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Add boost/io/detail/quoted_manip.hpp, with docs and test

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[SVN r63119]
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Beman Dawes
2010-06-19 20:30:31 +00:00
parent 81458c44a6 b925279bc9
commit ab59f094aa
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<?xml version="1.0" encoding="iso-8859-1"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=iso-8859-1" />
<title>Boost &quot;quoted&quot; I/O manipulator</title>
<meta name="generator" content="Microsoft FrontPage 5.0" />
<link rel="stylesheet" type="text/css" href="../../../doc/html/minimal.css" />
</head>
<body>
<table border="0" cellpadding="5" cellspacing="0"
style="border-collapse: collapse">
<tbody>
<tr>
<td width="277"><a href="../../../index.htm"><img
src="../../../boost.png" alt="boost.png (6897 bytes)" align="middle"
width="300" height="86" border="0" /></a></td>
<td>
<h1 align="center">&quot;Quoted&quot;
I/O Manipulators<br>
for Strings</h1>
</td>
</tr>
</tbody>
</table>
<table border="1" cellpadding="5" cellspacing="1" style="border-collapse: collapse" bordercolor="#111111">
<tr>
<td>
<p align="center"><b>&quot;Quoted&quot;
I/O Manipulators
for Strings are not yet accepted into Boost as public components. Thus the
header file is currently located in &lt;boost/io/detail/quoted_manip.hpp&gt;, and
this documentation page is not linked to from official documentation.</b></td>
</tr>
</table>
<h2>Introduction</h2>
<p>C++ Standard library stream I/O for strings that contain embedded spaces
can produce unexpected results. For example,</p>
<blockquote>
<pre>std::stringstream ss;
std::string original = &quot;fooled you&quot;;
std::string round_trip;
ss &lt;&lt; original;
ss &gt;&gt; round_trip;
std::cout &lt;&lt; original; // outputs: fooled you
std::cout &lt;&lt; round_trip; // outputs: fooled
assert(original == round_trip); // assert will fire</pre>
</blockquote>
<p>The Boost <code>quoted</code> stream I/O manipulator places delimiters, defaulted
to the double-quote (<code>&quot;</code>), around strings on output, and strips off
the delimiters on input. This ensures strings with embedded spaces round-trip as
desired. For example,</p>
<blockquote>
<pre>std::stringstream ss;
std::string original = &quot;fooled you&quot;;
std::string round_trip;
ss &lt;&lt; quoted(original);
ss &gt;&gt; quoted(round_trip);
std::cout &lt;&lt; quoted(original); // outputs: &quot;fooled you&quot;
std::cout &lt;&lt; round_trip; // outputs: fooled you
assert(original == round_trip); // assert will not fire</pre>
</blockquote>
<p>If the string contains the delimiter character, on output that character will
be preceded by an escape character, as will the escape character itself:</p>
<blockquote>
<pre>std::cout &lt;&lt; quoted(&quot;'Jack &amp; Jill'&quot;, '&amp;', '\''); // outputs: '&amp;'Jack &amp;&amp; Jill&amp;''</pre>
</blockquote>
<h2>Header <a href="../../../boost/io/detail/quoted_manip.hpp">&lt;boost/io/quoted_manip.hpp&gt;</a> synopsis</h2>
<pre>namespace boost
{
namespace io
{
// manipulator for const std::basic_string&amp;
template &lt;class Char, class Traits, class Alloc&gt;
<b><i>unspecified-type1</i></b> quoted(const std::basic_string&lt;Char, Traits, Alloc&gt;&amp; string, Char escape='\\', Char delim='\&quot;');
// manipulator for const C-string*
template &lt;class Char&gt;
<b><i>unspecified-type2</i></b> quoted(const Char* string, Char escape='\\', Char delim='\&quot;');
// manipulator for non-const std::basic_string&amp;
template &lt;class Char, class Traits, class Alloc&gt;
<b><i>unspecified-type3</i></b> quoted(std::basic_string&lt;Char, Traits, Alloc&gt;&amp; string, Char escape='\\', Char delim='\&quot;');
}
}</pre>
<p><i><b><code>unspecified_type1</code></b></i>, <i><b><code>unspecified_type2</code></b></i>,
and <i><b><code>unspecified_type3</code></b></i> are implementation supplied
types with implementation supplied <code>operator&lt;&lt;</code>:</p>
<blockquote>
<pre>template &lt;class Char, class Traits&gt;
std::basic_ostream&lt;Char, Traits&gt;&amp;
operator&lt;&lt;(std::basic_ostream&lt;Char, Traits&gt;&amp; os, const <i><b><code>unspecified_typeN</code></b></i>&amp; proxy);</pre>
<p><i>Effects:</i> Inserts characters into <code>os</code>:</p>
<ul>
<li><code>delim</code>.</li>
<li>Each character in <code>string</code>. If the character to be output is
equal to <code>escape</code> or <code>delim</code>, as determined by <code>
operator==</code>, first output <code>escape</code>. </li>
<li><code>delim</code>.</li>
</ul>
<p><i>Remarks:</i> <code>string</code>, <code>escape</code>, and <code>delim</code>
have the type and value of the corresponding arguments of the call to the <code>
quoted</code> function that constructed <code>proxy</code>.</p>
<p><i>Returns:</i> <code>os</code>. </p>
</blockquote>
<p><i><b><code>unspecified_type3</code></b></i> is an implementation supplied
type with an implementation supplied <code>operator&gt;&gt;</code>:</p>
<blockquote>
<pre>template &lt;class Char, class Traits&gt;
std::basic_istream&lt;Char, Traits&gt;&amp;
operator&gt;&gt;(std::basic_istream&lt;Char, Traits&gt;&amp; is, const <i><b><code>unspecified_type3</code></b></i>&amp; proxy);</pre>
<p><i>Effects:</i> Extracts characters from <code>os</code>:</p>
<ul>
<li>If the first character extracted is equal to delim, as determined by
<code>operator==</code>, then:<ul>
<li>Turn off the <code>skipws</code> flag.</li>
<li><code>string.clear()</code></li>
<li>Until an unescaped <code>delim</code> character is reached or <code>
is.not_good()</code>, extract
characters from <code>os</code> and append them to <code>string</code>,
except that if an <code>escape</code> is reached, ignore it and append the
next character to <code>string</code>.</li>
<li>Discard the final <code>delim</code> character.</li>
<li>Restore the <code>skipws</code> flag to its original value.</li>
</ul>
</li>
<li>Otherwise, <code>os &gt;&gt; string</code>.</li>
</ul>
<p><i>Remarks:</i> <code>string</code>, <code>escape</code>, and <code>delim</code>
have the type and value of the corresponding arguments of the call to the <code>
quoted</code> function that constructed <code>proxy</code>.</p>
<p><i>Returns:</i> <code>is</code>. </p>
</blockquote>
<h2>Acknowledgements</h2>
<p>The <code>quoted()</code> stream manipulator emerged from discussions on the
Boost developers mailing list. Participants included Beman Dawes, Rob Stewart,
Alexander Lamaison, Eric Niebler, Vicente Botet, Andrey Semashev, Phil Richards,
and Rob Murray. Eric Niebler's suggestions provided the basis for the name and
form of the templates. </p>
<hr>
<p><EFBFBD> Copyright Beman Dawes, 2002, 2006, 2007, 2009, 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>
<p>Revised
<!--webbot bot="Timestamp" S-Type="EDITED" S-Format="%d %B %Y" startspan -->19 June 2010<!--webbot bot="Timestamp" endspan i-checksum="17561" --></p>
</body>
</html>

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// boost/io/quoted_manip.hpp ---------------------------------------------------------//
// Copyright Beman Dawes 2010
// Distributed under the Boost Software License, Version 1.0.
// See http://www.boost.org/LICENSE_1_0.txt
// Library home page http://www.boost.org/libs/io
//--------------------------------------------------------------------------------------//
#ifndef BOOST_IO_QUOTED_MANIP
#define BOOST_IO_QUOTED_MANIP
#include <iosfwd>
#include <ios>
#include <string>
#include <iterator>
#include <boost/io/ios_state.hpp>
namespace boost
{
namespace io
{
namespace detail { template <class String, class Char> struct quoted_proxy; }
// ------------ public interface ------------------------------------------------//
// manipulator for const std::basic_string&
template <class Char, class Traits, class Alloc>
detail::quoted_proxy<std::basic_string<Char, Traits, Alloc> const &, Char>
quoted(const std::basic_string<Char, Traits, Alloc>& s,
Char escape='\\', Char delim='\"');
// manipulator for non-const std::basic_string&
template <class Char, class Traits, class Alloc>
detail::quoted_proxy<std::basic_string<Char, Traits, Alloc> &, Char>
quoted(std::basic_string<Char, Traits, Alloc>& s,
Char escape='\\', Char delim='\"');
// manipulator for const C-string*
template <class Char>
detail::quoted_proxy<const Char*, Char>
quoted(const Char* s, Char escape='\\', Char delim='\"');
// ----------- implementation details -------------------------------------------//
namespace detail
{
// proxy used as an argument pack
template <class String, class Char>
struct quoted_proxy
{
String string;
Char escape;
Char delim;
quoted_proxy(String s_, Char escape_, Char delim_)
: string(s_), escape(escape_), delim(delim_) {}
};
// abstract away difference between proxies with const or non-const basic_strings
template <class Char, class Traits, class Alloc>
std::basic_ostream<Char, Traits>&
basic_string_inserter_imp(std::basic_ostream<Char, Traits>& os,
std::basic_string<Char, Traits, Alloc> const & string, Char escape, Char delim)
{
os << delim;
typename std::basic_string<Char, Traits, Alloc>::const_iterator
end_it = string.end();
for (typename std::basic_string<Char, Traits, Alloc>::const_iterator
it = string.begin();
it != end_it;
++it )
{
if (*it == delim || *it == escape)
os << escape;
os << *it;
}
os << delim;
return os;
}
// inserter for const std::basic_string& proxies
template <class Char, class Traits, class Alloc>
inline
std::basic_ostream<Char, Traits>& operator<<(std::basic_ostream<Char, Traits>& os,
const quoted_proxy<std::basic_string<Char, Traits, Alloc> const &, Char>& proxy)
{
return basic_string_inserter_imp(os, proxy.string, proxy.escape, proxy.delim);
}
// inserter for non-const std::basic_string& proxies
template <class Char, class Traits, class Alloc>
inline
std::basic_ostream<Char, Traits>& operator<<(std::basic_ostream<Char, Traits>& os,
const quoted_proxy<std::basic_string<Char, Traits, Alloc>&, Char>& proxy)
{
return basic_string_inserter_imp(os, proxy.string, proxy.escape, proxy.delim);
}
// inserter for const C-string* proxies
template <class Char, class Traits>
std::basic_ostream<Char, Traits>& operator<<(std::basic_ostream<Char, Traits>& os,
const quoted_proxy<const Char*, Char>& proxy)
{
os << proxy.delim;
for (const Char* it = proxy.string;
*it;
++it )
{
if (*it == proxy.delim || *it == proxy.escape)
os << proxy.escape;
os << *it;
}
os << proxy.delim;
return os;
}
// extractor for non-const std::basic_string& proxies
template <class Char, class Traits, class Alloc>
std::basic_istream<Char, Traits>& operator>>(std::basic_istream<Char, Traits>& is,
const quoted_proxy<std::basic_string<Char, Traits, Alloc>&, Char>& proxy)
{
Char c;
is >> c;
if (c != proxy.delim)
{
proxy.string = c;
is >> proxy.string;
return is;
}
proxy.string.clear();
{
boost::io::ios_flags_saver ifs(is);
is >> std::noskipws;
for (;;)
{
is >> c;
if (!is.good()) // cope with I/O errors or end-of-file
break;
if (c == proxy.escape)
{
is >> c;
if (!is.good()) // cope with I/O errors or end-of-file
break;
}
else if (c == proxy.delim)
break;
proxy.string += c;
}
}
return is;
}
} // namespace detail
// manipulator implementation for const std::basic_string&
template <class Char, class Traits, class Alloc>
inline detail::quoted_proxy<std::basic_string<Char, Traits, Alloc> const &, Char>
quoted(const std::basic_string<Char, Traits, Alloc>& s, Char escape, Char delim)
{
return detail::quoted_proxy<std::basic_string<Char, Traits, Alloc> const &, Char>
(s, escape, delim);
}
// manipulator implementation for non-const std::basic_string&
template <class Char, class Traits, class Alloc>
inline detail::quoted_proxy<std::basic_string<Char, Traits, Alloc> &, Char>
quoted(std::basic_string<Char, Traits, Alloc>& s, Char escape, Char delim)
{
return detail::quoted_proxy<std::basic_string<Char, Traits, Alloc>&, Char>
(s, escape, delim);
}
// manipulator implementation for const C-string*
template <class Char>
inline detail::quoted_proxy<const Char*, Char>
quoted(const Char* s, Char escape, Char delim)
{
return detail::quoted_proxy<const Char*, Char> (s, escape, delim);
}
} // namespace io
} // namespace boost
#endif // BOOST_IO_QUOTED_MANIP

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: # input files : # input files
# : std::locale-support # : std::locale-support
] ]
[ run quoted_manip_test.cpp ]
; ;

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// libs/io/test/quote_manip_test.cpp ----------------------------------------------- //
// Copyright Beman Dawes 2010
// Distributed under the Boost Software License, Version 1.0.
// See http://www.boost.org/LICENSE_1_0.txt
// Library home page: http://www.boost.org/libs/io
// ---------------------------------------------------------------------------------- //
#include <boost/io/detail/quoted_manip.hpp>
#include <boost/detail/lightweight_test.hpp>
#include <iostream>
#include <sstream>
using boost::io::quoted;
using std::string;
using std::wstring;
int main()
{
std::stringstream ss;
std::wstringstream wss;
const string s1("foo\\bar, \" *");
string r; // test results
ss << quoted(s1);
ss >> r;
BOOST_TEST_EQ(r, "\"foo\\\\bar, \\\" *\"");
ss << quoted(s1.c_str());
ss >> r;
BOOST_TEST_EQ(r, "\"foo\\\\bar, \\\" *\"");
ss << quoted(s1);
ss >> quoted(r);
BOOST_TEST_EQ(r, s1);
ss << quoted(s1.c_str());
ss >> quoted(r);
BOOST_TEST_EQ(r, s1);
string s2("'Jack & Jill'");
ss << quoted(s2, '&', '\'');
ss >> r;
BOOST_TEST_EQ(r, "'&'Jack && Jill&''");
ss << quoted(s2, '&', '\'');
ss >> quoted(r, '&', '\'');
BOOST_TEST_EQ(r, s2);
wstring ws1(L"foo$bar, \" *");
wstring wr; // test results
wss << quoted(ws1, L'$');
wss >> wr;
BOOST_TEST(wr == wstring(L"\"foo$$bar, $\" *\""));
wss << quoted(ws1, L'$');
wss >> quoted(wr, L'$');
BOOST_TEST(wr == ws1);
const string s3("const string");
ss << quoted(s3);
ss >> quoted(r);
BOOST_TEST_EQ(r, s3);
// missing end delimiter test
ss << "\"abc"; // load ss with faulty quoting
ss >> quoted(r); // this loops if istream error/eof not detected
BOOST_TEST_EQ(r, "abc");
// no initial delmiter test
ss << "abc";
ss >> quoted(r);
BOOST_TEST_EQ(r, "abc");
// no initial delmiter, space in ss
ss << "abc def";
ss >> quoted(r);
BOOST_TEST_EQ(r, "abc");
// these should fail to compile because the arguments are const:
// ss >> quoted(s1);
// ss >> quoted("foo");
return 0;
}