pyvconv.py

   1 import libxml2
   2 import re
   3
   4 class RenderCommand:
   5     def __init__(self, name_str, cmd_str, optset_list):
   6         self.name_str    = name_str
   7         self.cmd_str = cmd_str
   8
   9         self.var_list = {}
  10         self.var_list["in"]  = None
  11         self.var_list["out"] = None
  12         self.var_list["quality"] = None
  13
  14         self.optset_list = optset_list
  15
  16     def set_var(self, var_str, val_str):
  17         if val_str.find("&") != -1:
  18             raise "Warning: Trying to execute arbitrary code"
  19         self.var_list[var_str] = val_str
  20
  21     def _insert_known_vars(self, instr):
  22         for var in self.var_list:
  23             if self.var_list[var] != None:
  24                 p = re.compile( '\$\{' + var + '\}')
  25                 instr = p.sub( self.var_list[var], instr)
  26         return instr
  27
  28     def _contains_vars(self, instr):
  29         if instr.find("$") != -1:
  30             return True
  31         else:
  32             return False
  33
  34     def execute(self):
  35         cmd_to_run = self.cmd_str
  36
  37         # insert all known variables in cmd string
  38         cmd_to_run = self._insert_known_vars(cmd_to_run)
  39
  40         # for the optional parameters where all subparameters are known, expand expression otherwise remove totally
  41         for opts_name_str in self.optset_list:
  42             opts_expr_str = self._insert_known_vars(self.optset_list[opts_name_str])
  43             p = re.compile("\$\[" + opts_name_str + "\]")
  44             if self._contains_vars(opts_expr_str):
  45                 cmd_to_run = p.sub("", cmd_to_run)
  46             else:
  47                 cmd_to_run = p.sub(opts_expr_str, cmd_str)
  48
  49         print cmd_to_run
  50
  51 class RenderCommands:
  52     def __init__(self):
  53         self.command_list = {}
  54         self._read_config()
  55
  56     def _read_config(self):
  57         doc = libxml2.parseFile("rendercommands.xml")
  58         cmd_xmllist = doc.xpathEval( '//command')
  59
  60         for cmdnode in cmd_xmllist:
  61             cmd_name_str = None
  62             cmd_call_str = None
  63             for p in cmdnode.properties:
  64                 if p.name=="name":
  65                     cmd_name_str = str(p.children)
  66                 elif p.name=="call":
  67                     cmd_call_str = str(p.children)
  68
  69             optset_list = {}
  70
  71             if cmdnode.children:
  72                 for optset in cmdnode.children:
  73                     if optset.properties:
  74                         opts_name_str = None
  75                         opts_expr_str = None
  76                         for p in optset.properties:
  77                             if p.name == "name":
  78                                 opts_name_str = str(p.children)
  79                             elif p.name == "expr":
  80                                 opts_expr_str = str(p.children)
  81                         if opts_name_str == None or opts_expr_str == None:
  82                             print opts_name_str
  83                             print opts_expr_str
  84                             raise "optionsetting must have both name and expr"
  85
  86                         optset_list[opts_name_str] = opts_expr_str
  87
  88             if cmd_name_str == None or cmd_call_str == None:
  89                 print cmd_name_str
  90                 print cmd_call_str
  91                 raise "command must have both name and call"
  92
  93             self.command_list[cmd_name_str] = RenderCommand(cmd_name_str, cmd_call_str, optset_list)
  94
  95     def __iter__(self):
  96         return self.command_list.values().__iter__()
  97
  98 def main():
  99     commands = RenderCommands()
 100
 101     for c in commands:
 102         c.set_var("in",  "source.avi")
 103         c.set_var("out", "dest.avi")
 104         c.execute()
 105
 106 if __name__ == "__main__":
 107     main()