*/
package org.opendaylight.yangtools.triemap;
-import java.util.Iterator;
-import java.util.Map.Entry;
-import java.util.NoSuchElementException;
+import com.google.common.base.VerifyException;
/**
- * Similar to Scala's ListMap. Stores a linked set of entries, guaranteed to contain unique entry keys.
+ * Similar to Scala's ListMap, this is a single-linked list of set of map entries. Aside from the java.util.Set
+ * contract, this class fulfills the requirements for an immutable map entryset.
*
* @author Robert Varga
*
*/
abstract class LNodeEntries<K, V> extends LNodeEntry<K, V> {
private static final class Single<K, V> extends LNodeEntries<K, V> {
- Single(final K k, final V v) {
- super(k, v);
- }
-
- @Override
- boolean isSingle() {
- return true;
+ Single(final K key, final V value) {
+ super(key, value);
}
@Override
}
private static final class Multiple<K, V> extends LNodeEntries<K, V> {
- // Modified during remove only
+ // Modified during remove only, otherwise final
LNodeEntries<K, V> next;
// Used in remove() only
- Multiple(final LNodeEntries<K, V> e) {
- this(e.getKey(), e.getValue(), null);
+ Multiple(final LNodeEntries<K, V> entry) {
+ this(entry.getKey(), entry.getValue(), null);
}
- Multiple(final K k, final V v, final LNodeEntries<K, V> next) {
- super(k, v);
+ Multiple(final K key, final V value, final LNodeEntries<K, V> next) {
+ super(key, value);
this.next = next;
}
- @Override
- boolean isSingle() {
- return next == null;
- }
-
@Override
LNodeEntries<K, V> next() {
return next;
}
}
- LNodeEntries(final K k, final V v) {
- super(k, v);
+ LNodeEntries(final K key, final V value) {
+ super(key, value);
}
static <K,V> LNodeEntries<K, V> map(final K k1, final V v1, final K k2, final V v2) {
return new Multiple<>(k1, v1, new Single<>(k2, v2));
}
- abstract boolean isSingle();
-
+ /**
+ * Return the remainder of this list. Useful for implementing Iterator-like contract. Null indicates there are no
+ * more entries.
+ *
+ * @return Remainder of this list, or null if nothing remains
+ */
abstract LNodeEntries<K, V> next();
final LNodeEntry<K, V> findEntry(final Equivalence<? super K> equiv, final K key) {
return new Multiple<>(key, value, this);
}
- final LNodeEntries<K, V> replace(final LNodeEntry<K, V> entry, final V v) {
- final LNodeEntries<K, V> removed = remove(entry);
- return removed == null ? new Single<>(entry.getKey(), v) : new Multiple<>(entry.getKey(), v, removed);
+ final LNodeEntries<K, V> replace(final LNodeEntry<K, V> entry, final V value) {
+ final LNodeEntries<K, V> removed;
+ return (removed = remove(entry)) == null ? new Single<>(entry.getKey(), value)
+ : new Multiple<>(entry.getKey(), value, removed);
}
final LNodeEntries<K, V> remove(final LNodeEntry<K, V> entry) {
return next();
}
+ // This will result in a list with a long tail, i.e last entry storing explicit null. Overhead is amortized
+ // against the number of entries. We do not retain chains shorter than two, so the worst-case overhead is
+ // half-a-reference for an entry.
final Multiple<K, V> ret = new Multiple<>(this);
Multiple<K, V> last = ret;
LNodeEntries<K, V> cur = next();
while (cur != null) {
- // We cannot use equals() here, as it is wired to key/value equality,
- // which we really do not want.
+ // We cannot use equals() here, as it is wired to key equality and we must never compare entries based on
+ // that property. This method is intended to remove a known reference, so identity is what we want.
if (entry == cur) {
last.next = cur.next();
return ret;
cur = cur.next();
}
- throw new IllegalStateException(String.format("Entry %s not found", entry));
- }
-
- // No need to specialize these two methods, as they are invoked only from a stable LNode, at which point it is
- // guaranteed to be a Multiple.
- final int size() {
- int sz = 1;
- for (LNodeEntries<?, ?> wlk = next(); wlk != null; wlk = wlk.next()) {
- sz++;
- }
- return sz;
- }
-
- final Iterator<Entry<K, V>> iterator() {
- return new NodeIterator<>(this);
- }
-
- static final class NodeIterator<K,V> implements Iterator<Entry<K, V>> {
- private LNodeEntries<K, V> n;
-
- NodeIterator(final LNodeEntries<K, V> n) {
- this.n = n;
- }
-
- @Override
- public boolean hasNext() {
- return n != null;
- }
-
- @Override
- public Entry<K, V> next() {
- if (n == null) {
- throw new NoSuchElementException();
- }
-
- final Entry<K, V> res = n;
- n = n.next();
- return res;
- }
+ throw new VerifyException(String.format("Failed to find entry %s", entry));
}
}
Code Review / yangtools.git / blobdiff