Package com.inductiveautomation.ignition.common.expressions

Class AbstractExpression

java.lang.Object

com.inductiveautomation.ignition.common.expressions.AbstractExpression

All Implemented Interfaces:

Expression

Direct Known Subclasses:

AbstractAlertExpressionContext.AlertVariableExpression, ArithmeticExpression, BitwiseExpression, BitwiseNot, BoundPropertyExpression, BoundPropertyExpression, BoundTagExpression, BoundVariableExpression, ComparisonExpression, EqualityExpression, FunctionExpression, LikeExpression, LogicalExpression, NonLocalizedToStringExpression, NotExpression, PropertyBasedExpressionParseContext.PropertyReferenceExpression, SubscriptExpression, TagPathReadExpression, TagReferenceBinder.SubscribedTagExpression, TagReferenceBinder.TagReadExpression, ToStringExpression, UMinusExpression

public abstract class AbstractExpression
extends Object
implements Expression

A base implementation of Expression that handles child management and lifecycle propagation.

Field Summary

Fields

Modifier and Type	Field	Description
protected Expression[]	children
protected CommonContext	context
protected InteractionListener	updateListener

Constructor Summary

Constructors

Constructor	Description
AbstractExpression()

Method Summary

Modifier and Type	Method	Description
void	connect(CommonContext context, InteractionListener updateListener)	Gives the expression a chance to connect itself to things, if necessary.
void	disconnect()	Tells the expression to disconnect from anything it was connected to.
Expression[]	getChildren()	The children (if any) that this expression is dependent on for its execution.
void	setChildren(Expression[] expressions)
void	shutdown()	Tells the expression to shutdown any polling operations.
void	startup()	Tells the expression to startup any polling operations.

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.inductiveautomation.ignition.common.expressions.Expression

execute, getOpName, getType

Field Details

children

protected Expression[] children

context

protected transient CommonContext context

updateListener

protected InteractionListener updateListener

Constructor Details

AbstractExpression

public AbstractExpression()

Method Details

getChildren

public Expression[] getChildren()

Description copied from interface: Expression

The children (if any) that this expression is dependent on for its execution.

Specified by:

getChildren in interface Expression

Returns:

an array of child Expressions, or an empty array if no children exist

setChildren

public void setChildren(Expression[] expressions)

connect

public void connect(CommonContext context,
 InteractionListener updateListener)

Description copied from interface: Expression

Gives the expression a chance to connect itself to things, if necessary. Most expressions do not have any connections. An expression should notify the updateListener if they change.

Specified by:

connect in interface Expression

Parameters:

context - the CommonContext used to look up external resources

updateListener - the InteractionListener to notify when the expression value changes

disconnect

public void disconnect()

Description copied from interface: Expression

Tells the expression to disconnect from anything it was connected to.

Specified by:

disconnect in interface Expression

shutdown

public void shutdown()

Description copied from interface: Expression

Tells the expression to shutdown any polling operations.

Specified by:

shutdown in interface Expression

startup

public void startup()

Description copied from interface: Expression

Tells the expression to startup any polling operations. Expressions that use this can remember the updateListener from connect() to feed update notification to.

Specified by:

startup in interface Expression