gls_cpp_lang_support.h

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/*! \file
  \brief  Macros and helper code to determine what subset of C++11/14/17 is available.

  \par Copyright Information

  Copyright (c) 2016 The DiSTI Corporation.<br>
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  <br>
  All rights reserved.<br>

  This Software contains proprietary trade secrets of DiSTI and may not be
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  NO WARRANTY. THE SOFTWARE IS PROVIDED "AS-IS," WITHOUT WARRANTY OF ANY KIND,
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  The aforementioned terms and restrictions are governed by the laws of the
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*/

#ifndef INCLUDED_GLS_CPP_LANG_SUPPORT_H
#define INCLUDED_GLS_CPP_LANG_SUPPORT_H

// Conditional C++11 support
//
// We use a subset of C++11 features to improve efficiency and correctness of code.
//
// We attempt to detect compiler support, but for unusual configurations, it can be
// enabled with project-level defines. Define DISTI_HAS_CPP11 to enable all features.
// Enable specific features by defining any of the following:
//
//   DISTI_HAS_RVAL_REFS            // For rvalue references
//   DISTI_HAS_METHOD_OVERRIDE      // For "override" and "final" keywords
//   DISTI_HAS_SPECIAL_MEM_FUN_DEL  // For "= delete"
//   DISTI_HAS_TYPE_TRAITS          // For compile-time checking via type-traits
//   DISTI_HAS_STATIC_ASSERT        // For static_assert support
//
// If our detection is incorrect, override it with a corresponding "NO" define:
//
//   DISTI_NO_RVAL_REFS             // For rvalue references
//   DISTI_NO_METHOD_OVERRIDE       // For "override" and "final" keywords
//   DISTI_NO_METHOD_FINAL          // For "final" keyword
//   DISTI_NO_SPECIAL_MEM_FUN_DEL   // For "= delete"
//   DISTI_NO_TYPE_TRAITS           // For compile-time checking via type-traits
//   DISTI_NO_STATIC_ASSERT         // For static_assert support

/////////////////////////////////////////////////////////////////////////////////////
// Microsoft C++ Compiler -- https://msdn.microsoft.com/en-us/library/hh567368.aspx
/////////////////////////////////////////////////////////////////////////////////////
#if defined( _MSC_VER )
#    if _MSC_VER >= 1700 // >= VS2012
#        define DISTI_HAS_RVAL_REFS
#        define DISTI_HAS_METHOD_OVERRIDE
#        define DISTI_HAS_TYPE_TRAITS
#        define DISTI_HAS_STATIC_ASSERT
#    endif
#    if _MSC_VER >= 1800 // >= VS2013
#        define DISTI_HAS_SPECIAL_MEM_FUN_DEL
#    endif
////////////////////////////////////////////////////////////////////////////////
// GCC versions -- https://gcc.gnu.org/projects/cxx-status.html#cxx11
////////////////////////////////////////////////////////////////////////////////
#elif defined( __GNUC__ )
    // __cpp_rvalue_references doesn't seem to be defined in GCC, despite the documentation, so we have an alternative check also
#    if __cpp_rvalue_references >= 200610 || ( ( __GNUC__ > 4 || ( __GNUC__ == 4 && __GNUC_MINOR__ >= 3 ) ) && ( defined( __GXX_EXPERIMENTAL_CXX0X__ ) || __cplusplus >= 201103L ) )
#        define DISTI_HAS_RVAL_REFS
#    endif
#    if __cpp_static_assert >= 200410 && ( defined( __GXX_EXPERIMENTAL_CXX0X__ ) || __cplusplus >= 201103L )
#        define DISTI_HAS_STATIC_ASSERT
#    endif
#    if( __GNUC__ > 4 || ( __GNUC__ == 4 && __GNUC_MINOR__ >= 7 ) ) && ( defined( __GXX_EXPERIMENTAL_CXX0X__ ) || __cplusplus >= 201103L )
#        define DISTI_HAS_METHOD_OVERRIDE

        // This actually depends on which standard library is in use, but it's a safe bet.
#        define DISTI_HAS_TYPE_TRAITS
#    endif
#    if( __GNUC__ > 4 || ( __GNUC__ == 4 && __GNUC_MINOR__ >= 4 ) ) && ( defined( __GXX_EXPERIMENTAL_CXX0X__ ) || __cplusplus >= 201103L )
#        define DISTI_HAS_SPECIAL_MEM_FUN_DEL
#    endif
////////////////////////////////////////////////////////////////////////////////
// Clang versions -- http://clang.llvm.org/cxx_status.html
////////////////////////////////////////////////////////////////////////////////
#elif defined( __clang__ )
#    if __has_feature( cxx_rvalue_references )
#        define DISTI_HAS_RVAL_REFS
#    endif
#    if __has_feature( cxx_override_control )
#        define DISTI_HAS_METHOD_OVERRIDE
#    endif
#    if __has_feature( cxx_defaulted_functions ) && __has_feature( cxx_deleted_functions )
#        define DISTI_HAS_SPECIAL_MEM_FUN_DEL
#    endif
#    if __has_feature( cxx_static_assert )
#        define DISTI_HAS_STATIC_ASSERT
#    endif

    // This actually depends on which standard library is in use, but it's a safe bet.
#    define DISTI_HAS_TYPE_TRAITS
#endif

///////////////////////////////////////////////////////////////////////////////////////////////////
// Shortcut for unrecognized compilers
///////////////////////////////////////////////////////////////////////////////////////////////////
#ifdef DISTI_HAS_CPP11 // A single switch to enable everything since compiler is highly compliant
    // These macros can help with cross-platform portability
#    define DISTI_IF_HAS_CPP11( x ) x
#    define DISTI_IF_HAS_CPP11_ELSE( x, y ) x

#    define DISTI_HAS_RVAL_REFS
#    define DISTI_HAS_METHOD_OVERRIDE
#    define DISTI_HAS_SPECIAL_MEM_FUN_DEL
#    define DISTI_HAS_TYPE_TRAITS
#    define DISTI_HAS_STATIC_ASSERT
#else // Not fully C++11; some features may be enabled piecemeal
    // These macros can help with cross-platform portability
#    define DISTI_IF_HAS_CPP11( x )
#    define DISTI_IF_HAS_CPP11_ELSE( x, y ) y
#endif

///////////////////////////////////////////////////////////////////////////////////////////////////
// Individual C++11 features. See comment above on DISTI_NO_* vs. DISTI_HAS_* macros.
///////////////////////////////////////////////////////////////////////////////////////////////////
#if !defined( DISTI_NO_RVAL_REFS ) && defined( DISTI_HAS_RVAL_REFS )
#    include <utility>
#    define DISTI_RVAL_MOVE( x ) std::move( x )
#    define DISTI_IF_HAS_RVAL_REFS_ELSE( x, y ) x
#else
#    undef DISTI_HAS_RVAL_REFS
#    define DISTI_RVAL_MOVE( x ) ( x )
#    define DISTI_IF_HAS_RVAL_REFS_ELSE( x, y ) y
#endif

///////////////////////////////////////////////////////////////////////////////////////////////////
#if !defined( DISTI_NO_METHOD_OVERRIDE ) && defined( DISTI_HAS_METHOD_OVERRIDE )
    // Add this to the end of an overridden method
#    define DISTI_METHOD_OVERRIDE override
    // Add this to the end of a method that should not be overridden
#    define DISTI_METHOD_FINAL final
#else
#    undef DISTI_HAS_METHOD_OVERRIDE
#    define DISTI_METHOD_OVERRIDE
#    define DISTI_METHOD_FINAL
#endif

///////////////////////////////////////////////////////////////////////////////////////////////////
#if !defined( DISTI_NO_SPECIAL_MEM_FUN_DEL ) && defined( DISTI_HAS_SPECIAL_MEM_FUN_DEL )
    // Add these to the end of special member functions to delete them.
#    define DISTI_SPECIAL_MEM_FUN_DELETE = delete
#else
#    undef DISTI_HAS_SPECIAL_MEM_FUN_DEL
#    define DISTI_SPECIAL_MEM_FUN_DELETE
#endif

///////////////////////////////////////////////////////////////////////////////////////////////////
#if !defined( DISTI_NO_TYPE_TRAITS ) && defined( DISTI_HAS_TYPE_TRAITS )
    // Use this by including <type_traits> and then providing a default, e.g.,
    //   DISTI_IF_HAS_TYPE_TRAITS_ELSE( std::is_const<T>::value, false )
#    define DISTI_IF_HAS_TYPE_TRAITS_ELSE( x, y ) x
#else
#    undef DISTI_HAS_TYPE_TRAITS
#    define DISTI_IF_HAS_TYPE_TRAITS_ELSE( x, y ) y

namespace disti
{
// The _cppLangSupportDetail namespace is here to hide implementation details, mostly for things
// that are standard but not available on all supported platforms.
namespace _cppLangSupportDetail
{
    /// Replacement for std::is_convertible, adapted from Loki 0.1.7.
    /////////////////////////////////////////////////////////////////////////////////
    /// \copyright The Loki Library, Copyright (c) 2001 by Andrei Alexandrescu<br />
    /// This code accompanies the book:
    /// Alexandrescu, Andrei. "Modern C++ Design: Generic Programming and Design
    ///     Patterns Applied". Copyright (c) 2001. Addison-Wesley.<br />
    /// Permission to use, copy, modify, distribute and sell this software for any
    ///     purpose is hereby granted without fee, provided that the above copyright
    ///     notice appear in all copies and that both that copyright notice and this
    ///     permission notice appear in supporting documentation.<br />
    /// The author or Addison-Welsey Longman make no representations about the
    ///     suitability of this software for any purpose. It is provided "as is"
    ///     without express or implied warranty.<br />
    /////////////////////////////////////////////////////////////////////////////////
    template<class T, class U>
    struct is_convertible
    {
    private:
        typedef char Small;
        struct Big
        {
            char dummy[ 2 ];
        };
        static Big   Test( ... );
        static Small Test( U );
        static T     MakeT();

    public:
        enum
        {
            value = sizeof( Small ) == sizeof( ( Test( MakeT() ) ) )
        };
    };

    template<class T>
    struct is_convertible<T, T>
    {
        enum
        {
            value = true
        };
    }; //< Replacement for std::is_convertible, adapted from Loki 0.1.7.
    template<class T>
    struct is_convertible<void, T>
    {
        enum
        {
            value = false
        };
    }; //< Replacement for std::is_convertible, adapted from Loki 0.1.7.
    template<class T>
    struct is_convertible<T, void>
    {
        enum
        {
            value = false
        };
    }; //< Replacement for std::is_convertible, adapted from Loki 0.1.7.
    template<>
    struct is_convertible<void, void>
    {
        enum
        {
            value = true
        };
    }; //< Replacement for std::is_convertible, adapted from Loki 0.1.7.
} // namespace _cppLangSupportDetail
} // namespace disti
#endif

///////////////////////////////////////////////////////////////////////////////////////////////////
#if defined( DISTI_NO_STATIC_ASSERT )
#    undef DISTI_HAS_STATIC_ASSERT
#    define DISTI_STATIC_ASSERT( expr, msg )
#else
#    define DISTI_PREPROC_STRINGIFY_HELPER( s ) #    s
#    define DISTI_PREPROC_STRINGIFY( s ) DISTI_PREPROC_STRINGIFY_HELPER( s )

#    if defined( DISTI_HAS_STATIC_ASSERT )
  /// \brief Uses C++11's static_assert() because it is available on this platform.
  /// \param expr a compile-time integral or pointer expression
  /// \param msg  a C identifier that will appear in compiler diagnostics
  /// \note For older compilers' benefit, \a msg should be a C identifier such as:
  /// \code{.cpp}
  ///    DISTI_STATIC_ASSERT( (std::is_convertible<T*,ConvertsTo*>::value), class_does_not_inherit_from_##ConvertsTo )
  /// \endcode
  ///  which shows a compile-time error that typically includes: "ERROR_class_does_not_inherit_from_Group".
  ///  If it is not a C identifier, you may get spurious error messages at compile time compilers without static_assert.
#        define DISTI_STATIC_ASSERT( expr, msg ) static_assert( expr, DISTI_PREPROC_STRINGIFY( msg ) )
#    else
namespace disti
{
namespace _cppLangSupportDetail
{
    // Helpers for DISTI_STATIC_ASSERT
    // \note Adapted from Loki 0.1.7.
    template<int>
    struct CompileTimeError;
    template<>
    struct CompileTimeError<true>
    {
        CompileTimeError() {}
    };
} // namespace _cppLangSupportDetail
} // namespace disti

/// \brief Poor man's version of C++11's static_assert()
/// \param expr a compile-time integral or pointer expression
/// \param msg  a C identifier that will appear in compiler diagnostics
/// \note For older compilers' benefit, \a msg should be a C identifier such as:
/// \code{.cpp}
///    DISTI_STATIC_ASSERT( (std::is_convertible<T*,ConvertsTo*>::value), class_does_not_inherit_from_##ConvertsTo )
/// \endcode
///  which shows a compile-time error that typically includes: "ERROR_class_does_not_inherit_from_Group".
///  If it is not a C identifier, you may get spurious error messages at compile time compilers without static_assert.
/// \note Adapted from Loki 0.1.7.
#        define DISTI_STATIC_ASSERT( expr, msg )                                                 \
            {                                                                                    \
                ::disti::_cppLangSupportDetail::CompileTimeError<( ( expr ) != 0 )> ERROR_##msg; \
                (void)ERROR_##msg;                                                               \
            }
#    endif
#endif

////////////////////////////////////////////////////////////////////////////////
/// Convenience macro to check that one type converts to another at compile-time.
/// \param T A class to check
/// \param ConvertsTo A class to test T* against to verify that it can be
///                   converted to ConvertsTo* without a cast.
/// \note This macro appears here for grouping with like code, but macros
///       aren't scoped to namespace.
////////////////////////////////////////////////////////////////////////////////
#ifdef DISTI_HAS_TYPE_TRAITS
#    define DISTI_STATIC_ASSERT_IS_CONVERTIBLE_TO( T, ConvertsTo ) DISTI_STATIC_ASSERT( ( std::is_convertible<T*, ConvertsTo*>::value ), class_does_not_inherit_from_##ConvertsTo );
#else
#    define DISTI_STATIC_ASSERT_IS_CONVERTIBLE_TO( T, ConvertsTo ) DISTI_STATIC_ASSERT( (::disti::_cppLangSupportDetail::is_convertible<T*, ConvertsTo*>::value ), class_does_not_inherit_from_##ConvertsTo )
#endif

#endif