jvanzyl 00/11/25 13:31:31
Modified: src/java/org/apache/velocity/runtime/directive Foreach.java
Log:
- Changed the following:
o An empty list is not an exception. it is valid to have an empty list.
a new flag INFO_EMPTY_LIST_OBJECT has been added to the class to
indicate this. an exception is not thrown.
o A check is made in render() to see if we had an empty list.
If we did then we will try to init() again to get a sample
from the list object. An initial check is made, then a sync,
then the check is repeated to keep any additional threads that
made it through the first check from running init(). I don't
want to have to synchronize the outter check so I check twice
to keep multiple threads from running init().
o Localized the listObject to the render to prevent any unforseen
MT issues.
So the upshot is that an empty list will behave properly now,
it simply will not be rendered and not throw an exception.
Revision Changes Path
1.22 +109 -50
jakarta-velocity/src/java/org/apache/velocity/runtime/directive/Foreach.java
Index: Foreach.java
===================================================================
RCS file:
/home/cvs/jakarta-velocity/src/java/org/apache/velocity/runtime/directive/Foreach.java,v
retrieving revision 1.21
retrieving revision 1.22
diff -u -r1.21 -r1.22
--- Foreach.java 2000/11/24 23:59:47 1.21
+++ Foreach.java 2000/11/25 21:31:30 1.22
@@ -85,13 +85,14 @@
*
* @author <a href="mailto:[EMAIL PROTECTED]">Jason van Zyl</a>
* @author <a href="mailto:[EMAIL PROTECTED]">Geir Magnusson Jr.</a>
- * @version $Id: Foreach.java,v 1.21 2000/11/24 23:59:47 jon Exp $
+ * @version $Id: Foreach.java,v 1.22 2000/11/25 21:31:30 jvanzyl Exp $
*/
public class Foreach extends Directive
{
- private final static int ARRAY = 1;
- private final static int ITERATOR = 2;
- private final static int MAP = 3;
+ private final static int INFO_ARRAY = 1;
+ private final static int INFO_ITERATOR = 2;
+ private final static int INFO_MAP = 3;
+ private final static int INFO_EMPTY_LIST_OBJECT = 4;
private final static String COUNTER_IDENTIFIER =
VelocityResources.getString(Runtime.COUNTER_NAME);
@@ -119,70 +120,87 @@
Object sampleElement = null;
elementKey = node.jjtGetChild(0).getFirstToken().image.substring(1);
- // This is a refence node and it needs to
- // be inititialized.
+ /*
+ * This is a refence node and it needs to
+ * be inititialized.
+ */
node.jjtGetChild(2).init(context, null);
listObject = node.jjtGetChild(2).value(context);
- // If the listObject is null then we know that this
- // whole foreach directive is useless. We need to
- // throw a ReferenceException which is caught by
- // the SimpleNode.init() and logged. But we also need
- // to set a flag so that the rendering of this node
- // is ignored as the output would be useless.
+ /*
+ * If the listObject is null then we know that this
+ * whole foreach directive is useless. We need to
+ * throw a ReferenceException which is caught by
+ * the SimpleNode.init() and logged. But we also need
+ * to set a flag so that the rendering of this node
+ * is ignored as the output would be useless.
+ */
- // Slight problem with this approach. The list object
- // may have been #set previously, this usually wouldn't
- // be the case, but this check should be moved into
- // the rendering phase.
+ /*
+ * Slight problem with this approach. The list object
+ * may have been #set previously, this usually wouldn't
+ * be the case, but this check should be moved into
+ * the rendering phase.
+ */
if (listObject == null)
{
node.setInvalid();
throw new ReferenceException("#foreach", node.jjtGetChild(2));
}
- // Figure out what type of object the list
- // element is so that we don't have to do it
- // everytime the node is traversed.
- //if (listObject instanceof Object[])
- try
+ /*
+ * Figure out what type of object the list
+ * element is so that we don't have to do it
+ * everytime the node is traversed.
+ * if (listObject instanceof Object[])
+ */
+ if (listObject instanceof Object[])
{
- if (listObject instanceof Object[])
- {
- node.setInfo(ARRAY);
- Object[] arrayObject = ((Object[]) listObject);
+ Object[] arrayObject = ((Object[]) listObject);
- if (arrayObject.length == 0)
- node.setInvalid();
- else
- sampleElement = arrayObject[0];
- }
- else if (Introspector.implementsMethod(listObject, "iterator"))
+ if (arrayObject.length == 0)
+ {
+ node.setInfo(INFO_EMPTY_LIST_OBJECT);
+ }
+ else
+ {
+ node.setInfo(INFO_ARRAY);
+ sampleElement = arrayObject[0];
+ }
+ }
+ else if (Introspector.implementsMethod(listObject, "iterator"))
+ {
+ if (((Collection) listObject).size() == 0)
{
- node.setInfo(ITERATOR);
+ node.setInfo(INFO_EMPTY_LIST_OBJECT);
+ }
+ else
+ {
+ node.setInfo(INFO_ITERATOR);
sampleElement = ((Collection) listObject).iterator().next();
- }
- else if (Introspector.implementsMethod(listObject, "values"))
+ }
+ }
+ else if (Introspector.implementsMethod(listObject, "values"))
+ {
+ if (((Map) listObject).size() == 0)
{
- node.setInfo(MAP);
- sampleElement = ((Map) listObject).values().iterator().next();
+ node.setInfo(INFO_EMPTY_LIST_OBJECT);
}
else
{
- // If it's not an array or an object that provides
- // an iterator then the node is invalid and should
- // not be rendered.
- node.setInvalid();
- Runtime.warn ("Could not determine type of iterator for #foreach
loop ");
- throw new NodeException ("Could not determine type of iterator for
#foreach loop " , node);
- }
+ node.setInfo(INFO_MAP);
+ sampleElement = ((Map) listObject).values().iterator().next();
+ }
}
- catch (java.util.NoSuchElementException nsee)
+ else
{
+ // If it's not an array or an object that provides
+ // an iterator then the node is invalid and should
+ // not be rendered.
node.setInvalid();
- Runtime.warn ("Iterator for #foreach loop did not contain any values ");
- throw new NodeException ("Iterator for #foreach loop did not contain
any values ", node);
- }
+ Runtime.warn ("Could not determine type of iterator for #foreach loop
");
+ throw new NodeException ("Could not determine type of iterator for
#foreach loop " , node);
+ }
// This is a little trick so that we can initialize
// all the blocks in the foreach properly given
@@ -199,15 +217,56 @@
public boolean render(Context context, Writer writer, Node node)
throws IOException
{
+ /*
+ * If the node has been set to invalid then it is because
+ * the list object placed in the context is not an array,
+ * does not provide an Iterator, or is not Map. In these
+ * cases there is nothing we can do, and nothing will
+ * be rendered.
+ */
if (node.isInvalid())
return false;
+
+ if (node.getInfo() == INFO_EMPTY_LIST_OBJECT)
+ {
+ /*
+ * If the list object had no elements
+ * then lets try to init again. If the list
+ * object is still empty then an exception
+ * will be thrown again. But we will keep
+ * trying!
+ */
+ synchronized(this)
+ {
+ /*
+ * Check again for other threads that
+ * got through above. Don't want to
+ * have to synchronize on every render,
+ * but we don't want to init() multiple
+ * times here either. A few threads might
+ * get into this block, but only one thread
+ * will try the init().
+ */
+ if (node.getInfo() == INFO_EMPTY_LIST_OBJECT)
+ {
+ try
+ {
+ init(context, node);
+ }
+ catch (Exception e)
+ {
+ // do nothing.
+ }
+ }
+ }
+ }
Iterator i;
- listObject = node.jjtGetChild(2).value(context);
+ Object listObject = node.jjtGetChild(2).value(context);
- if (node.getInfo() == ARRAY)
+ if (node.getInfo() == INFO_ARRAY)
i = new ArrayIterator((Object[]) listObject);
- else if (node.getInfo() == MAP)
+ else if (node.getInfo() == INFO_MAP)
i = ((Map) listObject).values().iterator();
else
i = ((Collection) listObject).iterator();
