Additional filtering hook during the parsing loop.

Added the hook implementation.

Added more context information to the filtering hook. The previous patch can be ignored.

The last patch generates variable name conflicts within the parse method. Adding a new patch to fix the issue.

Thanks for the review.

Answer of Q1:
I am using feeds tamper, but it is a tool for additional processing of mapped field(s). Correct me if something more can be done with it.

My use case is that I want to filter the context nodes before passing them for processing with feeds tamper.
Normally this is implemented with the "Context" XPath expression in the parser settings, but in my case the expression is becoming too large, complex with a lot of sub-expression repetitions within it - hard to maintain/change. In some of the use cases I need to be able to use node set manipulations like intersection and subtraction when XPath 1.0 allows only union with the "|" syntax.

This is the reason that a hook was implemented, with some PHP code all of the above was solved in a matter of 2-3 screens of code.

Answer of Q2:
The parameter name $source in the original implementation needs to be of type FeedsSource and it is passed as additional context information to the filtering hook. Part of the process method without rename of the variable would look like this:

...
foreach ($all_nodes as $node) {
      if(in_array(true, module_invoke_all('feeds_xpathparser_filter_node', $source, $node), true)) {
        continue;
      }

      $parsed_item = $variables = array();
      foreach ($source_config['sources'] as $source => $query) {
        ...
      }
      ...
    }
....

The inner loop defines iteration key variable with the same name as the parameter, replacing the FeedsSource with a string on the first iteration, making the call to the filtering hook with wrong source context in the second iteration of the outer loop.

Answer of Q3:
Thanks, for spotting the typo.

Answer of Q4:
Will fix the constants to the convention specs.

Thanks for the fast response.

1. I will rename the hook and add the document parameter.

2. I will do the refactoring and upload a patch with all the discussed fixes.

Best regards,
Nikolay D.

Adding the patch fixing the issues discussed.