ReflectionWindowFunctionSupplier.java
/*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.facebook.presto.operator.window;
import com.facebook.presto.common.QualifiedObjectName;
import com.facebook.presto.common.type.Type;
import com.facebook.presto.spi.function.Description;
import com.facebook.presto.spi.function.Signature;
import com.facebook.presto.spi.function.ValueWindowFunction;
import com.facebook.presto.spi.function.WindowFunction;
import com.google.common.collect.Lists;
import java.lang.reflect.AnnotatedElement;
import java.lang.reflect.Constructor;
import java.util.List;
import static com.facebook.presto.metadata.BuiltInTypeAndFunctionNamespaceManager.JAVA_BUILTIN_NAMESPACE;
import static com.facebook.presto.spi.function.FunctionKind.WINDOW;
import static java.util.Objects.requireNonNull;
public class ReflectionWindowFunctionSupplier<T extends WindowFunction>
extends AbstractWindowFunctionSupplier
{
private final Constructor<T> constructor;
public ReflectionWindowFunctionSupplier(String name, Type returnType, List<? extends Type> argumentTypes, Class<T> type)
{
this(new Signature(QualifiedObjectName.valueOf(JAVA_BUILTIN_NAMESPACE, name), WINDOW, returnType.getTypeSignature(), Lists.transform(argumentTypes, Type::getTypeSignature)), type);
}
public ReflectionWindowFunctionSupplier(Signature signature, Class<T> type)
{
super(signature, getDescription(requireNonNull(type, "type is null")));
try {
if (signature.getArgumentTypes().isEmpty()) {
constructor = type.getConstructor();
}
else {
constructor = type.getConstructor(List.class);
}
}
catch (NoSuchMethodException e) {
throw new RuntimeException(e);
}
}
@Override
protected T newWindowFunction(List<Integer> inputs, boolean ignoreNulls)
{
try {
T windowFunction;
if (getSignature().getArgumentTypes().isEmpty()) {
windowFunction = constructor.newInstance();
}
else {
windowFunction = constructor.newInstance(inputs);
}
if (windowFunction instanceof ValueWindowFunction) {
((ValueWindowFunction) windowFunction).setIgnoreNulls(ignoreNulls);
}
return windowFunction;
}
catch (ReflectiveOperationException e) {
throw new RuntimeException(e);
}
}
private static String getDescription(AnnotatedElement annotatedElement)
{
Description description = annotatedElement.getAnnotation(Description.class);
return (description == null) ? null : description.value();
}
}