filebot/source/net/filebot/Resource.java

58 lines
1.1 KiB
Java

package net.filebot;
import java.util.function.Function;
@FunctionalInterface
public interface Resource<R> {
R get() throws Exception;
default Resource<R> memoize() {
return new MemoizedResource<R>(this);
}
default <T> Resource<T> transform(Function<R, T> function) {
return new TransformedResource<R, T>(this, function);
}
static <T> Resource<T> lazy(Resource<T> resource) {
return resource.memoize();
}
}
class MemoizedResource<R> implements Resource<R> {
private final Resource<R> resource;
private R value;
public MemoizedResource(Resource<R> resource) {
this.resource = resource;
}
@Override
public synchronized R get() throws Exception {
if (value == null) {
value = resource.get();
}
return value;
}
}
class TransformedResource<R, T> implements Resource<T> {
private final Resource<R> resource;
private final Function<R, T> function;
public TransformedResource(Resource<R> resource, Function<R, T> function) {
this.resource = resource;
this.function = function;
}
@Override
public T get() throws Exception {
return function.apply(resource.get());
}
}