Detailed Description

template<typename T>
class maliput::drake::systems::InputPort< T >

An InputPort is a System resource that describes the kind of input a System accepts, on a given port.

It does not directly contain any runtime input port data; that is always contained in a Context. The actual value will be either the value of an OutputPort to which this is connected, or a fixed value set in a Context.

@tparam_default_scalar

#include <src/maliput/drake/systems/framework/input_port.h>

Inheritance diagram for InputPort< T >:

[legend]

Public Member Functions
Eigen::VectorBlock< const VectorX< T > >	Eval (const Context< T > &context) const
	Returns a reference to the up-to-date value of this input port contained in the given Context. More...

template<typename ValueType , typename = std::enable_if_t<std::is_same_v<AbstractValue, ValueType>>>
const AbstractValue &	Eval (const Context< T > &context) const

template<typename ValueType , typename = std::enable_if_t<!std::is_same_v<AbstractValue, ValueType> && (!std::is_base_of_v<BasicVector<T>, ValueType> \|\| std::is_same_v<BasicVector<T>, ValueType>)>>
const ValueType &	Eval (const Context< T > &context) const

template<typename ValueType , typename = std::enable_if_t<std::is_base_of_v<BasicVector<T>, ValueType> && !std::is_same_v<BasicVector<T>, ValueType>>>
const ValueType &	Eval (const Context< T > &context, int=0) const

template<typename ValueType >
FixedInputPortValue &	FixValue (Context< T > *context, const ValueType &value) const
	Provides a fixed value for this InputPort in the given Context. More...

bool	HasValue (const Context< T > &context) const
	Returns true iff this port is connected or has had a fixed value provided in the given Context. More...

const System< T > &	get_system () const
	Returns a reference to the System that owns this input port. More...

InputPortIndex	get_index () const
	Returns the index of this input port within the owning System. More...

std::optional< RandomDistribution >	get_random_type () const
	Returns the RandomDistribution if this is a random port. More...

bool	is_random () const
	Returns true if this is a random port. More...

PortDataType	get_data_type () const
	Returns the port data type. More...

const std::string &	get_name () const
	Get port name. More...

std::string	GetFullDescription () const
	Returns a verbose human-readable description of port. More...

int	size () const
	Returns the fixed size expected for a vector-valued port. More...

DependencyTicket	ticket () const
	(Advanced.) Returns the DependencyTicket for this port within the owning System. More...

Public Member Functions inherited from InputPortBase
	~InputPortBase () override

InputPortIndex	get_index () const
	Returns the index of this input port within the owning System. More...

bool	is_random () const
	Returns true if this is a random port. More...

std::optional< RandomDistribution >	get_random_type () const
	Returns the RandomDistribution if this is a random port. More...

PortDataType	get_data_type () const
	Returns the port data type. More...

const std::string &	get_name () const
	Get port name. More...

std::string	GetFullDescription () const
	Returns a verbose human-readable description of port. More...

int	size () const
	Returns the fixed size expected for a vector-valued port. More...

DependencyTicket	ticket () const
	(Advanced.) Returns the DependencyTicket for this port within the owning System. More...

Public Member Functions inherited from PortBase
virtual	~PortBase ()

const std::string &	get_name () const
	Get port name. More...

std::string	GetFullDescription () const
	Returns a verbose human-readable description of port. More...

PortDataType	get_data_type () const
	Returns the port data type. More...

int	size () const
	Returns the fixed size expected for a vector-valued port. More...

const internal::SystemMessageInterface &	get_system_interface () const

DependencyTicket	ticket () const
	(Advanced.) Returns the DependencyTicket for this port within the owning System. More...

Friends
class	internal::FrameworkFactory

Additional Inherited Members
Protected Types inherited from InputPortBase
using	EvalAbstractCallback = std::function< const AbstractValue *(const ContextBase &)>
	Signature of a function suitable for returning the cached value of a particular input port. More...

Protected Member Functions inherited from InputPortBase
	InputPortBase (internal::SystemMessageInterface *owning_system, internal::SystemId owning_system_id, std::string name, InputPortIndex index, DependencyTicket ticket, PortDataType data_type, int size, const std::optional< RandomDistribution > &random_type, EvalAbstractCallback eval)
	Provides derived classes the ability to set the base class members at construction. More...

const AbstractValue &	DoEvalRequired (const ContextBase &context) const
	Evaluate this port; throws an exception if the port is not connected. More...

const AbstractValue *	DoEvalOptional (const ContextBase &context) const
	Evaluate this port; returns nullptr if the port is not connected. More...

void	ThrowRequiredMissing () const
	Throws an exception that this port is not connected, but was expected to be connected (i.e., an Eval caller expected that it was always connected). More...

Protected Member Functions inherited from PortBase
	PortBase (const char kind_string, internal::SystemMessageInterface owning_system, internal::SystemId owning_system_id, std::string name, int index, DependencyTicket ticket, PortDataType data_type, int size)
	Provides derived classes the ability to set the base class members at construction. More...

int	get_int_index () const
	Returns the index of this port within the owning System (i.e., an InputPortIndex or OutputPortIndex, but as a bare integer). More...

internal::SystemMessageInterface &	get_mutable_system_interface ()
	Returns get_system_interface(), but without the const. More...

void	ValidateSystemId (internal::SystemId id) const
	(Internal use only) Checks whether the given id (nominally obtained from a Context passed to this port) was created for the system that owns this port. More...

void	ThrowValidateContextMismatch () const
	(Internal use only) Throws std::exception with a message that the sanity check(s) related to ValidateContext have failed. More...

template<typename ValueType >
const ValueType &	PortEvalCast (const AbstractValue &abstract) const
	Pull a value of a given type from an abstract value or issue a nice message if the type is not correct. More...

template<typename ValueType , typename T >
const ValueType &	PortEvalCast (const BasicVector< T > &basic) const
	Downcast a basic vector to a more specific subclass (e.g., as generated by //tools/vector_gen) or issue a nice message if the type is not correct. More...

template<typename ValueType >
const ValueType &	ThrowBadCast (const AbstractValue &abstract) const
	Reports that the user provided a bad ValueType argument to Eval. More...

template<typename ValueType , typename T >
const ValueType &	ThrowBadCast (const BasicVector< T > &basic) const
	Reports that the user provided a bad ValueType argument to Eval. More...

void	ThrowBadCast (const std::string &value_typename, const std::string &eval_typename) const
	Reports that the user provided a bad ValueType argument to Eval. More...

Member Function Documentation

◆ Eval() [1/4]

Eigen::VectorBlock<const VectorX<T> > Eval ( const Context< T > & context ) const

Returns a reference to the up-to-date value of this input port contained in the given Context.

This is the preferred way to obtain an input port's value since it will not be recalculated once up to date.

If the value is not already up to date with respect to its prerequisites, it will recalculate an up-to-date value before the reference is returned. The recalculation may be arbitrarily expensive, but Eval() is constant time and very fast if the value is already up to date.

Template Parameters

ValueType The type of the const-reference returned by this method. When omitted, the return type is an Eigen::VectorBlock (this is only valid when this is a vector-valued port). For abstract ports, the ValueType either can be the declared type of the port (e.g., lcmt_iiwa_status), or else in advanced use cases can be AbstractValue to get the type-erased value.

Returns: reference to the up-to-date value; if a ValueType is provided, the return type is const ValueType&; if a ValueType is omitted, the return type is Eigen::VectorBlock<const VectorX<T>>.

Exceptions

std::exception if the port is not connected. (Use HasValue() to check first, if necessary.)

Precondition: The input port is vector-valued (when no ValueType is provided).; The input port is of type ValueType (when ValueType is provided).

◆ Eval() [2/4]

const AbstractValue& Eval ( const Context< T > & context ) const

◆ Eval() [3/4]

const ValueType& Eval ( const Context< T > & context ) const

◆ Eval() [4/4]

const ValueType& Eval	(	const Context< T > &	context,
		int	= `0`
	)		const

◆ FixValue()

FixedInputPortValue& FixValue	(	Context< T > *	context,
		const ValueType &	value
	)		const

Provides a fixed value for this InputPort in the given Context.

If the port is already connected, this value will override the connected source value. (By "connected" we mean that the port appeared in a DiagramBuilder::Connect() call.)

For vector-valued input ports, you can provide an Eigen vector expression, a BasicVector object, or a scalar (treated as a Vector1). In each of these cases the value is copied into a Value<BasicVector>. If the original value was a BasicVector-derived object, its concrete type is maintained although the stored type is still Value<BasicVector>. The supplied vector must have the right size for the vector port or an std::logic_error is thrown.

For abstract-valued input ports, you can provide any ValueType that is compatible with the model type provided when the port was declared. If the type has a copy constructor it will be copied into a Value<ValueType> object for storage. Otherwise it must have an accessible Clone() method and it is stored using the type returned by that method, which must be ValueType or a base class of ValueType. Eigen objects and expressions are not accepted directly, but you can store then in abstract ports by providing an already-abstract object like Value<MatrixXd>(your_matrix).

The returned FixedInputPortValue reference may be used to modify the input port's value subsequently using the appropriate FixedInputPortValue method, which will ensure that cache invalidation notifications are delivered.

Template Parameters

ValueType The type of the supplied value object. This will be inferred so no template argument need be specified. The type must be copy constructible or have an accessible Clone() method.

Parameters

[in,out]	context	A Context that is compatible with the System that owns this port.
[in]	value	The fixed value for this port. Must be convertible to the input port's data type.

Returns: a reference to the FixedInputPortValue object in the Context that contains this port's value.

Precondition: context is compatible with the System that owns this InputPort.; value is compatible with this InputPort's data type.

◆ get_data_type()

PortDataType get_data_type

Returns the port data type.

◆ get_index()

InputPortIndex get_index

Returns the index of this input port within the owning System.

For a Diagram, this will be the index within the Diagram, not the index within a LeafSystem whose input port was exported.

◆ get_name()

const std::string& get_name

Get port name.

◆ get_random_type()

std::optional<RandomDistribution> get_random_type

Returns the RandomDistribution if this is a random port.

◆ get_system()

const System<T>& get_system ( ) const

Returns a reference to the System that owns this input port.

Note that for a Diagram input port this will be the Diagram, not the LeafSystem whose input port was exported.

◆ GetFullDescription()

std::string GetFullDescription

Returns a verbose human-readable description of port.

This is useful for error messages or debugging.

◆ HasValue()

bool HasValue ( const Context< T > & context ) const

Returns true iff this port is connected or has had a fixed value provided in the given Context.

Beware that at the moment, this could be an expensive operation, because the value is brought up-to-date as part of this operation.

◆ is_random()

bool is_random

Returns true if this is a random port.

◆ size()

int size

Returns the fixed size expected for a vector-valued port.

Not meaningful for abstract-valued ports.

◆ ticket()

DependencyTicket ticket

(Advanced.) Returns the DependencyTicket for this port within the owning System.

Friends And Related Function Documentation

◆ internal::FrameworkFactory

friend class internal::FrameworkFactory

friend

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

input_port.h