id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
5350	Patch for lexical_cast: additional optimizations	Antony Polukhin <antoshkka@…>	Antony Polukhin	"Patch to Boost Lexical Cast library, that returns Target directly constructed from Source in cases, when:[[BR]]
1) Source and Target are arithmetics (and not char or wchar_t), and all values of Source are in range of Target[[BR]]
2) Source and Target are both char or both wchar_t[[BR]]
3) Source is array of CharT and Target is std::basic_string<CharT, ...>[[BR]]
4) Source and Target are std::basic_string with same template parameters[[BR]]

It gives performance boost more than 10 times in case 1), about 7 times in case 2), and about 1.5 times in cases 3) and 4).

Existing tests for Boost Lexical Cast library cover considered cases.
Patch was successfully tested on Intel 11.1.072, g++-4.4.5, VC++9 compilers. 

It has the same behaviour, when casting out of bounds (int -> unsigned int, int -> short, unsigned int -> int). For checking bounds it uses boost::numeric::conversion_traits from <boost/numeric/conversion/conversion_traits.hpp>

Closes the ticket #4397[[BR]]

Was discussed at [http://lists.boost.org/Archives/boost/2011/03/178882.php Boost mailing list]"	Patches	closed	Boost 1.47.0	lexical_cast	Boost Development Trunk	Optimization	fixed		antoshkka@…