package org.glassfish.pfl.basic.func ;
public interface NullaryPredicate {
public boolean evaluate() ;
public class Factory {
private Factory() {}
public static NullaryPredicate makeConstant( final boolean value ) {
return new NullaryPredicate() {
@Override
public boolean evaluate() {
return value ;
}
} ;
}
public static NullaryPredicate makeFuture(
final NullaryPredicate closure ) {
return new NullaryPredicate() {
private boolean evaluated = false ;
private boolean value ;
@Override
public synchronized boolean evaluate()
{
if (!evaluated) {
evaluated = true ;
value = closure.evaluate() ;
}
return value ;
}
} ;
}
}
}