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Optimization for many combinations of types

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[SVN r34950]
This commit is contained in:
Alexander Nasonov
2006-08-25 20:34:57 +00:00
parent c17002aa73
commit 2fca4d02a1
1 changed files with 631 additions and 15 deletions
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646
include/boost/lexical_cast.hpp
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@@ -11,17 +11,22 @@
// enhanced with contributions from Terje Slettebo,
// with additional fixes and suggestions from Gennaro Prota,
// Beman Dawes, Dave Abrahams, Daryle Walker, Peter Dimov,
// and other Boosters
// when: November 2000, March 2003, June 2005
// Alexander Nasonov and other Boosters
// when: November 2000, March 2003, June 2005, June 2006
#include <climits>
#include <cstddef>
#include <istream>
#include <locale>
#include <string>
#include <typeinfo>
#include <boost/config.hpp>
#include <boost/limits.hpp>
#include <boost/mpl/if.hpp>
#include <boost/throw_exception.hpp>
#include <boost/type_traits/is_pointer.hpp>
#include <boost/call_traits.hpp>
#include <boost/static_assert.hpp>
#ifdef BOOST_NO_STRINGSTREAM
#include <strstream>
@@ -80,8 +85,8 @@ namespace boost
typedef char type;
};
#ifndef DISABLE_WIDE_CHAR_SUPPORT
#if !defined(BOOST_NO_INTRINSIC_WCHAR_T)
#ifndef DISABLE_WIDE_CHAR_SUPPORT
#ifndef BOOST_NO_INTRINSIC_WCHAR_T
template<>
struct stream_char<wchar_t>
{
@@ -106,7 +111,7 @@ namespace boost
{
typedef wchar_t type;
};
#endif
#endif
template<typename TargetChar, typename SourceChar>
struct widest_char
@@ -120,7 +125,325 @@ namespace boost
typedef wchar_t type;
};
}
namespace detail // lcast_src_length
{
// Return max. length of string representation of Source;
// 0 if unlimited (with exceptions for some types, see below).
// Values with limited string representation are placed to
// the buffer locally defined in lexical_cast function.
// 1 is returned for few types such as CharT const* or
// std::basic_string<CharT> that already have an internal
// buffer ready to be reused by lexical_stream_limited_src.
// Each specialization should have a correspondent operator<<
// defined in lexical_stream_limited_src.
template< class CharT // A result of widest_char transformation.
, class Source // Source type of lexical_cast.
>
struct lcast_src_length
{
BOOST_STATIC_CONSTANT(std::size_t, value = 0);
// To check coverage, build the test with
// bjam --v2 profile optimization=off
static void check_coverage() {}
};
template<>
struct lcast_src_length<char, bool>
{
BOOST_STATIC_CONSTANT(std::size_t, value = 1);
static void check_coverage() {}
};
template<>
struct lcast_src_length<char, char>
{
BOOST_STATIC_CONSTANT(std::size_t, value = 1);
static void check_coverage() {}
};
// No specializations for:
// lcast_src_length<char, signed char>
// lcast_src_length<char, unsigned char>
// lcast_src_length<char, signed char*>
// lcast_src_length<char, unsigned char*>
// lcast_src_length<char, signed char const*>
// lcast_src_length<char, unsigned char const*>
#ifndef DISABLE_WIDE_CHAR_SUPPORT
template<>
struct lcast_src_length<wchar_t, bool>
{
BOOST_STATIC_CONSTANT(std::size_t, value = 1);
static void check_coverage() {}
};
template<>
struct lcast_src_length<wchar_t, char>
{
BOOST_STATIC_CONSTANT(std::size_t, value = 1);
static void check_coverage() {}
};
#ifndef BOOST_NO_INTRINSIC_WCHAR_T
template<>
struct lcast_src_length<wchar_t, wchar_t>
{
BOOST_STATIC_CONSTANT(std::size_t, value = 1);
static void check_coverage() {}
};
#endif
#endif
template<>
struct lcast_src_length<char, char const*>
{
BOOST_STATIC_CONSTANT(std::size_t, value = 1);
static void check_coverage() {}
};
template<>
struct lcast_src_length<char, char*>
{
BOOST_STATIC_CONSTANT(std::size_t, value = 1);
static void check_coverage() {}
};
#ifndef DISABLE_WIDE_CHAR_SUPPORT
template<>
struct lcast_src_length<wchar_t, wchar_t const*>
{
BOOST_STATIC_CONSTANT(std::size_t, value = 1);
static void check_coverage() {}
};
template<>
struct lcast_src_length<wchar_t, wchar_t*>
{
BOOST_STATIC_CONSTANT(std::size_t, value = 1);
static void check_coverage() {}
};
#endif
#ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
template<class CharT, class Traits, class Alloc>
struct lcast_src_length< CharT, std::basic_string<CharT,Traits,Alloc> >
{
BOOST_STATIC_CONSTANT(std::size_t, value = 1);
static void check_coverage() {}
};
#else
template<>
struct lcast_src_length< char, std::basic_string<char> >
{
BOOST_STATIC_CONSTANT(std::size_t, value = 1);
static void check_coverage() {}
};
#ifndef DISABLE_WIDE_CHAR_SUPPORT
template<>
struct lcast_src_length< wchar_t, std::basic_string<wchar_t> >
{
BOOST_STATIC_CONSTANT(std::size_t, value = 1);
static void check_coverage() {}
};
#endif
#endif
// Helper for integral types.
// Notes on length calculation:
// Max length for 32bit int with grouping "\1" and thousands_sep ',':
// "-2,1,4,7,4,8,3,6,4,7"
// ^ - is_signed
// ^ - 1 digit not counted by digits10
// ^^^^^^^^^^^^^^^^^^ - digits10 * 2
//
// Constant is_specialized is used instead of constant 1
// to prevent buffer overflow in a rare case when
// <boost/limits.hpp> doesn't add missing specialization for
// numeric_limits<T> for some integral type T.
// When is_specialized is false, the whole expression is 0.
template<class Source>
struct lcast_src_length_integral
{
#if !defined(__BORLANDC__) || __BORLANDC__ >= 0x581
BOOST_STATIC_CONSTANT(std::size_t, value =
std::numeric_limits<Source>::is_signed +
std::numeric_limits<Source>::is_specialized + // == 1
std::numeric_limits<Source>::digits10 * 2
);
#else
BOOST_STATIC_CONSTANT(std::size_t, value = 156); // 256bit integers
#endif
};
#define BOOST_AUX_LEXICAL_CAST_DEF1(CharT, T) template<> \
struct lcast_src_length<CharT, T> : lcast_src_length_integral<T> \
{ static void check_coverage() {} };
#ifdef DISABLE_WIDE_CHAR_SUPPORT
#define BOOST_AUX_LEXICAL_CAST_DEF(T) BOOST_AUX_LEXICAL_CAST_DEF1(char, T)
#else
#define BOOST_AUX_LEXICAL_CAST_DEF(T) \
BOOST_AUX_LEXICAL_CAST_DEF1(char, T) \
BOOST_AUX_LEXICAL_CAST_DEF1(wchar_t, T)
#endif
BOOST_AUX_LEXICAL_CAST_DEF(short)
BOOST_AUX_LEXICAL_CAST_DEF(unsigned short)
BOOST_AUX_LEXICAL_CAST_DEF(int)
BOOST_AUX_LEXICAL_CAST_DEF(unsigned int)
BOOST_AUX_LEXICAL_CAST_DEF(long)
BOOST_AUX_LEXICAL_CAST_DEF(unsigned long)
#if defined(BOOST_HAS_LONG_LONG)
BOOST_AUX_LEXICAL_CAST_DEF(boost::ulong_long_type)
BOOST_AUX_LEXICAL_CAST_DEF(boost::long_long_type )
#elif defined(BOOST_HAS_MS_INT64)
BOOST_AUX_LEXICAL_CAST_DEF(unsigned __int64)
BOOST_AUX_LEXICAL_CAST_DEF( __int64)
#endif
#undef BOOST_AUX_LEXICAL_CAST_DEF
#undef BOOST_AUX_LEXICAL_CAST_DEF1
}
namespace detail // '0' and '-' constants
{
template<typename CharT> struct lcast_char_constants;
template<>
struct lcast_char_constants<char>
{
BOOST_STATIC_CONSTANT(char, zero = '0');
BOOST_STATIC_CONSTANT(char, minus = '-');
};
#ifndef DISABLE_WIDE_CHAR_SUPPORT
template<>
struct lcast_char_constants<wchar_t>
{
BOOST_STATIC_CONSTANT(wchar_t, zero = L'0');
BOOST_STATIC_CONSTANT(wchar_t, minus = L'-');
};
#endif
}
namespace detail // public access to basic_streambuf<CharT>::setg
{
template<typename CharT>
class lexical_streambuf : public std::basic_streambuf<CharT>
{
public:
void setbuf(CharT* start, CharT* finish)
{
this->setg(start, start, finish);
}
};
}
namespace detail // lcast_to_unsigned
{
#if (defined _MSC_VER)
# pragma warning( push )
// C4146: unary minus operator applied to unsigned type, result still unsigned
# pragma warning( disable : 4146 )
#endif
inline unsigned int lcast_to_unsigned(int value)
{
unsigned int uval = value;
return value < 0 ? -uval : uval;
}
inline unsigned long lcast_to_unsigned(long value)
{
unsigned long uval = value;
return value < 0 ? -uval : uval;
}
#if defined(BOOST_HAS_LONG_LONG)
inline boost::ulong_long_type lcast_to_unsigned(boost::long_long_type v)
{
boost::ulong_long_type uval = v;
return v < 0 ? -uval : uval;
}
#elif defined(BOOST_HAS_MS_INT64)
inline unsigned __int64 lcast_to_unsigned(__int64 value)
{
unsigned __int64 uval = value;
return value < 0 ? -uval : uval;
}
#endif
#if (defined _MSC_VER)
# pragma warning( pop ) // C4146: unary minus operator applied to unsigned type, result still unsigned
#endif
}
namespace detail // lcast_put_unsigned
{
// I'd personally put lcast_put_unsigned in .cpp file if not
// boost practice for header-only libraries (Alexander Nasonov).
template<typename T, typename CharT>
CharT* lcast_put_unsigned(T n, CharT* finish)
{
typedef std::numpunct<CharT> numpunct;
CharT thousands_sep = 0;
#if !defined(MEASURE_LEXICAL_CAST_PERFORMANCE_WITHOUT_LOCALE_OVERHEAD)
std::locale loc;
numpunct const& np = BOOST_USE_FACET(numpunct, loc);
std::string const& grouping = np.grouping();
std::string::size_type const grouping_size = grouping.size();
if(grouping_size)
thousands_sep = np.thousands_sep();
#else // dead branch in production code
char const* grouping = "";
std::size_t grouping_size = 0;
#endif
std::string::size_type group = 0; // current group number
char last_grp_size = grouping[0] <= 0 ? CHAR_MAX : grouping[0];
// a) Since grouping is const, grouping[grouping.size()] returns 0.
// b) It's safe to assume here and below that CHAR_MAX
// is equivalent to unlimited grouping:
#if !defined(__BORLANDC__) || __BORLANDC__ >= 0x581
BOOST_STATIC_ASSERT(std::numeric_limits<T>::digits10 < CHAR_MAX);
#endif
char left = last_grp_size;
do
{
if(left == 0)
{
++group;
if(group < grouping_size)
{
char const grp_size = grouping[group];
last_grp_size = grp_size <= 0 ? CHAR_MAX : grp_size;
}
left = last_grp_size;
--finish;
*finish = thousands_sep;
}
--left;
--finish;
int const digit = n % 10;
int const cdigit = digit + lcast_char_constants<CharT>::zero;
*finish = static_cast<char>(cdigit);
n /= 10;
} while(n);
return finish;
}
}
namespace detail // stream wrapper for handling lexical conversions
{
template<typename Target, typename Source>
@@ -132,7 +455,7 @@ namespace boost
typename stream_char<Source>::type>::type char_type;
public:
lexical_stream()
lexical_stream(char_type* = 0, char_type* = 0)
{
stream.unsetf(std::ios::skipws);
@@ -186,13 +509,13 @@ namespace boost
#if defined(BOOST_NO_STRINGSTREAM)
stream << '\0';
#endif
output = stream.str();
stream.str().swap(output);
return true;
}
#ifndef DISABLE_WIDE_CHAR_SUPPORT
bool operator>>(std::wstring &output)
{
output = stream.str();
stream.str().swap(output);
return true;
}
#endif
@@ -207,6 +530,281 @@ namespace boost
};
}
namespace detail // optimized stream wrapper
{
// String representation of Source has an upper limit.
template<typename CharT>
class lexical_stream_limited_src
{
// A string representation of Source is written to [start, finish).
// Currently, it is assumed that [start, finish) is big enough
// to hold a string representation of any Source value.
CharT* start;
CharT* finish;
private:
static void widen_and_assign(char*p, char ch)
{
*p = ch;
}
#ifndef DISABLE_WIDE_CHAR_SUPPORT
static void widen_and_assign(wchar_t* p, char ch)
{
std::locale loc;
*p = BOOST_USE_FACET(std::ctype<wchar_t>, loc).widen(ch);
}
static void widen_and_assign(wchar_t* p, wchar_t ch)
{
*p = ch;
}
static void widen_and_assign(char*, wchar_t ch); // undefined
#endif
// Undefined:
lexical_stream_limited_src(lexical_stream_limited_src const&);
void operator=(lexical_stream_limited_src const&);
public:
lexical_stream_limited_src(CharT* start, CharT* finish)
: start(start)
, finish(finish)
{}
public: // output
template<class Traits, class Alloc>
bool operator<<(std::basic_string<CharT, Traits, Alloc> const& str)
{
start = const_cast<CharT*>(str.data());
finish = start + str.length();
return true;
}
bool operator<<(bool);
bool operator<<(char);
#if !defined(DISABLE_WIDE_CHAR_SUPPORT) && !defined(BOOST_NO_INTRINSIC_WCHAR_T)
bool operator<<(wchar_t);
#endif
bool operator<<(CharT const*);
bool operator<<(short);
bool operator<<(int);
bool operator<<(long);
bool operator<<(unsigned short);
bool operator<<(unsigned int);
bool operator<<(unsigned long);
#if defined(BOOST_HAS_LONG_LONG)
bool operator<<(boost::ulong_long_type);
bool operator<<(boost::long_long_type );
#elif defined(BOOST_HAS_MS_INT64)
bool operator<<(unsigned __int64);
bool operator<<( __int64);
#endif
public: // input
template<typename InputStreamable>
bool operator>>(InputStreamable& output)
{
#if (defined _MSC_VER)
# pragma warning( push )
// conditional expression is constant
# pragma warning( disable : 4127 )
#endif
if(is_pointer<InputStreamable>::value)
return false;
lexical_streambuf<CharT> sb;
sb.setbuf(start, finish);
std::basic_istream<CharT> stream(&sb);
stream.unsetf(std::ios::skipws);
typedef std::numeric_limits<InputStreamable> limits;
if(limits::is_specialized)
stream.precision(limits::digits10 + 1);
#if (defined _MSC_VER)
# pragma warning( pop )
#endif
return stream >> output &&
stream.get() ==
#if defined(__GNUC__) && (__GNUC__<3) && defined(BOOST_NO_STD_WSTRING)
// GCC 2.9x lacks std::char_traits<>::eof().
// We use BOOST_NO_STD_WSTRING to filter out STLport and libstdc++-v3
// configurations, which do provide std::char_traits<>::eof().
EOF;
#else
std::char_traits<CharT>::eof();
#endif
}
bool operator>>(CharT&);
bool operator>>(std::string&);
#ifndef DISABLE_WIDE_CHAR_SUPPORT
bool operator>>(std::wstring&);
#endif
};
template<typename CharT>
inline bool lexical_stream_limited_src<CharT>::operator<<(bool value)
{
*start = value + lcast_char_constants<CharT>::zero;
finish = start + 1;
return true;
}
template<typename CharT>
inline bool lexical_stream_limited_src<CharT>::operator<<(char ch)
{
widen_and_assign(start, ch);
finish = start + 1;
return true;
}
#if !defined(DISABLE_WIDE_CHAR_SUPPORT) && !defined(BOOST_NO_INTRINSIC_WCHAR_T)
template<typename CharT>
inline bool lexical_stream_limited_src<CharT>::operator<<(wchar_t ch)
{
widen_and_assign(start, ch);
finish = start + 1;
return true;
}
#endif
template<typename CharT>
inline bool lexical_stream_limited_src<CharT>::operator<<(short n)
{
start = lcast_put_unsigned(lcast_to_unsigned(n), finish);
if(n < 0)
*--start = lcast_char_constants<CharT>::minus;
return true;
}
template<typename CharT>
inline bool lexical_stream_limited_src<CharT>::operator<<(int n)
{
start = lcast_put_unsigned(lcast_to_unsigned(n), finish);
if(n < 0)
*--start = lcast_char_constants<CharT>::minus;
return true;
}
template<typename CharT>
inline bool lexical_stream_limited_src<CharT>::operator<<(long n)
{
start = lcast_put_unsigned(lcast_to_unsigned(n), finish);
if(n < 0)
*--start = lcast_char_constants<CharT>::minus;
return true;
}
#if defined(BOOST_HAS_LONG_LONG)
template<typename CharT>
inline bool lexical_stream_limited_src<CharT>::operator<<(
boost::long_long_type n)
{
start = lcast_put_unsigned(lcast_to_unsigned(n), finish);
if(n < 0)
*--start = lcast_char_constants<CharT>::minus;
return true;
}
#elif defined(BOOST_HAS_MS_INT64)
template<typename CharT>
inline bool lexical_stream_limited_src<CharT>::operator<<(__int64 n)
{
start = lcast_put_unsigned(lcast_to_unsigned(n), finish);
if(n < 0)
*--start = lcast_char_constants<CharT>::minus;
return true;
}
#endif
template<typename CharT>
inline bool lexical_stream_limited_src<CharT>::operator<<(
unsigned short n)
{
start = lcast_put_unsigned(+n, finish);
return true;
}
template<typename CharT>
inline bool lexical_stream_limited_src<CharT>::operator<<(
unsigned int n)
{
start = lcast_put_unsigned(n, finish);
return true;
}
template<typename CharT>
inline bool lexical_stream_limited_src<CharT>::operator<<(
unsigned long n)
{
start = lcast_put_unsigned(n, finish);
return true;
}
#if defined(BOOST_HAS_LONG_LONG)
template<typename CharT>
inline bool lexical_stream_limited_src<CharT>::operator<<(
boost::ulong_long_type n)
{
start = lcast_put_unsigned(n, finish);
return true;
}
#elif defined(BOOST_HAS_MS_INT64)
template<typename CharT>
inline bool lexical_stream_limited_src<CharT>::operator<<(
unsigned __int64 n)
{
start = lcast_put_unsigned(n, finish);
return true;
}
#endif
template<typename CharT>
inline bool lexical_stream_limited_src<CharT>::operator<<(
CharT const* str)
{
start = const_cast<CharT*>(str);
finish = start + std::char_traits<CharT>::length(str);
return true;
}
template<typename CharT>
inline bool lexical_stream_limited_src<CharT>::operator>>(CharT& output)
{
bool const ok = (finish - start == 1);
if(ok)
output = *start;
return ok;
}
template<typename CharT>
inline bool lexical_stream_limited_src<CharT>::operator>>(
std::string& str)
{
str.assign(start, finish);
return true;
}
#ifndef DISABLE_WIDE_CHAR_SUPPORT
template<typename CharT>
inline bool lexical_stream_limited_src<CharT>::operator>>(
std::wstring& str)
{
str.assign(start, finish);
return true;
}
#endif
}
#ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
// call-by-const reference version
@@ -225,12 +823,20 @@ namespace boost
typedef const T * type;
};
template<typename Target, typename Source>
template< typename Target
, typename Source
, bool Unlimited // string representation of Source is unlimited
, typename CharT
>
Target lexical_cast(
BOOST_DEDUCED_TYPENAME boost::call_traits<Source>::value_type arg)
BOOST_DEDUCED_TYPENAME boost::call_traits<Source>::value_type arg,
CharT* buf, std::size_t src_len)
{
detail::lexical_stream<Target, Source> interpreter;
BOOST_DEDUCED_TYPENAME mpl::if_c<
Unlimited
, detail::lexical_stream<Target, Source>
, detail::lexical_stream_limited_src<CharT>
>::type interpreter(buf, buf + src_len);
// The original form, reproduced below, is more elegant
// but yields a spurious C4701 warning ("possible use of
@@ -255,8 +861,18 @@ namespace boost
template<typename Target, typename Source>
inline Target lexical_cast(const Source &arg)
{
typedef typename detail::array_to_pointer_decay<Source>::type NewSource;
return detail::lexical_cast<Target, NewSource>(arg);
typedef typename detail::array_to_pointer_decay<Source>::type src;
typedef typename detail::widest_char<
typename detail::stream_char<Target>::type
, typename detail::stream_char<src>::type
>::type char_type;
typedef detail::lcast_src_length<char_type, src> lcast_src_length;
std::size_t const src_len = lcast_src_length::value;
char_type buf[src_len + 1];
lcast_src_length::check_coverage();
return detail::lexical_cast<Target, src, !src_len>(arg, buf, src_len);
}
#else