commands.py

   1 # Pyvconv - A simple frontend for ffmpeg/mencoder
   2 # Copyright (C) 2008,  Kristian Rumberg (kristianrumberg@gmail.com)
   3
   4 # Permission to use, copy, modify, and/or distribute this software for any
   5 # purpose with or without fee is hereby granted, provided that the above
   6 # copyright notice and this permission notice appear in all copies.
   7
   8 # THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
   9 # WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  10 # MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  11 # ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  12 # WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  13 # ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  14 # OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  15
  16 import libxml2
  17 import re
  18
  19 class Error(Exception):
  20     def __init__(self, value):
  21         Exception.__init__(self)
  22         self.value = value
  23     def __str__(self):
  24         return repr(self.value)
  25
  26 class Variable:
  27     def __init__(self, namestr, defaultstr, exprstr = None):
  28         self.namestr = namestr
  29         self.defaultstr = defaultstr
  30         self.exprstr = exprstr
  31
  32     def __str__(self):
  33         return self.namestr
  34
  35     def has_value(self):
  36         return self.defaultstr != None
  37
  38     def get_value(self):
  39         if self.defaultstr == None:
  40             raise Error("Error: Trying to eval variable " + self.namestr + " with no value")
  41         return self.defaultstr
  42
  43 class OptionalSetting:
  44     def __init__(self, namestr, exprstr):
  45         self.namestr = namestr
  46         self.exprstr = exprstr
  47
  48     def get_name(self):
  49         return self.namestr
  50
  51     def get_value(self, var_list):
  52         instr = self.exprstr
  53         for var in var_list:
  54             if var_list[var].has_value():
  55                 p = re.compile( "\$\{" + var + "\}")
  56                 instr = p.sub( var_list[var].get_value(), instr)
  57         if instr.find("$") != -1:
  58             instr = "" # if not all variables were found, return empty option
  59         return instr
  60
  61 class Command:
  62     def __init__(self, namestr, callstr, var_list, optset_list):
  63         self.namestr = namestr
  64         self.callstr = callstr
  65         self.var_list = var_list
  66         self.optset_list = optset_list
  67
  68     def get_name(self):
  69         return self.namestr
  70
  71     def put_var(self, var):
  72         self.var_list[str(var)] = var
  73
  74     def get_vars(self):
  75         return self.var_list
  76
  77     def __str__(self):
  78         instr = self.callstr
  79
  80         p = re.compile("\$\[(\w+)\]")
  81         for o in p.findall(instr):
  82             if o not in self.optset_list:
  83                 raise Error("Error: Optional variable not defined")
  84             instr = p.sub(self.optset_list[o].get_value(self.var_list), instr)
  85
  86         p = re.compile("\$\{(\w+)\}")
  87         for o in p.findall(instr):
  88             if o not in self.var_list:
  89                 raise Error("Error: Variable \"" + o + "\" has not been assigned")
  90             val = self.var_list[o].get_value()
  91             instr = instr.replace("${" + o + "}", val)
  92
  93         if instr.find("$") != -1:
  94             raise Error("Error: all variables were not expanded")
  95         return instr
  96
  97 class CommandList:
  98     def __init__(self):
  99         self.cmdcall_dict = {}
 100         self._read_config()
 101
 102     def _read_properties(self, propnode, mand_propnames, opt_propnames = []):
 103         propdict = {}
 104
 105         for p in propnode:
 106             if p.name in mand_propnames:
 107                 propdict[p.name] = str(p.content)
 108             elif p.name != "text" and p.name not in opt_propnames:
 109                 raise Error("Error parsing XML: only name and call are accepted properties in the element command, found " + str(p.name))
 110
 111         if len(mand_propnames) != len(propdict.keys()):
 112             raise Error("Error parsing XML: must supply both name and call in element command")
 113
 114         for p in propnode:
 115             if p.name in opt_propnames:
 116                 propdict[p.name] = str(p.content)
 117             elif p.name != "text" and p.name not in mand_propnames:
 118                 raise Error("Error parsing XML: only name and call are accepted properties in the element command, found " + str(p.name))
 119
 120         return propdict
 121
 122     def _read_config(self):
 123         doc = libxml2.parseFile("commands.xml")
 124         cmd_xmllist = doc.xpathEval( '//command')
 125
 126         # read all commands from XML description
 127         for cmdnode in cmd_xmllist:
 128             if cmdnode.type == "element" and cmdnode.name == "command":
 129
 130                 var_list = {}
 131                 optset_list = {}
 132
 133                 if cmdnode.children:
 134                     for varsetnode in cmdnode.children:
 135                         if varsetnode.type == "element" and varsetnode.name == "variable":
 136                             props =  self._read_properties(varsetnode.properties, ["name", "expr"], ["default"])
 137                             defprop = None
 138                             if "default" in props:
 139                                 defprop = props["default"]
 140                             var_list[props["name"]] = Variable(props["name"], defprop, props["expr"])
 141
 142                         elif varsetnode.type == "element" and varsetnode.name == "optionalsetting":
 143                             props = self._read_properties(varsetnode.properties, ["name", "expr"])
 144                             optset_list[props["name"]] = OptionalSetting(props["name"], props["expr"])
 145
 146                         elif varsetnode.name != "text":
 147                             raise Error("Error parsing XML: only variable and optionalsetting elements allowed in command")
 148
 149                 props = self._read_properties(cmdnode.properties, ["name", "call"])
 150                 self.cmdcall_dict[props["name"]] = Command(props["name"], props["call"], var_list, optset_list)
 151
 152             else:
 153                 raise Error("Error parsing XML: only command elements are supported")
 154
 155     def __iter__(self):
 156         return self.cmdcall_dict.values().__iter__()
 157
 158     def __getitem__(self, name):
 159         return self.cmdcall_dict[name]
 160
 161