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/**
* @file stringize.h
* @author Nat Goodspeed
* @date 2008-12-17
* @brief stringize(item) template function and STRINGIZE(expression) macro
*
* $LicenseInfo:firstyear=2008&license=viewerlgpl$
* Second Life Viewer Source Code
* Copyright (C) 2010, Linden Research, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation;
* version 2.1 of the License only.
*
* 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* Linden Research, Inc., 945 Battery Street, San Francisco, CA 94111 USA
* $/LicenseInfo$
*/
#if ! defined(LL_STRINGIZE_H)
#define LL_STRINGIZE_H
#include <sstream>
#include "llstring.h"
#include <boost/call_traits.hpp>
/**
* stream_to(std::ostream&, items, ...) streams each item in the parameter list
* to the passed std::ostream using the insertion operator <<. This can be
* used, for instance, to make a simple print() function, e.g.:
*
* @code
* template <typename... Items>
* void print(Items&&... items)
* {
* stream_to(std::cout, std::forward<Items>(items)...);
* }
* @endcode
*/
// recursion tail
template <typename CHARTYPE>
void stream_to(std::basic_ostream<CHARTYPE>& out) {}
// stream one or more items
template <typename CHARTYPE, typename T, typename... Items>
void stream_to(std::basic_ostream<CHARTYPE>& out, T&& item, Items&&... items)
{
out << std::forward<T>(item);
stream_to(out, std::forward<Items>(items)...);
}
// why we use function overloads, not function template specializations:
// http://www.gotw.ca/publications/mill17.htm
/**
* gstringize(item, ...) encapsulates an idiom we use constantly, using
* operator<<(std::ostringstream&, TYPE) followed by std::ostringstream::str()
* or their wstring equivalents to render a string expressing one or more items.
*/
// two or more args - the case of a single argument is handled separately
template <typename CHARTYPE, typename T0, typename T1, typename... Items>
auto gstringize(T0&& item0, T1&& item1, Items&&... items)
{
std::basic_ostringstream<CHARTYPE> out;
stream_to(out, std::forward<T0>(item0), std::forward<T1>(item1),
std::forward<Items>(items)...);
return out.str();
}
// generic single argument: stream to out, as above
template <typename CHARTYPE, typename T>
struct gstringize_impl
{
auto operator()(typename boost::call_traits<T>::param_type arg)
{
std::basic_ostringstream<CHARTYPE> out;
out << arg;
return out.str();
}
};
// partially specialize for a single STRING argument -
// note that ll_convert<T>(T) already handles the trivial case
template <typename OUTCHAR, typename INCHAR>
struct gstringize_impl<OUTCHAR, std::basic_string<INCHAR>>
{
auto operator()(const std::basic_string<INCHAR>& arg)
{
return ll_convert<std::basic_string<OUTCHAR>>(arg);
}
};
// partially specialize for a single CHARTYPE* argument -
// since it's not a basic_string and we do want to optimize this common case
template <typename OUTCHAR, typename INCHAR>
struct gstringize_impl<OUTCHAR, INCHAR*>
{
auto operator()(const INCHAR* arg)
{
return ll_convert<std::basic_string<OUTCHAR>>(arg);
}
};
// gstringize(single argument)
template <typename CHARTYPE, typename T>
auto gstringize(T&& item)
{
// use decay<T> so we don't require separate specializations
// for T, const T, T&, const T& ...
return gstringize_impl<CHARTYPE, std::decay_t<T>>()(std::forward<T>(item));
}
/**
* Specialization of gstringize for std::string return types
*/
template <typename... Items>
auto stringize(Items&&... items)
{
return gstringize<char>(std::forward<Items>(items)...);
}
/**
* Specialization of gstringize for std::wstring return types
*/
template <typename... Items>
auto wstringize(Items&&... items)
{
return gstringize<wchar_t>(std::forward<Items>(items)...);
}
/**
* stringize_f(functor)
*/
template <typename CHARTYPE, typename Functor>
std::basic_string<CHARTYPE> stringize_f(Functor const & f)
{
std::basic_ostringstream<CHARTYPE> out;
f(out);
return out.str();
}
/**
* STRINGIZE(item1 << item2 << item3 ...) effectively expands to the
* following:
* @code
* std::ostringstream out;
* out << item1 << item2 << item3 ... ;
* return out.str();
* @endcode
*/
#define STRINGIZE(EXPRESSION) (stringize_f<char>([&](std::ostream& out){ out << EXPRESSION; }))
/**
* WSTRINGIZE() is the wstring equivalent of STRINGIZE()
*/
#define WSTRINGIZE(EXPRESSION) (stringize_f<wchar_t>([&](std::wostream& out){ out << EXPRESSION; }))
/**
* destringize(str)
* defined for symmetry with stringize
* @NOTE - this has distinct behavior from boost::lexical_cast<T> regarding
* leading/trailing whitespace and handling of bad_lexical_cast exceptions
* @NOTE - no need for dewstringize(), since passing std::wstring will Do The
* Right Thing
*/
template <typename T, typename CHARTYPE>
T destringize(std::basic_string<CHARTYPE> const & str)
{
T val;
std::basic_istringstream<CHARTYPE> in(str);
in >> val;
return val;
}
/**
* destringize_f(str, functor)
*/
template <typename CHARTYPE, typename Functor>
void destringize_f(std::basic_string<CHARTYPE> const & str, Functor const & f)
{
std::basic_istringstream<CHARTYPE> in(str);
f(in);
}
/**
* DESTRINGIZE(str, item1 >> item2 >> item3 ...) effectively expands to the
* following:
* @code
* std::istringstream in(str);
* in >> item1 >> item2 >> item3 ... ;
* @endcode
*/
#define DESTRINGIZE(STR, EXPRESSION) (destringize_f((STR), [&](auto& in){in >> EXPRESSION;}))
// legacy name, just use DESTRINGIZE() going forward
#define DEWSTRINGIZE(STR, EXPRESSION) DESTRINGIZE(STR, EXPRESSION)
#endif /* ! defined(LL_STRINGIZE_H) */
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