]929<tt>Script</tt> variable will be set to "<tt>test.sh</tt>", and the
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]930<tt>Argv</tt> list will contain <tt>["-a", "-x", "-y", "bar"]</tt>, because they
931were specified after the last positional argument (which is the script
932name).</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]933
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]934<p>There are several limitations to when <tt>cl::ConsumeAfter</tt> options can
935be specified. For example, only one <tt>cl::ConsumeAfter</tt> can be specified
936per program, there must be at least one <a href="#positional">positional
Chris Lattnerbe801bf2004-05-06 22:03:59 +0000[diff] [blame]937argument</a> specified, there must not be any <a href="#cl::list">cl::list</a>
938positional arguments, and the <tt>cl::ConsumeAfter</tt> option should be a <a
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]939href="#cl::list">cl::list</a> option.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]940
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]941</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]942
943<!-- ======================================================================= -->
Chris Lattnerbe801bf2004-05-06 22:03:59 +0000[diff] [blame]944<div class="doc_subsection">
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]945 <a name="storage">Internal vs External Storage</a>
946</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]947
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]948<div class="doc_text">
949
950<p>By default, all command line options automatically hold the value that they
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]951parse from the command line. This is very convenient in the common case,
952especially when combined with the ability to define command line options in the
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]953files that use them. This is called the internal storage model.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]954
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]955<p>Sometimes, however, it is nice to separate the command line option processing
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]956code from the storage of the value parsed. For example, lets say that we have a
957'<tt>-debug</tt>' option that we would like to use to enable debug information
958across the entire body of our program. In this case, the boolean value
959controlling the debug code should be globally accessable (in a header file, for
960example) yet the command line option processing code should not be exposed to
961all of these clients (requiring lots of .cpp files to #include
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]962<tt>CommandLine.h</tt>).</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]963
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]964<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]965
Misha Brukman1fc9f8e2005-02-09 22:49:05 +0000[diff] [blame]966<div class="doc_code">
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]967<pre>
968<i>// DebugFlag.h - Get access to the '-debug' command line option
969//
970
971// DebugFlag - This boolean is set to true if the '-debug' command line option
972// is specified. This should probably not be referenced directly, instead, use
973// the DEBUG macro below.
974//</i>
975extern bool DebugFlag;
976
977<i>// DEBUG macro - This macro should be used by code to emit debug information.
978// In the '-debug' option is specified on the command line, and if this is a
979// debug build, then the code specified as the option to the macro will be
980// executed. Otherwise it will not be. Example:
981//
Misha Brukman1fc9f8e2005-02-09 22:49:05 +0000[diff] [blame]982// DEBUG(std::cerr &lt;&lt; "Bitset contains: " &lt;&lt; Bitset &lt;&lt; "\n");
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]983//</i>
Misha Brukman1fc9f8e2005-02-09 22:49:05 +0000[diff] [blame]984<span class="doc_hilite">#ifdef NDEBUG
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]985#define DEBUG(X)
986#else
Misha Brukman1fc9f8e2005-02-09 22:49:05 +0000[diff] [blame]987#define DEBUG(X)</span> do { if (DebugFlag) { X; } } while (0)
988<span class="doc_hilite">#endif</span>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]989</pre>
Misha Brukman1fc9f8e2005-02-09 22:49:05 +0000[diff] [blame]990</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]991
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]992<p>This allows clients to blissfully use the <tt>DEBUG()</tt> macro, or the
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]993<tt>DebugFlag</tt> explicitly if they want to. Now we just need to be able to
994set the <tt>DebugFlag</tt> boolean when the option is set. To do this, we pass
995an additial argument to our command line argument processor, and we specify
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]996where to fill in with the <a href="#cl::location">cl::location</a>
997attribute:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]998
Misha Brukman1fc9f8e2005-02-09 22:49:05 +0000[diff] [blame]999<div class="doc_code">
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1000<pre>
Misha Brukman1fc9f8e2005-02-09 22:49:05 +0000[diff] [blame]1001bool DebugFlag; <i>// the actual value</i>
Chris Lattner589a4cc2003-08-01 21:30:37 +0000[diff] [blame]1002static <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]1003Debug("<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]1004</pre>
Misha Brukman1fc9f8e2005-02-09 22:49:05 +0000[diff] [blame]1005</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1006
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1007<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]1008the <tt><a href="#cl::opt">cl::opt</a></tt> template, indicating that the
1009template should not maintain a copy of the value itself. In addition to this,
1010we specify the <tt><a href="#cl::location">cl::location</a></tt> attribute, so
1011that <tt>DebugFlag</tt> is automatically set.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1012
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1013</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1014
1015<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1016<div class="doc_subsection">
1017 <a name="attributes">Option Attributes</a>
1018</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1019
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1020<div class="doc_text">
1021
1022<p>This section describes the basic attributes that you can specify on
1023options.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1024
1025<ul>
1026
1027<li>The option name attribute (which is required for all options, except <a
1028href="#positional">positional options</a>) specifies what the option name is.
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1029This option is specified in simple double quotes:
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1030
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1031<pre>
1032<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]1033</pre>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1034
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1035</li>
1036
1037<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]1038description for the option to be shown in the <tt>--help</tt> output for the
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1039program.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1040
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1041<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]1042specifies a string that can be used to fine tune the <tt>--help</tt> output for
1043a command line option. Look <a href="#value_desc_example">here</a> for an
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1044example.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1045
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1046<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]1047inital value for a <a href="#cl::opt">scalar</a> option. If this attribute is
1048not specified then the command line option value defaults to the value created
Brian Gaeke9d292ff2003-08-19 22:56:22 +0000[diff] [blame]1049by the default constructor for the type. <b>Warning</b>: If you specify both
1050<b><tt>cl::init</tt></b> and <b><tt>cl::location</tt></b> for an option,
1051you must specify <b><tt>cl::location</tt></b> first, so that when the
1052command-line parser sees <b><tt>cl::init</tt></b>, it knows where to put the
1053initial 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]1054the right order.)</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1055
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1056<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]1057store the value for a parsed command line option if using external storage. See
1058the section on <a href="#storage">Internal vs External Storage</a> for more
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1059information.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1060
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1061<li><a name="cl::aliasopt">The <b><tt>cl::aliasopt</tt></b></a> attribute
Misha Brukman1fc9f8e2005-02-09 22:49:05 +0000[diff] [blame]1062specifies which option a <tt><a href="#cl::alias">cl::alias</a></tt> option is
1063an alias for.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1064
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1065<li><a name="cl::values">The <b><tt>cl::values</tt></b></a> attribute specifies
1066the string-to-value mapping to be used by the generic parser. It takes a
Chris Lattnerb406ead2004-07-16 00:10:54 +0000[diff] [blame]1067<b>clEnumValEnd terminated</b> list of (option, value, description) triplets
1068that
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1069specify the option name, the value mapped to, and the description shown in the
1070<tt>--help</tt> for the tool. Because the generic parser is used most
1071frequently with enum values, two macros are often useful:
1072
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1073<ol>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1074
1075<li><a name="clEnumVal">The <b><tt>clEnumVal</tt></b></a> macro is used as a
1076nice simple way to specify a triplet for an enum. This macro automatically
1077makes the option name be the same as the enum name. The first option to the
1078macro is the enum, the second is the description for the command line
1079option.</li>
1080
1081<li><a name="clEnumValN">The <b><tt>clEnumValN</tt></b></a> macro is used to
1082specify macro options where the option name doesn't equal the enum name. For
1083this macro, the first argument is the enum value, the second is the flag name,
1084and the second is the description.</li>
1085
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1086</ol>
1087
1088You 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]1089that does not support it.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1090
1091</ul>
1092
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1093</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1094
1095<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1096<div class="doc_subsection">
1097 <a name="modifiers">Option Modifiers</a>
1098</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1099
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1100<div class="doc_text">
1101
1102<p>Option modifiers are the flags and expressions that you pass into the
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1103constructors for <tt><a href="#cl::opt">cl::opt</a></tt> and <tt><a
1104href="#cl::list">cl::list</a></tt>. These modifiers give you the ability to
1105tweak how options are parsed and how <tt>--help</tt> output is generated to fit
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1106your application well.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1107
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1108<p>These options fall into five main catagories:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1109
1110<ol>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1111<li><a href="#hiding">Hiding an option from <tt>--help</tt> output</a></li>
1112<li><a href="#numoccurrences">Controlling the number of occurrences
1113 required and allowed</a></li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1114<li><a href="#valrequired">Controlling whether or not a value must be
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1115 specified</a></li>
1116<li><a href="#formatting">Controlling other formatting options</a></li>
1117<li><a href="#misc">Miscellaneous option modifiers</a></li>
1118</ol>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1119
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1120<p>It is not possible to specify two options from the same catagory (you'll get
1121a runtime error) to a single option, except for options in the miscellaneous
Chris Lattner32a32842003-05-22 20:36:06 +0000[diff] [blame]1122catagory. The CommandLine library specifies defaults for all of these settings
1123that are the most useful in practice and the most common, which mean that you
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1124usually shouldn't have to worry about these.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1125
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1126</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1127
1128<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1129<div class="doc_subsubsection">
1130 <a name="hiding">Hiding an option from <tt>--help</tt> output</a>
1131</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1132
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1133<div class="doc_text">
1134
1135<p>The <tt>cl::NotHidden</tt>, <tt>cl::Hidden</tt>, and
1136<tt>cl::ReallyHidden</tt> modifiers are used to control whether or not an option
1137appears in the <tt>--help</tt> and <tt>--help-hidden</tt> output for the
1138compiled program:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1139
1140<ul>
1141
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1142<li><a name="cl::NotHidden">The <b><tt>cl::NotHidden</tt></b></a> modifier
1143(which is the default for <tt><a href="#cl::opt">cl::opt</a></tt> and <tt><a
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1144href="#cl::list">cl::list</a></tt> options), indicates the option is to appear
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1145in both help listings.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1146
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1147<li><a name="cl::Hidden">The <b><tt>cl::Hidden</tt></b></a> modifier (which is the
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1148default for <tt><a href="#cl::alias">cl::alias</a></tt> options), indicates that
1149the option should not appear in the <tt>--help</tt> output, but should appear in
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1150the <tt>--help-hidden</tt> output.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1151
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1152<li><a name="cl::ReallyHidden">The <b><tt>cl::ReallyHidden</tt></b></a> modifier,
1153indicates that the option should not appear in any help output.</li>
1154
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1155</ul>
1156
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1157</div>
1158
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1159<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1160<div class="doc_subsubsection">
1161 <a name="numoccurrences">Controlling the number of occurrences required and
1162 allowed</a>
1163</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1164
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1165<div class="doc_text">
1166
1167<p>This group of options is used to control how many time an option is allowed
1168(or required) to be specified on the command line of your program. Specifying a
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1169value for this setting allows the CommandLine library to do error checking for
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1170you.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1171
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1172<p>The allowed values for this option group are:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1173
1174<ul>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1175
1176<li><a name="cl::Optional">The <b><tt>cl::Optional</tt></b></a> modifier (which
1177is 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]1178href="#cl::alias">cl::alias</a></tt> classes) indicates that your program will
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1179allow either zero or one occurrence of the option to be specified.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1180
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1181<li><a name="cl::ZeroOrMore">The <b><tt>cl::ZeroOrMore</tt></b></a> modifier
1182(which is the default for the <tt><a href="#cl::list">cl::list</a></tt> class)
1183indicates that your program will allow the option to be specified zero or more
1184times.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1185
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1186<li><a name="cl::Required">The <b><tt>cl::Required</tt></b></a> modifier
1187indicates that the specified option must be specified exactly one time.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1188
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1189<li><a name="cl::OneOrMore">The <b><tt>cl::OneOrMore</tt></b></a> modifier
1190indicates that the option must be specified at least one time.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1191
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1192<li>The <b><tt>cl::ConsumeAfter</tt></b> modifier is described in the <a
1193href="#positional">Positional arguments section</a></li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1194
1195</ul>
1196
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1197<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]1198value specified by the <tt><a href="#cl::init">cl::init</a></tt> attribute. If
1199the <tt><a href="#cl::init">cl::init</a></tt> attribute is not specified, the
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1200option value is initialized with the default constructor for the data type.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1201
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1202<p>If an option is specified multiple times for an option of the <tt><a
1203href="#cl::opt">cl::opt</a></tt> class, only the last value will be
1204retained.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1205
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1206</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1207
1208<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1209<div class="doc_subsubsection">
1210 <a name="valrequired">Controlling whether or not a value must be specified</a>
1211</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1212
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1213<div class="doc_text">
1214
1215<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]1216value to be present. In the case of the CommandLine library, a value is either
1217specified 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]1218string (e.g. '<tt>-o a.out</tt>').</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1219
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1220<p>The allowed values for this option group are:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1221
1222<ul>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1223
1224<li><a name="cl::ValueOptional">The <b><tt>cl::ValueOptional</tt></b></a> modifier
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1225(which is the default for <tt>bool</tt> typed options) specifies that it is
1226acceptable to have a value, or not. A boolean argument can be enabled just by
1227appearing on the command line, or it can have an explicit '<tt>-foo=true</tt>'.
1228If an option is specified with this mode, it is illegal for the value to be
1229provided without the equal sign. Therefore '<tt>-foo true</tt>' is illegal. To
1230get this behavior, you must use the <a
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1231href="#cl::ValueRequired">cl::ValueRequired</a> modifier.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1232
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1233<li><a name="cl::ValueRequired">The <b><tt>cl::ValueRequired</tt></b></a> modifier
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1234(which is the default for all other types except for <a
1235href="#onealternative">unnamed alternatives using the generic parser</a>)
1236specifies that a value must be provided. This mode informs the command line
1237library that if an option is not provides with an equal sign, that the next
1238argument provided must be the value. This allows things like '<tt>-o
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1239a.out</tt>' to work.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1240
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1241<li><a name="cl::ValueDisallowed">The <b><tt>cl::ValueDisallowed</tt></b></a>
1242modifier (which is the default for <a href="#onealternative">unnamed
1243alternatives using the generic parser</a>) indicates that it is a runtime error
1244for the user to specify a value. This can be provided to disallow users from
1245providing options to boolean options (like '<tt>-foo=true</tt>').</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1246
1247</ul>
1248
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1249<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]1250want them to. As mentioned above, you can specify the <a
1251href="#cl::ValueDisallowed">cl::ValueDisallowed</a> modifier to a boolean
1252argument to restrict your command line parser. These options are mostly useful
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1253when <a href="#extensionguide">extending the library</a>.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1254
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1255</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1256
1257<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1258<div class="doc_subsubsection">
1259 <a name="formatting">Controlling other formatting options</a>
1260</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1261
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1262<div class="doc_text">
1263
1264<p>The formatting option group is used to specify that the command line option
1265has special abilities and is otherwise different from other command line
1266arguments. As usual, you can only specify at most one of these arguments.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1267
1268<ul>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1269
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1270<li><a name="cl::NormalFormatting">The <b><tt>cl::NormalFormatting</tt></b></a>
1271modifier (which is the default all options) specifies that this option is
1272"normal".</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1273
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1274<li><a name="cl::Positional">The <b><tt>cl::Positional</tt></b></a> modifier
1275specifies that this is a positional argument, that does not have a command line
1276option associated with it. See the <a href="#positional">Positional
1277Arguments</a> section for more information.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1278
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1279<li>The <b><a href="#cl::ConsumeAfter"><tt>cl::ConsumeAfter</tt></a></b> modifier
1280specifies 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]1281
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1282<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]1283that this option prefixes its value. With 'Prefix' options, the equal sign does
1284not separate the value from the option name specified. Instead, the value is
1285everything after the prefix, including any equal sign if present. This is useful
1286for 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]1287linker tool or <tt>-DNAME=value</tt> in a compiler tool. Here, the
Reid Spencer5f8448f2004-11-24 06:13:42 +0000[diff] [blame]1288'<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]1289options, that have the <b><tt><a href="#cl::Prefix">cl::Prefix</a></tt></b>
1290modifier added to allow the CommandLine library to recognize them. Note that
1291<b><tt><a href="#cl::Prefix">cl::Prefix</a></tt></b> options must not have the
1292<b><tt><a href="#cl::ValueDisallowed">cl::ValueDisallowed</a></tt></b> modifier
1293specified.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1294
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1295<li><a name="cl::Grouping">The <b><tt>cl::Grouping</tt></b></a> modifier is used
1296to implement unix style tools (like <tt>ls</tt>) that have lots of single letter
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1297arguments, but only require a single dash. For example, the '<tt>ls -labF</tt>'
1298command actually enables four different options, all of which are single
Misha Brukmanc43d9142005-05-10 22:05:27 +0000[diff] [blame]1299letters. Note that <b><tt><a href="#cl::Grouping">cl::Grouping</a></tt></b>
1300options cannot have values.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1301
1302</ul>
1303
Misha Brukmanc43d9142005-05-10 22:05:27 +0000[diff] [blame]1304<p>The CommandLine library does not restrict how you use the <b><tt><a
1305href="#cl::Prefix">cl::Prefix</a></tt></b> or <b><tt><a
1306href="#cl::Grouping">cl::Grouping</a></tt></b> modifiers, but it is possible to
1307specify ambiguous argument settings. Thus, it is possible to have multiple
1308letter options that are prefix or grouping options, and they will still work as
1309designed.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1310
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1311<p>To do this, the CommandLine library uses a greedy algorithm to parse the
1312input option into (potentially multiple) prefix and grouping options. The
1313strategy basically looks like this:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1314
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1315<div class="doc_code"><tt>parse(string OrigInput) {</tt>
Misha Brukmanc53aefb2004-05-12 18:42:35 +0000[diff] [blame]1316
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1317<ol>
1318<li><tt>string input = OrigInput;</tt>
1319<li><tt>if (isOption(input)) return getOption(input).parse();</tt>&nbsp;&nbsp;&nbsp;&nbsp;<i>// Normal option</i>
1320<li><tt>while (!isOption(input) &amp;&amp; !input.empty()) input.pop_back();</tt>&nbsp;&nbsp;&nbsp;&nbsp;<i>// Remove the last letter</i>
1321<li><tt>if (input.empty()) return error();</tt>&nbsp;&nbsp;&nbsp;&nbsp;<i>// No matching option</i>
1322<li><tt>if (getOption(input).isPrefix())<br>
1323&nbsp;&nbsp;return getOption(input).parse(input);</tt>
1324<li><tt>while (!input.empty()) {&nbsp;&nbsp;&nbsp;&nbsp;<i>// Must be grouping options</i><br>
1325&nbsp;&nbsp;getOption(input).parse();<br>
1326&nbsp;&nbsp;OrigInput.erase(OrigInput.begin(), OrigInput.begin()+input.length());<br>
1327&nbsp;&nbsp;input = OrigInput;<br>
1328&nbsp;&nbsp;while (!isOption(input) &amp;&amp; !input.empty()) input.pop_back();<br>
1329}</tt>
Misha Brukmanc53aefb2004-05-12 18:42:35 +0000[diff] [blame]1330<li><tt>if (!OrigInput.empty()) error();</tt></li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1331</ol>
Misha Brukmanc53aefb2004-05-12 18:42:35 +0000[diff] [blame]1332
1333<p><tt>}</tt></p>
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]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>
Chris Lattner32a32842003-05-22 20:36:06 +0000[diff] [blame]1337
1338<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1339<div class="doc_subsubsection">
1340 <a name="misc">Miscellaneous option modifiers</a>
1341</div>
Chris Lattner32a32842003-05-22 20:36:06 +0000[diff] [blame]1342
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1343<div class="doc_text">
1344
1345<p>The miscellaneous option modifiers are the only flags where you can specify
1346more than one flag from the set: they are not mutually exclusive. These flags
1347specify boolean properties that modify the option.</p>
Chris Lattner32a32842003-05-22 20:36:06 +0000[diff] [blame]1348
1349<ul>
1350
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1351<li><a name="cl::CommaSeparated">The <b><tt>cl::CommaSeparated</tt></b></a> modifier
Chris Lattner32a32842003-05-22 20:36:06 +0000[diff] [blame]1352indicates that any commas specified for an option's value should be used to
1353split the value up into multiple values for the option. For example, these two
1354options are equivalent when <tt>cl::CommaSeparated</tt> is specified:
1355"<tt>-foo=a -foo=b -foo=c</tt>" and "<tt>-foo=a,b,c</tt>". This option only
1356makes 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]1357more values (i.e. it is a <a href="#cl::list">cl::list</a> option).</li>
1358
Chris Lattnerbe801bf2004-05-06 22:03:59 +0000[diff] [blame]1359<li><a name="cl::PositionalEatsArgs">The
1360<b><tt>cl::PositionalEatsArgs</tt></b></a> modifier (which only applies to
1361positional arguments, and only makes sense for lists) indicates that positional
1362argument should consume any strings after it (including strings that start with
1363a "-") up until another recognized positional argument. For example, if you
1364have two "eating" positional arguments "<tt>pos1</tt>" and "<tt>pos2</tt>" the
1365string "<tt>-pos1 -foo -bar baz -pos2 -bork</tt>" would cause the "<tt>-foo -bar
1366-baz</tt>" strings to be applied to the "<tt>-pos1</tt>" option and the
1367"<tt>-bork</tt>" string to be applied to the "<tt>-pos2</tt>" option.</li>
1368
Chris Lattner32a32842003-05-22 20:36:06 +0000[diff] [blame]1369</ul>
1370
Chris Lattnerbe801bf2004-05-06 22:03:59 +0000[diff] [blame]1371<p>So far, these are the only two miscellaneous option modifiers.</p>
Chris Lattner32a32842003-05-22 20:36:06 +0000[diff] [blame]1372
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1373</div>
Chris Lattner32a32842003-05-22 20:36:06 +0000[diff] [blame]1374
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1375<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1376<div class="doc_subsection">
1377 <a name="toplevel">Top-Level Classes and Functions</a>
1378</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1379
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1380<div class="doc_text">
1381
1382<p>Despite all of the built-in flexibility, the CommandLine option library
1383really only consists of one function (<a
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1384href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>)
1385and three main classes: <a href="#cl::opt"><tt>cl::opt</tt></a>, <a
1386href="#cl::list"><tt>cl::list</tt></a>, and <a
1387href="#cl::alias"><tt>cl::alias</tt></a>. This section describes these three
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1388classes in detail.</p>
1389
1390</div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1391
1392<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1393<div class="doc_subsubsection">
1394 <a name="cl::ParseCommandLineOptions">The <tt>cl::ParseCommandLineOptions</tt>
1395 function</a>
1396</div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1397
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1398<div class="doc_text">
1399
1400<p>The <tt>cl::ParseCommandLineOptions</tt> function is designed to be called
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1401directly from <tt>main</tt>, and is used to fill in the values of all of the
1402command line option variables once <tt>argc</tt> and <tt>argv</tt> are
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1403available.</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1404
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1405<p>The <tt>cl::ParseCommandLineOptions</tt> function requires two parameters
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1406(<tt>argc</tt> and <tt>argv</tt>), but may also take an optional third parameter
1407which holds <a href="#description">additional extra text</a> to emit when the
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1408<tt>--help</tt> option is invoked.</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1409
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1410</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1411
1412<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1413<div class="doc_subsubsection">
1414 <a name="cl::ParseEnvironmentOptions">The <tt>cl::ParseEnvironmentOptions</tt>
1415 function</a>
1416</div>
Brian Gaekee5842852003-08-19 23:11:43 +0000[diff] [blame]1417
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1418<div class="doc_text">
Brian Gaekee5842852003-08-19 23:11:43 +0000[diff] [blame]1419
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1420<p>The <tt>cl::ParseEnvironmentOptions</tt> function has mostly the same effects
1421as <a
1422href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>,
1423except that it is designed to take values for options from an environment
1424variable, for those cases in which reading the command line is not convenient or
1425not desired. It fills in the values of all the command line option variables
1426just like <a
1427href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>
1428does.</p>
1429
1430<p>It takes three parameters: first, the name of the program (since
1431<tt>argv</tt> may not be available, it can't just look in <tt>argv[0]</tt>),
1432second, the name of the environment variable to examine, and third, the optional
Brian Gaekee5842852003-08-19 23:11:43 +0000[diff] [blame]1433<a href="#description">additional extra text</a> to emit when the
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1434<tt>--help</tt> option is invoked.</p>
Brian Gaekee5842852003-08-19 23:11:43 +0000[diff] [blame]1435
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1436<p><tt>cl::ParseEnvironmentOptions</tt> will break the environment
Brian Gaekee5842852003-08-19 23:11:43 +0000[diff] [blame]1437variable's value up into words and then process them using
1438<a href="#cl::ParseCommandLineOptions"><tt>cl::ParseCommandLineOptions</tt></a>.
1439<b>Note:</b> Currently <tt>cl::ParseEnvironmentOptions</tt> does not support
1440quoting, so an environment variable containing <tt>-option "foo bar"</tt> will
1441be parsed as three words, <tt>-option</tt>, <tt>"foo</tt>, and <tt>bar"</tt>,
1442which is different from what you would get from the shell with the same
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1443input.</p>
1444
1445</div>
Brian Gaekee5842852003-08-19 23:11:43 +0000[diff] [blame]1446
1447<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1448<div class="doc_subsubsection">
1449 <a name="cl::opt">The <tt>cl::opt</tt> class</a>
1450</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1451
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1452<div class="doc_text">
1453
1454<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]1455options, and is the one used most of the time. It is a templated class which
1456can take up to three arguments (all except for the first have default values
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1457though):</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1458
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1459<div class="doc_code"><pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1460<b>namespace</b> cl {
1461 <b>template</b> &lt;<b>class</b> DataType, <b>bool</b> ExternalStorage = <b>false</b>,
1462 <b>class</b> ParserClass = parser&lt;DataType&gt; &gt;
1463 <b>class</b> opt;
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1464}
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1465</pre></div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1466
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1467<p>The first template argument specifies what underlying data type the command
1468line argument is, and is used to select a default parser implementation. The
1469second template argument is used to specify whether the option should contain
1470the storage for the option (the default) or whether external storage should be
1471used to contain the value parsed for the option (see <a href="#storage">Internal
1472vs External Storage</a> for more information).</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1473
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1474<p>The third template argument specifies which parser to use. The default value
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1475selects an instantiation of the <tt>parser</tt> class based on the underlying
1476data type of the option. In general, this default works well for most
1477applications, so this option is only used when using a <a
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1478href="#customparser">custom parser</a>.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1479
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1480</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1481
1482<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1483<div class="doc_subsubsection">
1484 <a name="cl::list">The <tt>cl::list</tt> class</a>
1485</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1486
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1487<div class="doc_text">
1488
1489<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]1490line options. It too is a templated class which can take up to three
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1491arguments:</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1492
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1493<div class="doc_code"><pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1494<b>namespace</b> cl {
1495 <b>template</b> &lt;<b>class</b> DataType, <b>class</b> Storage = <b>bool</b>,
1496 <b>class</b> ParserClass = parser&lt;DataType&gt; &gt;
1497 <b>class</b> list;
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1498}
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1499</pre></div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1500
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1501<p>This class works the exact same as the <a
1502href="#cl::opt"><tt>cl::opt</tt></a> class, except that the second argument is
1503the <b>type</b> of the external storage, not a boolean value. For this class,
1504the marker type '<tt>bool</tt>' is used to indicate that internal storage should
1505be used.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1506
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1507</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1508
1509<!-- _______________________________________________________________________ -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1510<div class="doc_subsubsection">
1511 <a name="cl::alias">The <tt>cl::alias</tt> class</a>
1512</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1513
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1514<div class="doc_text">
1515
1516<p>The <tt>cl::alias</tt> class is a nontemplated class that is used to form
1517aliases for other arguments.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1518
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1519<div class="doc_code"><pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1520<b>namespace</b> cl {
1521 <b>class</b> alias;
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1522}
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1523</pre></div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1524
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1525<p>The <a href="#cl::aliasopt"><tt>cl::aliasopt</tt></a> attribute should be
1526used to specify which option this is an alias for. Alias arguments default to
1527being <a href="#cl::Hidden">Hidden</a>, and use the aliased options parser to do
1528the conversion from string to data.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1529
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1530</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1531
Reid Spencer9bbba0912004-11-16 06:11:52 +0000[diff] [blame]1532<!-- _______________________________________________________________________ -->
1533<div class="doc_subsubsection">
1534 <a name="cl::extrahelp">The <tt>cl::extrahelp</tt> class</a>
1535</div>
1536
1537<div class="doc_text">
1538
1539<p>The <tt>cl::extrahelp</tt> class is a nontemplated class that allows extra
1540help text to be printed out for the <tt>--help</tt> option.</p>
1541
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1542<div class="doc_code"><pre>
Reid Spencer9bbba0912004-11-16 06:11:52 +0000[diff] [blame]1543<b>namespace</b> cl {
1544 <b>struct</b> extrahelp;
1545}
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1546</pre></div>
Reid Spencer9bbba0912004-11-16 06:11:52 +0000[diff] [blame]1547
1548<p>To use the extrahelp, simply construct one with a <tt>const char*</tt>
1549parameter to the constructor. The text passed to the constructor will be printed
1550at the bottom of the help message, verbatim. Note that multiple
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1551<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]1552your tool needs to print additional help information, put all that help into a
1553single <tt>cl::extrahelp</tt> instance.</p>
1554<p>For example:</p>
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1555<div class="doc_code"><pre>
Reid Spencer9bbba0912004-11-16 06:11:52 +0000[diff] [blame]1556 cl::extrahelp("\nADDITIONAL HELP:\n\n This is the extra help\n");
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1557</pre></div>
Reid Spencer9bbba0912004-11-16 06:11:52 +0000[diff] [blame]1558</div>
1559
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1560<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1561<div class="doc_subsection">
1562 <a name="builtinparsers">Builtin parsers</a>
1563</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1564
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1565<div class="doc_text">
1566
1567<p>Parsers control how the string value taken from the command line is
1568translated into a typed value, suitable for use in a C++ program. By default,
1569the CommandLine library uses an instance of <tt>parser&lt;type&gt;</tt> if the
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1570command line option specifies that it uses values of type '<tt>type</tt>'.
1571Because of this, custom option processing is specified with specializations of
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1572the '<tt>parser</tt>' class.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1573
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1574<p>The CommandLine library provides the following builtin parser
1575specializations, which are sufficient for most applications. It can, however,
1576also be extended to work with new data types and new ways of interpreting the
1577same data. See the <a href="#customparser">Writing a Custom Parser</a> for more
1578details on this type of library extension.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1579
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1580<ul>
1581
1582<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]1583can be used to map strings values to any data type, through the use of the <a
1584href="#cl::values">cl::values</a> property, which specifies the mapping
1585information. The most common use of this parser is for parsing enum values,
1586which allows you to use the CommandLine library for all of the error checking to
1587make sure that only valid enum values are specified (as opposed to accepting
1588arbitrary strings). Despite this, however, the generic parser class can be used
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1589for any data type.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1590
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1591<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]1592is used to convert boolean strings to a boolean value. Currently accepted
1593strings are "<tt>true</tt>", "<tt>TRUE</tt>", "<tt>True</tt>", "<tt>1</tt>",
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1594"<tt>false</tt>", "<tt>FALSE</tt>", "<tt>False</tt>", and "<tt>0</tt>".</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1595
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1596<li><a name="stringparser">The <b><tt>parser&lt;string&gt;</tt>
1597specialization</b></a> simply stores the parsed string into the string value
1598specified. No conversion or modification of the data is performed.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1599
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1600<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]1601uses the C <tt>strtol</tt> function to parse the string input. As such, it will
1602accept a decimal number (with an optional '+' or '-' prefix) which must start
1603with a non-zero digit. It accepts octal numbers, which are identified with a
1604'<tt>0</tt>' prefix digit, and hexadecimal numbers with a prefix of
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1605'<tt>0x</tt>' or '<tt>0X</tt>'.</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1606
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1607<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]1608<b><tt>parser&lt;float&gt;</tt> specializations</b> use the standard C
1609<tt>strtod</tt> function to convert floating point strings into floating point
1610values. As such, a broad range of string formats is supported, including
1611exponential notation (ex: <tt>1.7e15</tt>) and properly supports locales.
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1612</li>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1613
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1614</ul>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]1615
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1616</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]1617
1618<!-- *********************************************************************** -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1619<div class="doc_section">
1620 <a name="extensionguide">Extension Guide</a>
1621</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]1622<!-- *********************************************************************** -->
1623
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1624<div class="doc_text">
1625
1626<p>Although the CommandLine library has a lot of functionality built into it
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1627already (as discussed previously), one of its true strengths lie in its
1628extensibility. This section discusses how the CommandLine library works under
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1629the covers and illustrates how to do some simple, common, extensions.</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1630
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1631</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]1632
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1633<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1634<div class="doc_subsection">
1635 <a name="customparser">Writing a custom parser</a>
1636</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1637
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1638<div class="doc_text">
1639
1640<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]1641As <a href="#builtinparsers">discussed previously</a>, parsers are the portion
1642of the CommandLine library that turns string input from the user into a
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1643particular parsed data type, validating the input in the process.</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1644
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1645<p>There are two ways to use a new parser:</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1646
1647<ol>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1648
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1649<li>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1650
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1651<p>Specialize the <a href="#genericparser"><tt>cl::parser</tt></a> template for
1652your custom data type.<p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1653
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1654<p>This approach has the advantage that users of your custom data type will
1655automatically use your custom parser whenever they define an option with a value
1656type of your data type. The disadvantage of this approach is that it doesn't
1657work if your fundemental data type is something that is already supported.</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1658
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1659</li>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1660
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1661<li>
1662
1663<p>Write an independent class, using it explicitly from options that need
1664it.</p>
1665
1666<p>This approach works well in situations where you would line to parse an
1667option using special syntax for a not-very-special data-type. The drawback of
1668this approach is that users of your parser have to be aware that they are using
1669your parser, instead of the builtin ones.</p>
1670
1671</li>
1672
1673</ol>
1674
1675<p>To guide the discussion, we will discuss a custom parser that accepts file
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1676sizes, specified with an optional unit after the numeric size. For example, we
1677would like to parse "102kb", "41M", "1G" into the appropriate integer value. In
1678this case, the underlying data type we want to parse into is
1679'<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]1680this the default for all <tt>unsigned</tt> options.</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1681
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1682<p>To start out, we declare our new <tt>FileSizeParser</tt> class:</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1683
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1684<div class="doc_code"><pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1685<b>struct</b> FileSizeParser : <b>public</b> cl::basic_parser&lt;<b>unsigned</b>&gt; {
1686 <i>// parse - Return true on error.</i>
1687 <b>bool</b> parse(cl::Option &amp;O, <b>const char</b> *ArgName, <b>const</b> std::string &amp;ArgValue,
1688 <b>unsigned</b> &amp;Val);
1689};
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1690</pre></div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1691
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1692<p>Our new class inherits from the <tt>cl::basic_parser</tt> template class to
1693fill in the default, boiler plate, code for us. We give it the data type that
1694we parse into (the last argument to the <tt>parse</tt> method so that clients of
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1695our custom parser know what object type to pass in to the parse method (here we
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1696declare that we parse into '<tt>unsigned</tt>' variables.</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1697
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1698<p>For most purposes, the only method that must be implemented in a custom
1699parser is the <tt>parse</tt> method. The <tt>parse</tt> method is called
1700whenever the option is invoked, passing in the option itself, the option name,
1701the string to parse, and a reference to a return value. If the string to parse
1702is not well formed, the parser should output an error message and return true.
1703Otherwise it should return false and set '<tt>Val</tt>' to the parsed value. In
1704our example, we implement <tt>parse</tt> as:</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1705
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1706<div class="doc_code"><pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1707<b>bool</b> FileSizeParser::parse(cl::Option &amp;O, <b>const char</b> *ArgName,
1708 <b>const</b> std::string &amp;Arg, <b>unsigned</b> &amp;Val) {
1709 <b>const char</b> *ArgStart = Arg.c_str();
1710 <b>char</b> *End;
1711
1712 <i>// Parse integer part, leaving 'End' pointing to the first non-integer char</i>
1713 Val = (unsigned)strtol(ArgStart, &amp;End, 0);
1714
1715 <b>while</b> (1) {
1716 <b>switch</b> (*End++) {
Chris Lattnerce5fcc32005-08-22 16:24:25 +0000[diff] [blame^]1717 <b>case</b> 0: <b>return</b> false; <i>// No error</i>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1718 <b>case</b> 'i': <i>// Ignore the 'i' in KiB if people use that</i>
1719 <b>case</b> 'b': <b>case</b> 'B': <i>// Ignore B suffix</i>
1720 <b>break</b>;
1721
1722 <b>case</b> 'g': <b>case</b> 'G': Val *= 1024*1024*1024; <b>break</b>;
1723 <b>case</b> 'm': <b>case</b> 'M': Val *= 1024*1024; <b>break</b>;
1724 <b>case</b> 'k': <b>case</b> 'K': Val *= 1024; <b>break</b>;
1725
1726 default:
1727 <i>// Print an error message if unrecognized character!</i>
1728 <b>return</b> O.error(": '" + Arg + "' value invalid for file size argument!");
1729 }
1730 }
1731}
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1732</pre></div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1733
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1734<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]1735interested in. Although it has some holes (it allows "<tt>123KKK</tt>" for
1736example), it is good enough for this example. Note that we use the option
1737itself to print out the error message (the <tt>error</tt> method always returns
1738true) 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]1739parser class, we can use it like this:</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1740
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1741<div class="doc_code"><pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1742<b>static</b> <a href="#cl::opt">cl::opt</a>&lt;<b>unsigned</b>, <b>false</b>, FileSizeParser&gt;
1743MFS(<i>"max-file-size"</i>, <a href="#cl::desc">cl::desc</a>(<i>"Maximum file size to accept"</i>),
1744 <a href="#cl::value_desc">cl::value_desc</a>("<i>size</i>"));
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1745</pre></div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1746
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1747<p>Which adds this to the output of our program:</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1748
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1749<div class="doc_code"><pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1750OPTIONS:
1751 -help - display available options (--help-hidden for more)
1752 ...
1753 <b>-max-file-size=&lt;size&gt; - Maximum file size to accept</b>
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1754</pre></div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1755
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1756<p>And we can test that our parse works correctly now (the test program just
1757prints out the max-file-size argument value):</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1758
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1759<div class="doc_code"><pre>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1760$ ./test
1761MFS: 0
1762$ ./test -max-file-size=123MB
1763MFS: 128974848
1764$ ./test -max-file-size=3G
1765MFS: 3221225472
1766$ ./test -max-file-size=dog
1767-max-file-size option: 'dog' value invalid for file size argument!
Misha Brukmanf75c4b42005-03-11 00:00:33 +0000[diff] [blame]1768</pre></div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1769
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1770<p>It looks like it works. The error message that we get is nice and helpful,
1771and we seem to accept reasonable file sizes. This wraps up the "custom parser"
1772tutorial.</p>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1773
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1774</div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1775
1776<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1777<div class="doc_subsection">
1778 <a name="explotingexternal">Exploiting external storage</a>
1779</div>
Chris Lattnerc1ae40c2002-08-07 18:27:04 +0000[diff] [blame]1780
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1781<div class="doc_text">
Reid Spencerb993feb2004-08-30 05:56:51 +0000[diff] [blame]1782 <p>Several of the LLVM libraries define static <tt>cl::opt</tt> instances that
1783 will automatically be included in any program that links with that library.
1784 This is a feature. However, sometimes it is necessary to know the value of the
1785 command line option outside of the library. In these cases the library does or
1786 should provide an external storage location that is accessible to users of the
1787 library. Examples of this include the <tt>llvm::DebugFlag</tt> exported by the
1788 <tt>lib/Support/Debug.cpp</tt> file and the <tt>llvm::TimePassesIsEnabled</tt>
1789 flag exported by the <tt>lib/VMCore/Pass.cpp</tt> file.</p>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1790
Reid Spencerb993feb2004-08-30 05:56:51 +0000[diff] [blame]1791<p>TODO: complete this section</p>
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1792
1793</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1794
1795<!-- ======================================================================= -->
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1796<div class="doc_subsection">
1797 <a name="dynamicopts">Dynamically adding command line options</a>
1798</div>
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1799
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1800<div class="doc_text">
Chris Lattnere76d4ab2002-08-06 19:36:06 +0000[diff] [blame]1801
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1802<p>TODO: fill in this section</p>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]1803
Misha Brukman9718e962003-10-24 19:59:21 +0000[diff] [blame]1804</div>
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]1805
Chris Lattner209c7f42001-07-23 23:03:12 +0000[diff] [blame]1806<!-- *********************************************************************** -->
1807
1808<hr>
Misha Brukmanc53aefb2004-05-12 18:42:35 +0000[diff] [blame]1809<address>
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1814
1815 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
1816 <a href="http://llvm.cs.uiuc.edu">LLVM Compiler Infrastructure</a><br>
Misha Brukman3c299112003-11-07 18:11:14 +0000[diff] [blame]1817 Last modified: $Date$
Misha Brukmanc53aefb2004-05-12 18:42:35 +0000[diff] [blame]1818</address>
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