MONDRIAN: Fix UnionIterator and its test under retroweaver.

[git-p4: depot-paths = "//open/mondrian/": change = 11006]

src/main/mondrian/olap/Util.java

@@ -1313,7 +1313,7 @@ public static <T> String commaList(
      * }</pre></blockquote>
      *
      * @param iterables Array of one or more iterables
-     * @return iterable over the union
+     * @return iterable over the union of the iterables
      */
     public static <T> Iterable<T> union(
         final Iterable<? extends T>... iterables) {
@@ -1324,6 +1324,29 @@ public Iterator<T> iterator() {
         };
     }
 
+    /**
+     * Returns the union of a list of collections.
+     *
+     * <p>This method exists for code that will be retrowoven to run on JDK 1.4.
+     * Retroweaver has its own version of the {@link Iterable} interface, which
+     * is problematic since the {@link Collection} classes don't implement it.
+     * This method solves some of these problems by working in terms of
+     * collections; retroweaver deals with these correctly.
+     *
+     * @see #union(Iterable[])
+     *
+     * @param collections Array of one or more collections
+     * @return iterable over the union of the collections
+     */
+    public static <T> Iterable<T> union(
+        final Collection<? extends T>... collections) {
+        return new Iterable<T>() {
+            public Iterator<T> iterator() {
+                return new UnionIterator<T>(collections);
+            }
+        };
+    }
+
     /**
      * Makes a name distinct from other names which have already been used
      * and shorter than a length limit, adds it to the list, and returns it.

src/main/mondrian/util/UnionIterator.java

@@ -8,6 +8,8 @@
 */
 package mondrian.util;
 
+import mondrian.olap.Util;
+
 import java.util.*;
 
 /**
@@ -23,8 +25,37 @@ public class UnionIterator<T> implements Iterator<T> {
     private final Iterator<Iterable<? extends T>> iterableIterator;
     private Iterator<? extends T> iterator;
 
+    /**
+     * Creates a UnionIterator.
+     *
+     * @param iterables Array of iterables
+     */
     public UnionIterator(Iterable<? extends T>... iterables) {
-        this.iterableIterator = Arrays.asList(iterables).iterator();
+        List<Iterable<? extends T>> list;
+        if (Util.PreJdk15) {
+            // Retroweaver has its own version of Iterable, but
+            // Collection doesn't implement it. Solve the problem by
+            // creating an explicit Iterable wrapper.
+            list = new ArrayList<Iterable<? extends T>>(iterables.length);
+            for (Iterable<? extends T> iterable : iterables) {
+                //noinspection unchecked
+                list.add(new MyIterable(iterable));
+            }
+        } else {
+            list = Arrays.asList(iterables);
+        }
+        this.iterableIterator = list.iterator();
+        moveToNext();
+    }
+
+    public UnionIterator(Collection<? extends T>... iterables) {
+        List<Iterable<? extends T>> list =
+            new ArrayList<Iterable<? extends T>>(iterables.length);
+        for (Iterable<? extends T> iterable : iterables) {
+            //noinspection unchecked
+            list.add(new MyIterable(iterable));
+        }
+        this.iterableIterator = list.iterator();
         moveToNext();
     }
 
@@ -40,6 +71,10 @@ public T next() {
         return t;
     }
 
+    /**
+     * Moves to the next iterator that has at least one element.
+     * Called after finishing an iterator, or at the start.
+     */
     private void moveToNext() {
         do {
             if (iterableIterator.hasNext()) {
@@ -54,6 +89,23 @@ private void moveToNext() {
     public void remove() {
         iterator.remove();
     }
+
+    private static class MyIterable<T> implements Iterable {
+        private final Iterable<T> iterable;
+
+        /**
+         * Creates a MyIterable.
+         *
+         * @param iterable Iterable
+         */
+        public MyIterable(Iterable<T> iterable) {
+            this.iterable = iterable;
+        }
+
+        public Iterator<T> iterator() {
+            return iterable.iterator();
+        }
+    }
 }
 
 // End UnionIterator.java

testsrc/main/mondrian/olap/UtilTestCase.java

@@ -13,6 +13,8 @@
 
 import java.util.*;
 
+import mondrian.util.UnionIterator;
+
 /**
  * Tests for methods in {@link mondrian.olap.Util}.
  */
@@ -426,6 +428,26 @@ public void testUnionIterator() {
             total += s + ";";
         }
         assertEquals("", total);
+
+        total = "";
+        UnionIterator<String> unionIterator =
+            new UnionIterator<String>(xyList, abcList);
+        while (unionIterator.hasNext()) {
+            total += unionIterator.next() + ";";
+        }
+        assertEquals("x;y;a;b;c;", total);
+
+        if (Util.PreJdk15) {
+            // Retrowoven code gives 'ArrayStoreException' when it encounters
+            // 'Util.union()' applied to java.util.Iterator objects.
+            return;
+        }
+
+        total = "";
+        for (String s : Util.union((Iterable<String>) xyList, abcList)) {
+            total += s + ";";
+        }
+        assertEquals("x;y;a;b;c;", total);
     }
 }