org.antlr.v4.runtime.misc.OrderedHashSet Maven / Gradle / Ivy
/*
* Copyright (c) 2012-2017 The ANTLR Project. All rights reserved.
* Use of this file is governed by the BSD 3-clause license that
* can be found in the LICENSE.txt file in the project root.
*/
package org.antlr.v4.runtime.misc;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.List;
/** A HashMap that remembers the order that the elements were added.
* You can alter the ith element with set(i,value) too :) Unique list.
* I need the replace/set-element-i functionality so I'm subclassing
* LinkedHashSet.
*/
public class OrderedHashSet extends LinkedHashSet {
/** Track the elements as they are added to the set */
protected ArrayList elements = new ArrayList();
public T get(int i) {
return elements.get(i);
}
/** Replace an existing value with a new value; updates the element
* list and the hash table, but not the key as that has not changed.
*/
public T set(int i, T value) {
T oldElement = elements.get(i);
elements.set(i,value); // update list
super.remove(oldElement); // now update the set: remove/add
super.add(value);
return oldElement;
}
public boolean remove(int i) {
T o = elements.remove(i);
return super.remove(o);
}
/** Add a value to list; keep in hashtable for consistency also;
* Key is object itself. Good for say asking if a certain string is in
* a list of strings.
*/
@Override
public boolean add(T value) {
boolean result = super.add(value);
if ( result ) { // only track if new element not in set
elements.add(value);
}
return result;
}
@Override
public boolean remove(Object o) {
throw new UnsupportedOperationException();
}
@Override
public void clear() {
elements.clear();
super.clear();
}
@Override
public int hashCode() {
return elements.hashCode();
}
@Override
public boolean equals(Object o) {
if (!(o instanceof OrderedHashSet)) {
return false;
}
// System.out.print("equals " + this + ", " + o+" = ");
boolean same = elements!=null && elements.equals(((OrderedHashSet)o).elements);
// System.out.println(same);
return same;
}
@Override
public Iterator iterator() {
return elements.iterator();
}
/** Return the List holding list of table elements. Note that you are
* NOT getting a copy so don't write to the list.
*/
public List elements() {
return elements;
}
@Override
public Object clone() {
@SuppressWarnings("unchecked") // safe (result of clone)
OrderedHashSet dup = (OrderedHashSet)super.clone();
dup.elements = new ArrayList(this.elements);
return dup;
}
@Override
public Object[] toArray() {
return elements.toArray();
}
@Override
public String toString() {
return elements.toString();
}
}