truncation_test.hpp

新版本TR1的stl

/* /////////////////////////////////////////////////////////////////////////
 * File:        stlsoft/conversion/truncation_test.hpp
 *
 * Purpose:     Runtime checking for numeric conversions.
 *
 * Created:     10th August 2006
 * Updated:     24th January 2007
 *
 * Home:        http://stlsoft.org/
 *
 * Copyright (c) 2006-2007, Matthew Wilson and Synesis Software
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * - Redistributions of source code must retain the above copyright notice, this
 *   list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright notice,
 *   this list of conditions and the following disclaimer in the documentation
 *   and/or other materials provided with the distribution.
 * - Neither the name(s) of Matthew Wilson and Synesis Software nor the names of
 *   any contributors may be used to endorse or promote products derived from
 *   this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 * ////////////////////////////////////////////////////////////////////// */


/** \file stlsoft/conversion/truncation_test.hpp
 *
 * \brief [C++ only] Definition of the stlsoft::truncation_test functions
 *   (\ref group__library__conversion "Conversion" Library).
 */

#ifndef STLSOFT_INCL_STLSOFT_CONVERSION_HPP_TRUNCATION_TEST
#define STLSOFT_INCL_STLSOFT_CONVERSION_HPP_TRUNCATION_TEST

#ifndef STLSOFT_DOCUMENTATION_SKIP_SECTION
# define STLSOFT_VER_STLSOFT_CONVERSION_HPP_TRUNCATION_TEST_MAJOR      1
# define STLSOFT_VER_STLSOFT_CONVERSION_HPP_TRUNCATION_TEST_MINOR      0
# define STLSOFT_VER_STLSOFT_CONVERSION_HPP_TRUNCATION_TEST_REVISION   3
# define STLSOFT_VER_STLSOFT_CONVERSION_HPP_TRUNCATION_TEST_EDIT       41
#endif /* !STLSOFT_DOCUMENTATION_SKIP_SECTION */

/* /////////////////////////////////////////////////////////////////////////
 * Auto-generation and compatibility
 */

/*
*/

/* /////////////////////////////////////////////////////////////////////////
 * Includes
 */

#ifndef STLSOFT_INCL_STLSOFT_H_STLSOFT
# include <stlsoft/stlsoft.h>
#endif /* !STLSOFT_INCL_STLSOFT_H_STLSOFT */

#ifndef STLSOFT_INCL_STLSOFT_UTIL_H_LIMIT_TRAITS
# include <stlsoft/util/limit_traits.h>
#endif /* !STLSOFT_INCL_STLSOFT_UTIL_H_LIMIT_TRAITS */
#ifndef STLSOFT_INCL_STLSOFT_UTIL_HPP_SIGN_TRAITS
# include <stlsoft/util/sign_traits.hpp>
#endif /* !STLSOFT_INCL_STLSOFT_UTIL_HPP_SIGN_TRAITS */

#ifndef STLSOFT_INCL_STLSOFT_META_HPP_IS_INTEGRAL_TYPE
# include <stlsoft/meta/is_integral_type.hpp>
#endif /* !STLSOFT_INCL_STLSOFT_META_HPP_IS_INTEGRAL_TYPE */
#ifndef STLSOFT_INCL_STLSOFT_META_HPP_IS_SIGNED_TYPE
# include <stlsoft/meta/is_signed_type.hpp>
#endif /* !STLSOFT_INCL_STLSOFT_META_HPP_IS_SIGNED_TYPE */

#ifdef STLSOFT_UNITTEST
# include <limits.h>
#endif /* STLSOFT_UNITTEST */
#if defined(STLSOFT_UNITTEST) || \
    defined(_DEBUG)
# include <typeinfo>
#endif /* STLSOFT_UNITTEST || _DEBUG */

/* /////////////////////////////////////////////////////////////////////////
 * Namespace
 */

#ifndef _STLSOFT_NO_NAMESPACE
namespace stlsoft
{
#endif /* _STLSOFT_NO_NAMESPACE */

/* /////////////////////////////////////////////////////////////////////////
 * Functions
 *
 *
 * Assume 11 types:
 *     char, signed char, unsigned char
 *     short, unsigned short
 *     int, unsigned int
 *     long, unsigned long
 *     long long, unsigned long long
 *
 * That gives 121 permutations:
 *     (a) 11 where the type is the same
 *     (b) 20 where the sign is the same and sizeof(FROM) <= sizeof(TO); superset of (a)
 *     (c) 10 where FROM is unsigned and sizeof(FROM) < sizeof(TO)
 *     (d) 80 that must be determined dynamically
 *
 *
 * The strategy is as follows:
 *

if( signof(FROM) == signof(TO) &&       // Compile-time test 1
    sizeof(FROM) <= sizeof(TO))
{
    return true;
}
else if(unsigned == signof(FROM) &&     // Compile-time test 2
        sizeof(FROM) < sizeof(TO))
{
    return true;
}
else
{
    return runtime_test<TO>(from);
}

 *
 * The runtime test evaluates to the following:
 *
 *  If the FROM type is signed, then

 */

#ifndef STLSOFT_DOCUMENTATION_SKIP_SECTION

    // The permutations are:
    //
    // 1a FROM signed | TO signed | sizeof(FROM) < sizeof(TO)       =>  Always yes
    // 1b FROM signed | TO signed | sizeof(FROM) = sizeof(TO)       =>  Always yes
    // 1c FROM signed | TO signed | sizeof(FROM) > sizeof(TO)       =>  Runtime test
    //
    // 2a FROM unsigned | TO signed | sizeof(FROM) < sizeof(TO)     =>  Runtime test
    // 2b FROM unsigned | TO signed | sizeof(FROM) = sizeof(TO)     =>  Runtime test
    // 2c FROM unsigned | TO signed | sizeof(FROM) > sizeof(TO)     =>  Runtime test
    //
    // 3a FROM signed | TO unsigned | sizeof(FROM) < sizeof(TO)     =>  Always yes
    // 3b FROM signed | TO unsigned | sizeof(FROM) = sizeof(TO)     =>  Runtime test
    // 3c FROM signed | TO unsigned | sizeof(FROM) > sizeof(TO)     =>  Runtime test
    //
    // 4a FROM unsigned | TO unsigned | sizeof(FROM) < sizeof(TO)   =>  Always yes
    // 4b FROM unsigned | TO unsigned | sizeof(FROM) = sizeof(TO)   =>  Always yes
    // 4c FROM unsigned | TO unsigned | sizeof(FROM) > sizeof(TO)   =>  Runtime test



template<   ss_typename_param_k TO
        ,   ss_typename_param_k FROM
        >
inline bool truncation_test_helper_runtime_test_different_sign_FROM_is_signed(FROM from, yes_type, TO)
{
#ifdef _DEBUG
    char const  *TO_    =   typeid(TO).name();
    char const  *FROM_  =   typeid(FROM).name();

    STLSOFT_SUPPRESS_UNUSED(TO_);
    STLSOFT_SUPPRESS_UNUSED(FROM_);
#endif /* _DEBUG */

    enum {  TO_is_signed            =   is_signed_type<TO>::value                   };
    enum {  FROM_is_signed          =   is_signed_type<FROM>::value                 };

    const ss_size_t sizeofFROM  =   sizeof(FROM);
    const ss_size_t sizeofTO    =   sizeof(TO);

    STLSOFT_SUPPRESS_UNUSED(sizeofFROM);
    STLSOFT_SUPPRESS_UNUSED(sizeofTO);

    STLSOFT_STATIC_ASSERT((0 == int(TO_is_signed)) != (0 == int(FROM_is_signed)));
    STLSOFT_STATIC_ASSERT(0 != int(FROM_is_signed));
    STLSOFT_STATIC_ASSERT(0 == int(TO_is_signed));

    // FROM is signed
    // TO is unsigned
    //
    // Truncation occurs if:
    //
    // - from < 0
    // - from > toMax
    // - from

    if(from < 0)
    {
        return false;
    }
    else if(sizeofFROM < sizeofTO)               // 3a
    {
        return true;
    }
    else
    {
        if(sizeofFROM == sizeofTO)
        {
            TO  toMax   =   limit_traits<TO>::maximum();

            if(toMax < static_cast<TO>(from))
            {
                return false;
            }
            else
            {
                return true;
            }
        }
        else                                        // 3b & 3c
        {
            FROM    toMax   =   static_cast<FROM>(limit_traits<TO>::maximum());

            if(from > toMax)
            {
                return false;
            }
            else
            {
                return true;
            }
        }
    }
}

template<   ss_typename_param_k TO
        ,   ss_typename_param_k FROM
        >
inline bool truncation_test_helper_runtime_test_different_sign_FROM_is_signed(FROM from, no_type, TO)
{
#ifdef _DEBUG
    char const  *TO_    =   typeid(TO).name();