/*
* 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.metadata.Signature;
import com.facebook.presto.metadata.TypeVariableConstraint;
import com.facebook.presto.spi.function.WindowFunction;
import com.facebook.presto.spi.function.WindowFunctionSignature;
import com.facebook.presto.spi.type.TypeSignature;
import com.google.common.collect.ImmutableList;
import java.util.List;
import java.util.stream.Stream;
import static com.facebook.presto.metadata.FunctionKind.WINDOW;
import static com.facebook.presto.metadata.Signature.typeVariable;
import static com.facebook.presto.spi.type.TypeSignature.parseTypeSignature;
import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.collect.ImmutableList.toImmutableList;
public final class WindowAnnotationsParser
{
private WindowAnnotationsParser() {}
public static List<SqlWindowFunction> parseFunctionDefinition(Class<? extends WindowFunction> clazz)
{
WindowFunctionSignature[] signatures = clazz.getAnnotationsByType(WindowFunctionSignature.class);
checkArgument(signatures.length > 0, "Class is not annotated with @WindowFunctionSignature: %s", clazz.getName());
return Stream.of(signatures)
.map(signature -> parse(clazz, signature))
.collect(toImmutableList());
}
private static SqlWindowFunction parse(Class<? extends WindowFunction> clazz, WindowFunctionSignature window)
{
List<TypeVariableConstraint> typeVariables = ImmutableList.of();
if (!window.typeVariable().isEmpty()) {
typeVariables = ImmutableList.of(typeVariable(window.typeVariable()));
}
List<TypeSignature> argumentTypes = Stream.of(window.argumentTypes())
.map(TypeSignature::parseTypeSignature)
.collect(toImmutableList());
Signature signature = new Signature(
window.name(),
WINDOW,
typeVariables,
ImmutableList.of(),
parseTypeSignature(window.returnType()),
argumentTypes,
false);
return new SqlWindowFunction(new ReflectionWindowFunctionSupplier<>(signature, clazz));
}
}