com.umbraltech.rxchange.adapter.collections.ListChangeAdapter Maven / Gradle / Ivy
/*
* Copyright 2018 - present, RxChange contributors
*
* 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.umbraltech.rxchange.adapter.collections;
import com.google.common.collect.ImmutableList;
import com.umbraltech.rxchange.message.ChangeMessage;
import com.umbraltech.rxchange.message.MetaChangeMessage;
import com.umbraltech.rxchange.type.ChangeType;
import io.reactivex.Observable;
import io.reactivex.subjects.PublishSubject;
import java.util.ArrayList;
import java.util.List;
/**
* An adapter that implements the reactive change model for lists
*
* @param the type of data held by the list
*/
public class ListChangeAdapter {
private final PublishSubject>> publishSubject = PublishSubject.create();
private final List dataList = new ArrayList<>();
/**
* Default constructor
*/
public ListChangeAdapter() {
// Stub
}
/**
* Initializes the adapter with a list of elements, without emitting a change message
*
* @param initialDataList the initial list of elements
*/
public ListChangeAdapter(final List initialDataList) {
dataList.addAll(initialDataList);
}
/**
* Adds an element to the list and emits a change message to surrounding observers
*
* The metadata in the emitted change message will contain the element that was just added
*
* @param data the data to be added to the list
* @return {@code true} always
*/
public boolean add(final D data) {
final List oldListSnapshot = ImmutableList.copyOf(dataList);
dataList.add(data);
final List newListSnapshot = ImmutableList.copyOf(dataList);
// Signal addition
publishSubject.onNext(new MetaChangeMessage<>(oldListSnapshot, newListSnapshot, ChangeType.ADD, data));
return true;
}
/**
* Adds an element to the list at the specified index and emits a change message to surrounding observers
*
* The metadata in the emitted change message will contain the element that was just added
*
* @param index the index at which the element is added
* @param data the data to be added to the list
* @return {@code true} if the data was added to the list, {@code false} otherwise
*/
public boolean addAt(final int index, final D data) {
// Validate index
if (index < 0 || index > dataList.size()) {
return false;
}
final List oldListSnapshot = ImmutableList.copyOf(dataList);
dataList.add(index, data);
final List newListSnapshot = ImmutableList.copyOf(dataList);
// Signal addition
publishSubject.onNext(new MetaChangeMessage<>(oldListSnapshot, newListSnapshot, ChangeType.ADD, data));
return true;
}
/**
* Adds a list of elements and emits a change message to surrounding observers
*
* The metadata in the emitted change message will contain a snapshot of the list
* of elements that were just added
*
* @param dataList the list of elements to be added
* @return {@code true} always
*/
public boolean addAll(final List dataList) {
final List oldListSnapshot = ImmutableList.copyOf(this.dataList);
this.dataList.addAll(dataList);
final List newListSnapshot = ImmutableList.copyOf(this.dataList);
final List changeSnapshot = ImmutableList.copyOf(dataList);
// Signal addition
publishSubject.onNext(new MetaChangeMessage<>(oldListSnapshot, newListSnapshot, ChangeType.ADD,
changeSnapshot));
return true;
}
/**
* Removes the specified element and emits a change message to surrounding observers
*
* The metadata in the emitted change message will contain the element that was just removed
*
* @param data the element to be removed
* @return {@code true} if the element was removed, {@code false} otherwise
*/
public boolean remove(final D data) {
// Validate item
if (!dataList.contains(data)) {
return false;
}
final List oldListSnapshot = ImmutableList.copyOf(dataList);
dataList.remove(data);
final List newListSnapshot = ImmutableList.copyOf(dataList);
// Signal removal
publishSubject.onNext(new MetaChangeMessage<>(oldListSnapshot, newListSnapshot, ChangeType.REMOVE, data));
return true;
}
/**
* Removes the element at a specified index and emits a change message to surrounding observers
*
* The metadata in the emitted change message will contain the element that was just removed
*
* @param index the index of the element to be removed
* @return {@code true} if the element was removed, {@code false} otherwise
*/
public boolean removeAt(final int index) {
// Validate index
if ((index < 0) || (index >= dataList.size())) {
return false;
}
final List oldListSnapshot = ImmutableList.copyOf(dataList);
final D data = dataList.remove(index);
final List newListSnapshot = ImmutableList.copyOf(dataList);
// Signal removal
publishSubject.onNext(new MetaChangeMessage<>(oldListSnapshot, newListSnapshot, ChangeType.REMOVE, data));
return true;
}
/**
* Removes the specified list of elements and emits a change message to surrounding observers
*
* The metadata in the emitted change message will contain the collection that was just removed
*
* @param dataList the list of elements to be removed
* @return {@code true} if all of the elements removed, {@code false} otherwise
*/
public boolean removeAll(final List dataList) {
// Validate items
if (!this.dataList.containsAll(dataList)) {
return false;
}
final List oldListSnapshot = ImmutableList.copyOf(this.dataList);
this.dataList.removeAll(dataList);
final List newListSnapshot = ImmutableList.copyOf(this.dataList);
final List changeSnapshot = ImmutableList.copyOf(dataList);
// Signal removal
publishSubject.onNext(new MetaChangeMessage<>(oldListSnapshot, newListSnapshot, ChangeType.REMOVE,
changeSnapshot));
return true;
}
/**
* Updates the element at the specified index with new data
*
* The metadata in the emitted change message will contain the value
* of the element that was just updated
*
* @param index the index of the element within the list
* @param data the new data for the element
* @return {@code true} if the element was updated, {@code false} otherwise
*/
public boolean update(final int index, final D data) {
// Validate index
if ((index < 0) || (index >= dataList.size())) {
return false;
}
final List oldListSnapshot = ImmutableList.copyOf(dataList);
dataList.set(index, data);
final List newListSnapshot = ImmutableList.copyOf(dataList);
// Signal update
publishSubject.onNext(new MetaChangeMessage<>(oldListSnapshot, newListSnapshot, ChangeType.UPDATE, data));
return true;
}
/**
* Returns the value of the element within the list
*
* @param index the index of the element
* @return the element at the specified index
*/
public D get(final int index) {
return dataList.get(index);
}
/**
* Returns an immutable snapshot of the current list
*
* @return the list of elements
*/
public List getAll() {
return ImmutableList.copyOf(dataList);
}
/**
* Returns a reference to the observable used for listening to change messages
*
* @return the observable reference
*/
public Observable>> getObservable() {
return publishSubject;
}
}