Package com.inductiveautomation.perspective.gateway.binding

Class PerspectiveExpression

java.lang.Object

com.inductiveautomation.perspective.gateway.binding.PerspectiveExpression

All Implemented Interfaces:

InteractionListener, ExpressionSourceStackMonitor

Direct Known Subclasses:

PerspectiveTransformExpression

public class PerspectiveExpression
extends Object
implements ExpressionSourceStackMonitor

Helper class that simplifies the creation and proper evaluation of expressions that execute in and around the binding / transform system.

Also simplifies the lifecycle so the user doesn't need to worry about the difference between startup/shutdown and connect/disconnect

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
protected static class	PerspectiveExpression.PerspectiveExpressionCommonContext

Field Summary

Fields

Modifier and Type	Field	Description
protected static final ELParserHarness	PARSER

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	PerspectiveExpression(BindingContext bindingContext, Expression expression, List<PropertyReference> references)

Method Summary

Modifier and Type	Method	Description
void	childInteractionUpdated()
void	childInteractionUpdated(List<Object> sourceStack)
static PerspectiveExpression	create(BindingContext context, String source)
void	evaluateExpression()	Submits evaluation task to the executor
QualifiedValue	execute()	Synchronously calls execute on the expression, on calling thread.
Collection<PropertyReference>	resolveReferences()
void	shutdown()
void	startup(Consumer<QualifiedValue> expressionValueCallback)
void	startup(Consumer<QualifiedValue> expressionValueCallback, Function<ExpressionException,QualifiedValue> errorHandler)	Connects and starts up the underlying expression.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

PARSER

protected static final ELParserHarness PARSER

Constructor Details

PerspectiveExpression

protected PerspectiveExpression(BindingContext bindingContext,
 Expression expression,
 List<PropertyReference> references)

Parameters:

bindingContext - The binding context

expression - The expression to evaluate

Method Details

create

public static PerspectiveExpression create(BindingContext context,
 String source)
                                    throws ConfigurationException

Throws:

ConfigurationException

execute

public QualifiedValue execute()
                       throws ExpressionException

Synchronously calls execute on the expression, on calling thread.

Throws:

ExpressionException

resolveReferences

public Collection<PropertyReference> resolveReferences()

startup

public void startup(Consumer<QualifiedValue> expressionValueCallback)

startup

public void startup(Consumer<QualifiedValue> expressionValueCallback,
 Function<ExpressionException,QualifiedValue> errorHandler)

Connects and starts up the underlying expression.

Parameters:

expressionValueCallback - Callback that will be invoked when the expression produces a value. Will be called at least once, meaning that the initial value will be produced immediately.

errorHandler - Will be invoked if the expression throws, must create a qualified value to use. Single-arg constructor just returns QualifiedValue.EXPRESSION_EVAL_ERROR

shutdown

public void shutdown()

childInteractionUpdated

public void childInteractionUpdated(List<Object> sourceStack)

Specified by:

childInteractionUpdated in interface ExpressionSourceStackMonitor

childInteractionUpdated

public void childInteractionUpdated()

Specified by:

childInteractionUpdated in interface InteractionListener

evaluateExpression

public void evaluateExpression()

Submits evaluation task to the executor