org.epics.pvmanager
Class ExpressionLanguage.Filter<T>

java.lang.Object
  org.epics.pvmanager.ExpressionLanguage.Filter<T>

Type Parameters:

T - the type to cast to before the filtering

Enclosing class:

ExpressionLanguage

public abstract static class ExpressionLanguage.Filter<T>
extends java.lang.Object

Filters a data stream, removing updates that match the given function. Looks for objects of a specific type, and filters based on previous and current value.

ExpressionLanguage.Filter

public ExpressionLanguage.Filter(java.lang.Class<T> clazz)

Creates a filter which looks for and cases data objects of the given class.

Parameters:

clazz - the argument type of the filter

ExpressionLanguage.Filter

public ExpressionLanguage.Filter(java.lang.Class<T> clazz,
                                 boolean filterUnmatched)

Creates a filter which looks for and cases data objects of the given class. If objects do not match, returns filterUnmatched.

Parameters:

clazz - the argument type of the filter

filterUnmatched - whether objects that don't match the class should be filtered or not

filter

public abstract boolean filter(T previousValue,
                               T currentValue)

Determines whether the new value should be filtered or not. The filtering is done based on the previousValue, which is always a value that passed the filtering. The first value ever to be passed to the filter will have null for previousValue.

Parameters:

previousValue - the previous data update

currentValue - the current data update

Returns:

true if the current data update should be dropped

and

public ExpressionLanguage.Filter<?> and(ExpressionLanguage.Filter<?> filter)

Returns a new filter that is the logical AND of this and the given one.

Parameters:

filter - another filter

Returns:

a new filter that is the AND of the two

or

public ExpressionLanguage.Filter<?> or(ExpressionLanguage.Filter<?> filter)

Returns a new filter that is the logical OR of this and the given one.

Parameters:

filter - another filter

Returns:

a new filter that is the OR of the two