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From "offbynull (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (LANG-864) Collection wrappers to for unmodifiable / nonnull-safe collections
Date Fri, 28 Dec 2012 06:28:12 GMT

     [ https://issues.apache.org/jira/browse/LANG-864?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

offbynull updated LANG-864:
---------------------------

    Summary: Collection wrappers to for unmodifiable / nonnull-safe collections  (was: Collection
wrappers to for unmodifiable / null-safe collections)
    
> Collection wrappers to for unmodifiable / nonnull-safe collections
> ------------------------------------------------------------------
>
>                 Key: LANG-864
>                 URL: https://issues.apache.org/jira/browse/LANG-864
>             Project: Commons Lang
>          Issue Type: New Feature
>            Reporter: offbynull
>            Priority: Minor
>
> Would it be possible to add something like this to commons lang? Commons collection looks
like it's pretty much dead, and the only alternative for this kind of stuff is Google's horribly
designed and massively confusing Guava library.
> Below are a couple of quick and dirty (untested) examples of the kind of wrappers I'm
talking about. Note the isLocked/locked methods and the viewBlacklist method. Using these
methods, it's easy for a component receiving a list/set to identify that it's currently unmodifiable
and that the collection restricts certain values (e.g. null? maybe others?).
> {code}
> public final class LockableBlacklistableList<T> implements List<T> {
>     private boolean locked;
>     private List<T> list;
>     private Set<T> blacklist;
>     public LockableBlacklistableList(List<T> backingList, T... blacklist) {
>         if (backingList == null) {
>             throw new NullPointerException();
>         }
>         if (!backingList.isEmpty()) {
>             throw new IllegalArgumentException();
>         }
>         this.blacklist = new HashSet<>(Arrays.asList(blacklist));
>         this.list = backingList;
>     }
>     public void lock() {
>         locked = true;
>     }
>     public boolean isLocked() {
>         return locked;
>     }
>     public Set<T> viewBlacklist() {
>         return Collections.unmodifiableSet(blacklist);
>     }
>     @Override
>     public int size() {
>         return list.size();
>     }
>     @Override
>     public boolean isEmpty() {
>         return list.isEmpty();
>     }
>     @Override
>     public boolean contains(Object o) {
>         return list.contains(o);
>     }
>     @Override
>     public Iterator<T> iterator() {
>         final Iterator<T> it = list.iterator();
>         return new Iterator<T>() {
>             @Override
>             public boolean hasNext() {
>                 return it.hasNext();
>             }
>             @Override
>             public T next() {
>                 return it.next();
>             }
>             @Override
>             public void remove() {
>                 if (locked) {
>                     throw new IllegalStateException();
>                 }
>                 it.remove();
>             }
>         };
>     }
>     @Override
>     public Object[] toArray() {
>         return list.toArray();
>     }
>     @Override
>     public <T> T[] toArray(T[] a) {
>         return list.toArray(a);
>     }
>     @Override
>     public boolean add(T e) {
>         if (locked) {
>             throw new IllegalStateException();
>         }
>         return list.add(e);
>     }
>     @Override
>     public boolean remove(Object o) {
>         if (locked) {
>             throw new IllegalStateException();
>         }
>         return list.remove(o);
>     }
>     @Override
>     public boolean containsAll(Collection<?> c) {
>         return list.containsAll(c);
>     }
>     @Override
>     public boolean addAll(Collection<? extends T> c) {
>         if (locked) {
>             throw new IllegalStateException();
>         }
>         for (T item : c) {
>             if (blacklist.contains(item)) {
>                 throw new IllegalArgumentException();
>             }
>         }
>         return list.addAll(c);
>     }
>     @Override
>     public boolean addAll(int index, Collection<? extends T> c) {
>         if (locked) {
>             throw new IllegalStateException();
>         }
>         for (T item : c) {
>             if (blacklist.contains(item)) {
>                 throw new IllegalArgumentException();
>             }
>         }
>         return list.addAll(index, c);
>     }
>     @Override
>     public boolean removeAll(Collection<?> c) {
>         if (locked) {
>             throw new IllegalStateException();
>         }
>         return list.removeAll(c);
>     }
>     @Override
>     public boolean retainAll(Collection<?> c) {
>         if (locked) {
>             throw new IllegalStateException();
>         }
>         return list.retainAll(c);
>     }
>     @Override
>     public void clear() {
>         if (locked) {
>             throw new IllegalStateException();
>         }
>         list.clear();
>     }
>     @Override
>     public boolean equals(Object o) {
>         return list.equals(o);
>     }
>     @Override
>     public int hashCode() {
>         return list.hashCode();
>     }
>     @Override
>     public T get(int index) {
>         return list.get(index);
>     }
>     @Override
>     public T set(int index, T element) {
>         if (locked) {
>             throw new IllegalStateException();
>         }
>         if (blacklist.contains(element)) {
>             throw new IllegalArgumentException();
>         }
>         return list.set(index, element);
>     }
>     @Override
>     public void add(int index, T element) {
>         if (locked) {
>             throw new IllegalStateException();
>         }
>         if (blacklist.contains(element)) {
>             throw new IllegalArgumentException();
>         }
>         list.add(index, element);
>     }
>     @Override
>     public T remove(int index) {
>         if (locked) {
>             throw new IllegalStateException();
>         }
>         return list.remove(index);
>     }
>     @Override
>     public int indexOf(Object o) {
>         return list.indexOf(o);
>     }
>     @Override
>     public int lastIndexOf(Object o) {
>         return list.lastIndexOf(o);
>     }
>     @Override
>     public ListIterator<T> listIterator() {
>         final ListIterator<T> backingListIt = list.listIterator();
>         return new ListIterator<T>() {
>             @Override
>             public boolean hasNext() {
>                 return backingListIt.hasNext();
>             }
>             @Override
>             public T next() {
>                 return backingListIt.next();
>             }
>             @Override
>             public boolean hasPrevious() {
>                 return backingListIt.hasPrevious();
>             }
>             @Override
>             public T previous() {
>                 return backingListIt.previous();
>             }
>             @Override
>             public int nextIndex() {
>                 return backingListIt.nextIndex();
>             }
>             @Override
>             public int previousIndex() {
>                 return backingListIt.previousIndex();
>             }
>             @Override
>             public void remove() {
>                 if (locked) {
>                     throw new IllegalStateException();
>                 }
>                 backingListIt.remove();
>             }
>             @Override
>             public void set(T e) {
>                 if (locked) {
>                     throw new IllegalStateException();
>                 }
>                 if (blacklist.contains(e)) {
>                     throw new IllegalArgumentException();
>                 }
>                 backingListIt.set(e);
>             }
>             @Override
>             public void add(T e) {
>                 if (locked) {
>                     throw new IllegalStateException();
>                 }
>                 if (blacklist.contains(e)) {
>                     throw new IllegalArgumentException();
>                 }
>                 backingListIt.add(e);
>             }
>         };
>     }
>     @Override
>     public ListIterator<T> listIterator(int index) {
>         final ListIterator<T> backingListIt = list.listIterator(index);
>         return new ListIterator<T>() {
>             @Override
>             public boolean hasNext() {
>                 return backingListIt.hasNext();
>             }
>             @Override
>             public T next() {
>                 return backingListIt.next();
>             }
>             @Override
>             public boolean hasPrevious() {
>                 return backingListIt.hasPrevious();
>             }
>             @Override
>             public T previous() {
>                 return backingListIt.previous();
>             }
>             @Override
>             public int nextIndex() {
>                 return backingListIt.nextIndex();
>             }
>             @Override
>             public int previousIndex() {
>                 return backingListIt.previousIndex();
>             }
>             @Override
>             public void remove() {
>                 if (locked) {
>                     throw new IllegalStateException();
>                 }
>                 backingListIt.remove();
>             }
>             @Override
>             public void set(T e) {
>                 if (locked) {
>                     throw new IllegalStateException();
>                 }
>                 if (blacklist.contains(e)) {
>                     throw new IllegalArgumentException();
>                 }
>                 backingListIt.set(e);
>             }
>             @Override
>             public void add(T e) {
>                 if (locked) {
>                     throw new IllegalStateException();
>                 }
>                 if (blacklist.contains(e)) {
>                     throw new IllegalArgumentException();
>                 }
>                 backingListIt.add(e);
>             }
>         };
>     }
>     @Override
>     public List<T> subList(int fromIndex, int toIndex) {
>         LockableBlacklistableList<T> ret = new LockableBlacklistableList<>(
>                 list.subList(fromIndex, toIndex));
>         ret.locked = locked;
>         ret.blacklist = blacklist;
>         return ret;
>     }
> }
> {code}
> {code}
> public final class LockableBlacklistableSet<T> implements Set<T> {
>     private boolean locked;
>     private Set<T> set;
>     private Set<T> blacklist;
>     public LockableBlacklistableSet(Set<T> backingSet, T... blacklist) {
>         if (backingSet == null) {
>             throw new NullPointerException();
>         }
>         if (!backingSet.isEmpty()) {
>             throw new IllegalArgumentException();
>         }
>         this.blacklist = new HashSet<>(Arrays.asList(blacklist));
>         this.set = backingSet;
>     }
>     
>     public void lock() {
>         locked = true;
>     }
>     public boolean isLocked() {
>         return locked;
>     }
>     public Set<T> viewBlacklist() {
>         return Collections.unmodifiableSet(blacklist);
>     }
>     public int size() {
>         return set.size();
>     }
>     public boolean isEmpty() {
>         return set.isEmpty();
>     }
>     public boolean contains(Object o) {
>         return set.contains(o);
>     }
>     public Iterator<T> iterator() {
>         final Iterator<T> it = set.iterator();
>         return new Iterator<T>() {
>             @Override
>             public boolean hasNext() {
>                 return it.hasNext();
>             }
>             @Override
>             public T next() {
>                 return it.next();
>             }
>             @Override
>             public void remove() {
>                 if (locked) {
>                     throw new IllegalStateException();
>                 }
>                 it.remove();
>             }
>         };
>     }
>     public Object[] toArray() {
>         return set.toArray();
>     }
>     public <T> T[] toArray(T[] a) {
>         return set.toArray(a);
>     }
>     public boolean add(T e) {
>         if (locked) {
>             throw new IllegalStateException();
>         }
>         if (blacklist.contains(item)) {
>             throw new IllegalArgumentException();
>         }
>         return set.add(e);
>     }
>     public boolean remove(Object o) {
>         if (locked) {
>             throw new IllegalStateException();
>         }
>         return set.remove(o);
>     }
>     public boolean containsAll(Collection<?> c) {
>         return set.containsAll(c);
>     }
>     public boolean addAll(Collection<? extends T> c) {
>         if (locked) {
>             throw new IllegalStateException();
>         }
>         for (T item : c) {
>             if (blacklist.contains(item)) {
>                 throw new IllegalArgumentException();
>             }
>         }
>         return set.addAll(c);
>     }
>     public boolean retainAll(Collection<?> c) {
>         if (locked) {
>             throw new IllegalStateException();
>         }
>         return set.retainAll(c);
>     }
>     public boolean removeAll(Collection<?> c) {
>         if (locked) {
>             throw new IllegalStateException();
>         }
>         return set.removeAll(c);
>     }
>     public void clear() {
>         if (locked) {
>             throw new IllegalStateException();
>         }
>         set.clear();
>     }
>     public boolean equals(Object o) {
>         return set.equals(o);
>     }
>     public int hashCode() {
>         return set.hashCode();
>     }
> }
> {code}

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