std.hpp

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#ifndef GENESIS_UTILS_CORE_STD_H_
#define GENESIS_UTILS_CORE_STD_H_
 
/*
    Genesis - A toolkit for working with phylogenetic data.
    Copyright (C) 2014-2024 Lucas Czech
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.
 
    This program 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 General Public License for more details.
 
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
    Contact:
    Lucas Czech <lczech@carnegiescience.edu>
    Department of Plant Biology, Carnegie Institution For Science
    260 Panama Street, Stanford, CA 94305, USA
*/
 
#include <cstdint>
#include <memory>
#include <stdexcept>
#include <string>
 
namespace genesis {
namespace utils {
 
// =================================================================================================
//     Expection Handling
// =================================================================================================
 
// Try to find a macro that expands to the current function name.
#ifdef __cplusplus
#    define GENESIS_FUNC __PRETTY_FUNCTION__
#else
#    if defined __STDC_VERSION__
#        define GENESIS_FUNC __func__
#    else
#        define GENESIS_FUNC __FUNCTION__
// #        define GENESIS_FUNC ((const char *) 0)
#    endif
#endif
 
// =================================================================================================
//     Compiler Attributes
// =================================================================================================
 
// We define them here as specified by later standards.
// Using them this way allows us to easily switch them off (by turning them into empty statements).
// #define GENESIS_LIKELY   [[likely]]
// #define GENESIS_UNLIKELY [[unlikely]]
#define GENESIS_LIKELY
#define GENESIS_UNLIKELY
 
// =================================================================================================
//     Shortcomings of the C++ 11 STL...
// =================================================================================================
 
template<typename T, typename... Args>
std::unique_ptr<T> make_unique(Args&&... args)
{
    return std::unique_ptr<T>(new T(std::forward<Args>(args)...));
}
 
template <typename T>
class ArrowOperatorProxy {
public:
 
    explicit ArrowOperatorProxy( T const& v )
        : t(v)
    {}
 
    T* operator ->() const {
        return &t;
    }
 
private:
 
    T t;
};
 
// =================================================================================================
//     Hash Helpers
// =================================================================================================
 
inline constexpr std::size_t combine_hashes_32( std::size_t h1, std::size_t h2 )
{
    return h1 ^ ( h2 + 0x9e3779b9 + ( h1 << 6 ) + ( h1 >> 2 ));
}
 
inline constexpr std::size_t combine_hashes_64( std::size_t h1, std::size_t h2 )
{
    return h1 ^ ( h2 + 0x9e3779b97f4a7c16 + ( h1 << 12 ) + ( h1 >> 4 ));
}
 
inline constexpr std::size_t combine_hashes( std::size_t h1, std::size_t h2 )
{
    // We use a run-time check for the size of size_t,
    // which however most likely is already resolved at compile time.
    // The inner functions use the golden ratio phi = (1 + sqrt(5))/2 as an irrational number
    // with random independent bits, by using its inverse and the max size:
    // 2^64 / phi = 0x9e3779b97f4a7c16 for the 64bit version for example.
    // Furthermore, shifting is added in order to spread bits around for greater diversity.
    // This whole approach follows the Boost hash combine functions.
 
    static_assert(
        ( sizeof( std::size_t ) == 4 ) || ( sizeof( std::size_t ) == 8 ),
        "Need sizeof( std::size_t ) to be 4 or 8 (32bit or 64bit integer)"
    );
    return ( sizeof( std::size_t ) == 4 )
        ? combine_hashes_32( h1, h2 )
        : combine_hashes_64( h1, h2 )
    ;
 
    // constexpr in C++11 cannot have multiple return values
    // if( sizeof( std::size_t ) == 4 ) {
    //     return combine_hashes_32( seed, value );
    // } else if( sizeof( std::size_t ) == 8 ) {
    //     return combine_hashes_64( seed, value );
    // } else {
    //     throw std::runtime_error( "Invalid std::size_t size." );
    // }
}
 
template <typename T>
inline constexpr std::size_t hash_combine( std::size_t seed, T const& value )
{
    return combine_hashes( seed, std::hash<T>()( value ));
}
 
} // namespace utils
} // namespace genesis
 
#endif // include guard