sfatables/xmlextension.py

   1 # Matches and targets are specified using XML files.
   2 # They provide the following information:
   3 #   - The context required by the match
   4 #   - The processor that actually implements the match or target
   5 #   - The parameters that the processor needs to evaluate the context
   6
   7 import libxml2
   8
   9 class Xmlextension:
  10     def __init__(self, file_path):
  11
  12         self.context = ""
  13         self.processor = ""
  14         self.operand = "VALUE"
  15         self.arguments = []
  16         self.terminal = 0
  17
  18         self.xmldoc = libxml2.parseFile(file_path)
  19
  20         # TODO: Check xmldoc against a schema
  21         p = self.xmldoc.xpathNewContext()
  22
  23         # <context select="..."/>
  24         # <rule><argument param="..."/></rule>
  25         # <processor name="..."/>
  26
  27         context = p.xpathEval('//context/@select')
  28         self.context = context[0].content
  29
  30         processor = p.xpathEval('//processor/@filename')
  31         self.context = processor[0].content
  32
  33         name = p.xpathEval('//rule/argument/name')
  34         help = p.xpathEval('//rule/argument/help')
  35         target = p.xpathEval('//rule/argument/operand')
  36
  37         context = p.xpathEval('//attributes/attribute[@terminal="yes"]')
  38         self.terminal = (context != [])
  39
  40         self.arguments = [{'name':name_help_target[0].content,'help':name_help_target[1].content,'target':name_help_target[2].content} for name_help_target in zip(name,help,target)]
  41
  42         p.xpathFreeContext()
  43         self.xmldoc.freeDoc()
  44
  45         return
  46