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HHH-14882 StandardStack needs to support null entries

This commit is contained in:
Sanne Grinovero 2021-10-18 11:35:45 +01:00 committed by Sanne Grinovero
parent ef3fe11ae6
commit 9dd6cd06c9
1 changed files with 19 additions and 6 deletions
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25
hibernate-core/src/main/java/org/hibernate/internal/util/collections/StandardStack.java
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@ -10,25 +10,31 @@ import java.util.ArrayDeque;
import java.util.Deque;
/**
* A general-purpose stack impl.
* A general-purpose stack impl supporting null values.
*
* @param <T> The type of things stored in the stack
*
* @author Steve Ebersole
* @author Sanne Grinovero
*/
public final class StandardStack<T> implements Stack<T> {
private ArrayDeque<T> internalStack;
private ArrayDeque internalStack;
private static final Object NULL_TOKEN = new Object();
public StandardStack() {
}
@Override
public void push(T newCurrent) {
stackInstanceExpected().addFirst( newCurrent );
Object toStore = newCurrent;
if ( newCurrent == null ) {
toStore = NULL_TOKEN;
}
stackInstanceExpected().addFirst( toStore );
}
private Deque<T> stackInstanceExpected() {
private Deque stackInstanceExpected() {
if ( internalStack == null ) {
//"7" picked to use 8, but skipping the odd initialCapacity method
internalStack = new ArrayDeque<>(7);
@ -38,7 +44,14 @@ public final class StandardStack<T> implements Stack<T> {
@Override
public T pop() {
return stackInstanceExpected().removeFirst();
return convert( stackInstanceExpected().removeFirst() );
}
private T convert(final Object internalStoredObject) {
if ( internalStoredObject == NULL_TOKEN ) {
return null;
}
return (T) internalStoredObject;
}
@Override
@ -46,7 +59,7 @@ public final class StandardStack<T> implements Stack<T> {
if ( internalStack == null ) {
return null;
}
return internalStack.peek();
return convert( internalStack.peek() );
}
@Override