RandomDraw< POL > Class Template Reference

#include "lib/random-draw.hpp"

Description

template<class POL>
class lib::RandomDraw< POL >

A component and builder to draw limited parameter values based on some source of randomness (or hash input).

Effectively this is a function which "draws" on invocation. Probabilities and ranges can be configured by builder API.

Template Parameters

POL	configuration policy baseclass

Definition at line 174 of file random-draw.hpp.

Public Member Functions
	RandomDraw ()
	Drawing is disabled by default, always yielding "zero".
template<class FUN , typename = disable_if_self<RandomDraw, FUN>>
	RandomDraw (FUN &&fun)
	Build a RandomDraw by attaching a value-processing function, which is adapted to accept the nominal input type. More...
RandomDraw &&	fixedVal (Tar v)
template<class FUN >
RandomDraw &&	mapping (FUN &&fun)
RandomDraw &&	maxVal (Tar m)
RandomDraw &&	minVal (Tar m)
RandomDraw &&	probability (double p)
RandomDraw &&	shuffle (size_t seed=55)
Public Member Functions inherited from LazyInit< POL >
	LazyInit (std::function< SIG > &targetFunctor, INI &&initialiser, ARGS &&...parentCtorArgs)
	prepare an initialiser to be activated on first use
	LazyInit (LazyInit const &ref)
	LazyInit (LazyInit &&rref)
void	installEmptyInitialiser ()
void	installInitialiser (std::function< SIG > &targetFunctor, INI &&initialiser)
bool	isInit () const
LazyInit &	operator= (LazyInit const &ref)
LazyInit &	operator= (LazyInit &&rref)

Private Types
using	Disabled = typename Lazy::MarkDisabled
using	Fun = function< Sig >
using	Lazy = LazyInit< POL >
using	Sig = typename _Fun< POL >::Sig
using	Tar = typename _Fun< POL >::Ret

Private Member Functions
template<class FUN >
auto	adaptIn (FUN &&fun)
template<class FUN >
auto	adaptOut (FUN &&fun)
double	asRand (size_t hash)
Tar	drawLimited (size_t hash)
template<class FUN >
void	installAdapted (FUN &&fun)
Tar	limited (double val)

Private Attributes
Tar	maxResult_ {Tar::maxVal()}
	maximum result val actually to produce < max
Tar	minResult_ {Tar::minVal()}
	minimum result val actually to produce > min
double	probability_ {0}
	probability that value is in [min .. max] \ neutral
size_t	shuffle_ {0}
	statefull additional randomisation to inject into hash

Static Private Attributes
static double constexpr	CAP_EPSILON = 1/(2.0 * QUANTISER)
static size_t constexpr	QUANTISER = 1 << 4 + util::ilog2 (Tar::maxVal()-Tar::minVal())

Additional Inherited Members
Protected Member Functions inherited from LazyInit< POL >
	LazyInit (MarkDisabled, ARGS &&...parentCtorArgs)

Constructor & Destructor Documentation

RandomDraw()

RandomDraw ( FUN &&  fun )

inline

Build a RandomDraw by attaching a value-processing function, which is adapted to accept the nominal input type.

The effect of the given function is determined by its output value...

• size_t: the function output is used as source of randomness
• double: output is directly used as draw value [0.0..1.0[
• void(RandomDraw&, ...) : the function manipulates the current instance, to control parameters dynamically, based on input.

Definition at line 278 of file random-draw.hpp.

Member Function Documentation

limited()

Tar limited ( double  val )

inlineprivate

quantise into limited result value

Definition at line 192 of file random-draw.hpp.

asRand()

double asRand ( size_t  hash )

inlineprivate

draw from source of randomness

Definition at line 243 of file random-draw.hpp.

drawLimited()

Tar drawLimited ( size_t  hash )

inlineprivate

core operation: draw and quantise into limited value

Definition at line 252 of file random-draw.hpp.

installAdapted()

void installAdapted ( FUN &&  fun )

inlineprivate

adapt a function and install it to control drawing and mapping

Definition at line 349 of file random-draw.hpp.

adaptIn()

auto adaptIn ( FUN &&  fun )

inlineprivate

adapt input side of a given function to conform to the global input arguments as defined in the Policy base function.

Returns

a function pre-fitted with a suitable Adapter from the Policy

Definition at line 361 of file random-draw.hpp.

adaptOut()

auto adaptOut ( FUN &&  fun )

inlineprivate

adapt output side of a given function, allowing to handle it's results

• a function producing the overall result-type is installed as-is
• a size_t result is assumed to be a hash and passed into drawLimited
• likewise a double is assumed to be already a random val to be limited
• special treatment is given to a function returning a RandomDraw instance by value; such a function is assumed to set some parametrisation based on the input data, allowing to change parameters dynamically.

  Returns

  adapted function which produces a result value of type #Tar

Definition at line 392 of file random-draw.hpp.

Inheritance diagram for RandomDraw< POL >:

Collaboration diagram for RandomDraw< POL >:

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The documentation for this class was generated from the following file:

• random-draw.hpp