Compare commits

...

29 Commits

Author SHA1 Message Date
6032348b4c Branch for working on the documentation tools documentation.
[SVN r68640]
2011-02-04 21:18:24 +00:00
3279399fe3 Remove BOOST_ENABLE_ASSERT_MSG_HANDLER; use BOOST_ENABLE_ASSERT_HANDLER in its stead
[SVN r68423]
2011-01-24 20:15:36 +00:00
87875cadda Add BOOST_ASSERT_MSG. Add macros to configure output stream.
[SVN r68414]
2011-01-24 15:37:13 +00:00
c58748cfd9 use declval to fix #5098
[SVN r68373]
2011-01-22 22:18:48 +00:00
58bb88d4bd Revert [67111] (addition of boost/detail/iomanip.hpp) and all the commits that depend on it. ([68137], [68140], [68141], [68154], and [68165]).
[SVN r68168]
2011-01-15 08:11:51 +00:00
11d50ecb9f Replacing the use of <iomanip> with <boost/detail/iomanip.hpp> across Boost.
On Linux, GNU's libstdc++, which is the default stdlib for icc and clang,
cannot parse the <iomanip> header in version 4.5+ (which thankfully neither
compiler advises the use of yet), as it's original C++98-friendly
implementation has been replaced with a gnu++0x implementation.
<boost/detail/iomanip.hpp> is a portable implementation of <iomanip>, providing
boost::detail::setfill, boost::detail::setbase, boost::detail::setw,
boost::detail::setprecision, boost::detail::setiosflags and
boost::detail::resetiosflags. 



[SVN r68140]
2011-01-14 02:35:58 +00:00
636283d7c2 Limit warning suppression to old versions of VC++, fixes #4432
[SVN r67278]
2010-12-16 17:30:46 +00:00
1df0bf80bc Stop inspect complaining that assert is used in BOOST_ASSERT.
[SVN r66574]
2010-11-14 18:37:37 +00:00
71e78a0081 Add declval and common type from Vicente J. Botet Escriba.
Regenerate docs.

[SVN r65443]
2010-09-17 12:12:03 +00:00
f7e4b0e399 Make sure that utility/index.html has a complete list of components. Fixes #4629.
[SVN r65437]
2010-09-16 15:40:47 +00:00
fb1d2effef correction to result_of documentation
[SVN r64696]
2010-08-09 16:23:50 +00:00
94b91e8c92 updated result_of documentation
[SVN r64695]
2010-08-09 16:07:20 +00:00
a4b8043e68 Fix some header links.
[SVN r64006]
2010-07-14 08:15:33 +00:00
b4a08fc80e Added test for private_int_array_pair, hoping to (possibly) fix a minion-clang/darwin-4.2.1 failure at boost.org/development/tests/trunk/developer/utility_.html
[SVN r63045]
2010-06-17 16:53:55 +00:00
9da96d9737 Added value_init_workaround_test, reviewed by Fernando Cacciola, see #3869
[SVN r63014]
2010-06-16 08:45:43 +00:00
a991936c96 Made memset call in value_init conditional, see #3869. Updated the section "compiler issues" of its documentation.
[SVN r62307]
2010-05-30 09:19:09 +00:00
6239e685a2 value_init_test now uses lightweight_test by Peter Dimov; see #4246. Fernando Cacciola mailed me he agreed as well.
[SVN r62158]
2010-05-22 22:05:54 +00:00
e601fcb9c9 Locally disabled a trivial MSVC warning in value_init.hpp (C4512, "assignment operator could not be generated")
[SVN r62030]
2010-05-16 11:08:00 +00:00
f29a5db08e Hopefully fixed value_initialized compile errors on clang and comeau (strict mode) reported by Christopher Jefferson, see #4213
[SVN r61947]
2010-05-13 14:36:06 +00:00
22743ee125 Added boost::initialized<T> as was agreed at http://lists.boost.org/Archives/boost/2010/04/164916.php -- see #3472
[SVN r61883]
2010-05-09 20:51:24 +00:00
e3c982287a add tr1_result_of that always behaves as TR1 specifies, fix Boost.TR1's result_of to use tr1_result_of
[SVN r61248]
2010-04-13 15:01:11 +00:00
82e1111bb8 Revert [60052], as it causes other libraries to break.
[SVN r61097]
2010-04-06 07:56:54 +00:00
9339b32178 Updated copyright notice.
[SVN r61075]
2010-04-05 19:08:01 +00:00
3770221507 Hopefully fixed #3984 (std::bitset constructor issue). Tested by Juergen Hunold on msvc-10.0, msvc-9.0, and gcc-4.4. See thread starting at http://lists.boost.org/Archives/boost/2010/03/162690.php
[SVN r60331]
2010-03-07 21:42:22 +00:00
e6cb3a77ee Fix a couple of comments.
[SVN r60294]
2010-03-07 13:11:10 +00:00
bbccfbbab4 Remove use of deprecated macro in result_of test.
[SVN r60293]
2010-03-07 13:10:54 +00:00
74a6a693d3 Remove use of deprecated config macro in result_of.
[SVN r60052]
2010-03-01 19:39:52 +00:00
bf713ad47a Revert unintentional reference to "noncopyable_adl_barrier" test that's not checked in.
[SVN r59332]
2010-01-28 14:41:16 +00:00
76b17c497b Support different MS calling conventions, thanks to Nicolas Lelong.
Closes #3833.


[SVN r59247]
2010-01-24 02:08:46 +00:00
28 changed files with 1409 additions and 198 deletions

View File

@ -17,36 +17,89 @@
<td colspan="2" height="64">&nbsp;</td>
</tr>
</table>
<p>
<a href="#BOOST_ASSERT">BOOST_ASSERT</a><br>
<a href="#BOOST_ASSERT_MSG">BOOST_ASSERT_MSG</a><br>
<a href="#BOOST_VERIFY">BOOST_VERIFY</a></p>
<h2><a name="BOOST_ASSERT">BOOST_ASSERT</a></h2>
<p>
The header <STRONG>&lt;boost/assert.hpp&gt;</STRONG> defines the macro <b>BOOST_ASSERT</b>,
which is similar to the standard <STRONG>assert</STRONG> macro defined in <STRONG>&lt;cassert&gt;</STRONG>.
The macro is intended to be used in Boost libraries.
The macro is intended to be used in both Boost libraries and user
code.
</p>
<P>By default, <tt>BOOST_ASSERT(expr)</tt> is equivalent to <tt>assert(expr)</tt>.</P>
<P>When the macro <STRONG>BOOST_DISABLE_ASSERTS</STRONG> is defined when <STRONG>&lt;boost/assert.hpp&gt;</STRONG>
<P>If the macro <STRONG>BOOST_DISABLE_ASSERTS</STRONG> is defined when <STRONG>&lt;boost/assert.hpp&gt;</STRONG>
is included, <tt>BOOST_ASSERT(expr)</tt> is defined as <tt>((void)0)</tt>. This
allows users to selectively disable <STRONG>BOOST_ASSERT</STRONG> without
affecting the definition of the standard <STRONG>assert</STRONG>.</P>
<P>When the macro <STRONG>BOOST_ENABLE_ASSERT_HANDLER</STRONG> is defined when <STRONG>&lt;boost/assert.hpp&gt;</STRONG>
<P>If the macro <STRONG>BOOST_ENABLE_ASSERT_HANDLER</STRONG> is defined when <STRONG>&lt;boost/assert.hpp&gt;</STRONG>
is included, <tt>BOOST_ASSERT(expr)</tt> evaluates <b>expr</b> and, if the
result is false, evaluates the expression</P>
<blockquote>
<P><tt>::boost::assertion_failed(#expr, <a href="current_function.html">BOOST_CURRENT_FUNCTION</a>,
__FILE__, __LINE__)</tt></P>
</blockquote>
<P><STRONG>assertion_failed</STRONG> is declared in <STRONG>&lt;boost/assert.hpp&gt;</STRONG>
as</P>
<pre>
namespace boost
<blockquote>
<pre>namespace boost
{
void assertion_failed(char const * expr, char const * function, char const * file, long line);
void assertion_failed(char const * expr, char const * function, char const * file, long line);
}
</pre>
</blockquote>
<p>but it is never defined. The user is expected to supply an appropriate
definition.</p>
<P>As is the case with <STRONG>&lt;cassert&gt;</STRONG>, <STRONG>&lt;boost/assert.hpp&gt;</STRONG>
can be included multiple times in a single translation unit. <STRONG>BOOST_ASSERT</STRONG>
will be redefined each time as specified above.</P>
<h2><a name="BOOST_ASSERT_MSG">BOOST_ASSERT_MSG</a></h2>
<p>
The header <STRONG>&lt;boost/assert.hpp&gt;</STRONG> defines the macro <b>BOOST_ASSERT_MSG</b>,
which is similar to the standard <STRONG>assert</STRONG> macro defined in <STRONG>&lt;cassert&gt;</STRONG>,
but with an additional macro parameter supplying an error message. The macro is intended to be used in both Boost libraries
and user code.
</p>
<P> <tt>BOOST_ASSERT_MSG(expr, msg)</tt> is equivalent to <code>
((void)0)</code> if <b>BOOST_DISABLE_ASSERTS</b> or <b>NDEBUG</b> are
defined or <code>expr</code> evaluates to <code>true</code>. If those
macros and <STRONG>BOOST_ENABLE_ASSERT_HANDLER</STRONG> are not
defined, and <code>expr</code> evaluates to <code>false</code>, an error
message that includes <tt>#expr</tt>, <tt>msg</tt>, <tt> <a href="current_function.html">BOOST_CURRENT_FUNCTION</a></tt>, <tt>
__FILE__</tt>, and <tt>__LINE__</tt> is sent to output stream <b>
BOOST_ASSERT_MSG_OSTREAM</b>
and <code>std::abort()</code> is called.</P>
<P> <b>BOOST_ASSERT_MSG_OSTREAM</b> defines the output stream. It defaults to <code>std::cerr</code>.
Integrated development environments (IDE's) like Microsoft Visual Studio
may produce easier to understand output if messages go to a different
stream, such as <code>std::cout</code>. Users may define <b>BOOST_ASSERT_MSG_OSTREAM</b> before including <STRONG>&lt;boost/assert.hpp&gt;</STRONG>
to specify a different output stream.&nbsp; </P>
<P>If the macro <STRONG>BOOST_ENABLE_ASSERT_HANDLER</STRONG> is defined when <STRONG>&lt;boost/assert.hpp&gt;</STRONG>
is included, instead of sending a error message to an output
stream, this expression is evaluated</P>
<blockquote>
<P><tt>::boost::assertion_failed_msg(#expr, msg, <a href="current_function.html">BOOST_CURRENT_FUNCTION</a>,
__FILE__, __LINE__)</tt></P>
</blockquote>
<P><STRONG>assertion_failed_msg</STRONG> is declared in <STRONG>&lt;boost/assert.hpp&gt;</STRONG>
as</P>
<blockquote>
<pre>namespace boost
{
void assertion_failed_msg(char const * expr, char const * msg, char const * function, char const * file, long line);
}
</pre>
</blockquote>
<p>but it is never defined. The user is expected to supply an appropriate
definition.</p>
<P>As is the case with <STRONG>&lt;cassert&gt;</STRONG>, <STRONG>&lt;boost/assert.hpp&gt;</STRONG>
can be included multiple times in a single translation unit. <STRONG>BOOST_ASSERT_MSG</STRONG>
will be redefined each time as specified above.</P>
<h2><a name="BOOST_VERIFY">BOOST_VERIFY</a></h2>
<p><STRONG>&lt;boost/assert.hpp&gt;</STRONG> also defines the macro <STRONG>BOOST_VERIFY</STRONG>.
It has exactly the same behavior as <STRONG>BOOST_ASSERT</STRONG>, except that
the expression that is passed to <STRONG>BOOST_VERIFY</STRONG> is always
@ -54,8 +107,9 @@ void assertion_failed(char const * expr, char const * function, char const * fil
effects; it can also help suppress warnings about unused variables when the
only use of the variable is inside an assertion.</p>
<p><br>
<small>Copyright <20> 2002, 2007 by Peter Dimov. Distributed under the Boost Software
<small>Copyright <20> 2002, 2007 by Peter Dimov.&nbsp; Copyright <20> 2011
by Beman Dawes. Distributed under the Boost Software
License, Version 1.0. See accompanying file <A href="../../LICENSE_1_0.txt">LICENSE_1_0.txt</A>
or copy at <A href="http://www.boost.org/LICENSE_1_0.txt">http://www.boost.org/LICENSE_1_0.txt</A>.</small></p>
</body>
</html>
</html>

View File

@ -2,6 +2,7 @@
// assert_test.cpp - a test for boost/assert.hpp
//
// Copyright (c) 2002 Peter Dimov and Multi Media Ltd.
// Copyright (2) Beman Dawes 2011
//
// Distributed under the Boost Software License, Version 1.0. (See
// accompanying file LICENSE_1_0.txt or copy at
@ -20,6 +21,11 @@ void test_default()
BOOST_ASSERT(x);
BOOST_ASSERT(x == 1);
BOOST_ASSERT(&x);
BOOST_ASSERT_MSG(1, "msg");
BOOST_ASSERT_MSG(x, "msg");
BOOST_ASSERT_MSG(x == 1, "msg");
BOOST_ASSERT_MSG(&x, "msg");
}
#define BOOST_DISABLE_ASSERTS
@ -34,13 +40,23 @@ void test_disabled()
BOOST_ASSERT(x == 1);
BOOST_ASSERT(&x);
BOOST_ASSERT_MSG(1, "msg");
BOOST_ASSERT_MSG(x, "msg");
BOOST_ASSERT_MSG(x == 1, "msg");
BOOST_ASSERT_MSG(&x, "msg");
BOOST_ASSERT(0);
BOOST_ASSERT(!x);
BOOST_ASSERT(x == 0);
BOOST_ASSERT_MSG(0, "msg");
BOOST_ASSERT_MSG(!x, "msg");
BOOST_ASSERT_MSG(x == 0, "msg");
void * p = 0;
BOOST_ASSERT(p);
BOOST_ASSERT_MSG(p, "msg");
// supress warnings
p = &x;
@ -55,6 +71,7 @@ void test_disabled()
#include <cstdio>
int handler_invoked = 0;
int msg_handler_invoked = 0;
void boost::assertion_failed(char const * expr, char const * function, char const * file, long line)
{
@ -66,11 +83,24 @@ void boost::assertion_failed(char const * expr, char const * function, char cons
++handler_invoked;
}
void boost::assertion_failed_msg(char const * expr, char const * msg, char const * function,
char const * file, long line)
{
#if !defined(BOOST_NO_STDC_NAMESPACE)
using std::printf;
#endif
printf("Expression: %s Message: %s\nFunction: %s\nFile: %s\nLine: %ld\n\n",
expr, msg, function, file, line);
++msg_handler_invoked;
}
struct X
{
static void f()
{
BOOST_ASSERT(0);
BOOST_ASSERT_MSG(0, "msg f()");
}
};
@ -83,21 +113,35 @@ void test_handler()
BOOST_ASSERT(x == 1);
BOOST_ASSERT(&x);
BOOST_ASSERT_MSG(1, "msg2");
BOOST_ASSERT_MSG(x, "msg3");
BOOST_ASSERT_MSG(x == 1, "msg4");
BOOST_ASSERT_MSG(&x, "msg5");
BOOST_ASSERT(0);
BOOST_ASSERT(!x);
BOOST_ASSERT(x == 0);
BOOST_ASSERT_MSG(0,"msg 0");
BOOST_ASSERT_MSG(!x, "msg !x");
BOOST_ASSERT_MSG(x == 0, "msg x == 0");
void * p = 0;
BOOST_ASSERT(p);
BOOST_ASSERT_MSG(p, "msg p");
X::f();
BOOST_ASSERT(handler_invoked == 5);
BOOST_TEST(handler_invoked == 5);
BOOST_ASSERT_MSG(msg_handler_invoked == 5, "msg_handler_invoked count is wrong");
BOOST_TEST(msg_handler_invoked == 5);
}
#undef BOOST_ENABLE_ASSERT_HANDLER
#undef BOOST_ENABLE_ASSERT_MSG_HANDLER
int main()
{

68
doc/Jamfile.v2 Normal file
View File

@ -0,0 +1,68 @@
# Copyright John Maddock 2005. Use, modification, and distribution are
# subject to the Boost Software License, Version 1.0. (See accompanying
# file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
project : requirements
# Path for links to Boost:
<xsl:param>boost.root=../../../..
# Some general style settings:
<xsl:param>table.footnote.number.format=1
<xsl:param>footnote.number.format=1
# HTML options first:
# Use graphics not text for navigation:
<xsl:param>navig.graphics=1
# PDF Options:
# TOC Generation: this is needed for FOP-0.9 and later:
<xsl:param>fop1.extensions=0
<xsl:param>xep.extensions=1
# TOC generation: this is needed for FOP 0.2, but must not be set to zero for FOP-0.9!
<xsl:param>fop.extensions=0
# No indent on body text:
<xsl:param>body.start.indent=0pt
# Margin size:
<xsl:param>page.margin.inner=0.5in
# Margin size:
<xsl:param>page.margin.outer=0.5in
# Paper type = A4
<xsl:param>paper.type=A4
# Yes, we want graphics for admonishments:
<xsl:param>admon.graphics=1
# Set this one for PDF generation *only*:
# default pnd graphics are awful in PDF form,
# better use SVG's instead:
<format>pdf:<xsl:param>admon.graphics.extension=".svg"
<format>pdf:<xsl:param>admon.graphics.path=$(boost-images)/
<format>pdf:<xsl:param>boost.url.prefix=http://www.boost.org/doc/libs/release/libs/utility/doc/html
;
using quickbook ;
path-constant boost-images : ../../../doc/src/images ;
xml declval : declval.qbk ;
boostbook standalone
:
declval
:
# File name of HTML output:
<xsl:param>root.filename=declval
# How far down we chunk nested sections, basically all of them:
<xsl:param>chunk.section.depth=0
# Don't put the first section on the same page as the TOC:
<xsl:param>chunk.first.sections=0
# How far down sections get TOC's
<xsl:param>toc.section.depth=1
# Max depth in each TOC:
<xsl:param>toc.max.depth=1
# How far down we go with TOC's
<xsl:param>generate.section.toc.level=1
;

104
doc/declval.qbk Normal file
View File

@ -0,0 +1,104 @@
[/
/ Copyright (c) 2008 Howard Hinnant
/ Copyright (c) 2008 Beman Dawes
/ Copyright (c) 2009-20010 Vicente J. Botet Escriba
/
/ Distributed under the Boost Software License, Version 1.0. (See accompanying
/ file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
/]
[article Declval
[quickbook 1.5]
[authors [Hinnant, Howard]]
[authors [Dawes, Beman]]
[authors [Botet Escriba, Vicente J.]]
[copyright 2008 Howard Hinnant]
[copyright 2008 Beman Dawes]
[copyright 2009-2010 Vicente J. Botet Escriba]
[license
Distributed under the Boost Software License, Version 1.0.
(See accompanying file LICENSE_1_0.txt or copy at
[@http://www.boost.org/LICENSE_1_0.txt])
]
]
[/===============]
[section Overview]
[/===============]
The motivation for `declval` was introduced in [@http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2009/n2958.html#Value N2958:
Moving Swap Forward]. Here follows a rewording of this chapter.
With the provision of decltype, late-specified return types, and default template-arguments for function templates a
new generation of SFINAE patterns will emerge to at least partially compensate the lack of concepts on the C++0x timescale.
Using this technique, it is sometimes necessary to obtain an object of a known type in a non-using context, e.g. given the declaration
template<class T>
T&& declval(); // not used
as part of the function template declaration
template<class To, class From>
decltype(static_cast<To>(declval<From>())) convert(From&&);
or as part of a class template definition
template<class> class result_of;
template<class Fn, class... ArgTypes>
struct result_of<Fn(ArgTypes...)>
{
typedef decltype(declval<Fn>()(declval<ArgTypes>()...)) type;
};
The role of the function template declval() is a transformation of a type T into a value without using or evaluating this function.
The name is supposed to direct the reader's attention to the fact that the expression `declval<T>()` is an lvalue if and only if
T is an lvalue-reference, otherwise an rvalue. To extend the domain of this function we can do a bit better by changing its declaration to
template<class T>
typename std::add_rvalue_reference<T>::type declval(); // not used
which ensures that we can also use cv void as template parameter. The careful reader might have noticed that `declval()`
already exists under the name create() as part of the definition of the semantics of the type trait is_convertible in the C==0x standard.
The provision of a new library component that allows the production of values in unevaluated expressions is considered as
important to realize constrained templates in C++0x where concepts are not available.
This extremely light-weight function is expected to be part of the daily tool-box of the C++0x programmer.
[endsect]
[/=================]
[section:reference Reference ]
[/=================]
`#include <boost/utility/declval.hpp>`
namespace boost {
template <typename T>
typename add_rvalue_reference<T>::type declval(); //noexcept; // as unevaluated operand
} // namespace boost
The library provides the function template declval to simplify the definition of expressions which occur as unevaluated operands.
template <typename T>
typename add_rvalue_reference<T>::type declval();
[*Remarks:] If this function is used, the program is ill-formed.
[*Remarks:] The template parameter T of declval may be an incomplete type.
[*Example:]
template <class To, class From>
decltype(static_cast<To>(declval<From>())) convert(From&&);
Declares a function template convert which only participats in overloading if the type From can be explicitly converted to type To.
[endsect]

163
doc/html/declval.html Normal file
View File

@ -0,0 +1,163 @@
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=US-ASCII">
<title>Declval</title>
<link rel="stylesheet" href="../../../../doc/src/boostbook.css" type="text/css">
<meta name="generator" content="DocBook XSL Stylesheets V1.74.0">
<link rel="home" href="declval.html" title="Declval">
</head>
<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
<table cellpadding="2" width="100%"><tr>
<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../boost.png"></td>
<td align="center"><a href="../../../../index.html">Home</a></td>
<td align="center"><a href="../../../../libs/libraries.htm">Libraries</a></td>
<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td>
<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td>
<td align="center"><a href="../../../../more/index.htm">More</a></td>
</tr></table>
<hr>
<div class="spirit-nav"></div>
<div class="article" lang="en">
<div class="titlepage">
<div>
<div><h2 class="title">
<a name="declval"></a>Declval</h2></div>
<div><div class="authorgroup">
<div class="author"><h3 class="author">
<span class="firstname">Howard</span> <span class="surname">Hinnant</span>
</h3></div>
<div class="author"><h3 class="author">
<span class="firstname">Beman</span> <span class="surname">Dawes</span>
</h3></div>
<div class="author"><h3 class="author">
<span class="firstname">Vicente J.</span> <span class="surname">Botet Escriba</span>
</h3></div>
</div></div>
<div><p class="copyright">Copyright &#169; 2008 Howard Hinnant</p></div>
<div><p class="copyright">Copyright &#169; 2008 Beman Dawes</p></div>
<div><p class="copyright">Copyright &#169; 2009 -2010 Vicente J. Botet Escriba</p></div>
<div><div class="legalnotice">
<a name="id879409"></a><p>
Distributed under the Boost Software License, Version 1.0. (See accompanying
file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
</p>
</div></div>
</div>
<hr>
</div>
<div class="toc">
<p><b>Table of Contents</b></p>
<dl>
<dt><span class="section"><a href="declval.html#declval.overview">Overview</a></span></dt>
<dt><span class="section"><a href="declval.html#declval.reference"> Reference </a></span></dt>
</dl>
</div>
<div class="section" lang="en">
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="declval.overview"></a><a class="link" href="declval.html#declval.overview" title="Overview">Overview</a>
</h2></div></div></div>
<p>
The motivation for <code class="computeroutput"><span class="identifier">declval</span></code>
was introduced in <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2009/n2958.html#Value" target="_top">N2958:
Moving Swap Forward</a>. Here follows a rewording of this chapter.
</p>
<p>
With the provision of decltype, late-specified return types, and default template-arguments
for function templates a new generation of SFINAE patterns will emerge to at
least partially compensate the lack of concepts on the C++0x timescale. Using
this technique, it is sometimes necessary to obtain an object of a known type
in a non-using context, e.g. given the declaration
</p>
<pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">&gt;</span>
<span class="identifier">T</span><span class="special">&amp;&amp;</span> <span class="identifier">declval</span><span class="special">();</span> <span class="comment">// not used
</span></pre>
<p>
as part of the function template declaration
</p>
<pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">To</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">From</span><span class="special">&gt;</span>
<span class="identifier">decltype</span><span class="special">(</span><span class="keyword">static_cast</span><span class="special">&lt;</span><span class="identifier">To</span><span class="special">&gt;(</span><span class="identifier">declval</span><span class="special">&lt;</span><span class="identifier">From</span><span class="special">&gt;()))</span> <span class="identifier">convert</span><span class="special">(</span><span class="identifier">From</span><span class="special">&amp;&amp;);</span>
</pre>
<p>
or as part of a class template definition
</p>
<pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">class</span><span class="special">&gt;</span> <span class="keyword">class</span> <span class="identifier">result_of</span><span class="special">;</span>
<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Fn</span><span class="special">,</span> <span class="keyword">class</span><span class="special">...</span> <span class="identifier">ArgTypes</span><span class="special">&gt;</span>
<span class="keyword">struct</span> <span class="identifier">result_of</span><span class="special">&lt;</span><span class="identifier">Fn</span><span class="special">(</span><span class="identifier">ArgTypes</span><span class="special">...)&gt;</span>
<span class="special">{</span>
<span class="keyword">typedef</span> <span class="identifier">decltype</span><span class="special">(</span><span class="identifier">declval</span><span class="special">&lt;</span><span class="identifier">Fn</span><span class="special">&gt;()(</span><span class="identifier">declval</span><span class="special">&lt;</span><span class="identifier">ArgTypes</span><span class="special">&gt;()...))</span> <span class="identifier">type</span><span class="special">;</span>
<span class="special">};</span>
</pre>
<p>
The role of the function template declval() is a transformation of a type T
into a value without using or evaluating this function. The name is supposed
to direct the reader's attention to the fact that the expression <code class="computeroutput"><span class="identifier">declval</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;()</span></code> is
an lvalue if and only if T is an lvalue-reference, otherwise an rvalue. To
extend the domain of this function we can do a bit better by changing its declaration
to
</p>
<pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">&gt;</span>
<span class="keyword">typename</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">add_rvalue_reference</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;::</span><span class="identifier">type</span> <span class="identifier">declval</span><span class="special">();</span> <span class="comment">// not used
</span></pre>
<p>
which ensures that we can also use cv void as template parameter. The careful
reader might have noticed that <code class="computeroutput"><span class="identifier">declval</span><span class="special">()</span></code> already exists under the name create() as
part of the definition of the semantics of the type trait is_convertible in
the C==0x standard.
</p>
<p>
The provision of a new library component that allows the production of values
in unevaluated expressions is considered as important to realize constrained
templates in C++0x where concepts are not available. This extremely light-weight
function is expected to be part of the daily tool-box of the C++0x programmer.
</p>
</div>
<div class="section" lang="en">
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="declval.reference"></a><a class="link" href="declval.html#declval.reference" title="Reference"> Reference </a>
</h2></div></div></div>
<p>
<code class="computeroutput"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">utility</span><span class="special">/</span><span class="identifier">declval</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span></code>
</p>
<pre class="programlisting"><span class="keyword">namespace</span> <span class="identifier">boost</span> <span class="special">{</span>
<span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">&gt;</span>
<span class="keyword">typename</span> <span class="identifier">add_rvalue_reference</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;::</span><span class="identifier">type</span> <span class="identifier">declval</span><span class="special">();</span> <span class="comment">//noexcept; // as unevaluated operand
</span>
<span class="special">}</span> <span class="comment">// namespace boost
</span></pre>
<p>
The library provides the function template declval to simplify the definition
of expressions which occur as unevaluated operands.
</p>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">&gt;</span>
<span class="keyword">typename</span> <span class="identifier">add_rvalue_reference</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;::</span><span class="identifier">type</span> <span class="identifier">declval</span><span class="special">();</span>
</pre>
<p>
<span class="bold"><strong>Remarks:</strong></span> If this function is used, the program
is ill-formed.
</p>
<p>
<span class="bold"><strong>Remarks:</strong></span> The template parameter T of declval
may be an incomplete type.
</p>
<p>
<span class="bold"><strong>Example:</strong></span>
</p>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">To</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">From</span><span class="special">&gt;</span>
<span class="identifier">decltype</span><span class="special">(</span><span class="keyword">static_cast</span><span class="special">&lt;</span><span class="identifier">To</span><span class="special">&gt;(</span><span class="identifier">declval</span><span class="special">&lt;</span><span class="identifier">From</span><span class="special">&gt;()))</span> <span class="identifier">convert</span><span class="special">(</span><span class="identifier">From</span><span class="special">&amp;&amp;);</span>
</pre>
<p>
Declares a function template convert which only participats in overloading
if the type From can be explicitly converted to type To.
</p>
</div>
</div>
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
<td align="left"><p><small>Last revised: September 16, 2010 at 16:19:10 GMT</small></p></td>
<td align="right"><div class="copyright-footer"></div></td>
</tr></table>
<hr>
<div class="spirit-nav"></div>
</body>
</html>

View File

@ -1,8 +1,11 @@
//
// boost/assert.hpp - BOOST_ASSERT(expr)
// BOOST_ASSERT_MSG(expr, msg)
// BOOST_VERIFY(expr)
//
// Copyright (c) 2001, 2002 Peter Dimov and Multi Media Ltd.
// Copyright (c) 2007 Peter Dimov
// Copyright (c) Beman Dawes 2011
//
// Distributed under the Boost Software License, Version 1.0. (See
// accompanying file LICENSE_1_0.txt or copy at
@ -13,6 +16,16 @@
// See http://www.boost.org/libs/utility/assert.html for documentation.
//
//
// Stop inspect complaining about use of 'assert':
//
// boostinspect:naassert_macro
//
//--------------------------------------------------------------------------------------//
// BOOST_ASSERT //
//--------------------------------------------------------------------------------------//
#undef BOOST_ASSERT
#if defined(BOOST_DISABLE_ASSERTS)
@ -25,18 +38,86 @@
namespace boost
{
void assertion_failed(char const * expr, char const * function, char const * file, long line); // user defined
void assertion_failed(char const * expr,
char const * function, char const * file, long line); // user defined
} // namespace boost
#define BOOST_ASSERT(expr) ((expr)? ((void)0): ::boost::assertion_failed(#expr, BOOST_CURRENT_FUNCTION, __FILE__, __LINE__))
#define BOOST_ASSERT(expr) ((expr) \
? ((void)0) \
: ::boost::assertion_failed(#expr, BOOST_CURRENT_FUNCTION, __FILE__, __LINE__))
#else
# include <assert.h> // .h to support old libraries w/o <cassert> - effect is the same
# define BOOST_ASSERT(expr) assert(expr)
#endif
//--------------------------------------------------------------------------------------//
// BOOST_ASSERT_MSG //
//--------------------------------------------------------------------------------------//
# undef BOOST_ASSERT_MSG
#if defined(BOOST_DISABLE_ASSERTS) || defined(NDEBUG)
#define BOOST_ASSERT_MSG(expr, msg) ((void)0)
#elif defined(BOOST_ENABLE_ASSERT_HANDLER)
#include <boost/current_function.hpp>
namespace boost
{
void assertion_failed_msg(char const * expr, char const * msg,
char const * function, char const * file, long line); // user defined
} // namespace boost
#define BOOST_ASSERT_MSG(expr, msg) ((expr) \
? ((void)0) \
: ::boost::assertion_failed_msg(#expr, msg, BOOST_CURRENT_FUNCTION, __FILE__, __LINE__))
#else
#ifndef BOOST_ASSERT_HPP
#define BOOST_ASSERT_HPP
#include <cstdlib>
#include <iostream>
#include <boost/current_function.hpp>
// IDE's like Visual Studio perform better if output goes to std::cout or
// some other stream, so allow user to configure output stream:
#ifndef BOOST_ASSERT_MSG_OSTREAM
# define BOOST_ASSERT_MSG_OSTREAM std::cerr
#endif
namespace boost
{
namespace assertion
{
namespace detail
{
inline void assertion_failed_msg(char const * expr, char const * msg, char const * function,
char const * file, long line)
{
BOOST_ASSERT_MSG_OSTREAM
<< "***** Internal Program Error - assertion (" << expr << ") failed in "
<< function << ":\n"
<< file << '(' << line << "): " << msg << std::endl;
std::abort();
}
} // detail
} // assertion
} // detail
#endif
#define BOOST_ASSERT_MSG(expr, msg) ((expr) \
? ((void)0) \
: ::boost::assertion::detail::assertion_failed_msg(#expr, msg, \
BOOST_CURRENT_FUNCTION, __FILE__, __LINE__))
#endif
//--------------------------------------------------------------------------------------//
// BOOST_VERIFY //
//--------------------------------------------------------------------------------------//
#undef BOOST_VERIFY
#if defined(BOOST_DISABLE_ASSERTS) || ( !defined(BOOST_ENABLE_ASSERT_HANDLER) && defined(NDEBUG) )

View File

@ -8,6 +8,8 @@
// See http://www.boost.org/libs/utility/operators.htm for documentation.
// Revision History
// 16 Dec 10 Limit warning suppression for 4284 to older versions of VC++
// (Matthew Bradbury, fixes #4432)
// 07 Aug 08 Added "euclidean" spelling. (Daniel Frey)
// 03 Apr 08 Make sure "convertible to bool" is sufficient
// for T::operator<, etc. (Daniel Frey)
@ -88,7 +90,7 @@
# pragma set woff 1234
#endif
#if defined(BOOST_MSVC)
#if BOOST_WORKAROUND(BOOST_MSVC, < 1600)
# pragma warning( disable : 4284 ) // complaint about return type of
#endif // operator-> not begin a UDT

View File

@ -4,7 +4,7 @@
// License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
//
// See http://www.boost.org/lib/optional for documentation.
// See http://www.boost.org/libs/optional for documentation.
//
// You are welcome to contact the author at:
// fernando_cacciola@hotmail.com

View File

@ -0,0 +1,44 @@
// common_type.hpp ---------------------------------------------------------//
// Copyright 2010 Vicente J. Botet Escriba
// Distributed under the Boost Software License, Version 1.0.
// See http://www.boost.org/LICENSE_1_0.txt
#ifndef BOOST_TYPE_TRAITS_EXT_DECLVAL__HPP
#define BOOST_TYPE_TRAITS_EXT_DECLVAL__HPP
#include <boost/config.hpp>
//----------------------------------------------------------------------------//
#include <boost/type_traits/add_rvalue_reference.hpp>
//----------------------------------------------------------------------------//
// //
// C++03 implementation of //
// Written by Vicente J. Botet Escriba //
//~ 20.3.4 Function template declval [declval]
//~ 1 The library provides the function template declval to simplify the definition of expressions which occur as
//~ unevaluated operands.
//~ 2 Remarks: If this function is used, the program is ill-formed.
//~ 3 Remarks: The template parameter T of declval may be an incomplete type.
//~ [ Example:
//~ template <class To, class From>
//~ decltype(static_cast<To>(declval<From>())) convert(From&&);
//~ declares a function template convert which only participats in overloading if the type From can be
//~ explicitly converted to type To. For another example see class template common_type (20.7.6.6). <20>end
//~ example ]
// //
//----------------------------------------------------------------------------//
namespace boost {
template <typename T>
typename add_rvalue_reference<T>::type declval(); //noexcept; // as unevaluated operand
} // namespace boost
#endif // BOOST_TYPE_TRAITS_EXT_DECLVAL__HPP

View File

@ -5,7 +5,7 @@
// License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
//
// See http://www.boost.org/lib/optional for documentation.
// See http://www.boost.org/libs/optional for documentation.
//
// You are welcome to contact the author at:
// fernando_cacciola@hotmail.com

View File

@ -5,7 +5,7 @@
// License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
//
// See http://www.boost.org/lib/optional for documentation.
// See http://www.boost.org/libs/optional for documentation.
//
// You are welcome to contact the author at:
// fernando_cacciola@hotmail.com

View File

@ -10,47 +10,6 @@
# error Boost result_of - do not include this file!
#endif
#if defined(BOOST_HAS_DECLTYPE)
// As of N2588, C++0x result_of only supports function call
// expressions of the form f(x). This precludes support for member
// function pointers, which are invoked with expressions of the form
// o->*f(x). This implementation supports both.
template<typename F BOOST_PP_COMMA_IF(BOOST_PP_ITERATION())
BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),typename T)>
struct result_of<F(BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),T))>
: mpl::if_<
mpl::or_< is_pointer<F>, is_member_function_pointer<F> >
, detail::result_of_impl<
typename remove_cv<F>::type,
typename remove_cv<F>::type(BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),T)), false
>
, detail::result_of_decltype_impl<
F(BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),T))
>
>::type
{};
namespace detail {
# define BOOST_RESULT_OF_STATIC_MEMBERS(z, n, _) \
static T ## n t ## n; \
/**/
template<typename F BOOST_PP_COMMA_IF(BOOST_PP_ITERATION())
BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),typename T)>
class result_of_decltype_impl<F(BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),T))>
{
static F f;
BOOST_PP_REPEAT(BOOST_PP_ITERATION(), BOOST_RESULT_OF_STATIC_MEMBERS, _)
public:
typedef decltype(f(BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),t))) type;
};
} // namespace detail
#else // defined(BOOST_HAS_DECLTYPE)
// CWPro8 requires an argument in a function type specialization
#if BOOST_WORKAROUND(__MWERKS__, BOOST_TESTED_AT(0x3002)) && BOOST_PP_ITERATION() == 0
# define BOOST_RESULT_OF_ARGS void
@ -61,22 +20,64 @@ public:
#if !BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x551))
template<typename F BOOST_PP_COMMA_IF(BOOST_PP_ITERATION())
BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),typename T)>
struct result_of<F(BOOST_RESULT_OF_ARGS)>
struct tr1_result_of<F(BOOST_RESULT_OF_ARGS)>
: mpl::if_<
mpl::or_< is_pointer<F>, is_member_function_pointer<F> >
, boost::detail::result_of_impl<
, boost::detail::tr1_result_of_impl<
typename remove_cv<F>::type,
typename remove_cv<F>::type(BOOST_RESULT_OF_ARGS),
(boost::detail::has_result_type<F>::value)>
, boost::detail::result_of_impl<
, boost::detail::tr1_result_of_impl<
F,
F(BOOST_RESULT_OF_ARGS),
(boost::detail::has_result_type<F>::value)> >::type { };
#endif
#undef BOOST_RESULT_OF_ARGS
#if !defined(BOOST_NO_DECLTYPE) && defined(BOOST_RESULT_OF_USE_DECLTYPE)
#endif // defined(BOOST_HAS_DECLTYPE)
// Uses declval following N3225 20.7.7.6 when F is not a pointer.
template<typename F BOOST_PP_COMMA_IF(BOOST_PP_ITERATION())
BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),typename T)>
struct result_of<F(BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),T))>
: mpl::if_<
mpl::or_< is_pointer<F>, is_member_function_pointer<F> >
, detail::tr1_result_of_impl<
typename remove_cv<F>::type,
typename remove_cv<F>::type(BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),T)), false
>
, detail::cpp0x_result_of_impl<
F(BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),T))
>
>::type
{};
namespace detail {
template<typename F BOOST_PP_COMMA_IF(BOOST_PP_ITERATION())
BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),typename T)>
struct cpp0x_result_of_impl<F(BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),T))>
{
typedef decltype(
boost::declval<F>()(
BOOST_PP_ENUM_BINARY_PARAMS(BOOST_PP_ITERATION(), declval<T, >() BOOST_PP_INTERCEPT)
)
) type;
};
} // namespace detail
#else // defined(BOOST_NO_DECLTYPE)
#if !BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x551))
template<typename F BOOST_PP_COMMA_IF(BOOST_PP_ITERATION())
BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),typename T)>
struct result_of<F(BOOST_RESULT_OF_ARGS)>
: tr1_result_of<F(BOOST_RESULT_OF_ARGS)> { };
#endif
#endif // defined(BOOST_NO_DECLTYPE)
#undef BOOST_RESULT_OF_ARGS
#if BOOST_PP_ITERATION() >= 1
@ -84,14 +85,14 @@ namespace detail {
template<typename R, typename FArgs BOOST_PP_COMMA_IF(BOOST_PP_ITERATION())
BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),typename T)>
struct result_of_impl<R (*)(BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),T)), FArgs, false>
struct tr1_result_of_impl<R (*)(BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),T)), FArgs, false>
{
typedef R type;
};
template<typename R, typename FArgs BOOST_PP_COMMA_IF(BOOST_PP_ITERATION())
BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),typename T)>
struct result_of_impl<R (&)(BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),T)), FArgs, false>
struct tr1_result_of_impl<R (&)(BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),T)), FArgs, false>
{
typedef R type;
};
@ -99,7 +100,7 @@ struct result_of_impl<R (&)(BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),T)), FArgs
#if !BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x551))
template<typename R, typename FArgs BOOST_PP_COMMA_IF(BOOST_PP_ITERATION())
BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),typename T)>
struct result_of_impl<R (T0::*)
struct tr1_result_of_impl<R (T0::*)
(BOOST_PP_ENUM_SHIFTED_PARAMS(BOOST_PP_ITERATION(),T)),
FArgs, false>
{
@ -108,7 +109,7 @@ struct result_of_impl<R (T0::*)
template<typename R, typename FArgs BOOST_PP_COMMA_IF(BOOST_PP_ITERATION())
BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),typename T)>
struct result_of_impl<R (T0::*)
struct tr1_result_of_impl<R (T0::*)
(BOOST_PP_ENUM_SHIFTED_PARAMS(BOOST_PP_ITERATION(),T))
const,
FArgs, false>
@ -118,7 +119,7 @@ struct result_of_impl<R (T0::*)
template<typename R, typename FArgs BOOST_PP_COMMA_IF(BOOST_PP_ITERATION())
BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),typename T)>
struct result_of_impl<R (T0::*)
struct tr1_result_of_impl<R (T0::*)
(BOOST_PP_ENUM_SHIFTED_PARAMS(BOOST_PP_ITERATION(),T))
volatile,
FArgs, false>
@ -128,7 +129,7 @@ struct result_of_impl<R (T0::*)
template<typename R, typename FArgs BOOST_PP_COMMA_IF(BOOST_PP_ITERATION())
BOOST_PP_ENUM_PARAMS(BOOST_PP_ITERATION(),typename T)>
struct result_of_impl<R (T0::*)
struct tr1_result_of_impl<R (T0::*)
(BOOST_PP_ENUM_SHIFTED_PARAMS(BOOST_PP_ITERATION(),T))
const volatile,
FArgs, false>

View File

@ -5,7 +5,7 @@
// License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
//
// See http://www.boost.org/lib/optional for documentation.
// See http://www.boost.org/libs/optional for documentation.
//
// You are welcome to contact the author at:
// fernando_cacciola@hotmail.com

View File

@ -13,7 +13,9 @@
#include <boost/preprocessor/iteration/iterate.hpp>
#include <boost/preprocessor/punctuation/comma_if.hpp>
#include <boost/preprocessor/repetition/enum_params.hpp>
#include <boost/preprocessor/repetition/enum_binary_params.hpp>
#include <boost/preprocessor/repetition/enum_shifted_params.hpp>
#include <boost/preprocessor/facilities/intercept.hpp>
#include <boost/detail/workaround.hpp>
#include <boost/mpl/has_xxx.hpp>
#include <boost/mpl/if.hpp>
@ -22,6 +24,7 @@
#include <boost/type_traits/is_pointer.hpp>
#include <boost/type_traits/is_member_function_pointer.hpp>
#include <boost/type_traits/remove_cv.hpp>
#include <boost/utility/declval.hpp>
#ifndef BOOST_RESULT_OF_NUM_ARGS
# define BOOST_RESULT_OF_NUM_ARGS 10
@ -30,14 +33,15 @@
namespace boost {
template<typename F> struct result_of;
template<typename F> struct tr1_result_of; // a TR1-style implementation of result_of
#if !defined(BOOST_NO_SFINAE) && !defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)
namespace detail {
BOOST_MPL_HAS_XXX_TRAIT_DEF(result_type)
template<typename F, typename FArgs, bool HasResultType> struct result_of_impl;
template<typename F> struct result_of_decltype_impl;
template<typename F, typename FArgs, bool HasResultType> struct tr1_result_of_impl;
template<typename F> struct cpp0x_result_of_impl;
template<typename F>
struct result_of_void_impl
@ -60,10 +64,10 @@ struct result_of_void_impl<R (&)(void)>
// Determine the return type of a function pointer or pointer to member.
template<typename F, typename FArgs>
struct result_of_pointer
: result_of_impl<typename remove_cv<F>::type, FArgs, false> { };
: tr1_result_of_impl<typename remove_cv<F>::type, FArgs, false> { };
template<typename F, typename FArgs>
struct result_of_impl<F, FArgs, true>
struct tr1_result_of_impl<F, FArgs, true>
{
typedef typename F::result_type type;
};
@ -79,7 +83,7 @@ struct result_of_nested_result : F::template result<FArgs>
{};
template<typename F, typename FArgs>
struct result_of_impl<F, FArgs, false>
struct tr1_result_of_impl<F, FArgs, false>
: mpl::if_<is_function_with_no_args<FArgs>,
result_of_void_impl<F>,
result_of_nested_result<F, FArgs> >::type

View File

@ -5,7 +5,7 @@
// License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
//
// See http://www.boost.org/lib/optional for documentation.
// See http://www.boost.org/libs/optional for documentation.
//
// You are welcome to contact the author at:
// fernando_cacciola@hotmail.com

View File

@ -9,6 +9,8 @@
// 23 May 2008 (Fixed operator= const issue, added initialized_value) Niels Dekker, Fernando Cacciola
// 21 Ago 2008 (Added swap) Niels Dekker, Fernando Cacciola
// 20 Feb 2009 (Fixed logical const-ness issues) Niels Dekker, Fernando Cacciola
// 03 Apr 2010 (Added initialized<T>, suggested by Jeffrey Hellrung, fixing #3472) Niels Dekker
// 30 May 2010 (Made memset call conditional, fixing #3869) Niels Dekker
//
#ifndef BOOST_UTILITY_VALUE_INIT_21AGO2002_HPP
#define BOOST_UTILITY_VALUE_INIT_21AGO2002_HPP
@ -20,6 +22,7 @@
// contains. More details on these issues are at libs/utility/value_init.htm
#include <boost/aligned_storage.hpp>
#include <boost/config.hpp> // For BOOST_NO_COMPLETE_VALUE_INITIALIZATION.
#include <boost/detail/workaround.hpp>
#include <boost/static_assert.hpp>
#include <boost/type_traits/cv_traits.hpp>
@ -28,10 +31,39 @@
#include <cstring>
#include <new>
#ifdef BOOST_MSVC
#pragma warning(push)
#if _MSC_VER >= 1310
// It is safe to ignore the following warning from MSVC 7.1 or higher:
// "warning C4351: new behavior: elements of array will be default initialized"
#pragma warning(disable: 4351)
// It is safe to ignore the following MSVC warning, which may pop up when T is
// a const type: "warning C4512: assignment operator could not be generated".
#pragma warning(disable: 4512)
#endif
#endif
#ifdef BOOST_NO_COMPLETE_VALUE_INITIALIZATION
// Implementation detail: The macro BOOST_DETAIL_VALUE_INIT_WORKAROUND_SUGGESTED
// suggests that a workaround should be applied, because of compiler issues
// regarding value-initialization.
#define BOOST_DETAIL_VALUE_INIT_WORKAROUND_SUGGESTED
#endif
// Implementation detail: The macro BOOST_DETAIL_VALUE_INIT_WORKAROUND
// switches the value-initialization workaround either on or off.
#ifndef BOOST_DETAIL_VALUE_INIT_WORKAROUND
#ifdef BOOST_DETAIL_VALUE_INIT_WORKAROUND_SUGGESTED
#define BOOST_DETAIL_VALUE_INIT_WORKAROUND 1
#else
#define BOOST_DETAIL_VALUE_INIT_WORKAROUND 0
#endif
#endif
namespace boost {
template<class T>
class value_initialized
class initialized
{
private :
struct wrapper
@ -40,6 +72,18 @@ class value_initialized
typename
#endif
remove_const<T>::type data;
wrapper()
:
data()
{
}
wrapper(T const & arg)
:
data(arg)
{
}
};
mutable
@ -55,30 +99,25 @@ class value_initialized
public :
value_initialized()
initialized()
{
#if BOOST_DETAIL_VALUE_INIT_WORKAROUND
std::memset(&x, 0, sizeof(x));
#ifdef BOOST_MSVC
#pragma warning(push)
#if _MSC_VER >= 1310
// When using MSVC 7.1 or higher, the following placement new expression may trigger warning C4345:
// "behavior change: an object of POD type constructed with an initializer of the form ()
// will be default-initialized". It is safe to ignore this warning when using value_initialized.
#pragma warning(disable: 4345)
#endif
#endif
new (wrapper_address()) wrapper();
#ifdef BOOST_MSVC
#pragma warning(pop)
#endif
}
value_initialized(value_initialized const & arg)
initialized(initialized const & arg)
{
new (wrapper_address()) wrapper( static_cast<wrapper const &>(*(arg.wrapper_address())));
}
value_initialized & operator=(value_initialized const & arg)
explicit initialized(T const & arg)
{
new (wrapper_address()) wrapper(arg);
}
initialized & operator=(initialized const & arg)
{
// Assignment is only allowed when T is non-const.
BOOST_STATIC_ASSERT( ! is_const<T>::value );
@ -86,7 +125,7 @@ class value_initialized
return *this;
}
~value_initialized()
~initialized()
{
wrapper_address()->wrapper::~wrapper();
}
@ -101,17 +140,81 @@ class value_initialized
return wrapper_address()->data;
}
void swap(value_initialized & arg)
void swap(initialized & arg)
{
::boost::swap( this->data(), arg.data() );
}
operator T const &() const { return this->data(); }
operator T const &() const
{
return wrapper_address()->data;
}
operator T&() { return this->data(); }
operator T&()
{
return wrapper_address()->data;
}
} ;
template<class T>
T const& get ( initialized<T> const& x )
{
return x.data() ;
}
template<class T>
T& get ( initialized<T>& x )
{
return x.data() ;
}
template<class T>
void swap ( initialized<T> & lhs, initialized<T> & rhs )
{
lhs.swap(rhs) ;
}
template<class T>
class value_initialized
{
private :
// initialized<T> does value-initialization by default.
initialized<T> m_data;
public :
value_initialized()
:
m_data()
{ }
T const & data() const
{
return m_data.data();
}
T& data()
{
return m_data.data();
}
void swap(value_initialized & arg)
{
m_data.swap(arg.m_data);
}
operator T const &() const
{
return m_data;
}
operator T&()
{
return m_data;
}
} ;
template<class T>
@ -119,6 +222,7 @@ T const& get ( value_initialized<T> const& x )
{
return x.data() ;
}
template<class T>
T& get ( value_initialized<T>& x )
{
@ -138,7 +242,7 @@ class initialized_value_t
template <class T> operator T() const
{
return get( value_initialized<T>() );
return initialized<T>().data();
}
};
@ -147,5 +251,8 @@ initialized_value_t const initialized_value = {} ;
} // namespace boost
#ifdef BOOST_MSVC
#pragma warning(pop)
#endif
#endif

View File

@ -14,20 +14,28 @@
<p>But that doesn't mean there isn't useful stuff here. Take a look:</p>
<blockquote>
<p>
<a href="utility.htm#addressof">addressof</a><br>
<a href="assert.html">assert</a><br>
<a href="base_from_member.html">base_from_member</a><br>
<a href="utility.htm#BOOST_BINARY">BOOST_BINARY</a><br>
<a href="call_traits.htm">call_traits</a><br>
<a href="checked_delete.html">checked_delete</a><br>
<a href="compressed_pair.htm">compressed_pair</a><br>
<a href="current_function.html">current_function</a><br>
<a href="enable_if.html">enable_if</a><br>
<a href="doc/html/declval.html">declval</a><br>
<a href="enable_if.html">enable_if</a><br>
<a href="in_place_factories.html">in_place_factory</a><br>
<a href="iterator_adaptors.htm">iterator_adaptors</a><br>
<a href="generator_iterator.htm">generator iterator adaptors</a><br>
<a href="utility.htm#functions_next_prior">next/prior</a><br>
<a href="utility.htm#Class_noncopyable">noncopyable</a><br>
<a href="operators.htm">operators</a><br>
<a href="utility.htm#result_of">result_of</a><br>
<a href="swap.html">swap</a><br>
<a href="throw_exception.html">throw_exception</a><br>
<a href="utility.htm">utility</a><br>
<a href="value_init.htm">value_init</a></p>
<a href="value_init.htm">value_init</a>
</p>
</blockquote>
<hr>
<p>&copy; Copyright Beman Dawes, 2001</p>

116
initialized_test.cpp Normal file
View File

@ -0,0 +1,116 @@
// Copyright 2010, Niels Dekker.
//
// Distributed under the Boost Software License, Version 1.0. (See
// accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
//
// Test program for boost::initialized<T>.
//
// 2 May 2010 (Created) Niels Dekker
#include <boost/utility/value_init.hpp>
#include <boost/detail/lightweight_test.hpp>
#include <string>
namespace
{
// Typical use case for boost::initialized<T>: A generic class that
// holds a value of type T, which must be initialized by either
// value-initialization or direct-initialization.
template <class T> class key_value_pair
{
std::string m_key;
boost::initialized<T> m_value;
public:
// Value-initializes the object held by m_value.
key_value_pair() { }
// Value-initializes the object held by m_value.
explicit key_value_pair(const std::string& key)
:
m_key(key)
{
}
// Direct-initializes the object held by m_value.
key_value_pair(const std::string& key, const T& value)
:
m_key(key), m_value(value)
{
}
const T& get_value() const
{
return m_value;
}
};
// Tells whether the argument is value-initialized.
bool is_value_initialized(const int& arg)
{
return arg == 0;
}
// Tells whether the argument is value-initialized.
bool is_value_initialized(const std::string& arg)
{
return arg.empty();
}
struct foo
{
int data;
};
bool operator==(const foo& lhs, const foo& rhs)
{
return lhs.data == rhs.data;
}
// Tells whether the argument is value-initialized.
bool is_value_initialized(const foo& arg)
{
return arg.data == 0;
}
template <class T>
void test_key_value_pair(const T& magic_value)
{
// The value component of a default key_value_pair must be value-initialized.
key_value_pair<T> default_key_value_pair;
BOOST_TEST( is_value_initialized(default_key_value_pair.get_value() ) );
// The value component of a key_value_pair that only has its key explicitly specified
// must also be value-initialized.
BOOST_TEST( is_value_initialized(key_value_pair<T>("key").get_value()) );
// However, the value component of the following key_value_pair must be
// "magic_value", as it must be direct-initialized.
BOOST_TEST( key_value_pair<T>("key", magic_value).get_value() == magic_value );
}
}
// Tests boost::initialize for a fundamental type, a type with a
// user-defined constructor, and a user-defined type without
// a user-defined constructor.
int main()
{
const int magic_number = 42;
test_key_value_pair(magic_number);
const std::string magic_string = "magic value";
test_key_value_pair(magic_string);
const foo magic_foo = { 42 };
test_key_value_pair(magic_foo);
return boost::report_errors();
}

View File

@ -0,0 +1,33 @@
// Copyright 2010, Niels Dekker.
//
// Distributed under the Boost Software License, Version 1.0. (See
// accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
//
// Test program for boost::initialized<T>. Must fail to compile.
//
// Initial: 2 May 2010
#include <boost/utility/value_init.hpp>
namespace
{
void direct_initialize_from_int()
{
// Okay: initialized<T> supports direct-initialization from T.
boost::initialized<int> direct_initialized_int(1);
}
void copy_initialize_from_int()
{
// The following line should not compile, because initialized<T>
// was not intended to supports copy-initialization from T.
boost::initialized<int> copy_initialized_int = 1;
}
}
int main()
{
// This should fail to compile, so there is no need to call any function.
return 0;
}

View File

@ -0,0 +1,37 @@
// Copyright 2010, Niels Dekker.
//
// Distributed under the Boost Software License, Version 1.0. (See
// accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
//
// Test program for boost::initialized<T>. Must fail to compile.
//
// Initial: 2 May 2010
#include <boost/utility/value_init.hpp>
namespace
{
void from_value_initialized_to_initialized()
{
boost::value_initialized<int> value_initialized_int;
// Okay: initialized<T> can be initialized by value_initialized<T>.
boost::initialized<int> initialized_int(value_initialized_int);
}
void from_initialized_to_value_initialized()
{
boost::initialized<int> initialized_int(13);
// The following line should not compile, because initialized<T>
// should not be convertible to value_initialized<T>.
boost::value_initialized<int> value_initialized_int(initialized_int);
}
}
int main()
{
// This should fail to compile, so there is no need to call any function.
return 0;
}

View File

@ -1,4 +1,4 @@
// Copyright (c) 2008 Joseph Gauterin, Niels Dekker
// Copyright (c) 2008 - 2010 Joseph Gauterin, Niels Dekker
//
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt or copy at
@ -17,8 +17,8 @@
int test_main(int, char*[])
{
typedef std::bitset<8> bitset_type;
const bitset_type initial_value1 = 1ul;
const bitset_type initial_value2 = 2ul;
const bitset_type initial_value1 = 1;
const bitset_type initial_value2 = 2;
bitset_type object1 = initial_value1;
bitset_type object2 = initial_value2;

View File

@ -32,9 +32,13 @@ test-suite utility
[ compile result_of_test.cpp ]
[ run ../shared_iterator_test.cpp ]
[ run ../value_init_test.cpp ]
[ run ../value_init_workaround_test.cpp ]
[ run ../initialized_test.cpp ]
[ compile-fail ../value_init_test_fail1.cpp ]
[ compile-fail ../value_init_test_fail2.cpp ]
[ compile-fail ../value_init_test_fail3.cpp ]
[ compile-fail ../initialized_test_fail1.cpp ]
[ compile-fail ../initialized_test_fail2.cpp ]
[ run ../verify_test.cpp ]
;

0
test/next_prior_test.cpp Executable file → Normal file
View File

View File

@ -5,6 +5,8 @@
// 1.0. (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
#define BOOST_RESULT_OF_USE_DECLTYPE
// For more information, see http://www.boost.org/libs/utility
#include <boost/utility/result_of.hpp>
#include <utility>
@ -96,6 +98,11 @@ struct no_result_type_or_result_of
unsigned int operator()();
unsigned short operator()() volatile;
const unsigned short operator()() const volatile;
#if !defined(BOOST_NO_RVALUE_REFERENCES)
short operator()(int&&);
int operator()(int&);
long operator()(int const&);
#endif
};
template<typename T>
@ -106,6 +113,11 @@ struct no_result_type_or_result_of_template
unsigned int operator()();
unsigned short operator()() volatile;
const unsigned short operator()() const volatile;
#if !defined(BOOST_NO_RVALUE_REFERENCES)
short operator()(int&&);
int operator()(int&);
long operator()(int const&);
#endif
};
struct X {};
@ -131,9 +143,21 @@ int main()
BOOST_STATIC_ASSERT((is_same<result_of<int_result_of_template<void>(double)>::type, int>::value));
BOOST_STATIC_ASSERT((is_same<result_of<const int_result_of_template<void>(double)>::type, int>::value));
BOOST_STATIC_ASSERT((is_same<tr1_result_of<int_result_type(float)>::type, int>::value));
BOOST_STATIC_ASSERT((is_same<tr1_result_of<int_result_of(double)>::type, int>::value));
BOOST_STATIC_ASSERT((is_same<tr1_result_of<const int_result_of(double)>::type, int>::value));
BOOST_STATIC_ASSERT((is_same<tr1_result_of<int_result_type_template<void>(float)>::type, int>::value));
BOOST_STATIC_ASSERT((is_same<tr1_result_of<int_result_of_template<void>(double)>::type, int>::value));
BOOST_STATIC_ASSERT((is_same<tr1_result_of<const int_result_of_template<void>(double)>::type, int>::value));
BOOST_STATIC_ASSERT((is_same<tr1_result_of<int_result_of(void)>::type, void>::value));
BOOST_STATIC_ASSERT((is_same<tr1_result_of<volatile int_result_of(void)>::type, void>::value));
BOOST_STATIC_ASSERT((is_same<tr1_result_of<int_result_of_template<void>(void)>::type, void>::value));
BOOST_STATIC_ASSERT((is_same<tr1_result_of<volatile int_result_of_template<void>(void)>::type, void>::value));
// Prior to decltype, result_of could not deduce the return type
// nullary function objects unless they exposed a result_type.
#if defined(BOOST_HAS_DECLTYPE)
#if !defined(BOOST_NO_DECLTYPE)
BOOST_STATIC_ASSERT((is_same<result_of<int_result_of(void)>::type, int>::value));
BOOST_STATIC_ASSERT((is_same<result_of<volatile int_result_of(void)>::type, int>::value));
BOOST_STATIC_ASSERT((is_same<result_of<int_result_of_template<void>(void)>::type, int>::value));
@ -145,11 +169,14 @@ int main()
BOOST_STATIC_ASSERT((is_same<result_of<volatile int_result_of_template<void>(void)>::type, void>::value));
#endif
BOOST_STATIC_ASSERT((is_same<tr1_result_of<int_result_type_and_float_result_of_and_char_return(char)>::type, int>::value));
BOOST_STATIC_ASSERT((is_same<tr1_result_of<int_result_type_and_float_result_of_and_char_return_template<void>(char)>::type, int>::value));
// Prior to decltype, result_of ignored a nested result<> if
// result_type was defined. After decltype, result_of deduces the
// actual return type of the function object, ignoring both
// result<> and result_type.
#if defined(BOOST_HAS_DECLTYPE)
#if !defined(BOOST_NO_DECLTYPE)
BOOST_STATIC_ASSERT((is_same<result_of<int_result_type_and_float_result_of_and_char_return(char)>::type, char>::value));
BOOST_STATIC_ASSERT((is_same<result_of<int_result_type_and_float_result_of_and_char_return_template<void>(char)>::type, char>::value));
#else
@ -168,6 +195,17 @@ int main()
BOOST_STATIC_ASSERT((is_same<result_of<mem_func_ptr_0(X)>::type, int>::value));
BOOST_STATIC_ASSERT((is_same<result_of<func_ptr(void)>::type, int>::value));
BOOST_STATIC_ASSERT((is_same<tr1_result_of<func_ptr(char, float)>::type, int>::value));
BOOST_STATIC_ASSERT((is_same<tr1_result_of<func_ref(char, float)>::type, int>::value));
BOOST_STATIC_ASSERT((is_same<tr1_result_of<func_ptr_0()>::type, int>::value));
BOOST_STATIC_ASSERT((is_same<tr1_result_of<func_ref_0()>::type, int>::value));
BOOST_STATIC_ASSERT((is_same<tr1_result_of<mem_func_ptr(X,char)>::type, int>::value));
BOOST_STATIC_ASSERT((is_same<tr1_result_of<mem_func_ptr_c(X,char)>::type, int>::value));
BOOST_STATIC_ASSERT((is_same<tr1_result_of<mem_func_ptr_v(X,char)>::type, int>::value));
BOOST_STATIC_ASSERT((is_same<tr1_result_of<mem_func_ptr_cv(X,char)>::type, int>::value));
BOOST_STATIC_ASSERT((is_same<tr1_result_of<mem_func_ptr_0(X)>::type, int>::value));
BOOST_STATIC_ASSERT((is_same<tr1_result_of<func_ptr(void)>::type, int>::value));
BOOST_STATIC_ASSERT((is_same<result_of<result_of_member_function_template(double)>::type, double>::value));
BOOST_STATIC_ASSERT((is_same<result_of<const result_of_member_function_template(double)>::type, const double>::value));
BOOST_STATIC_ASSERT((is_same<result_of<volatile result_of_member_function_template(double)>::type, volatile double>::value));
@ -177,11 +215,23 @@ int main()
BOOST_STATIC_ASSERT((is_same<result_of<result_of_member_function_template(int volatile &, int)>::type, int volatile &>::value));
BOOST_STATIC_ASSERT((is_same<result_of<result_of_member_function_template(int const volatile &, int)>::type, int const volatile &>::value));
BOOST_STATIC_ASSERT((is_same<tr1_result_of<result_of_member_function_template(double)>::type, double>::value));
BOOST_STATIC_ASSERT((is_same<tr1_result_of<const result_of_member_function_template(double)>::type, const double>::value));
BOOST_STATIC_ASSERT((is_same<tr1_result_of<volatile result_of_member_function_template(double)>::type, volatile double>::value));
BOOST_STATIC_ASSERT((is_same<tr1_result_of<const volatile result_of_member_function_template(double)>::type, const volatile double>::value));
BOOST_STATIC_ASSERT((is_same<tr1_result_of<result_of_member_function_template(int &, int)>::type, int &>::value));
BOOST_STATIC_ASSERT((is_same<tr1_result_of<result_of_member_function_template(int const &, int)>::type, int const &>::value));
BOOST_STATIC_ASSERT((is_same<tr1_result_of<result_of_member_function_template(int volatile &, int)>::type, int volatile &>::value));
BOOST_STATIC_ASSERT((is_same<tr1_result_of<result_of_member_function_template(int const volatile &, int)>::type, int const volatile &>::value));
typedef int (*pf_t)(int);
BOOST_STATIC_ASSERT((is_same<result_of<pf_t(int)>::type, int>::value));
BOOST_STATIC_ASSERT((is_same<result_of<pf_t const(int)>::type,int>::value));
#if defined(BOOST_HAS_DECLTYPE)
BOOST_STATIC_ASSERT((is_same<tr1_result_of<pf_t(int)>::type, int>::value));
BOOST_STATIC_ASSERT((is_same<tr1_result_of<pf_t const(int)>::type,int>::value));
#if !defined(BOOST_NO_DECLTYPE)
BOOST_STATIC_ASSERT((is_same<result_of<no_result_type_or_result_of(double)>::type, int>::value));
BOOST_STATIC_ASSERT((is_same<result_of<no_result_type_or_result_of(void)>::type, unsigned int>::value));
BOOST_STATIC_ASSERT((is_same<result_of<const no_result_type_or_result_of(double)>::type, short>::value));
@ -192,6 +242,14 @@ int main()
BOOST_STATIC_ASSERT((is_same<result_of<const no_result_type_or_result_of_template<void>(double)>::type, short>::value));
BOOST_STATIC_ASSERT((is_same<result_of<volatile no_result_type_or_result_of_template<void>(void)>::type, unsigned short>::value));
BOOST_STATIC_ASSERT((is_same<result_of<const volatile no_result_type_or_result_of_template<void>(void)>::type, const unsigned short>::value));
#if !defined(BOOST_NO_RVALUE_REFERENCES)
BOOST_STATIC_ASSERT((is_same<result_of<no_result_type_or_result_of(int&&)>::type, short>::value));
BOOST_STATIC_ASSERT((is_same<result_of<no_result_type_or_result_of(int&)>::type, int>::value));
BOOST_STATIC_ASSERT((is_same<result_of<no_result_type_or_result_of(int const&)>::type, long>::value));
BOOST_STATIC_ASSERT((is_same<result_of<no_result_type_or_result_of_template<void>(int&&)>::type, short>::value));
BOOST_STATIC_ASSERT((is_same<result_of<no_result_type_or_result_of_template<void>(int&)>::type, int>::value));
BOOST_STATIC_ASSERT((is_same<result_of<no_result_type_or_result_of_template<void>(int const&)>::type, long>::value));
#endif
#endif
return 0;

View File

@ -151,37 +151,95 @@ void f() {
<code>result_of&lt;F(T1, T2, ...,
T<em>N</em>)&gt;::type</code> defines the result type
of the expression <code>f(t1, t2,
...,t<em>N</em>)</code>. The implementation permits
...,t<em>N</em>)</code>. This implementation permits
the type <code>F</code> to be a function pointer,
function reference, member function pointer, or class
type.</p> <p>If your compiler does not support
<code>decltype</code>, then when <code>F</code> is a
class type with a member type <code>result_type</code>,
type. By default, <em>N</em> may be any value between 0 and
10. To change the upper limit, define the macro
<code>BOOST_RESULT_OF_NUM_ARGS</code> to the maximum
value for <em>N</em>. Class template <code>result_of</code>
resides in the header <code>&lt;<a
href="../../boost/utility/result_of.hpp">boost/utility/result_of.hpp</a>&gt;</code>.</p>
<p>If your compiler supports <code>decltype</code>,
then you can enable automatic result type deduction by
defining the macro <code>BOOST_RESULT_OF_USE_DECLTYPE</code>,
as in the following example.</p>
<blockquote>
<pre>#define BOOST_RESULT_OF_USE_DECLTYPE
#include &lt;boost/utility/result_of.hpp&gt;
struct functor {
template&lt;class T&gt;
T operator()(T x)
{
return x;
}
};
typedef boost::result_of&lt;
functor(int)
&gt;::type type;</pre>
</blockquote>
<p>If <code>decltype</code> is not enabled,
then automatic result type deduction of function
objects is not possible. Instead, <code>result_of</code>
uses the following protocol to allow the programmer to
specify a type. When <code>F</code> is a class type with a
member type <code>result_type</code>,
<code>result_of&lt;F(T1, T2, ...,
T<em>N</em>)&gt;</code> is
<code>F::result_type</code>. When <code>F</code>
does not contain <code>result_type</code>,
<code>F::result_type</code>. When <code>F</code> does
not contain <code>result_type</code>,
<code>result_of&lt;F(T1, T2, ...,
T<em>N</em>)&gt;</code> is <code>F::result&lt;F(T1,
T2, ..., T<em>N</em>)&gt;::type</code> when
<code><em>N</em> &gt; 0</code> or <code>void</code>
when <code><em>N</em> = 0</code>. For additional
information about <code>result_of</code>, see the
C++ Library Technical Report, <a
href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2005/n1836.pdf">N1836</a>,
or, for motivation and design rationale, the <code>result_of</code> <a
href="http://anubis.dkuug.dk/jtc1/sc22/wg21/docs/papers/2003/n1454.html">proposal</a>.</p>
when <code><em>N</em> = 0</code>. Note that it is the
responsibility of the programmer to ensure that
function objects accurately advertise their result
type via this protocol, as in the following
example.</p>
<p>Class template <code>result_of</code> resides in
the header <code>&lt;<a
href="../../boost/utility/result_of.hpp">boost/utility/result_of.hpp</a>&gt;</code>. By
default, <em>N</em> may be any value between 0 and
10. To change the upper limit, define the macro
<code>BOOST_RESULT_OF_NUM_ARGS</code> to the maximum
value for <em>N</em>.</p>
<blockquote>
<pre>struct functor {
template&lt;class&gt; struct result;
template&lt;class F, class T&gt;
struct result&lt;F(T)&gt; {
typedef T type;
};
template&lt;class T&gt;
T operator()(T x)
{
return x;
}
};
typedef boost::result_of&lt;
functor(int)
&gt;::type type;</pre>
</blockquote>
<a name="BOOST_NO_RESULT_OF"></a>
<p>This implementation of <code>result_of</code> requires class template partial specialization, the ability to parse function types properly, and support for SFINAE. If <code>result_of</code> is not supported by your compiler, including the header <code>boost/utility/result_of.hpp</code> will define the macro <code>BOOST_NO_RESULT_OF</code>. Contributed by Doug Gregor.</p>
<p>This implementation of <code>result_of</code>
requires class template partial specialization, the
ability to parse function types properly, and support
for SFINAE. If <code>result_of</code> is not supported
by your compiler, including the header
<code>boost/utility/result_of.hpp</code> will
define the macro <code>BOOST_NO_RESULT_OF</code>.</p>
<p>For additional information
about <code>result_of</code>, see the C++ Library
Technical Report,
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2005/n1836.pdf">N1836</a>,
or, for motivation and design rationale,
the <code>result_of</code> <a href="http://anubis.dkuug.dk/jtc1/sc22/wg21/docs/papers/2003/n1454.html">proposal</a>.</p>
Contributed by Doug Gregor.</p>
<h2>Class templates for the Base-from-Member Idiom</h2>
<p>See <a href="base_from_member.html">separate documentation</a>.</p>

View File

@ -33,6 +33,7 @@
<ul>
<li><a href="#val_init"><code>template class value_initialized&lt;T&gt;</code></a></li>
<li><a href="#initialized"><code>template class initialized&lt;T&gt;</code></a></li>
<li><a href="#initialized_value"><code>initialized_value</code></a></li>
</ul>
@ -123,6 +124,12 @@ constructed by the following declaration:
</pre>
</p>
<p>
The template <a href="#initialized"><code>initialized</code></a>
offers both value-initialization and direct-initialization.
It is especially useful as a data member type, allowing the very same object
to be either direct-initialized or value-initialized.
</p>
<p>
The <code>const</code> object <a href="#initialized_value"><code>initialized_value</code></a>
allows value-initializing a variable as follows:
<pre>
@ -216,37 +223,65 @@ it <em>may</em> in practice still be left uninitialized, because of those
compiler issues! It's hard to make a general statement on what those issues
are like, because they depend on the compiler you are using, its version number,
and the type of object you would like to have value-initialized.
Compilers usually support value-initialization for built-in types properly.
But objects of user-defined types that involve <em>aggregates</em> may <em>in some cases</em>
be partially, or even entirely left uninitialized, when they should be value-initialized.
All compilers we have tested so far support value-initialization for arithmetic types properly.
However, various compilers may leave some types of <em>aggregates</em> uninitialized, when they
should be value-initialized. Value-initialization of objects of a pointer-to-member type may also
go wrong on various compilers.
</p>
<p>
We have encountered issues regarding value-initialization on compilers by
Microsoft, Sun, Borland, and GNU. Here is a list of bug reports on those issues:
<table summary="Compiler bug reports regarding value-initialization" border="0" cellpadding="7" cellspacing="1" >
<tr><td>
<a href="https://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?FeedbackID=100744">
Microsoft Feedback ID 100744 - Value-initialization in new-expression</a>
<br>Reported by Pavel Kuznetsov (MetaCommunications Engineering), 2005-07-28
<br>
<a href="http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30111">
GCC Bug 30111 - Value-initialization of POD base class doesn't initialize members</a>
<br>Reported by Jonathan Wakely, 2006-12-07
<br>
<a href="http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33916">
GCC Bug 33916 - Default constructor fails to initialize array members</a>
<br>Reported by Michael Elizabeth Chastain, 2007-10-26
<br>
<a href="http://qc.codegear.com/wc/qcmain.aspx?d=51854">
Borland Report 51854 - Value-initialization: POD struct should be zero-initialized</a>
<br>Reported by Niels Dekker (LKEB, Leiden University Medical Center), 2007-09-11
<br>
</td></tr></table>
At the moment of writing, May 2010, the following reported issues regarding
value-initialization are still there in current compiler releases:
<ul>
<li>
<a href="https://connect.microsoft.com/VisualStudio/feedback/details/100744">
Microsoft Visual Studio Feedback ID 100744, Value-initialization in new-expression</a>
<br>Reported by Pavel Kuznetsov (MetaCommunications Engineering), 2005
</li><li>
<a href="http://connect.microsoft.com/VisualStudio/feedback/details/484295">
Microsoft Visual Studio Feedback ID 484295, VC++ does not value-initialize members of derived classes without user-declared constructor</a>
<br>Reported by Sylvester Hesp, 2009
</li><li>
<a href="https://connect.microsoft.com/VisualStudio/feedback/details/499606">
Microsoft Visual Studio Feedback ID 499606, Presence of copy constructor breaks member class initialization</a>
<br>Reported by Alex Vakulenko, 2009
</li><li>
<a href="http://qc.embarcadero.com/wc/qcmain.aspx?d=83751">
Embarcadero/C++Builder Report 83751, Value-initialization: arrays should have each element value-initialized</a>
<br>Reported by Niels Dekker (LKEB), 2010
</li><li>
<a href="http://qc.embarcadero.com/wc/qcmain.aspx?d=83851">
Embarcadero/C++Builder Report 83851, Value-initialized temporary triggers internal backend error C1798</a>
<br>Reported by Niels Dekker, 2010
</li><li>
<a href="http://qc.embarcadero.com/wc/qcmain.aspx?d=84279">
Embarcadero/C++Builder Report 84279, Internal compiler error (F1004), value-initializing member function pointer by "new T()"</a>
<br>Reported by Niels Dekker, 2010
</li><li>
Sun CR 6947016, Sun 5.10 may fail to value-initialize an object of a non-POD aggregate.
<br>Reported to Steve Clamage by Niels Dekker, 2010
</li><li>
IBM's XL V10.1 and V11.1 may fail to value-initialize a temporary of a non-POD aggregate.
<br>Reported to Michael Wong by Niels Dekker, 2010
</li><li>
Intel support issue 589832, Attempt to value-initialize pointer-to-member triggers internal error
on Intel 11.1.
<br>Reported by John Maddock, 2010
</li>
</ul>
Note that all known GCC issues regarding value-initialization are
fixed with GCC version 4.4, including
<a href="http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30111">GCC Bug 30111</a>.
Clang also has completely implemented value-initialization, as far as we know,
now that <a href="http://llvm.org/bugs/show_bug.cgi?id=7139">Clang Bug 7139</a> is fixed.
</p><p>
New versions of <code>value_initialized</code>
(Boost release version 1.35 or higher)
offer a workaround to these issues: <code>value_initialized</code> will now clear
its internal data, prior to constructing the object that it contains.
offer a workaround to these issues: <code>value_initialized</code> may now clear
its internal data, prior to constructing the object that it contains. It will do
so for those compilers that need to have such a workaround, based on the
<a href="../config/doc/html/boost_config/boost_macro_reference.html#boost_config.boost_macro_reference.macros_that_describe_defects"
>compiler defect macro</a> BOOST_NO_COMPLETE_VALUE_INITIALIZATION.
</p>
<h2><a name="types"></a>Types and objects</h2>
@ -340,6 +375,52 @@ the wrapped object is always performed with the <code>get()</code> idiom:</p>
<pre>value_initialized&lt;int&gt; x ;<br>get(x) = 1 ; // OK<br><br>value_initialized&lt;int const&gt; cx ;<br>get(x) = 1 ; // ERROR: Cannot modify a const object<br><br>value_initialized&lt;int&gt; const x_c ;<br>get(x_c) = 1 ; // ERROR: Cannot modify a const object<br><br>value_initialized&lt;int const&gt; const cx_c ;<br>get(cx_c) = 1 ; // ERROR: Cannot modify a const object<br></pre>
<h2><a name="initialized"><code>template class initialized&lt;T&gt;</code></a></h2>
<pre>namespace boost {<br><br>template&lt;class T&gt;<br>class initialized<br>{
<br> public :
<br> initialized() : x() {}
<br> explicit initialized(T const &amp; arg) : x(arg) {}
<br> operator T const &amp;() const;
<br> operator T&amp;();
<br> T const &amp;data() const;
<br> T&amp; data();
<br> void swap( value_initialized&lt;T&gt;&amp; );
<br>
<br> private :
<br> <i>unspecified</i> x ;
<br>} ;
<br>
<br>template&lt;class T&gt;
<br>T const&amp; get ( initialized&lt;T&gt; const&amp; x );
<br>
<br>template&lt;class T&gt;
<br>T&amp; get ( initialized&lt;T&gt;&amp; x );
<br>
<br>} // namespace boost
<br></pre>
The template class <code>boost::initialized&lt;T&gt;</code> supports both value-initialization
and direct-initialization, so its interface is a superset of the interface
of <code>value_initialized&lt;T&gt;</code>: Its default-constructor
value-initializes the wrapped object just like the default-constructor of
<code>value_initialized&lt;T&gt;</code>, but <code>boost::initialized&lt;T&gt;</code>
also offers an extra <code>explicit</code>
constructor, which direct-initializes the wrapped object by the specified value.
<p>
<code>initialized&lt;T&gt;</code> is especially useful when the wrapped
object must be either value-initialized or direct-initialized, depending on
runtime conditions. For example, <code>initialized&lt;T&gt;</code> could
hold the value of a data member that may be value-initialized by some
constructors, and direct-initialized by others.
On the other hand, if it is known beforehand that the
object must <i>always</i> be value-initialized, <code>value_initialized&lt;T&gt;</code>
may be preferable. And if the object must always be
direct-initialized, none of the two wrappers really needs to be used.
</p>
<h2><a name="initialized_value"><code>initialized_value</code></a></h2>
<pre>
@ -399,6 +480,9 @@ Special thanks to Bj&ouml;rn Karlsson who carefully edited and completed this do
<p>value_initialized was reimplemented by Fernando Cacciola and Niels Dekker
for Boost release version 1.35 (2008), offering a workaround to various compiler issues.
</p>
<p><code>boost::initialized</code> was very much inspired by feedback from Edward Diener and
Jeffrey Hellrung.
</p>
<p>initialized_value was written by Niels Dekker, and added to Boost release version 1.36 (2008).
</p>
<p>Developed by <a href="mailto:fernando_cacciola@hotmail.com">Fernando Cacciola</a>,
@ -407,9 +491,9 @@ for Boost release version 1.35 (2008), offering a workaround to various compiler
</p>
<hr>
<p>Revised 03 October 2009</p>
<p>Revised 30 May 2010</p>
<p>&copy; Copyright Fernando Cacciola, 2002, 2009.</p>
<p>&copy; Copyright Fernando Cacciola, 2002 - 2010.</p>
<p>Distributed under the Boost Software License, Version 1.0. See
<a href="http://www.boost.org/LICENSE_1_0.txt">www.boost.org/LICENSE_1_0.txt</a></p>

View File

@ -22,7 +22,7 @@
#pragma hdrstop
#endif
#include "boost/test/minimal.hpp"
#include <boost/detail/lightweight_test.hpp>
//
// Sample POD type
@ -215,7 +215,7 @@ template<class T>
void check_initialized_value ( T const& y )
{
T initializedValue = boost::initialized_value ;
BOOST_CHECK ( y == initializedValue ) ;
BOOST_TEST ( y == initializedValue ) ;
}
#ifdef __BORLANDC__
@ -245,128 +245,125 @@ void check_initialized_value( NonPOD const& )
template<class T>
bool test ( T const& y, T const& z )
{
const boost::unit_test::counter_t counter_before_test = boost::minimal_test::errors_counter();
const int errors_before_test = boost::detail::test_errors();
check_initialized_value(y);
boost::value_initialized<T> x ;
BOOST_CHECK ( y == x ) ;
BOOST_CHECK ( y == boost::get(x) ) ;
BOOST_TEST ( y == x ) ;
BOOST_TEST ( y == boost::get(x) ) ;
static_cast<T&>(x) = z ;
boost::get(x) = z ;
BOOST_CHECK ( x == z ) ;
BOOST_TEST ( x == z ) ;
boost::value_initialized<T> const x_c ;
BOOST_CHECK ( y == x_c ) ;
BOOST_CHECK ( y == boost::get(x_c) ) ;
BOOST_TEST ( y == x_c ) ;
BOOST_TEST ( y == boost::get(x_c) ) ;
T& x_c_ref = const_cast<T&>( boost::get(x_c) ) ;
x_c_ref = z ;
BOOST_CHECK ( x_c == z ) ;
BOOST_TEST ( x_c == z ) ;
boost::value_initialized<T> const copy1 = x;
BOOST_CHECK ( boost::get(copy1) == boost::get(x) ) ;
BOOST_TEST ( boost::get(copy1) == boost::get(x) ) ;
boost::value_initialized<T> copy2;
copy2 = x;
BOOST_CHECK ( boost::get(copy2) == boost::get(x) ) ;
BOOST_TEST ( boost::get(copy2) == boost::get(x) ) ;
boost::shared_ptr<boost::value_initialized<T> > ptr( new boost::value_initialized<T> );
BOOST_CHECK ( y == *ptr ) ;
BOOST_TEST ( y == *ptr ) ;
#if !BOOST_WORKAROUND(BOOST_MSVC, < 1300)
boost::value_initialized<T const> cx ;
BOOST_CHECK ( y == cx ) ;
BOOST_CHECK ( y == boost::get(cx) ) ;
BOOST_TEST ( y == cx ) ;
BOOST_TEST ( y == boost::get(cx) ) ;
boost::value_initialized<T const> const cx_c ;
BOOST_CHECK ( y == cx_c ) ;
BOOST_CHECK ( y == boost::get(cx_c) ) ;
BOOST_TEST ( y == cx_c ) ;
BOOST_TEST ( y == boost::get(cx_c) ) ;
#endif
return boost::minimal_test::errors_counter() == counter_before_test ;
return boost::detail::test_errors() == errors_before_test ;
}
int test_main(int, char **)
int main(int, char **)
{
BOOST_CHECK ( test( 0,1234 ) ) ;
BOOST_CHECK ( test( 0.0,12.34 ) ) ;
BOOST_CHECK ( test( POD(0,0,0.0), POD('a',1234,56.78f) ) ) ;
BOOST_CHECK ( test( NonPOD( std::string() ), NonPOD( std::string("something") ) ) ) ;
BOOST_TEST ( test( 0,1234 ) ) ;
BOOST_TEST ( test( 0.0,12.34 ) ) ;
BOOST_TEST ( test( POD(0,0,0.0), POD('a',1234,56.78f) ) ) ;
BOOST_TEST ( test( NonPOD( std::string() ), NonPOD( std::string("something") ) ) ) ;
NonPOD NonPOD_object( std::string("NonPOD_object") );
BOOST_CHECK ( test<NonPOD *>( 0, &NonPOD_object ) ) ;
BOOST_TEST ( test<NonPOD *>( 0, &NonPOD_object ) ) ;
AggregatePODStruct zeroInitializedAggregatePODStruct = { 0.0f, '\0', 0 };
AggregatePODStruct nonZeroInitializedAggregatePODStruct = { 1.25f, 'a', -1 };
BOOST_CHECK ( test(zeroInitializedAggregatePODStruct, nonZeroInitializedAggregatePODStruct) );
BOOST_TEST ( test(zeroInitializedAggregatePODStruct, nonZeroInitializedAggregatePODStruct) );
StringAndInt stringAndInt0;
StringAndInt stringAndInt1;
stringAndInt0.i = 0;
stringAndInt1.i = 1;
stringAndInt1.s = std::string("1");
BOOST_CHECK ( test(stringAndInt0, stringAndInt1) );
BOOST_TEST ( test(stringAndInt0, stringAndInt1) );
StructWithDestructor structWithDestructor0;
StructWithDestructor structWithDestructor1;
structWithDestructor0.i = 0;
structWithDestructor1.i = 1;
BOOST_CHECK ( test(structWithDestructor0, structWithDestructor1) );
BOOST_TEST ( test(structWithDestructor0, structWithDestructor1) );
StructWithVirtualFunction structWithVirtualFunction0;
StructWithVirtualFunction structWithVirtualFunction1;
structWithVirtualFunction0.i = 0;
structWithVirtualFunction1.i = 1;
BOOST_CHECK ( test(structWithVirtualFunction0, structWithVirtualFunction1) );
BOOST_TEST ( test(structWithVirtualFunction0, structWithVirtualFunction1) );
DerivedFromAggregatePODStruct derivedFromAggregatePODStruct0;
DerivedFromAggregatePODStruct derivedFromAggregatePODStruct1;
static_cast<AggregatePODStruct &>(derivedFromAggregatePODStruct0) = zeroInitializedAggregatePODStruct;
static_cast<AggregatePODStruct &>(derivedFromAggregatePODStruct1) = nonZeroInitializedAggregatePODStruct;
BOOST_CHECK ( test(derivedFromAggregatePODStruct0, derivedFromAggregatePODStruct1) );
BOOST_TEST ( test(derivedFromAggregatePODStruct0, derivedFromAggregatePODStruct1) );
AggregatePODStructWrapper aggregatePODStructWrapper0;
AggregatePODStructWrapper aggregatePODStructWrapper1;
aggregatePODStructWrapper0.dataMember = zeroInitializedAggregatePODStruct;
aggregatePODStructWrapper1.dataMember = nonZeroInitializedAggregatePODStruct;
BOOST_CHECK ( test(aggregatePODStructWrapper0, aggregatePODStructWrapper1) );
BOOST_TEST ( test(aggregatePODStructWrapper0, aggregatePODStructWrapper1) );
ArrayOfBytes zeroInitializedArrayOfBytes = { 0 };
boost::value_initialized<ArrayOfBytes> valueInitializedArrayOfBytes;
BOOST_CHECK (std::memcmp(get(valueInitializedArrayOfBytes), zeroInitializedArrayOfBytes, sizeof(ArrayOfBytes)) == 0);
BOOST_TEST (std::memcmp(get(valueInitializedArrayOfBytes), zeroInitializedArrayOfBytes, sizeof(ArrayOfBytes)) == 0);
boost::value_initialized<ArrayOfBytes> valueInitializedArrayOfBytes2;
valueInitializedArrayOfBytes2 = valueInitializedArrayOfBytes;
BOOST_CHECK (std::memcmp(get(valueInitializedArrayOfBytes), get(valueInitializedArrayOfBytes2), sizeof(ArrayOfBytes)) == 0);
BOOST_TEST (std::memcmp(get(valueInitializedArrayOfBytes), get(valueInitializedArrayOfBytes2), sizeof(ArrayOfBytes)) == 0);
boost::value_initialized<CopyFunctionCallTester> copyFunctionCallTester1;
BOOST_CHECK ( ! get(copyFunctionCallTester1).is_copy_constructed);
BOOST_CHECK ( ! get(copyFunctionCallTester1).is_assignment_called);
BOOST_TEST ( ! get(copyFunctionCallTester1).is_copy_constructed);
BOOST_TEST ( ! get(copyFunctionCallTester1).is_assignment_called);
boost::value_initialized<CopyFunctionCallTester> copyFunctionCallTester2 = boost::value_initialized<CopyFunctionCallTester>(copyFunctionCallTester1);
BOOST_CHECK ( get(copyFunctionCallTester2).is_copy_constructed);
BOOST_CHECK ( ! get(copyFunctionCallTester2).is_assignment_called);
BOOST_TEST ( get(copyFunctionCallTester2).is_copy_constructed);
BOOST_TEST ( ! get(copyFunctionCallTester2).is_assignment_called);
boost::value_initialized<CopyFunctionCallTester> copyFunctionCallTester3;
copyFunctionCallTester3 = boost::value_initialized<CopyFunctionCallTester>(copyFunctionCallTester1);
BOOST_CHECK ( ! get(copyFunctionCallTester3).is_copy_constructed);
BOOST_CHECK ( get(copyFunctionCallTester3).is_assignment_called);
BOOST_TEST ( ! get(copyFunctionCallTester3).is_copy_constructed);
BOOST_TEST ( get(copyFunctionCallTester3).is_assignment_called);
boost::value_initialized<SwapFunctionCallTester> swapFunctionCallTester1;
boost::value_initialized<SwapFunctionCallTester> swapFunctionCallTester2;
get(swapFunctionCallTester1).data = 1;
get(swapFunctionCallTester2).data = 2;
boost::swap(swapFunctionCallTester1, swapFunctionCallTester2);
BOOST_CHECK( get(swapFunctionCallTester1).data == 2 );
BOOST_CHECK( get(swapFunctionCallTester2).data == 1 );
BOOST_CHECK( get(swapFunctionCallTester1).is_custom_swap_called );
BOOST_CHECK( get(swapFunctionCallTester2).is_custom_swap_called );
BOOST_TEST( get(swapFunctionCallTester1).data == 2 );
BOOST_TEST( get(swapFunctionCallTester2).data == 1 );
BOOST_TEST( get(swapFunctionCallTester1).is_custom_swap_called );
BOOST_TEST( get(swapFunctionCallTester2).is_custom_swap_called );
return 0;
return boost::report_errors();
}
unsigned int expected_failures = 0;

View File

@ -0,0 +1,144 @@
// Copyright 2010, Niels Dekker.
//
// Distributed under the Boost Software License, Version 1.0. (See
// accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
//
// Test program for the boost::value_initialized<T> workaround.
//
// 17 June 2010 (Created) Niels Dekker
// Switch the workaround off, before inluding "value_init.hpp".
#define BOOST_DETAIL_VALUE_INIT_WORKAROUND 0
#include <boost/utility/value_init.hpp>
#include <iostream> // For cout.
#include <cstdlib> // For EXIT_SUCCESS and EXIT_FAILURE.
namespace
{
struct empty_struct
{
};
// A POD aggregate struct derived from an empty struct.
// Similar to struct Foo1 from Microsoft Visual C++ bug report 484295,
// "VC++ does not value-initialize members of derived classes without
// user-declared constructor", reported in 2009 by Sylvester Hesp:
// https://connect.microsoft.com/VisualStudio/feedback/details/484295
struct derived_struct: empty_struct
{
int data;
};
bool is_value_initialized(const derived_struct& arg)
{
return arg.data == 0;
}
class virtual_destructor_holder
{
public:
int i;
virtual ~virtual_destructor_holder()
{
}
};
bool is_value_initialized(const virtual_destructor_holder& arg)
{
return arg.i == 0;
}
// Equivalent to the Stats class from GCC Bug 33916,
// "Default constructor fails to initialize array members", reported in 2007 by
// Michael Elizabeth Chastain: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33916
// and fixed for GCC 4.2.4.
class private_int_array_pair
{
friend bool is_value_initialized(const private_int_array_pair& arg);
private:
int first[12];
int second[12];
};
bool is_value_initialized(const private_int_array_pair& arg)
{
for ( unsigned i = 0; i < 12; ++i)
{
if ( (arg.first[i] != 0) || (arg.second[i] != 0) )
{
return false;
}
}
return true;
}
template <typename T>
bool is_value_initialized(const T(& arg)[2])
{
return
is_value_initialized(arg[0]) &&
is_value_initialized(arg[1]);
}
template <typename T>
bool is_value_initialized(const boost::value_initialized<T>& arg)
{
return is_value_initialized(arg.data());
}
// Returns zero when the specified object is value-initializated, and one otherwise.
// Prints a message to standard output if the value-initialization has failed.
template <class T>
unsigned failed_to_value_initialized(const T& object, const char *const object_name)
{
if ( is_value_initialized(object) )
{
return 0u;
}
else
{
std::cout << "Note: Failed to value-initialize " << object_name << '.' << std::endl;
return 1u;
}
}
// A macro that passed both the name and the value of the specified object to
// the function above here.
#define FAILED_TO_VALUE_INITIALIZE(value) failed_to_value_initialized(value, #value)
// Equivalent to the dirty_stack() function from GCC Bug 33916,
// "Default constructor fails to initialize array members", reported in 2007 by
// Michael Elizabeth Chastain: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33916
void dirty_stack()
{
unsigned char array_on_stack[4096];
for (unsigned i = 0; i < sizeof(array_on_stack); ++i)
{
array_on_stack[i] = 0x11;
}
}
}
int main()
{
dirty_stack();
// TODO More types may be added later.
const unsigned num_failures =
FAILED_TO_VALUE_INITIALIZE(boost::value_initialized<derived_struct>()) +
FAILED_TO_VALUE_INITIALIZE(boost::value_initialized<virtual_destructor_holder[2]>()) +
FAILED_TO_VALUE_INITIALIZE(boost::value_initialized<private_int_array_pair>());
#ifdef BOOST_DETAIL_VALUE_INIT_WORKAROUND_SUGGESTED
// One or more failures are expected.
return num_failures > 0 ? EXIT_SUCCESS : EXIT_FAILURE;
#else
// No failures are expected.
return num_failures == 0 ? EXIT_SUCCESS : EXIT_FAILURE;
#endif
}