| Message ID | 1901588.qodTErPe42@descartes |
|---|---|
| State | New |
| Headers | show |
On 27/03/14 17:00 +0100, Rüdiger Sonderfeld wrote: >Hello Jonathan, > >thanks for your comments. > >> N.B. patches to the ChangeLog rarely apply cleanly (because someone >> else may have changed the ChangeLog since the patch was created) so >> the convention is to send the ChangeLog entry in the email body, or as >> a separate attachment, or by using 'git log -p @{u}..' so the commit >> log shows it, rather than as part of the patch. > >Yes, ChangeLog's can be a bit of a pain. I removed the ChangeLog from the >patch. But FYI there is a ChangeLog merge driver hidden in gnulib, which >can be helpful when dealing with ChangeLog files in git (and potentially >other version control systems) > >http://git.savannah.gnu.org/gitweb/?p=gnulib.git;a=blob;f=lib/git-merge-changelog.c Yes, I use that myself, and generate patches with the 'git lgp' command shown at http://gcc.gnu.org/wiki/GitMirror >> We could document that (fixed|scientific) has that effect in c++98 >> mode. > >Where should it be documented? Probably somewhere in doc/xml/manual/io.xml but I'm happy to do that once the patch is committed if you like. Thanks for the updated patch, I will try to remember to commit it when stage 1 starts. If you don't get a mail from me then please ping me as a reminder.
On 27 March 2014 23:56, Luke Allardyce wrote: > It looks like the new standard also requires the precision to be > ignored for hexfloat > >>For conversion from a floating-point type, if floatfield != (ios_base::fixed | ios_base:: scientific), str.precision() is specified as precision in the conversion specification. Otherwise, no precision is specified. Thanks for pointing out that difference. We'll need a test for that. > Also the old standard seems to require that ios_base::fixed | > ios_base::scientific (or any other combination) falls through to the > uppercase test; I was trying to use abi_tag for a solution as not only > would two versions of _S_format_float be necessary, but also num_get > due to the pre-instantiated templates for <char> and <wchar>, which > led me to http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60642. It might > just be more trouble than it's worth. I don't think we need to worry about that, if I understand correctly the combination of fixed|scientific has unspecified behaviour in C++03, so we can make our implementation do exactly what it does in C++11.
>> Also the old standard seems to require that ios_base::fixed | >> ios_base::scientific (or any other combination) falls through to the >> uppercase test; I was trying to use abi_tag for a solution as not only >> would two versions of _S_format_float be necessary, but also num_get >> due to the pre-instantiated templates for <char> and <wchar>, which >> led me to http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60642. It might >> just be more trouble than it's worth. > > I don't think we need to worry about that, if I understand correctly > the combination of fixed|scientific has unspecified behaviour in > C++03, so we can make our implementation do exactly what it does in > C++11. It seems to me that it is well defined, going from [lib.facet.num.put.virtuals] > 6 All tables used in describing stage 1 are ordered. That is, the first line whose condition is true applies. > A line without a condition is the default behavior when none of the earlier lines apply. So fixed|scientific would be equivalent to specifying neither according to table 58, and the resulting specifier would be %g or %G depending on whether uppercase is set or not.
On 16/04/14 14:26 +0900, Luke Allardyce wrote: >>> Also the old standard seems to require that ios_base::fixed | >>> ios_base::scientific (or any other combination) falls through to the >>> uppercase test; I was trying to use abi_tag for a solution as not only >>> would two versions of _S_format_float be necessary, but also num_get >>> due to the pre-instantiated templates for <char> and <wchar>, which >>> led me to http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60642. It might >>> just be more trouble than it's worth. >> >> I don't think we need to worry about that, if I understand correctly >> the combination of fixed|scientific has unspecified behaviour in >> C++03, so we can make our implementation do exactly what it does in >> C++11. > >It seems to me that it is well defined, going from [lib.facet.num.put.virtuals] > >> 6 All tables used in describing stage 1 are ordered. That is, the first line whose condition is true applies. >> A line without a condition is the default behavior when none of the earlier lines apply. > >So fixed|scientific would be equivalent to specifying neither >according to table 58, and the resulting specifier would be %g or %G >depending on whether uppercase is set or not. Thanks, I was wrong about that. Then I think we should just bite the bullet and provide the new behaviour. If we do have an abi_tag on those types in the next release then we can preserve the old behaviour in the old ABI and use the C++11 semantics for the abi_tagged type, which will be used for both C++03 and C++11 code. I am not too concerned that people who use a meaningless modifier in C++03 code get the C++11 behaviour. If they really want %g or %G then they shouldn't use fixed|scientific.
> Thanks, I was wrong about that. > > Then I think we should just bite the bullet and provide the new > behaviour. If we do have an abi_tag on those types in the next release > then we can preserve the old behaviour in the old ABI and use the > C++11 semantics for the abi_tagged type, which will be used for both > C++03 and C++11 code. I am not too concerned that people who use a > meaningless modifier in C++03 code get the C++11 behaviour. If they > really want %g or %G then they shouldn't use fixed|scientific. Does that mean abi_tag will be enabled with separate compiler flag / define rather than checking against the __cplusplus value?
diff --git a/libstdc++-v3/include/bits/ios_base.h b/libstdc++-v3/include/bits/ios_base.h index ae856de..b7fae43 100644 --- a/libstdc++-v3/include/bits/ios_base.h +++ b/libstdc++-v3/include/bits/ios_base.h @@ -969,6 +969,27 @@ namespace std _GLIBCXX_VISIBILITY(default) return __base; } +#if __cplusplus >= 201103L + // New C++11 floatfield manipulators + + /// Calls base.setf(ios_base::fixed | ios_base::scientific, + /// ios_base::floatfield). + inline ios_base& + hexfloat(ios_base& __base) + { + __base.setf(ios_base::fixed | ios_base::scientific, ios_base::floatfield); + return __base; + } + + /// Calls base.unsetf(ios_base::floatfield). + inline ios_base& + defaultfloat(ios_base& __base) + { + __base.unsetf(ios_base::floatfield); + return __base; + } +#endif // __cplusplus >= 201103L + _GLIBCXX_END_NAMESPACE_VERSION } // namespace diff --git a/libstdc++-v3/src/c++98/locale_facets.cc b/libstdc++-v3/src/c++98/locale_facets.cc index 3669acb..a21d665 100644 --- a/libstdc++-v3/src/c++98/locale_facets.cc +++ b/libstdc++-v3/src/c++98/locale_facets.cc @@ -82,6 +82,10 @@ namespace std _GLIBCXX_VISIBILITY(default) *__fptr++ = 'f'; else if (__fltfield == ios_base::scientific) *__fptr++ = (__flags & ios_base::uppercase) ? 'E' : 'e'; +#ifdef _GLIBCXX_USE_C99 + else if (__fltfield == (ios_base::fixed | ios_base::scientific)) + *__fptr++ = (__flags & ios_base::uppercase) ? 'A' : 'a'; +#endif else *__fptr++ = (__flags & ios_base::uppercase) ? 'G' : 'g'; *__fptr = '\0'; diff --git a/libstdc++-v3/testsuite/27_io/basic_ostream/inserters_arithmetic/char/hexfloat.cc b/libstdc++-v3/testsuite/27_io/basic_ostream/inserters_arithmetic/char/hexfloat.cc new file mode 100644 index 0000000..55c46ad --- /dev/null +++ b/libstdc++-v3/testsuite/27_io/basic_ostream/inserters_arithmetic/char/hexfloat.cc @@ -0,0 +1,141 @@ +// { dg-options "-std=gnu++11" } + +// 2014-03-27 Rüdiger Sonderfeld +// test the hexadecimal floating point inserters (facet num_put) + +// Copyright (C) 2014 Free Software Foundation, Inc. +// +// This file is part of the GNU ISO C++ Library. This library is free +// software; you can redistribute it and/or modify it under the +// terms of the GNU General Public License as published by the +// Free Software Foundation; either version 3, or (at your option) +// any later version. + +// This library is distributed in the hope that it will be useful, +// but WITHOUT ANY WARRANTY; without even the implied warranty of +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +// GNU General Public License for more details. + +// You should have received a copy of the GNU General Public License along +// with this library; see the file COPYING3. If not see +// <http://www.gnu.org/licenses/>. + +#include <iostream> +#include <iomanip> +#include <sstream> +#include <limits> +#include <testsuite_hooks.h> + +using namespace std; + +#ifndef _GLIBCXX_ASSERT +# define TEST_NUMPUT_VERBOSE 1 +#endif + +void +test01() +{ + { + ostringstream os; + double d = 272.; // 0x1.1p+8; + cout << os.precision() << endl; + os << hexfloat << setprecision(1); + os << d; +#ifdef TEST_NUMPUT_VERBOSE + cout << "got: " << os.str() << endl; +#endif + VERIFY( os && os.str() == "0x1.1p+8" ); + os.str(""); + os << uppercase << d; +#ifdef TEST_NUMPUT_VERBOSE + cout << "got: " << os.str() << endl; +#endif + VERIFY( os && os.str() == "0X1.1P+8" ); + os << nouppercase; + os.str(""); + os << defaultfloat << setprecision(6); + os << d; +#ifdef TEST_NUMPUT_VERBOSE + cout << "got: " << os.str() << endl; +#endif + VERIFY( os && os.str() == "272" ); + + os.str(""); + d = 15.; //0x1.ep+3; + os << hexfloat << setprecision(1); + os << d; +#ifdef TEST_NUMPUT_VERBOSE + cout << "got: " << os.str() << endl; +#endif + VERIFY( os && os.str() == "0x1.ep+3" ); + os.str(""); + os << uppercase << d; +#ifdef TEST_NUMPUT_VERBOSE + cout << "got: " << os.str() << endl; +#endif + VERIFY( os && os.str() == "0X1.EP+3" ); + os << nouppercase; + os.str(""); + os << defaultfloat << setprecision(6); + os << d; +#ifdef TEST_NUMPUT_VERBOSE + cout << "got: " << os.str() << endl; +#endif + VERIFY( os && os.str() == "15" ); + } + + { + ostringstream os; + long double d = 272.L; // 0x1.1p+8L; + os << hexfloat << setprecision(1); + os << d; +#ifdef TEST_NUMPUT_VERBOSE + cout << "got: " << os.str() << endl; +#endif + VERIFY( os && os.str() == "0x8.8p+5" ); + os.str(""); + os << uppercase << d; +#ifdef TEST_NUMPUT_VERBOSE + cout << "got: " << os.str() << endl; +#endif + VERIFY( os && os.str() == "0X8.8P+5" ); + os << nouppercase; + os.str(""); + os << defaultfloat << setprecision(6); + os << d; +#ifdef TEST_NUMPUT_VERBOSE + cout << "got: " << os.str() << endl; +#endif + VERIFY( os && os.str() == "272" ); + + os.str(""); + os << hexfloat << setprecision(1); + d = 15.; //0x1.ep+3; + os << d; +#ifdef TEST_NUMPUT_VERBOSE + cout << "got: " << os.str() << endl; +#endif + VERIFY( os && os.str() == "0xf.0p+0" ); + os.str(""); + os << uppercase << d; +#ifdef TEST_NUMPUT_VERBOSE + cout << "got: " << os.str() << endl; +#endif + VERIFY( os && os.str() == "0XF.0P+0" ); + os << nouppercase; + os.str(""); + os << defaultfloat << setprecision(6); + os << d; +#ifdef TEST_NUMPUT_VERBOSE + cout << "got: " << os.str() << endl; +#endif + VERIFY( os && os.str() == "15" ); + } +} + +int +main() +{ + test01(); + return 0; +}