Node.getValue() not working. about parboiled

[sirthias]

parboiled sets the value field of a parse tree node to the top element of the value stack at the time of the node construction. Does your parser contain action code that pushes custom objects onto the value stack? Only then will you see non-null values in your parse tree nodes...

[adpande]

Yes, you are right. When I am pushing values in the stack they are showing up. Will it not be good if we can get values of the child nodes??

[sirthias]

I'm not quite sure I get what you are asking for..
You can traverse the parse tree in any way you seem fit and, of course, also get to all members of potentially existing child nodes.

[adpande]

Sorry Sirthias, I was little confused. I got it working now. You may see such (may be silly) questions form me as this is the first time I am working with parsers. Thanks a lot for this wonderful library. One seggestion : If possible include a tutorial on "How to use ParseTree".

[sirthias]

No problem, just go ahead and ask questions if you think that I or other users might be able to help. But probably the parboiled user mailing list is a better place for such things...

[adpande]

Hi Mathias,

The Node.getValue() is still not working. I have the following parse tree:

[top_vars] 'def i\n <f c="dfdf">dfdfdf</f>\nend'
  [key] 'i\n '
  [value] '<f c="dfdf">dfdfdf</f>\n'
[top_vars] '\n\ndef j\n kfgfdgjdfg\nend'
  [key] 'j\n '
  [value] 'kfgfdgjdfg\n'
[top_vars] '\n\ndef k\n format = "mm-dd-yyyy"\nend'
  [key] 'k\n '
  [value] 'format = "mm-dd-yyyy"\n'

I am finding a node by using following Java code:

Node key = findNodeByLabel(n,"key");
Node value = findNodeByLabel(n,"value");

When I try to print the value of the node using

key.getValue().toString() it gives me null pointer exception. But If I try to print using the following code it works absolutely fine.

System.out.println("Key: "+ result.inputBuffer.extract(key.getStartIndex(),key.getEndIndex()).toString());

I am not sure what the problem is.

Thanks & Regards,
Abhishek

[sirthias]

I'm not sure I get what you are trying to do.
The "value" of a node is a custom object that you create! If you do not create anything the value will always be null. Could it be that you confuse the "value" of the node with its matched input text?
And: Please let's move these discussions to the user mailing list.