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Fixes #6186 (treat conversions to/from single wchar_t character as conversions to/from unsigned short. Test added, documentation updated)

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[SVN r75937]
This commit is contained in:
Antony Polukhin
2011-12-14 16:36:34 +00:00
parent f32fb4b5e5
commit 8627f8bb8a
4 changed files with 74 additions and 15 deletions
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12
doc/lexical_cast.qbk
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@@ -159,9 +159,21 @@ Read a good C++ book, study `std::sentry` and [@boost:libs/io/doc/ios_state.html
the rules of `scanf` for conversions. And in the C99 standard for unsigned input value minus sign is optional, so
if a negative number is read, no errors will arise and the result will be the two's complement.
[pre
]
* [*Question:] Why `boost::lexical_cast<int>(L'A');` outputs 65 and `boost::lexical_cast<wchar_t>(L"65");` does not throw?
* [*Answer:] If you are using an old version of Visual Studio or compile code with /Zc:wchar_t- flag,
`boost::lexical_cast` sees single `wchar_t` character as `unsigned short`. It is not a `boost::lexical_cast` mistake, but a
limitation of compiler options that you use.
[endsect]
[section Changes]
* [*boost 1.49.0 :]
* Added code to work with typedefed wchar_t (compilation flag /Zc:wchar_t- for Visual Studio).
* [*boost 1.48.0 :]
* Added code to work with Inf and NaN on any platform.

28
include/boost/lexical_cast.hpp
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@@ -17,8 +17,8 @@
// enhanced with contributions from Terje Slettebo,
// with additional fixes and suggestions from Gennaro Prota,
// Beman Dawes, Dave Abrahams, Daryle Walker, Peter Dimov,
// Alexander Nasonov, Antony Polukhin, Justin Viiret, Michael Hofmann
// and other Boosters
// Alexander Nasonov, Antony Polukhin, Justin Viiret, Michael Hofmann,
// Cheng Yang and other Boosters
// when: November 2000, March 2003, June 2005, June 2006, March 2011
#include <climits>
@@ -1093,8 +1093,6 @@ namespace boost
namespace detail // optimized stream wrapper
{
struct type_used_as_workaround_for_typedefed_wchar_ts{};
// String representation of Source has an upper limit.
template< class CharT // a result of widest_char transformation
, class Traits // usually char_traits<CharT>
@@ -1356,7 +1354,6 @@ namespace boost
/************************************ HELPER FUNCTIONS FOR OPERATORS >> ( ... ) ********************************/
private:
bool shr_unsigned(type_used_as_workaround_for_typedefed_wchar_ts /*var*/) {return true;}
template <typename Type>
bool shr_unsigned(Type& output)
@@ -1484,15 +1481,8 @@ namespace boost
}
/************************************ OPERATORS >> ( ... ) ********************************/
typedef BOOST_DEDUCED_TYPENAME ::boost::mpl::if_c<
::boost::is_same<CharT, unsigned short>::value
, type_used_as_workaround_for_typedefed_wchar_ts
, unsigned short
>::type ushort_ambiguity_workaround;
public:
bool operator>>(ushort_ambiguity_workaround& output){ return shr_unsigned(output); }
bool operator>>(unsigned short& output) { return shr_unsigned(output); }
bool operator>>(unsigned int& output) { return shr_unsigned(output); }
bool operator>>(unsigned long int& output) { return shr_unsigned(output); }
bool operator>>(short& output) { return shr_signed(output); }
@@ -1504,11 +1494,19 @@ namespace boost
#elif defined(BOOST_HAS_MS_INT64)
bool operator>>(unsigned __int64& output) { return shr_unsigned(output); }
bool operator>>(__int64& output) { return shr_signed(output); }
#endif
bool operator>>(CharT& output) { return shr_xchar(output); }
bool operator>>(char& output) { return shr_xchar(output); }
bool operator>>(unsigned char& output) { return shr_xchar(output); }
bool operator>>(signed char& output) { return shr_xchar(output); }
#if !defined(BOOST_LCAST_NO_WCHAR_T) && !defined(BOOST_NO_INTRINSIC_WCHAR_T)
bool operator>>(wchar_t& output) { return shr_xchar(output); }
#endif
#ifndef BOOST_NO_CHAR16_T
bool operator>>(char16_t& output) { return shr_xchar(output); }
#endif
#ifndef BOOST_NO_CHAR32_T
bool operator>>(char32_t& output) { return shr_xchar(output); }
#endif
#ifdef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
bool operator>>(std::string& str) { str.assign(start, finish); return true; }
# ifndef BOOST_LCAST_NO_WCHAR_T

1
test/Jamfile.v2
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@@ -36,5 +36,6 @@ test-suite conversion
[ run lexical_cast_containers_test.cpp ../../test/build//boost_unit_test_framework/<link>static ]
[ run lexical_cast_empty_input_test.cpp ../../test/build//boost_unit_test_framework/<link>static ]
[ compile lexical_cast_typedefed_wchar_test.cpp : <toolset>msvc:<nowchar>on ]
[ run lexical_cast_typedefed_wchar_test_runtime.cpp ../../test/build//boost_unit_test_framework/<link>static : : : <toolset>msvc:<nowchar>on ]
;

48
test/lexical_cast_typedefed_wchar_test_runtime.cpp Executable file
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@@ -0,0 +1,48 @@
// Unit test for boost::lexical_cast.
//
// See http://www.boost.org for most recent version, including documentation.
//
// Copyright Antony Polukhin, 2011.
//
// 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).
#include <boost/config.hpp>
#if defined(__INTEL_COMPILER)
#pragma warning(disable: 193 383 488 981 1418 1419)
#elif defined(BOOST_MSVC)
#pragma warning(disable: 4097 4100 4121 4127 4146 4244 4245 4511 4512 4701 4800)
#endif
#include <boost/lexical_cast.hpp>
#include <boost/test/unit_test.hpp>
using namespace boost;
void test_typedefed_wchar_t_runtime()
{
#ifndef BOOST_LCAST_NO_WCHAR_T
#ifdef BOOST_MSVC
BOOST_STATIC_ASSERT((boost::is_same<wchar_t, unsigned short>::value));
BOOST_CHECK_EQUAL(boost::lexical_cast<int>(L'A'), 65);
BOOST_CHECK_EQUAL(boost::lexical_cast<int>(L'B'), 66);
BOOST_CHECK_EQUAL(boost::lexical_cast<wchar_t>(L"65"), 65);
BOOST_CHECK_EQUAL(boost::lexical_cast<wchar_t>(L"66"), 66);
#endif
#endif
BOOST_CHECK(1);
}
unit_test::test_suite *init_unit_test_suite(int, char *[])
{
unit_test::test_suite *suite =
BOOST_TEST_SUITE("lexical_cast typedefed wchar_t runtime test");
suite->add(BOOST_TEST_CASE(&test_typedefed_wchar_t_runtime));
return suite;
}