A component built from a callable, with every optional hook set by a chained call; see field(). More...

#include <entitygen.hpp>

Inheritance diagram for dasmig::field_component< T >:

Public Types
using	generator = std::function< T(const generation_context &)>
	The callable that produces the value.

Public Member Functions
	field_component (std::wstring key, generator fn)
	Construct a field.

field_component	label (std::wstring text) &&
	Set the display label (default: the key).

field_component	depends_on (std::vector< std::wstring > keys) &&
	Declare the components this one reads; see component::depends_on().

field_component	format (std::function< std::wstring(const T &)> fn) &&
	Set how the value is shown by to_string().

field_component	json (std::function< json_value(const T &)> fn) &&
	Set how the value is written by to_json().

field_component	weight (double inclusion) &&
	Set the inclusion weight (0.0 to 1.0); see component::weight().

field_component	when (std::function< bool(const generation_context &)> fn) &&
	Generate the field only when the callable returns true; see component::should_generate().

field_component	validate (std::function< bool(const T &)> fn) &&
	Accept only values the callable accepts; see component::validate().

field_component	data_hash (std::uint64_t hash) &&
	Set the hash of the data the field draws from; see component::data_hash().

std::wstring	key () const override
	Unique key identifying this component (e.g. `"name"`, `"age"`).

std::wstring	label () const override
	Display name of this component, used by entity::to_string().

std::vector< std::wstring >	depends_on () const override
	Keys of the components this one reads from the context.

std::uint64_t	data_hash () const override
	Hash of the data this component draws from, for replay.

double	weight () const override
	Inclusion weight for this component (0.0 to 1.0).

std::any	generate (const generation_context &ctx) const override
	Generate a random value for this component.

std::wstring	to_string (const std::any &value) const override
	Convert a generated value to a displayable string.

json_value	to_json (const std::any &value) const override
	Convert a generated value to JSON, for entity::to_json().

bool	validate (const std::any &value) const override
	Validate a generated value.

bool	should_generate (const generation_context &ctx) const override
	Decide whether this component should be generated.

Public Member Functions inherited from dasmig::component
	component ()=default
	Default constructor.

	component (const component &)=default
	Copyable.

component &	operator= (const component &)=default
	Copyable.

	component (component &&) noexcept=default
	Movable.

component &	operator= (component &&) noexcept=default
	Movable.

virtual	~component ()=default
	Virtual destructor for proper cleanup of derived classes.

Additional Inherited Members
Static Protected Member Functions inherited from dasmig::component
static std::wstring	default_to_string (const std::any &value)
	Default conversion covering common standard types.

static json_value	default_to_json (const std::any &value, const std::wstring &display)
	Default JSON conversion used by to_json().

Detailed Description

template<typename T>
class dasmig::field_component< T >

A component built from a callable, with every optional hook set by a chained call; see field().

The setters work on a temporary and return it, so a field is written in one expression and passed to eg::add():

gen.add(dasmig::field(L"identity.age", [](const dasmig::generation_context& ctx) {
            return ctx.get<birth>(L"birth").age;
        })
        .label(L"Age")
        .depends_on({L"birth"}));

Template Parameters

T	The value type the callable returns.

Definition at line 691 of file entitygen.hpp.

Member Typedef Documentation

◆ generator

template<typename T >

using dasmig::field_component< T >::generator = std::function<T(const generation_context&)>

The callable that produces the value.

Definition at line 695 of file entitygen.hpp.

Constructor & Destructor Documentation

◆ field_component()

template<typename T >

dasmig::field_component< T >::field_component	(	std::wstring	key,
		generator	fn
	)

inline

Construct a field.

Parameters

key	Unique component key (dots make a path in the JSON).
fn	Callable invoked during generation.

Definition at line 700 of file entitygen.hpp.

Member Function Documentation

◆ data_hash() [1/2]

template<typename T >

std::uint64_t dasmig::field_component< T >::data_hash ( ) const

inlineoverridevirtual

Hash of the data this component draws from, for replay.

A component that calls a generator with data returns that generator's data_hash(). entity::signature() combines the hashes of the components that ran, so a replay shows whether the data changed.

Returns: The hash; 0 (no data) by default.

Reimplemented from dasmig::component.

Definition at line 762 of file entitygen.hpp.

◆ data_hash() [2/2]

template<typename T >

field_component dasmig::field_component< T >::data_hash ( std::uint64_t hash ) &&

inline

Set the hash of the data the field draws from; see component::data_hash().

Definition at line 753 of file entitygen.hpp.

◆ depends_on() [1/2]

template<typename T >

std::vector< std::wstring > dasmig::field_component< T >::depends_on ( ) const

inlineoverridevirtual

Keys of the components this one reads from the context.

A request that selects this component also generates its dependencies (transitively) and orders them before it, whatever the registration order. If a dependency is skipped (weight roll or should_generate()), this component is skipped too. A dependency that is not registered, or a cycle, makes generation throw.

Returns: The dependency keys; empty by default.

Reimplemented from dasmig::component.

Definition at line 761 of file entitygen.hpp.

◆ depends_on() [2/2]

template<typename T >

field_component dasmig::field_component< T >::depends_on ( std::vector< std::wstring > keys ) &&

inline

Declare the components this one reads; see component::depends_on().

Definition at line 710 of file entitygen.hpp.

◆ format()

template<typename T >

field_component dasmig::field_component< T >::format ( std::function< std::wstring(const T &)> fn ) &&

inline

Set how the value is shown by to_string().

Definition at line 717 of file entitygen.hpp.

◆ generate()

template<typename T >

std::any dasmig::field_component< T >::generate ( const generation_context & ctx ) const

inlineoverridevirtual

Generate a random value for this component.

Parameters

ctx	Context providing access to previously generated values and a seeded random engine.

Returns: The generated value wrapped in std::any.

Implements dasmig::component.

Definition at line 765 of file entitygen.hpp.

◆ json()

template<typename T >

field_component dasmig::field_component< T >::json ( std::function< json_value(const T &)> fn ) &&

inline

Set how the value is written by to_json().

Definition at line 724 of file entitygen.hpp.

◆ key()

template<typename T >

std::wstring dasmig::field_component< T >::key ( ) const

inlineoverridevirtual

Unique key identifying this component (e.g. "name", "age").

Returns: The component key as a wide string.

Implements dasmig::component.

Definition at line 759 of file entitygen.hpp.

◆ label() [1/2]

template<typename T >

std::wstring dasmig::field_component< T >::label ( ) const

inlineoverridevirtual

Display name of this component, used by entity::to_string().

The key stays the identifier (lookups, seeds, JSON). A key with dots is a path: L"identity.age" is written as {"identity":{"age":..}}.

Returns: The label; defaults to the key.

Reimplemented from dasmig::component.

Definition at line 760 of file entitygen.hpp.

◆ label() [2/2]

template<typename T >

field_component dasmig::field_component< T >::label ( std::wstring text ) &&

inline

Set the display label (default: the key).

Definition at line 703 of file entitygen.hpp.

◆ should_generate()

template<typename T >

bool dasmig::field_component< T >::should_generate ( const generation_context & ctx ) const

inlineoverridevirtual

Decide whether this component should be generated.

Unlike weight() (probabilistic), this is logic-driven. Return false to skip generation entirely based on the current context.

Parameters

ctx	Context with previously generated component values.

Returns: true to generate, false to skip.

Reimplemented from dasmig::component.

Definition at line 786 of file entitygen.hpp.

◆ to_json()

template<typename T >

json_value dasmig::field_component< T >::to_json ( const std::any & value ) const

inlineoverridevirtual

Convert a generated value to JSON, for entity::to_json().

The default writes bool as a boolean, integers as integers, double and float as numbers (non-finite ones as null), std::wstring and std::string as strings, and anything else as the string from to_string(). Override it to write a richer value: a json_value can hold arrays and objects.

Parameters

value The value previously returned by generate().

Returns: The JSON value.

Reimplemented from dasmig::component.

Definition at line 775 of file entitygen.hpp.

◆ to_string()

template<typename T >

std::wstring dasmig::field_component< T >::to_string ( const std::any & value ) const

inlineoverridevirtual

Convert a generated value to a displayable string.

Parameters

value The value previously returned by generate().

Returns: A human-readable wide-string representation.

See also: default_to_string()

Implements dasmig::component.

Definition at line 770 of file entitygen.hpp.

◆ validate() [1/2]

template<typename T >

bool dasmig::field_component< T >::validate ( const std::any & value ) const

inlineoverridevirtual

Validate a generated value.

Parameters

value The value to validate.

Returns: true to accept, false to retry generation.

See also: eg::max_retries()

Reimplemented from dasmig::component.

Definition at line 781 of file entitygen.hpp.

◆ validate() [2/2]

template<typename T >

field_component dasmig::field_component< T >::validate ( std::function< bool(const T &)> fn ) &&

inline

Accept only values the callable accepts; see component::validate().

Definition at line 746 of file entitygen.hpp.

◆ weight() [1/2]

template<typename T >

double dasmig::field_component< T >::weight ( ) const

inlineoverridevirtual

Inclusion weight for this component (0.0 to 1.0).

A value of 1.0 means always included; 0.5 means included roughly half the time. The generator may override this per-component at registration time via eg::add(comp, weight) or eg::weight().

Returns: The inclusion probability.

See also: eg::weight()

Reimplemented from dasmig::component.

Definition at line 763 of file entitygen.hpp.

◆ weight() [2/2]

template<typename T >

field_component dasmig::field_component< T >::weight ( double inclusion ) &&

inline

Set the inclusion weight (0.0 to 1.0); see component::weight().

Definition at line 731 of file entitygen.hpp.

◆ when()

template<typename T >

field_component dasmig::field_component< T >::when ( std::function< bool(const generation_context &)> fn ) &&

inline

Generate the field only when the callable returns true; see component::should_generate().

Definition at line 739 of file entitygen.hpp.

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

dasmig/entitygen.hpp

Public Types

Public Member Functions

Additional Inherited Members

Detailed Description

Member Typedef Documentation

◆ generator

Constructor & Destructor Documentation

◆ field_component()

Member Function Documentation

◆ data_hash() [1/2]

◆ data_hash() [2/2]

◆ depends_on() [1/2]

◆ depends_on() [2/2]

◆ format()

◆ generate()

◆ json()

◆ key()

◆ label() [1/2]

◆ label() [2/2]

◆ should_generate()

◆ to_json()

◆ to_string()

◆ validate() [1/2]

◆ validate() [2/2]

◆ weight() [1/2]

◆ weight() [2/2]

◆ when()