uk.gov.gchq.gaffer.function.context.FunctionContext 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 com.fasterxml.jackson.annotation.JsonTypeInfo;
import uk.gov.gchq.gaffer.function.Function;
import java.io.Serializable;
/**
* A FunctionContext wraps a {@link uk.gov.gchq.gaffer.function.Function}. It appends application-specific configuration data to
* the function so that it can be executed in the context of that application.
*
* @param The type of {@link uk.gov.gchq.gaffer.function.Function} wrapped by the context.
* @see uk.gov.gchq.gaffer.function.processor.Processor for details of how FunctionContext is used.
*/
public abstract class FunctionContext implements Serializable {
private static final long serialVersionUID = -3469570249850928140L;
private F function;
/**
* Default constructor - used for serialisation.
*/
public FunctionContext() {
}
/**
* Create a FunctionContext that wraps a given {@link uk.gov.gchq.gaffer.function.Function}.
*
* @param function {@link uk.gov.gchq.gaffer.function.Function} to be wrapped by the context.
*/
public FunctionContext(final F function) {
setFunction(function);
}
/**
* @return {@link uk.gov.gchq.gaffer.function.Function} wrapped by this context.
*/
@JsonTypeInfo(use = JsonTypeInfo.Id.CLASS, include = JsonTypeInfo.As.PROPERTY, property = "class")
public F getFunction() {
return function;
}
/**
* @param function {@link uk.gov.gchq.gaffer.function.Function} to be wrapped by this context.
*/
public void setFunction(final F function) {
this.function = function;
}
/**
* Implementation of the Builder pattern for {@link uk.gov.gchq.gaffer.function.context.FunctionContext}.
*
* @param The type of {@link uk.gov.gchq.gaffer.function.Function} wrapped by the context.
*/
public abstract static class Builder {
private final FunctionContext context;
private boolean executed = false;
/**
* Create a Builder to configure a {@link uk.gov.gchq.gaffer.function.context.FunctionContext}.
*
* @param context {@link uk.gov.gchq.gaffer.function.context.FunctionContext} to be configured.
*/
public Builder(final FunctionContext context) {
this.context = context;
}
/**
* Sets the {@link uk.gov.gchq.gaffer.function.Function} to be wrapped by the context and returns this
* Builder for further configuration.
*
* @param function {@link uk.gov.gchq.gaffer.function.Function} to be wrapped by the context.
* @return This Builder.
*/
public Builder execute(final F function) {
if (!executed) {
context.setFunction(function);
executed = true;
} else {
throw new IllegalStateException("Function has already been set");
}
return this;
}
/**
* Tests whether the {@link uk.gov.gchq.gaffer.function.Function} to be wrapped has been configured.
*
* @return False until aggregate(F) is called, then true.
*/
public boolean isExecuted() {
return executed;
}
/**
* Build the {@link uk.gov.gchq.gaffer.function.context.FunctionContext} configured by this Builder.
*
* @return Configured {@link uk.gov.gchq.gaffer.function.context.FunctionContext}
*/
public FunctionContext build() {
return getContext();
}
/**
* Get the {@link uk.gov.gchq.gaffer.function.context.FunctionContext} configured by this Builder. Equivalent
* to build().
*
* @return Configured {@link uk.gov.gchq.gaffer.function.context.FunctionContext}
*/
public FunctionContext getContext() {
return context;
}
}
}