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package com.oracle.truffle.js.runtime.util;
import java.util.HashMap;
import com.oracle.truffle.api.CompilerDirectives.TruffleBoundary;
ES6-compliant hash map implementation.
/**
* ES6-compliant hash map implementation.
*/
public final class JSHashMap {
public interface Cursor {
Advances to the next entry.
Returns: true if a next entry exists, false if there is no next entry.
/**
* Advances to the next entry.
*
* @return {@code true} if a next entry exists, {@code false} if there is no next entry.
*/
boolean advance();
The key of the current entry.
/**
* The key of the current entry.
*/
Object getKey();
The value of the current entry.
/**
* The value of the current entry.
*/
Object getValue();
Copies the cursor (including the current state/entry).
/**
* Copies the cursor (including the current state/entry).
*/
Cursor copy();
}
private final HashMap<Object, Node> map;
private final Node head;
private Node tail;
@TruffleBoundary(allowInlining = true)
public JSHashMap() {
this.map = new HashMap<>();
Node dummy = new Node(null, null, null, null);
this.head = dummy;
this.tail = dummy;
}
@TruffleBoundary(allowInlining = true)
public int size() {
return map.size();
}
Insert new entry, if key does not already exist, otherwise update the existing entry's value.
/**
* Insert new entry, if key does not already exist, otherwise update the existing entry's value.
*/
@TruffleBoundary
public void put(Object key, Object value) {
Node newNode = new Node(key, value, null, null);
Node oldNode = map.putIfAbsent(key, newNode);
if (oldNode == null) {
newNode.setPrev(tail);
tail.setNext(newNode);
tail = newNode;
} else {
oldNode.setValue(value);
}
}
@TruffleBoundary
public Object get(Object key) {
Node node = map.get(key);
return node == null ? null : node.getValue();
}
@TruffleBoundary
public boolean has(Object key) {
return map.containsKey(key);
}
@TruffleBoundary
public boolean remove(Object key) {
Node node = map.remove(key);
if (node == null) {
return false;
} else {
unlink(node);
return true;
}
}
private void unlink(Node node) {
Node next = node.getNext();
Node prev = node.getPrev();
prev.setNext(next);
if (next != null) {
next.setPrev(prev);
} else {
tail = prev;
}
node.setEmpty();
}
@TruffleBoundary
public void clear() {
map.clear();
for (Node current = head.getNext(); current != null; current = current.getNext()) {
current.setEmpty();
}
head.setNext(null);
tail = head;
}
@TruffleBoundary
@Override
public String toString() {
return map.toString();
}
public Cursor getEntries() {
return new CursorImpl(head);
}
private static final class CursorImpl implements Cursor {
private Node current;
CursorImpl(Node head) {
this.current = head;
}
@Override
public boolean advance() {
if (current == null) {
return false;
} else {
// if current is no longer in the map, back up to a previous node still in the map
while (current.isEmpty() && current.getPrev() != null) {
current = current.getPrev();
}
Node next = current.getNext();
assert next == null || next.getKey() != null;
current = next;
return next != null;
}
}
@Override
public Object getKey() {
Object key = current.getKey();
assert key != null;
return key;
}
@Override
public Object getValue() {
Object value = current.getValue();
assert value != null;
return value;
}
@Override
public String toString() {
return "Cursor [current=" + current + "]";
}
@Override
public Cursor copy() {
return new CursorImpl(current);
}
}
private static final class Node {
private Object key;
private Object value;
private Node prev;
private Node next;
Node(Object key, Object value, Node prev, Node next) {
this.key = key;
this.value = value;
this.prev = prev;
this.next = next;
}
Object getKey() {
return key;
}
Object getValue() {
return value;
}
void setValue(Object value) {
this.value = value;
}
Node getPrev() {
return prev;
}
void setPrev(Node prev) {
this.prev = prev;
}
Node getNext() {
return next;
}
void setNext(Node next) {
this.next = next;
}
void setEmpty() {
this.key = null;
this.value = null;
}
boolean isEmpty() {
return this.key == null;
}
@Override
public String toString() {
return "Node [key=" + key + ", value=" + value + "]";
}
}
}