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 match_dir = 'matches'
  10
  11 class Xmlextension:
  12     context = ""
  13     processor = ""
  14     operand = "VALUE"
  15     arguments = []
  16
  17     def __init__(self, component_name):
  18         filename = match_dir+"/"+component_name+".xml"
  19         self.xmldoc = libxml2.parseFile(filename)
  20
  21         # TODO: Check xmldoc against a schema
  22         p = self.xmldoc.xpathNewContext()
  23
  24         # <context select="..."/>
  25         # <rule><argument param="..."/></rule>
  26         # <processor name="..."/>
  27
  28         context = p.xpathEval('//context/@select')
  29         self.context = context[0].content
  30
  31         processor = p.xpathEval('//processor/@filename')
  32         self.context = processor[0].content
  33
  34         name = p.xpathEval('//rule/argument/name')
  35         help = p.xpathEval('//rule/argument/help')
  36         target = p.xpathEval('//rule/argument/operand')
  37
  38         self.arguments = map(lambda (name,help,target):{'name':name.content,'help':help.content,'target':target.content}, zip(name,help,target))
  39
  40         p.xpathFreeContext()
  41         self.xmldoc.freeDoc()
  42
  43         return
  44