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Hedera™ Hashgraph SDK for Java
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/*-
*
* Hedera Java SDK
*
* Copyright (C) 2020 - 2024 Hedera Hashgraph, LLC
*
* 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.hedera.hashgraph.sdk;
import java.util.*;
/**
* Internal utility class for a new lockable list type.
*
* @param the lockable list type
*/
class LockableList implements Iterable {
private ArrayList list = new ArrayList<>();
private int index = 0;
private boolean locked = false;
/**
* Constructor.
*/
LockableList() {
}
/**
* Assign a list of items to this list instance.
*
* @param list the lockable list
*/
LockableList(ArrayList list) {
this.list = list;
}
/**
* Verify that this list instance is not locked.
*/
void requireNotLocked() {
if (locked) {
throw new IllegalStateException("Cannot modify a locked list");
}
}
/**
* Make sure that this list instance has the requested capacity.
*
* @param capacity the minimum capacity
* @return the updated list
*/
LockableList ensureCapacity(int capacity) {
list.ensureCapacity(capacity);
return this;
}
/**
* Assign a list to this list instance.
*
* @param list the lockable list to assign
* @return the updated list
*/
LockableList setList(List list) {
requireNotLocked();
this.list = new ArrayList<>(list);
this.index = 0;
return this;
}
/**
* Extract the lockable list.
*
* @return the lockable list
*/
ArrayList getList() {
return list;
}
/**
* Add items to this list instance.
*
* @param elements the items to add
* @return the updated list
*/
LockableList add(T ...elements) {
requireNotLocked();
for (var e : elements) {
list.add(e);
}
return this;
}
/**
* Add all items to this list instance.
*
* @param elements the list of items to add
* @return the updated list
*/
LockableList addAll(Collection elements) {
requireNotLocked();
list.addAll(elements);
return this;
}
/**
* Shuffle the list items.
*
* @return the updated list
*/
public LockableList shuffle() {
requireNotLocked();
Collections.shuffle(list);
return this;
}
/**
* Remove an item from this list instance.
*
* @param element the element to remove
* @return the updated list
*/
LockableList remove(T element) {
requireNotLocked();
list.remove(element);
return this;
}
/**
* Extract the current list.
*
* @return the current list item
*/
T getCurrent() {
return get(index);
}
/**
* Extract the next item.
*
* @return the next list item
*/
T getNext() {
return get(advance());
}
/**
* Get a specific list item.
*
* @param index the index of the item
* @return the item
*/
T get(int index) {
return list.get(index);
}
/**
* Assign an item at the specified index.
*
* @param index the index of the item
* @param item the item
* @return the updated list
*/
LockableList set(int index, T item) {
requireNotLocked();
if (index == list.size()) {
list.add(item);
} else {
list.set(index, item);
}
return this;
}
/**
* Assign an item to the list if:
* - item at index is null
* - index is not greater than size of existing list
*
* @param index the requested index
* @param item the item
* @return the updated list
*/
LockableList setIfAbsent(int index, T item) {
if (index == list.size() || list.get(index) == null) {
set(index, item);
}
return this;
}
/**
* Advance to the next item wraps if needed.
*
* @return the next index wrapped
*/
int advance() {
var index = this.index;
this.index = (this.index + 1) % list.size();
return index;
}
/**
* Is the list empty?
*
* @return is the list empty
*/
boolean isEmpty() {
return list.isEmpty();
}
/**
* Is the list locked?
*
* @return is the list locked
*/
boolean isLocked() {
return locked;
}
/**
* Assign the lock status.
*
* @param locked the lock status
* @return the updated list
*/
LockableList setLocked(boolean locked) {
this.locked = locked;
return this;
}
/**
* How many items are in the list.
*
* @return the size of the list
*/
int size() {
return list.size();
}
/**
* Assign the current list index.
*
* @param index the index
* @return the updated list
*/
LockableList setIndex(int index) {
this.index = index;
return this;
}
/**
* What is the current index.
*
* @return the index of the current item
*/
int getIndex() {
return index;
}
/**
* Empty the list.
*
* @return an empty list
*/
LockableList clear() {
requireNotLocked();
list.clear();
return this;
}
@Override
public Iterator iterator() {
return list.iterator();
}
}