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 os
  17 import libxml2
  18 import re
  19
  20 class Error(Exception):
  21     def __init__(self, value):
  22         Exception.__init__(self)
  23         self.value = value
  24     def __str__(self):
  25         return repr(self.value)
  26
  27 class Variable:
  28     def __init__(self, namestr, defaultstr, exprstr = None):
  29         self.namestr = namestr
  30         self.defaultstr = defaultstr
  31         self.exprstr = exprstr
  32
  33     def __str__(self):
  34         return self.namestr
  35
  36     def has_value(self):
  37         return self.defaultstr != None
  38
  39     def get_value(self):
  40         if self.defaultstr == None:
  41             raise Error("Error: Trying to eval variable " + self.namestr + " with no value")
  42         return self.defaultstr
  43
  44 class OptionalSetting:
  45     def __init__(self, namestr, exprstr):
  46         self.namestr = namestr
  47         self.exprstr = exprstr
  48
  49     def get_name(self):
  50         return self.namestr
  51
  52     def get_value(self, var_list):
  53         instr = self.exprstr
  54         for var in var_list:
  55             if var_list[var].has_value():
  56                 p = re.compile( "\$\{" + var + "\}")
  57                 instr = p.sub( var_list[var].get_value(), instr)
  58         if instr.find("$") != -1:
  59             instr = "" # if not all variables were found, return empty option
  60         return instr
  61
  62 class Command:
  63     def __init__(self, namestr, callstr, var_list, optset_list):
  64         self.namestr = namestr
  65         self.callstr = callstr
  66         self.var_list = var_list
  67         self.optset_list = optset_list
  68
  69     def get_name(self):
  70         return self.namestr
  71
  72     def put_var(self, var):
  73         self.var_list[str(var)] = var
  74
  75     def get_vars(self):
  76         return self.var_list
  77
  78     def __str__(self):
  79         instr = self.callstr
  80
  81         p = re.compile("\$\[(\w+)\]")
  82         for o in p.findall(instr):
  83             if o not in self.optset_list:
  84                 raise Error("Error: Optional variable not defined")
  85             instr = p.sub(self.optset_list[o].get_value(self.var_list), instr)
  86
  87         p = re.compile("\$\{(\w+)\}")
  88         for o in p.findall(instr):
  89             if o not in self.var_list:
  90                 raise Error("Error: Variable \"" + o + "\" has not been assigned")
  91             val = self.var_list[o].get_value()
  92             instr = instr.replace("${" + o + "}", val)
  93
  94         if instr.find("$") != -1:
  95             raise Error("Error: all variables were not expanded")
  96         return instr
  97
  98 class CommandList:
  99     def __init__(self):
 100         self.cmdcall_dict = {}
 101         self._read_config()
 102
 103     def _read_properties(self, propnode, mand_propnames, opt_propnames = []):
 104         propdict = {}
 105
 106         for p in propnode:
 107             if p.name in mand_propnames:
 108                 propdict[p.name] = str(p.content)
 109             elif p.name != "text" and p.name not in opt_propnames:
 110                 raise Error("Error parsing XML: only name and call are accepted properties in the element command, found " + str(p.name))
 111
 112         if len(mand_propnames) != len(propdict.keys()):
 113             raise Error("Error parsing XML: must supply both name and call in element command")
 114
 115         for p in propnode:
 116             if p.name in opt_propnames:
 117                 propdict[p.name] = str(p.content)
 118             elif p.name != "text" and p.name not in mand_propnames:
 119                 raise Error("Error parsing XML: only name and call are accepted properties in the element command, found " + str(p.name))
 120
 121         return propdict
 122
 123     def _get_config_path(self):
 124         homeconf = os.path.expanduser("~") + "/.pyvconv/commands.xml"
 125         if os.path.isfile("commands.xml"):
 126             return "commands.xml"
 127         elif os.path.isfile(homeconf):
 128             return homeconf
 129         else:
 130             raise Error("Error: No config found")
 131
 132     def _read_config(self):
 133         doc = libxml2.parseFile(self._get_config_path())
 134         cmd_xmllist = doc.xpathEval( '//command')
 135
 136         # read all commands from XML description
 137         for cmdnode in cmd_xmllist:
 138             if cmdnode.type == "element" and cmdnode.name == "command":
 139
 140                 var_list = {}
 141                 optset_list = {}
 142
 143                 if cmdnode.children:
 144                     for varsetnode in cmdnode.children:
 145                         if varsetnode.type == "element" and varsetnode.name == "variable":
 146                             props =  self._read_properties(varsetnode.properties, ["name", "expr"], ["default"])
 147                             defprop = None
 148                             if "default" in props:
 149                                 defprop = props["default"]
 150                             var_list[props["name"]] = Variable(props["name"], defprop, props["expr"])
 151
 152                         elif varsetnode.type == "element" and varsetnode.name == "optionalsetting":
 153                             props = self._read_properties(varsetnode.properties, ["name", "expr"])
 154                             optset_list[props["name"]] = OptionalSetting(props["name"], props["expr"])
 155
 156                         elif varsetnode.name != "text":
 157                             raise Error("Error parsing XML: only variable and optionalsetting elements allowed in command")
 158
 159                 props = self._read_properties(cmdnode.properties, ["name", "call"])
 160                 self.cmdcall_dict[props["name"]] = Command(props["name"], props["call"], var_list, optset_list)
 161
 162             else:
 163                 raise Error("Error parsing XML: only command elements are supported")
 164
 165     def __iter__(self):
 166         return self.cmdcall_dict.values().__iter__()
 167
 168     def __getitem__(self, name):
 169         return self.cmdcall_dict[name]