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https://github.com/google/nomulus.git
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c458c05801
The dark lord Gosling designed the Java package naming system so that ownership flows from the DNS system. Since we own the domain name registry.google, it seems only appropriate that we should use google.registry as our package name.
109 lines
3.7 KiB
Java
109 lines
3.7 KiB
Java
// Copyright 2016 The Domain Registry Authors. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package google.registry.model;
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import static com.google.common.base.Preconditions.checkNotNull;
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import static com.google.common.base.Preconditions.checkState;
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import static google.registry.model.ofy.ObjectifyService.ofy;
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import com.google.common.base.Optional;
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import google.registry.model.ofy.ObjectifyService;
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import google.registry.util.TypeUtils.TypeInstantiator;
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import java.lang.reflect.Field;
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/** Interface for {@link ImmutableObject} subclasses that have a builder. */
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public interface Buildable {
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Builder<?> asBuilder();
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/**
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* Boilerplate for immutable builders.
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* <p>
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* This can be used without implementing {@link Buildable}.
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*/
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public abstract static class Builder<S> {
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private S instance;
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protected Builder() {
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this.instance = new TypeInstantiator<S>(getClass()){}.instantiate();
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// Only ImmutableObject is allowed, but enforcing that via the generics gets ugly.
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checkState(instance instanceof ImmutableObject);
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}
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protected Builder(S instance) {
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this.instance = checkNotNull(instance);
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}
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protected S getInstance() {
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return checkNotNull(instance, "Cannot modify state after calling 'build()'.");
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}
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/** Build the instance. */
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public S build() {
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try {
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// If this object has a Long or long Objectify @Id field that is not set, set it now.
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Field idField = null;
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try {
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idField = ModelUtils.getAllFields(instance.getClass()).get(
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ofy().factory().getMetadata(instance.getClass()).getKeyMetadata().getIdFieldName());
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} catch (Exception e) {
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// Expected if the class is not registered with Objectify.
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}
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if (idField != null
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&& !idField.getType().equals(String.class)
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&& Optional.fromNullable((Long) ModelUtils.getFieldValue(instance, idField))
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.or(0L) == 0) {
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ModelUtils.setFieldValue(instance, idField, ObjectifyService.allocateId());
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}
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return instance;
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} finally {
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// Clear the internal instance so you can't accidentally mutate it through this builder.
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instance = null;
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}
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}
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}
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/** Boilerplate for abstract immutable builders that need to be able to cast "this". */
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public abstract class GenericBuilder<S, B extends GenericBuilder<?, ?>> extends Builder<S> {
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protected GenericBuilder() {}
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protected GenericBuilder(S instance) {
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super(instance);
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}
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@SuppressWarnings("unchecked")
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protected B thisCastToDerived() {
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return (B) this;
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}
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}
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/**
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* Interface for objects that can produce an "overlay", which means a copy where non-null fields
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* from another object are copied over, but null fields on the source are not.
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* <p>
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* Warning: Do not use {@code emptyToNull} methods in the getters of an {@link Overlayable}! We
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* use null to mean "skip this field" whereas empty means "set this field to empty", so they are
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* semantically different.
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*
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* @param <T> the derived type
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*/
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public interface Overlayable<T> extends Buildable {
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/** Return an overlay of this object using non-null fields from the source. */
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T overlay(T source);
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}
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}
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