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/*
* esodata - data structures and other things, of varying utility
* Copyright 2022, Ben Culkin
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
package bjc.esodata;
import java.util.*;
/**
* Implements a keyed list.
*
* @author bjcul
*
* @param <Key> The type of the key
* @param <Val> The type of the value
*/
public class KeyedList<Key, Val> implements Iterable<Val> {
private List<Val> backing;
private Map<Key, Integer> indices;
private int currIdx = 0;
/**
* Create a new keyed list
*/
public KeyedList() {
backing = new ArrayList<>();
indices = new HashMap<>();
}
/**
* Add a item to this list.
*
* If an item already exists with the given key, the current one will not be
* added. Use <code>set</code> to handle that.
*
* @param key The key for this item.
* @param val The value for this item
*
* @return Whether or not this item was added to the list
*/
public boolean add(Key key, Val val) {
// TODO: Determine if this is the desired behavior
if (indices.containsKey(key))
return false;
backing.add(val);
indices.put(key, currIdx++);
return true;
}
/**
* Set the item associated with a given key.
*
* @param key The key to set
* @param newVal The new value for the key
*
* @return The previous value for the key, if there was one
*/
public Val set(Key key, Val newVal) {
if (indices.containsKey(key)) {
return backing.set(indices.get(key), newVal);
}
add(key, newVal);
return null;
}
/**
* Retrieve all of the keys for this list.
*
* @return An immutable set of the keys for this list
*/
public Set<Key> keys() {
// TODO: write mutable wrapper which will update the list appropriately
return Collections.unmodifiableSet(indices.keySet());
}
/**
* Retrieve the value associated with the given key.
*
* @param key The key to look up.
*
* @return The value for the given key.
*/
public Val get(Key key) {
return backing.get(indices.get(key));
}
/**
* Check if this list contains a value for a given key.
*
* @param key The key to look up.
*
* @return Whether this list contains a value for the given key.
*/
public boolean containsKey(Key key) {
return indices.containsKey(key);
}
@Override
public Iterator<Val> iterator() {
return backing.iterator();
}
/**
* Return an iterator that starts at the value for the given key.'
*
* @param key The key to start at.
*
* @return An iterator starting at the given key, or null if the key isn't
* present.
*/
public ListIterator<Val> iteratorFrom(Key key) {
if (indices.containsKey(key)) {
return backing.listIterator(indices.get(key));
}
return null;
}
}
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