/*
* Copyright 2014-2016 the original author or authors.
*
* 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 org.springframework.data.mongodb.core.convert;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Optional;
import org.springframework.data.mongodb.core.mapping.MongoPersistentEntity;
import org.springframework.util.Assert;
import org.springframework.util.StringUtils;
/**
* A path of objects nested into each other. The type allows access to all parent objects currently in creation even
* when resolving more nested objects. This allows to avoid re-resolving object instances that are logically equivalent
* to already resolved ones.
* <p>
* An immutable ordered set of target objects for {@link Document} to {@link Object} conversions. Object paths can be
* constructed by the {@link #toObjectPath(Object)} method and extended via {@link #push(Object)}.
*
* @author Thomas Darimont
* @author Oliver Gierke
* @since 1.6
*/
class ObjectPath {
public static final ObjectPath ROOT = new ObjectPath();
private final List<ObjectPathItem> items;
private ObjectPath() {
this.items = Collections.emptyList();
}
/**
* Creates a new {@link ObjectPath} from the given parent {@link ObjectPath} by adding the provided
* {@link ObjectPathItem} to it.
*
* @param parent can be {@literal null}.
* @param item
*/
private ObjectPath(ObjectPath parent, ObjectPath.ObjectPathItem item) {
List<ObjectPath.ObjectPathItem> items = new ArrayList<ObjectPath.ObjectPathItem>(parent.items);
items.add(item);
this.items = Collections.unmodifiableList(items);
}
/**
* Returns a copy of the {@link ObjectPath} with the given {@link Object} as current object.
*
* @param object must not be {@literal null}.
* @param entity must not be {@literal null}.
* @param id must not be {@literal null}.
* @return
*/
public ObjectPath push(Object object, MongoPersistentEntity<?> entity, Object id) {
Assert.notNull(object, "Object must not be null!");
Assert.notNull(entity, "MongoPersistentEntity must not be null!");
ObjectPathItem item = new ObjectPathItem(object, id, entity.getCollection());
return new ObjectPath(this, item);
}
/**
* Returns the object with the given id and stored in the given collection if it's contained in the {@link ObjectPath}
* .
*
* @param id must not be {@literal null}.
* @param collection must not be {@literal null} or empty.
* @return
*/
public Object getPathItem(Object id, String collection) {
Assert.notNull(id, "Id must not be null!");
Assert.hasText(collection, "Collection name must not be null!");
for (ObjectPathItem item : items) {
Object object = item.getObject();
if (object == null) {
continue;
}
if (item.getIdValue() == null) {
continue;
}
if (collection.equals(item.getCollection()) && id.equals(item.getIdValue())) {
return object;
}
}
return null;
}
/**
* Returns the current object of the {@link ObjectPath} or {@literal null} if the path is empty.
*
* @return
*/
public Optional<Object> getCurrentObject() {
return items.isEmpty() ? Optional.empty() : Optional.of(items.get(items.size() - 1).getObject());
}
/*
* (non-Javadoc)
* @see java.lang.Object#toString()
*/
@Override
public String toString() {
if (items.isEmpty()) {
return "[empty]";
}
List<String> strings = new ArrayList<String>(items.size());
for (ObjectPathItem item : items) {
strings.add(item.object.toString());
}
return StringUtils.collectionToDelimitedString(strings, " -> ");
}
/**
* An item in an {@link ObjectPath}.
*
* @author Thomas Darimont
* @author Oliver Gierke
*/
private static class ObjectPathItem {
private final Object object;
private final Object idValue;
private final String collection;
/**
* Creates a new {@link ObjectPathItem}.
*
* @param object
* @param idValue
* @param collection
*/
ObjectPathItem(Object object, Object idValue, String collection) {
this.object = object;
this.idValue = idValue;
this.collection = collection;
}
public Object getObject() {
return object;
}
public Object getIdValue() {
return idValue;
}
public String getCollection() {
return collection;
}
}
}