add a few classes and methods to the classpath

Add java.lang.CharSequence, java.util.AbstractSet,
java.util.AbstractCollection, Collections.unmodifiableSet,
 System.getProperty(String,String), etc.

classpath/java/util/AbstractCollection.java

@@ -0,0 +1,112 @@
+/* Copyright (c) 2008, Avian Contributors
+
+   Permission to use, copy, modify, and/or distribute this software
+   for any purpose with or without fee is hereby granted, provided
+   that the above copyright notice and this permission notice appear
+   in all copies.
+
+   There is NO WARRANTY for this software.  See license.txt for
+   details. */
+
+package java.util;
+
+/**
+ * @author zsombor
+ * 
+ */
+public abstract class AbstractCollection<T> implements Collection<T> {
+
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see java.util.Collection#add(java.lang.Object)
+	 */
+	public boolean add(T element) {
+		throw new UnsupportedOperationException("adding to "
+				+ this.getClass().getName());
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see java.util.Collection#addAll(java.util.Collection)
+	 */
+	public boolean addAll(Collection<? extends T> collection) {
+		boolean result = false;
+		for (T obj : collection) {
+			result |= add(obj);
+		}
+		return result;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see java.util.Collection#clear()
+	 */
+	public void clear() {
+		throw new UnsupportedOperationException("clear() in "
+				+ this.getClass().getName());
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see java.util.Collection#contains(java.lang.Object)
+	 */
+	public boolean contains(T element) {
+		if (element != null) {
+			for (Iterator<T> iter = iterator(); iter.hasNext();) {
+				if (element.equals(iter.next())) {
+					return true;
+				}
+			}
+		} else {
+			for (Iterator<T> iter = iterator(); iter.hasNext();) {
+				if (iter.next()==null) {
+					return true;
+				}
+			}
+			
+		}
+		return false;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see java.util.Collection#isEmpty()
+	 */
+	public boolean isEmpty() {
+		return size() == 0;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see java.util.Collection#remove(java.lang.Object)
+	 */
+	public boolean remove(T element) {
+		throw new UnsupportedOperationException("remove(T) in "
+				+ this.getClass().getName());
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see java.util.Collection#size()
+	 */
+	public abstract int size();
+
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see java.util.Collection#toArray(S[])
+	 */
+	public <S> S[] toArray(S[] array) {
+		return Collections.toArray(this, array);
+	}
+
+	public abstract Iterator<T> iterator();
+
+}

classpath/java/util/AbstractSet.java

@@ -0,0 +1,14 @@
+/* Copyright (c) 2008, Avian Contributors
+
+   Permission to use, copy, modify, and/or distribute this software
+   for any purpose with or without fee is hereby granted, provided
+   that the above copyright notice and this permission notice appear
+   in all copies.
+
+   There is NO WARRANTY for this software.  See license.txt for
+   details. */
+
+package java.util;
+
+public abstract class AbstractSet<T> extends AbstractCollection<T> implements Set<T> {
+}

classpath/java/util/Collections.java

@@ -187,4 +187,53 @@ public class Collections {
       }
     }
   }
+
+  static class UnmodifiableSet<T> implements Set<T> {
+	  Set<T> inner;
+
+	  UnmodifiableSet(Set<T> inner) {
+		  this.inner = inner;
+	  }
+	  
+	public boolean add(T element) {
+		throw new UnsupportedOperationException("not supported");
+	}
+
+	public boolean addAll(Collection<? extends T> collection) {
+		throw new UnsupportedOperationException("not supported");
+	}
+
+	public void clear() {
+		throw new UnsupportedOperationException("not supported");
+	}
+
+	public boolean contains(T element) {
+		return inner.contains(element);
+	}
+
+	public boolean isEmpty() {
+		return inner.isEmpty();
+	}
+
+	public Iterator<T> iterator() {
+		return inner.iterator();
+	}
+
+	public boolean remove(T element) {
+		throw new UnsupportedOperationException("not supported");
+	}
+
+	public int size() {
+		return inner.size();
+	}
+
+	public <S> S[] toArray(S[] array) {
+		return inner.toArray(array);
+	}
+	  
+  }
+  
+    public static <T> Set<T> unmodifiableSet(Set<T> hs) {
+		return new UnmodifiableSet<T>(hs);
+	}
 }

classpath/java/util/TreeSet.java

@@ -10,7 +10,7 @@
 
 package java.util;
 
-public class TreeSet<T> implements Collection<T> {
+public class TreeSet<T>  extends AbstractSet<T> implements Collection<T> {
   private PersistentSet<Cell<T>> set;
   private int size;
 
@@ -41,12 +41,6 @@ public class TreeSet<T> implements Collection<T> {
     return false;
   }
 
-  public boolean addAll(Collection<? extends T> collection) {
-    boolean change = false;
-    for (T t: collection) if (add(t)) change = true;
-    return change;
-  }
-
   // Used by hashMaps for replacement
   public void addAndReplace(T value) {
     PersistentSet.Path<Cell<T>> p = set.find(new Cell(value, null));
@@ -75,10 +69,6 @@ public class TreeSet<T> implements Collection<T> {
     }
   }
 
-  public <T> T[] toArray(T[] array) {
-    return Collections.toArray(this, array);
-  }
-
   public int size() {
     return size;
   }