corelib/include/ebcl/Utilities.hh

/******************************************************************************/
/* VARIOUS UTILITIES **********************************************************/
/******************************************************************************/

#ifndef _H_EBCL_UTILITIES
#define _H_EBCL_UTILITIES
#include <ebcl/Externals.hh>
namespace ebcl {


// IsPowerOf2( v ) - Is some integer a power of 2 ?
template< typename T >
static constexpr bool IsPowerOf2( T value );


/*= TEMPLATED HORRORS ========================================================*/

// MetaOr< ... > - Logical OR for templates
template< typename... >
	struct MetaOr : std::false_type
	{ };
template< typename T >
	struct MetaOr< T > : T
	{ };
template< typename T , typename... Rest >
	struct MetaOr< T , Rest... >
		: std::conditional_t< bool( T::value ) , T , MetaOr< Rest... > >
	{ };

/*----------------------------------------------------------------------------*/

// MetaAnd< ... > - Logical AND for templates
template< typename... >
	struct MetaAnd : std::true_type
	{ };
template< typename T >
	struct MetaAnd< T > : T
	{ };
template< typename T , typename... Rest >
	struct MetaAnd< T , Rest... >
		: std::conditional_t< bool( T::value ) , MetaAnd< Rest... > , T >
	{ };

/*----------------------------------------------------------------------------*/

// MetaNot< ... > - Logical NOT
template< typename T >
	struct MetaNot : std::integral_constant< bool , !bool( T::value ) >
	{ };

/*----------------------------------------------------------------------------*/

// MetaGet< N , List... > - Get the Nth element in a list
template< unsigned , typename... >
	struct MetaGet { };
template< typename T , typename... Rest >
	struct MetaGet< 0 , T , Rest... >
	{ using type = T; };
template< unsigned N , typename First , typename... Rest >
	struct MetaGet< N , First , Rest... >
		: MetaGet< N - 1 , Rest... >
	{ };
template< unsigned N , typename... List >
	using T_MetaGet = typename MetaGet< N , List... >::type;

/*----------------------------------------------------------------------------*/

// MetaLength< List... > - Get the length of a list
template< typename... >
	struct MetaLength
		: std::integral_constant< unsigned , 0 >
	{ };
template< typename T >
	struct MetaLength< T >
		: std::integral_constant< unsigned , 1 >
	{ };
template< typename First , typename... Rest >
	struct MetaLength< First , Rest... >
		: std::integral_constant< unsigned , MetaLength< Rest... >::value + 1 >
	{ };

/*----------------------------------------------------------------------------*/

// MetaContains< Type , List... > - Checks whether Type is in List
template< typename Type , typename... List >
	using MetaContains = MetaOr< std::is_same< Type , List >... >;

/*----------------------------------------------------------------------------*/

// MetaIndexOf< Type , List... > - Gets the index of Type in List. If Type is
// not in the list, the length of the list is returned.
template< typename Type , typename... List >
	struct MetaIndexOf { };
template< typename Type >
	struct MetaIndexOf< Type >
		: std::integral_constant< unsigned , 0 >
	{ };
template< typename Type , typename First , typename... Rest >
	struct MetaIndexOf< Type , First , Rest... >
		: std::conditional_t< std::is_same< Type , First >::value ,
			std::integral_constant< unsigned , 0 > ,
			std::integral_constant< unsigned ,
				MetaIndexOf< Type , Rest... >::value + 1 > >
	{ };

/*----------------------------------------------------------------------------*/

// CanCopyOrMove< Type > - Check whether a type can be copy- or move-constructed.
template< typename T >
	using CanCopyOrMove = MetaOr<
		std::is_copy_constructible< T > ,
		std::is_move_constructible< T > >;

/*----------------------------------------------------------------------------*/

// CanCopyConsAll< List... > - Checks that all listed types are copy-constructible
template< typename... List >
	using CanCopyConsAll = MetaOr< std::is_copy_constructible< List >... >;

// CanMoveConsAll< List... > - Checks that all listed types are move-constructible
template< typename... List >
	using CanMoveConsAll = MetaOr< std::is_move_constructible< List >... >;

// CanCopyAssAll< List... > - Checks that all listed types are copy-constructible
template< typename... List >
	using CanCopyAssAll = MetaOr< std::is_copy_assignable< List >... >;

// CanMoveAssAll< List... > - Checks that all listed types are move-constructible
template< typename... List >
	using CanMoveAssAll = MetaOr< std::is_move_assignable< List >... >;

/*----------------------------------------------------------------------------*/

// EnableForChild< P , C > - Enable if P is a parent class of C, or if P and C
// are the same.
template<
	typename Parent ,
	typename Child
> using EnableForChild =
	std::enable_if<
		std::is_base_of< Parent , Child >::value ,
		bool
	>;

template< typename C , typename P >
using T_EnableForChild = typename EnableForChild<C, P>::type;

// EnableForParent< C , P > - Enable if P is a parent class of C, and if P and
// C are distinct.
template<
	typename Child ,
	typename Parent
> using EnableForParent =
	std::enable_if<
		std::is_base_of< Parent , Child >::value
			&& !std::is_same< Parent , Child >::value ,
		bool
	>;

template< typename C , typename P >
using T_EnableForParent = typename EnableForParent<C, P>::type;

// EnableForHierarchy< T1 , T2 > - Enable if T1 and T2 are the same, or if
// T1 is the child of T2 or if T2 is the child of T1
template<
	typename T1 ,
	typename T2
> using EnableForHierarchy =
	std::enable_if< MetaOr<
			std::is_same< T1 , T2 > ,
			std::is_base_of< T1 , T2 > ,
			std::is_base_of< T2 , T1 >
		>::value ,
		bool
	>;

template<
	typename T1 ,
	typename T2
> using T_EnableForHierarchy = typename EnableForHierarchy< T1 , T2 >::type;

/*----------------------------------------------------------------------------*/

// Remove const and topmost reference
template< typename T >
using RemoveConstRef = std::remove_const< std::remove_reference_t< T > >;

template< typename T >
using T_RemoveConstRef = typename RemoveConstRef< T >::type;

/*----------------------------------------------------------------------------*/

// T_EnableIfTypesMatch - Make sure that the A type actually matches the V type.
template<
	typename V , typename A ,
	typename RA = T_RemoveConstRef< A >
> using EnableIfTypesMatch =
	std::enable_if< std::is_same< RA , V >::value , bool >;

template<
	typename V , typename A
> using T_EnableIfTypesMatch = typename EnableIfTypesMatch< V , A >::type;

/*----------------------------------------------------------------------------*/

/* In-place construction tag */
template< typename Type >
struct Construct
{
	explicit constexpr Construct( ) = default;
	static constexpr Construct< Type > v = Construct< Type >( );
};

using InPlace = Construct< void >;

/*----------------------------------------------------------------------------*/

template< typename T >
	struct T_CFunc { };

template< typename RT , typename... AT >
	struct T_CFunc< RT( AT... ) >
	{
		typedef RT (* type )( AT... );
	};

template< typename T >
	using F_CFunc = typename T_CFunc< T >::type;

/*----------------------------------------------------------------------------*/

// T_VarStorage< DataType > - A storage buffer with the correct size and
// alignment for the specified data type.
template< typename DataType >
	using T_VarStorage = typename std::aligned_storage<
			sizeof( DataType ) , alignof( DataType )
		>::type;

/*----------------------------------------------------------------------------*/

// Define a structure that can be used as a tag
#define M_DEFINE_TAG( NAME ) \
	struct NAME { }
// Define a tag structure that can carry arguments
#define M_DEFINE_TEMPLATE_TAG( NAME , ARGS... ) \
	template< ARGS > \
	M_DEFINE_TAG( NAME )

// A structure that can be used to carry a tag structure instance
template< typename Tag >
struct UseTag
{
	const Tag tag;

	template< typename ... ArgTypes >
	constexpr UseTag( ArgTypes&&... args ) noexcept
		: tag( std::forward< ArgTypes >( args ) ... ) { }
};


/*= MACRO HORRORS ============================================================*/

// M_UNUSED( Var ) - Macro for unused variables
#define M_UNUSED( Var ) ((void)Var)

// M_LSHIFT_OP( Type , Target ) - Declare a left-shift operator using the
// specified types
#define M_LSHIFT_OP( Type , Target ) \
	Type & operator<< ( Type& obj , Target value )

// M_WITH_INT( Name ) - Declare a template with a type that needs to be some
// sort of integer.
#define M_WITH_INT( Name ) \
	template< \
	typename Name , \
	typename = std::enable_if_t< std::is_integral< Name >::value > \
	>

// M_DECLARE_SWAP( Type ) - Declare the swap function for a given type
#define M_DECLARE_SWAP( Type ) \
	void swap( Type& lhs , Type& rhs ) noexcept

// M_DEFINE_SWAP( Type ) - Define the swap function for a given type
#define M_DEFINE_SWAP( Type ) \
	void swap( Type& lhs , Type& rhs ) noexcept

/*----------------------------------------------------------------------------*/
/* Helper macros for iterator declarations */

// Default constructor (forward, bidir, random)
#define M_ITER_CONS_DEF( NAME )						\
	NAME( ) noexcept

// Copy constructor/assignment (all types)
#define M_ITER_CONS_COPY( NAME )					\
	NAME( NAME const& other ) noexcept;				\
	NAME& operator =( NAME const& other ) noexcept

// Move constructor (not necessary)
#define M_ITER_CONS_MOVE( NAME )					\
	NAME( NAME&& other ) noexcept;					\
	NAME& operator =( NAME&& other ) noexcept

// Swap (all types)
#define M_ITER_SWAP( NAME )						\
	NAME& swap( NAME& other ) noexcept

// Equality/inequality (all types)
#define M_ITER_CMP_EQ( NAME )						\
	bool operator ==( NAME const& other ) const noexcept;		\
	bool operator !=( NAME const& other ) const noexcept

// Equality/inequality (all types)
#define M_ITER_CMP_ALL( NAME )						\
	M_ITER_CMP_EQ( NAME );						\
	bool operator >( NAME const& other ) const noexcept;		\
	bool operator >=( NAME const& other ) const noexcept;		\
	bool operator <( NAME const& other ) const noexcept;		\
	bool operator <=( NAME const& other ) const noexcept

// Dereference
#define M_ITER_DEREF( REF , PTR )					\
	REF operator* ( ) const noexcept;				\
	PTR operator-> ( ) const noexcept
#define M_ITER_DEREF_RANDOM( REF , PTR )				\
	M_ITER_DEREF( REF , PTR );					\
	REF operator[] ( const ptrdiff_t offset ) const noexcept

// Operations (increment, etc)
#define M_ITER_OPS_FWD( NAME )						\
	NAME& operator++ ( ) noexcept;					\
	NAME operator++ (int) noexcept
#define M_ITER_OPS_BIDIR( NAME )					\
	M_ITER_OPS_FWD( NAME );						\
	NAME& operator-- ( ) noexcept;					\
	NAME operator-- (int) noexcept
#define M_ITER_OPS_RANDOM( NAME )					\
	M_ITER_OPS_BIDIR( NAME );					\
	NAME operator +( const ptrdiff_t value ) const noexcept;	\
	NAME operator -( const ptrdiff_t value ) const noexcept;	\
	ptrdiff_t operator -( NAME const& other ) const noexcept;		\
	NAME& operator +=( const ptrdiff_t value ) noexcept;		\
	NAME& operator -=( const ptrdiff_t value ) noexcept


/*= ENDIAN DETECTION =========================================================*/
/*
 * Unfortunately there's no standard way to do this so we depend on some
 * GCC-specific stuff.
 */

#ifndef __BYTE_ORDER__
# error "We need the __BYTE_ORDER__ macro to exist :("
#endif

enum class E_Endian {
	LITTLE = __ORDER_LITTLE_ENDIAN__ ,
	BIG = __ORDER_BIG_ENDIAN__ ,
	NATIVE = __BYTE_ORDER__
};


static constexpr bool IsBigEndian( );
static constexpr bool IsLittleEndian( );


/*= ENDIAN CONVERSION ========================================================*/

template<
	typename T ,
	E_Endian E = E_Endian::NATIVE ,
	typename = std::enable_if_t<
		std::is_integral< T >::value
		|| std::is_floating_point< T >::value
		>
	>
struct T_LittleEndian
{
	static T convert( T value );
};


template<
	typename T ,
	E_Endian E = E_Endian::NATIVE ,
	typename = std::enable_if_t<
		std::is_integral< T >::value
		|| std::is_floating_point< T >::value
		>
	>
struct T_BigEndian
{
	static T convert( T value );
};


/*= ARRAY COPYING AND MOVING =================================================*/

template<
	typename Type ,
	bool IsTrivial = !std::is_class< Type >( )
> struct T_ArrayHelpers
{
	// Default-initialise items in an array
	static void init( Type* dest , const uint32_t size );
	// Copy-initialise items in an array
	static void init( Type* dest , const uint32_t size , Type const& value );

	// Delete items in an array
	static void destroy( Type* dest , const uint32_t size );

	// Copy array items using copy constructors
	static void copyNew( Type const* source , Type* dest , const uint32_t size );
	// Copy array items using assignment operators
	static void copyAssign( Type const* source , Type* dest , const uint32_t size );

	// Initialise destination items using move constructors
	static void moveNew( Type* source , Type* dest , const uint32_t size );
	// Move items using assignments
	static void moveAssign( Type* source , Type* dest , const uint32_t size );
	// Move items using move constructors and delete source items
	static void move( Type* source , Type* dest , const uint32_t size );
};


/*= COMPARATORS AND SORTING ==================================================*/

// F_Comparator< T > - T_Comparator function type
template< typename T >
using F_Comparator = std::function< int( T const& a , T const& b ) >;

// T_Comparator< T > - Default comparison function implementation
template< typename T >
struct T_Comparator
{
	static int compare( T const& a , T const& b );
};


// Helper macros to declare and define specialised hash functions.
#define M_DECLARE_COMPARATOR( Type ) \
	template< > \
	struct T_Comparator< Type > \
	{ \
		static int compare( Type const& , Type const& ); \
	}


#define M_DEFINE_COMPARATOR( Type ) \
	int ::ebcl::T_Comparator< Type >::compare( Type const & a , Type const & b )

// Instantiate some commonly used comparators
extern template struct T_Comparator< uint32_t >;

// Sort - Sort an array
template< typename T >
void Sort( T* array , uint32_t items , F_Comparator< T > comparator = T_Comparator< T >::compare );


/*= HASHING ==================================================================*/

// HashData( data , size ) - General hash function (Jenkin's one-at-a-time)
uint32_t HashData( uint8_t const* data , uint32_t size );

// Hash function template struct. Meant to be specialized. By default it uses
// the function above.
template< typename T , int S = sizeof( T ) >
struct T_HashFunction
{
	static uint32_t hash( T const& item );
};


// ComputeHash( T ) - The actual hash function.
template< typename T >
uint32_t ComputeHash( T const& item );

// CombineHash( &hv , T ) - Helper that consolidates multiple hashes into a
// single value.
template< typename T >
void CombineHash( uint32_t& hashValue , T const& item );

// Helper macros to declare and define specialised hash functions.
#define M_DECLARE_HASH( Type ) \
	template< > \
	struct T_HashFunction< Type > \
	{ \
		static uint32_t hash( Type const& ); \
	}


#define M_DEFINE_HASH( Type ) \
	uint32_t T_HashFunction< Type >::hash( Type const & item )


/*= PRIVATE IMPLEMENTATION BASE ==============================================*/

/* This class should be used as a base class for any non-performance-critical
 * class that contains a lot of private stuff. The idea is to limit the amount
 * of stuff exposed through the API, which in turns makes binary compatibility
 * somewhat easier.
 */
class A_PrivateImplementation
{
    private:
	using T_Destructor_ = std::function< void( void* ) >;
	void* p_;
	T_Destructor_ piDestructor_;

    protected:
	A_PrivateImplementation( ) = delete;
	A_PrivateImplementation( A_PrivateImplementation const& ) = delete;
	A_PrivateImplementation& operator=( A_PrivateImplementation const& ) = delete;

	A_PrivateImplementation( void* p , T_Destructor_ destructor );
	template< typename T >
		explicit A_PrivateImplementation( T* p );
	A_PrivateImplementation( A_PrivateImplementation&& ) noexcept;
	A_PrivateImplementation& operator=( A_PrivateImplementation&& ) noexcept;

    public:
	virtual ~A_PrivateImplementation( );

    protected:
	template< typename T >
		T& p( ) const;

    private:
	void callPrivateDestructor( ) noexcept;
};


} // namespace
#endif // _H_EBCL_UTILITIES
#include <ebcl/inline/Utilities.hh>