com.mantledillusion.vaadin.metrics.MetricsPredicate Maven / Gradle / Ivy
package com.mantledillusion.vaadin.metrics;
import com.mantledillusion.vaadin.metrics.api.Metric;
/**
* A stateless predicate for {@link Metric}s.
*
* A {@link MetricsPredicate} is able to cause a {@link AbstractMetricsQueue}
* to hold all of a session's events back until a {@link Metric} occurs that
* flushes the accumulated events.
*
* In contract to a {@link MetricsValve}, a predicate is stateless, so it reacts
* on every {@link Metric} individually and might close again after it has been
* opened.
*/
@FunctionalInterface
public interface MetricsPredicate {
/**
* Tests whether the given event matched this predicate.
*
* @param metric The event to test; might not be null.
* @return True if the predicate is fulfilled, false otherwise.
*/
boolean test(Metric metric);
/**
* Returns a clone of this predicate that reacts the same as this predicate
* does, but is stateless, so the state it might possibly have is not cloned.
*
* @return A functional clone, never null
*/
default MetricsPredicate functionalClone() {
return this;
}
/**
* Combines this predicate with the given one to an AND conjunction.
*
* Functionally equals the Java {@code &&} modifier.
*
* @param other The other predicate to combine with; might not be null.
* @return A new {@link MetricsPredicate} instance, containing both this and the
* given predicate for its {@link #test(Metric)}, never null
*/
default MetricsPredicate and(MetricsPredicate other) {
if (other == null) {
throw new IllegalArgumentException("Cannot create an AND conjunction with a null second predicate");
}
MetricsPredicate base = this;
return new MetricsPredicate() {
@Override
public boolean test(Metric metric) {
return base.test(metric) && other.test(metric);
}
@Override
public MetricsPredicate functionalClone() {
MetricsPredicate baseClone = base.functionalClone();
MetricsPredicate otherClone = other.functionalClone();
return baseClone.and(otherClone);
}
};
}
/**
* Combines this predicate with the given one to an OR conjunction.
*
* Functionally equals the Java {@code ||} modifier.
*
* @param other The other predicate to combine with; might not be null.
* @return A new {@link MetricsPredicate} instance, containing both this and the
* given predicate for its {@link #test(Metric)}, never null
*/
default MetricsPredicate or(MetricsPredicate other) {
if (other == null) {
throw new IllegalArgumentException("Cannot create an OR conjunction with a null second predicate");
}
MetricsPredicate base = this;
return new MetricsPredicate() {
@Override
public boolean test(Metric metric) {
return base.test(metric) || other.test(metric);
}
@Override
public MetricsPredicate functionalClone() {
MetricsPredicate baseClone = base.functionalClone();
MetricsPredicate otherClone = other.functionalClone();
return baseClone.or(otherClone);
}
};
}
/**
* Turns this (possibly stateless) {@link MetricsPredicate} into a stateful
* {@link MetricsValve}.
*
* @return A new {@link MetricsValve} containing this {@link MetricsPredicate}
* for its {@link #test(Metric)}, never null
*/
default MetricsValve asValve() {
return MetricsValve.of(this);
}
}