RFR 8024707: TRANSFORMEREXCEPTION : ITEM() RETURNS NULL WITH NODE LIST OF LENGTH =1 IN JAXP

[Aleksej Efimov]

Joe,
Thank you for a suggestion. But I modified it a little bit:

      public Node item(int index) {
          if (m_iter != null) {
-            int node;
+            int node = 0;
              int count = m_cachedNodes.size();
  
              if (count > index) {
                  node = m_cachedNodes.elementAt(index);
                  return m_dtm.getNode(node);
              } else if (m_last == -1) {
-                while (((node = m_iter.next()) != DTMAxisIterator.END)
-                           && count <= index) {
+                while (count <= index
+                        && ((node = m_iter.next()) != DTMAxisIterator.END)) {
                      m_cachedNodes.addElement(node);
                      count++;
                  }


We need a value assigned to 'node' to avoid compilation error with 
uninitialized 'node' variable. But this value doesn't mean nothing (let 
it be 0) because for the first while loop iteration the second "&&" 
condition will be always executed (we can reach the while loop only when 
"count<=index" - the outer if-else condition). The test passes with this 
new version.
As the result - new webrev: 
http://cr.openjdk.java.net/~aefimov/8024707/webrev.01/ 
<http://cr.openjdk.java.net/%7Eaefimov/8024707/webrev.01/>

Best Regards,
Aleksej

On 09/26/2013 10:46 PM, huizhe wang wrote:
> Hi Aleksej,
>
> From your tests, it appears that the getLength() method was 
> implemented correctly, and that the bug is not in the call to 
> m_iter.next(), but it should not be called again once the count is > 
> index.  So that fix would be to move the conditions around such that:
>     public Node item(int index) {
>         if (m_iter != null) {
>             int node;
>             int count = m_cachedNodes.size();
>
>             if (count > index) {
>                 node = m_cachedNodes.elementAt(index);
>                 return m_dtm.getNode(node);
>             } else if (m_last == -1) {
> -                while (((node = m_iter.next()) != DTMAxisIterator.END)
> -                           && count <= index) {
> +                while (count <= index
> +                           && ((node = m_iter.next()) != 
> DTMAxisIterator.END)) {
>                     m_cachedNodes.addElement(node);
>                     count++;
>                 }
>                 if (node == DTMAxisIterator.END) {
>                     m_last = count;
>                 } else {
>                     return m_dtm.getNode(node);
>                 }
>             }
>         }
>         return null;
>     }
>
> Thanks,
> Joe
>
>
> On 9/25/2013 4:10 AM, Aleksej Efimov wrote:
>> Hi Joe,
>> Your suggestion about getLength() brings to mine attention the 
>> following behavior of unmodified JDK:
>> If we slightly modify a TestFunc class [1] in such manner:
>>
>>     public static Node test( NodeList list ) {
>>                  Node ret = list.item(0);
>>                  System.err.println(list.getLength());
>>                  return ret;
>>     }
>>
>> And add more elements to in.xml:
>> <input1><seq-elem1>inp1_1</seq-elem1><seq-elem1>inp1_2</seq-elem1><seq-elem1>inp1_3</seq-elem1></input1>
>>
>> The test will fails:
>>
>>     2
>>     Transformation completed. Result:<?xml version="1.0"
>>     encoding="UTF-8"?>inp1_2
>>     Exception in thread "main" java.lang.RuntimeException: Incorrect
>>     transformation result
>>         at XSLT.main(XSLT.java:49)
>>
>> As you can see the length of 2 is incorrect value and the 'inp1_1' 
>> element is ignored. But If we do another one change to test function 
>> - first get the length() and then get the item:
>>
>>     public static Node test( NodeList list ) {
>>     	    System.err.println(list.getLength());
>>                  Node ret = list.item(0);
>>                  return ret;
>>     }
>>
>> The test will pass:
>>
>>     3
>>     Transformation completed. Result:<?xml version="1.0"
>>     encoding="UTF-8"?>inp1_1
>>
>> This behavior tells that item() method incorrectly caches the nodes 
>> (The method called first - do the caching). But the caching of nodes 
>> is done in correct way by getLength() function, but its according to 
>> the test results. Currently, I'm trying to understand why it's 
>> working in such way in a view of source code.
>>
>> -Aleksej
>>
>>
>>
>> [1] 
>> http://cr.openjdk.java.net/~aefimov/8024707/jdk/test/javax/xml/jaxp/parsers/8024707/TestFunc.java 
>> <http://cr.openjdk.java.net/%7Eaefimov/8024707/jdk/test/javax/xml/jaxp/parsers/8024707/TestFunc.java>
>>
>> On 09/20/2013 01:19 AM, huizhe wang wrote:
>>> Hi Aleksej,
>>>
>>> Looks like the getLength() method has the same problem.
>>>
>>> Joe
>>>
>>> On 9/17/2013 5:01 AM, Aleksej Efimov wrote:
>>>> Hi Everyone,
>>>>
>>>> There is a bug [1] in JAXP about transformation of one-item sized 
>>>> node list:
>>>> When the length of nodelist which is passed to a XSLT extension 
>>>> function is 1, the node gotten from the node list becomes null.
>>>> New test illustrates this issue [2]. Full webrev with proposed fix 
>>>> can be found here: [3].
>>>>
>>>> [1] http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=8024707
>>>> [2] 
>>>> http://cr.openjdk.java.net/~aefimov/8024707/raw_files/new/jdk/test/javax/xml/jaxp/parsers/8024707/XSLT.java
>>>> [3] http://cr.openjdk.java.net/~aefimov/8024707/
>>>>
>>>> Best regards,
>>>> Aleksej
>>>
>>
>