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authorMatthew Newhook <matthew@zeroc.com>2002-03-11 21:24:38 +0000
committerMatthew Newhook <matthew@zeroc.com>2002-03-11 21:24:38 +0000
commit6be9ce62c124247eacdea1ea41521252c25bd242 (patch)
tree3ed64e5b842da9be64a44c27be1088bfb77fe5ec /java/src/Freeze/LinkedList.java
parentchanging getProperty to return empty string instead of null (diff)
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added missing file.
Diffstat (limited to 'java/src/Freeze/LinkedList.java')
-rw-r--r--java/src/Freeze/LinkedList.java226
1 files changed, 226 insertions, 0 deletions
diff --git a/java/src/Freeze/LinkedList.java b/java/src/Freeze/LinkedList.java
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+++ b/java/src/Freeze/LinkedList.java
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+// **********************************************************************
+//
+// Copyright (c) 2001
+// MutableRealms, Inc.
+// Huntsville, AL, USA
+//
+// All Rights Reserved
+//
+// **********************************************************************
+
+package Freeze;
+
+//
+// Stripped down LinkedList implementation for use in the Evictor. The
+// API is similar to java.util.LinkedList.
+//
+// Major differences:
+// * listIterator() is not implemented.
+// * Operation riterator() returns a reverse iterator.
+// * This implementation also has the property that an Iterator can be
+// retained over structural changes to the list itself (similar to an
+// STL list).
+//
+class LinkedList
+{
+ public
+ LinkedList()
+ {
+ _header.next = _header.previous = _header;
+ }
+
+ public Object
+ getFirst()
+ {
+ if (_size == 0)
+ {
+ throw new java.util.NoSuchElementException();
+ }
+
+ return _header.next.element;
+ }
+
+ public void
+ addFirst(Object o)
+ {
+ addBefore(o, _header.next);
+ }
+
+ public boolean
+ isEmpty()
+ {
+ return _size == 0;
+ }
+
+ public int
+ size()
+ {
+ return _size;
+ }
+
+ public java.util.Iterator
+ iterator()
+ {
+ return new ForwardIterator();
+ }
+
+ public java.util.Iterator
+ riterator()
+ {
+ return new ReverseIterator();
+ }
+
+ private class ForwardIterator implements java.util.Iterator
+ {
+ public boolean
+ hasNext()
+ {
+ return _next != null;
+ }
+
+ public Object
+ next()
+ {
+ if (_next == null)
+ {
+ throw new java.util.NoSuchElementException();
+ }
+
+ _current = _next;
+
+ if (_next.next != _header)
+ {
+ _next = _next.next;
+ }
+ else
+ {
+ _next = null;
+ }
+ return _current.element;
+ }
+
+ public void
+ remove()
+ {
+ if (_current == null)
+ {
+ throw new IllegalStateException();
+ }
+ LinkedList.this.remove(_current);
+ _current = null;
+ }
+
+ ForwardIterator()
+ {
+ if (_header.next == _header)
+ {
+ _next = null;
+ }
+ else
+ {
+ _next = _header.next;
+ }
+ _current = null;
+ }
+
+ private Entry _current;
+ private Entry _next;
+ }
+
+ private class ReverseIterator implements java.util.Iterator
+ {
+ public boolean
+ hasNext()
+ {
+ return _next != null;
+ }
+
+ public Object
+ next()
+ {
+ if (_next == null)
+ {
+ throw new java.util.NoSuchElementException();
+ }
+
+ _current = _next;
+
+ if (_next.previous != _header)
+ {
+ _next = _next.previous;
+ }
+ else
+ {
+ _next = null;
+ }
+ return _current.element;
+ }
+
+ public void
+ remove()
+ {
+ if (_current == null)
+ {
+ throw new IllegalStateException();
+ }
+ LinkedList.this.remove(_current);
+ _current = null;
+ }
+
+ ReverseIterator()
+ {
+ if (_header.next == _header)
+ {
+ _next = null;
+ }
+ else
+ {
+ _next = _header.previous;
+ }
+ _current = null;
+ }
+
+ private Entry _current;
+ private Entry _next;
+ }
+
+ private static class Entry
+ {
+ Object element;
+ Entry next;
+ Entry previous;
+
+ Entry(Object element, Entry next, Entry previous)
+ {
+ this.element = element;
+ this.next = next;
+ this.previous = previous;
+ }
+ }
+
+ private Entry
+ addBefore(Object o, Entry e)
+ {
+ Entry newEntry = new Entry(o, e, e.previous);
+ newEntry.previous.next = newEntry;
+ newEntry.next.previous = newEntry;
+ _size++;
+ return newEntry;
+ }
+
+ private void
+ remove(Entry e)
+ {
+ if (e == _header)
+ {
+ throw new java.util.NoSuchElementException();
+ }
+
+ e.previous.next = e.next;
+ e.next.previous = e.previous;
+ _size--;
+ }
+
+ private Entry _header = new Entry(null, null, null);
+ private int _size = 0;
+}