uk.co.strangeskies.expression

Class DependentExpression<T>

java.lang.Object

uk.co.strangeskies.expression.ActiveExpression<T>

uk.co.strangeskies.expression.DependentExpression<T>

Type Parameters:

T - The type of the expression.

All Implemented Interfaces:

Expression<T>

Direct Known Subclasses:

LockingExpression

public abstract class DependentExpression<T>
extends ActiveExpression<T>

An expression which is dependent upon the evaluation of a number of other expressions.

Constructor Summary

Constructors

Constructor and Description
DependentExpression(java.util.Collection<? extends Expression<?>> dependencies)
DependentExpression(Expression<?>... dependencies)

Method Summary

Modifier and Type	Method and Description
protected <U> ExpressionDependency<U>	addDependency(Expression<U> dependency)
protected abstract T	evaluate()
T	getValueImpl(boolean dirty) Implementing classes should compute the value of the Expression here.

Methods inherited from class uk.co.strangeskies.expression.ActiveExpression

beginWrite, cancelChange, createObservable, endWrite, fireChange, getValue, invalidations, isChanging, write

Methods inherited from class java.lang.Object

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

Methods inherited from interface uk.co.strangeskies.expression.Expression

anonymize, decoupleValue, immutable, over, over

Constructor Detail

DependentExpression

public DependentExpression(java.util.Collection<? extends Expression<?>> dependencies)

DependentExpression

public DependentExpression(Expression<?>... dependencies)

Method Detail

addDependency

protected <U> ExpressionDependency<U> addDependency(Expression<U> dependency)

getValueImpl

public final T getValueImpl(boolean dirty)

Description copied from class: ActiveExpression

Implementing classes should compute the value of the Expression here. Read lock is guaranteed to be obtained. This method should never be invoked manually.

Specified by:

getValueImpl in class ActiveExpression<T>

Parameters:

dirty - Whether the expression has been mutated since this method was last invoked.

Returns:

The value of this Expression.

evaluate

protected abstract T evaluate()

Returns:

The value of this Expression as derived from the dependency Expressions.