cal::negating_lens< Lens, T > Struct Template Reference

A lens that negates the value before storing or accessing it. More...

#include <lens.hpp>

Inheritance diagram for cal::negating_lens< Lens, T >:

Public Types
typedef Lens	internal_type
	The type of the lens being wrapped.
typedef T	value_type
	The value type accepted by the lens.

Public Member Functions
	negating_lens (internal_type &&data)
	Wraps a lens.
internal_type	data ()
	Returns the internal lens.
const internal_type &	data () const
	Returns the internal lens.
	operator value_type () const
	Gets the value through the lens.
negating_lens< Lens, T > &	operator%= (const value_type &x)
	Modulo assignment through the lens.
negating_lens< Lens, T > &	operator&= (const value_type &x)
	Bitwise AND assignment through the lens.
negating_lens< Lens, T > &	operator*= (const value_type &x)
	Multiplication assignment through the lens.
negating_lens< Lens, T > &	operator++ ()
	Pre-increments through the lens.
negating_lens &	operator+= (const value_type &x)
	Addition assignment through the lens.
negating_lens< Lens, T > &	operator-- ()
	Pre-decrements through the lens.
negating_lens &	operator-= (const value_type &x)
	Subtraction assignment through the lens.
negating_lens< Lens, T > &	operator/= (const value_type &x)
	Division assignment through the lens.
negating_lens< Lens, T > &	operator<<= (const value_type &x)
	Bitwise left shift assignment through the lens.
negating_lens &	operator= (const value_type &x)
	Puts a value through the lens.
negating_lens &	operator= (value_type &&x)
	Puts a value through the lens (rvalue version).
negating_lens< Lens, T > &	operator>>= (const value_type &x)
	Bitwise right shift assignment through the lens.
negating_lens< Lens, T > &	operator^= (const value_type &x)
	Bitwise XOR assignment through the lens.
negating_lens< Lens, T > &	operator|= (const value_type &x)
	Bitwise OR assignment through the lens.

Detailed Description

template<class Lens, class T = typename lens_traits<Lens>::value_type>
struct cal::negating_lens< Lens, T >

A lens that negates the value before storing or accessing it.

If L is the negating_lens and x is the internal lens, the following relationships are satisfied:

L        ==   -x
L  = c  <==>   x  = -c
L += c  <==>   x -=  c
L -= c  <==>   x +=  c

The addition/subtraction-assignment operators are overloaded here to ensure better optimization for floating-point numbers (when -ffast-math or its equivalent is not enabled).