uk.gov.gchq.gaffer.function.context.PassThroughFunctionContext Maven / Gradle / Ivy
/*
* Copyright 2016 Crown Copyright
*
* 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 uk.gov.gchq.gaffer.function.context;
import uk.gov.gchq.gaffer.function.ConsumerProducerFunction;
import uk.gov.gchq.gaffer.function.Tuple;
import java.util.List;
/**
* A PassThroughFunctionContext extends a {@link uk.gov.gchq.gaffer.function.context.ConsumerFunctionContext} to wrap
* a {@link uk.gov.gchq.gaffer.function.ConsumerProducerFunction} where the consumed and produced data have the same structure
* (they have the same references and types). This is effectively equivalent to a
* {@link uk.gov.gchq.gaffer.function.context.ConsumerProducerFunctionContext} where the selection and projection references must
* be identical - PassThroughFunctionContext enforces that constraint.
*
* @param The type of reference used to select from and project into tuples in this context.
* @param The type of {@link uk.gov.gchq.gaffer.function.ConsumerProducerFunction} wrapped by the context.
*/
public class PassThroughFunctionContext extends ConsumerFunctionContext {
private static final long serialVersionUID = -823429611092360995L;
/**
* Default constructor - used for serialisation.
*/
public PassThroughFunctionContext() {
}
/**
* Create a PassThroughFunctionContext that wraps a
* {@link uk.gov.gchq.gaffer.function.ConsumerProducerFunction}, using the specified references for selection and projection.
*
* @param function {@link uk.gov.gchq.gaffer.function.ConsumerProducerFunction} to be wrapped by the context.
* @param selection References to select and project data.
*/
public PassThroughFunctionContext(final F function, final List selection) {
super(function, selection);
}
/**
* Project data into an output {@link uk.gov.gchq.gaffer.function.Tuple}.
*
* @param tuple Output tuple to project into.
* @param values Results to project.
*/
public void project(final Tuple tuple, final Object[] values) {
int i = 0;
for (final R reference : getSelection()) {
Object value = i < values.length ? values[i] : null;
tuple.put(reference, value);
i++;
}
}
/**
* Implementation of the Builder pattern for {@link uk.gov.gchq.gaffer.function.context.PassThroughFunctionContext}.
*
* @param The type of reference used to select from and project into tuples in the context.
* @param The type of {@link uk.gov.gchq.gaffer.function.ConsumerProducerFunction} wrapped by the context.
*/
public static class Builder extends ConsumerFunctionContext.Builder {
/**
* Create a Builder to configure a new
* {@link uk.gov.gchq.gaffer.function.context.PassThroughFunctionContext}.
*/
public Builder() {
this(new PassThroughFunctionContext());
}
/**
* Create a Builder to configure a {@link uk.gov.gchq.gaffer.function.context.PassThroughFunctionContext}.
*
* @param context {@link uk.gov.gchq.gaffer.function.context.PassThroughFunctionContext} to be configured.
*/
public Builder(final PassThroughFunctionContext context) {
super(context);
}
@Override
public Builder select(final R... newSelection) {
return (Builder) super.select(newSelection);
}
@Override
public Builder execute(final F function) {
return (Builder) super.execute(function);
}
@Override
public PassThroughFunctionContext build() {
return getContext();
}
@Override
public PassThroughFunctionContext getContext() {
return (PassThroughFunctionContext) super.getContext();
}
}
}