Package org.antlr.v4.runtime.atn

Class OpenAddressedHashSet<E>

java.lang.Object

java.util.AbstractCollection<E>

java.util.AbstractSet<E>

org.antlr.v4.runtime.atn.OpenAddressedHashSet<E>

Type Parameters:

E - element type (value equality via Object.equals(java.lang.Object) / Object.hashCode(), matching HPPC's default strategy)

All Implemented Interfaces:

Iterable<E>, Collection<E>, Set<E>

final class OpenAddressedHashSet<E>
extends AbstractSet<E>

Package-private JDK Set over an open-addressed HPPC table with O(1) empty clear().

Used on the epsilon-closure busy-set hot path so production code keeps the open-addressed storage (no per-element entry objects) while every public/protected API surface speaks only JDK collection interfaces. Subclasses of ParserATNSimulator therefore override ParserATNSimulator.closure(ATNConfig, ATNConfigSet, ATNConfigSet, Set, boolean, boolean, PredictionContextCache, int, boolean) with a standard Set parameter and never depend on HPPC types.

PERF: add(E), contains(java.lang.Object), remove(java.lang.Object), clear(), size(), and isEmpty() are thin delegates. clear() is O(1) when the set is already empty (stock HPPC always fills the table); only a non-empty table pays bulk zero. The set object is allocated once per EpsilonClosure and retained across predictions; only the underlying open-addressed table grows.

Not part of the published API. Same-package tests exercise this type via EpsilonClosure.retainedBusy() and direct construction.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private final class	OpenAddressedHashSet.SnapshotIterator	Snapshot iterator over elements present when iterator() was called.

Field Summary

Fields

Modifier and Type	Field	Description
private final com.carrotsearch.hppc.ObjectHashSet<E>	storage	Open-addressed storage.

Constructor Summary

Constructors

Constructor	Description
OpenAddressedHashSet(int expectedElements)

Method Summary

Modifier and Type	Method	Description
boolean	add(E e)
void	clear()	Clears all elements.
boolean	contains(Object o)
boolean	isEmpty()
Iterator<E>	iterator()	Iterator over a snapshot of current members.
boolean	remove(Object o)
int	size()
Object[]	toArray()

Methods inherited from class java.util.AbstractSet

equals, hashCode, removeAll

Methods inherited from class java.util.AbstractCollection

addAll, containsAll, retainAll, toArray, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.Collection

parallelStream, removeIf, stream, toArray

Methods inherited from interface java.lang.Iterable

forEach

Methods inherited from interface java.util.Set

addAll, containsAll, retainAll, spliterator, toArray

Field Details

storage

private final com.carrotsearch.hppc.ObjectHashSet<E> storage

Open-addressed storage. Empty-fast clear() is implemented on this adapter (not a HPPC subclass) so stock ObjectHashSet remains monomorphic and retained busy sets skip bulk Arrays.fill when already empty.

Constructor Details

OpenAddressedHashSet

OpenAddressedHashSet(int expectedElements)

Parameters:

expectedElements - expected element count used as a capacity hint for the underlying open-addressed table (same contract as ObjectHashSet(int))

Method Details

add

public boolean add(E e)

Specified by:

add in interface Collection<E>

Specified by:

add in interface Set<E>

Overrides:

add in class AbstractCollection<E>

contains

public boolean contains(Object o)

Specified by:

contains in interface Collection<E>

Specified by:

contains in interface Set<E>

Overrides:

contains in class AbstractCollection<E>

remove

public boolean remove(Object o)

Specified by:

remove in interface Collection<E>

Specified by:

remove in interface Set<E>

Overrides:

remove in class AbstractCollection<E>

clear

public void clear()

Clears all elements. Already-empty sets return immediately without touching HPPC's open-addressed table (stock ObjectHashSet.clear() always bulk-fills).

Specified by:

clear in interface Collection<E>

Specified by:

clear in interface Set<E>

Overrides:

clear in class AbstractCollection<E>

size

public int size()

Specified by:

size in interface Collection<E>

Specified by:

size in interface Set<E>

Specified by:

size in class AbstractCollection<E>

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface Collection<E>

Specified by:

isEmpty in interface Set<E>

Overrides:

isEmpty in class AbstractCollection<E>

toArray

public Object[] toArray()

Specified by:

toArray in interface Collection<E>

Specified by:

toArray in interface Set<E>

Overrides:

toArray in class AbstractCollection<E>

iterator

public Iterator<E> iterator()

Iterator over a snapshot of current members. Iterator.remove() is supported by delegating to remove(Object). A snapshot avoids concurrent-modification hazards against HPPC's open-addressed table (whose native cursor iterator does not support removal).

Iteration order is unspecified and may change after structural modification, matching typical hash-set contracts. Snapshot iterators do not reflect elements added after the iterator was created.

Specified by:

iterator in interface Collection<E>

Specified by:

iterator in interface Iterable<E>

Specified by:

iterator in interface Set<E>

Specified by:

iterator in class AbstractCollection<E>