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, extstr, var_list, optset_list):
  64         self.namestr = namestr
  65         self.callstr = callstr
  66         self.extstr = extstr
  67         self.var_list = var_list
  68         self.optset_list = optset_list
  69
  70     def get_name(self):
  71         return self.namestr
  72
  73     def get_outfile_extension(self):
  74         return self.extstr
  75
  76     def put_var(self, var):
  77         self.var_list[str(var)] = var
  78
  79     def get_vars(self):
  80         return self.var_list
  81
  82     def __str__(self):
  83         instr = self.callstr
  84
  85         p = re.compile("\$\[(\w+)\]")
  86         for o in p.findall(instr):
  87             if o not in self.optset_list:
  88                 raise Error("Error: Optional variable not defined")
  89             instr = p.sub(self.optset_list[o].get_value(self.var_list), instr)
  90
  91         p = re.compile("\$\{(\w+)\}")
  92         for o in p.findall(instr):
  93             if o not in self.var_list:
  94                 raise Error("Error: Variable \"" + o + "\" has not been assigned")
  95             val = self.var_list[o].get_value()
  96             instr = instr.replace("${" + o + "}", val)
  97
  98         if instr.find("$") != -1:
  99             raise Error("Error: all variables were not expanded")
 100         return instr
 101
 102 class CommandList:
 103     def __init__(self):
 104         self.cmdcall_dict = {}
 105         self._read_config()
 106
 107     def _read_properties(self, propnode, mand_propnames, opt_propnames = []):
 108         propdict = {}
 109
 110         for p in propnode:
 111             if p.name in mand_propnames:
 112                 propdict[p.name] = str(p.content)
 113             elif p.name != "text" and p.name not in opt_propnames:
 114                 raise Error("Error parsing XML: only name and call are accepted properties in the element command, found " + str(p.name))
 115
 116         if len(mand_propnames) != len(propdict.keys()):
 117             raise Error("Error parsing XML: must supply both name and call in element command")
 118
 119         for p in propnode:
 120             if p.name in opt_propnames:
 121                 propdict[p.name] = str(p.content)
 122             elif p.name != "text" and p.name not in mand_propnames:
 123                 raise Error("Error parsing XML: only name and call are accepted properties in the element command, found " + str(p.name))
 124
 125         return propdict
 126
 127     def _get_config_path(self):
 128         homeconf = os.path.expanduser("~") + "/.pyvconv/commands.xml"
 129         if os.path.isfile("commands.xml"):
 130             return "commands.xml"
 131         elif os.path.isfile(homeconf):
 132             return homeconf
 133         else:
 134             raise Error("Error: No config found")
 135
 136     def _cmd_program_found_in_path(self, programstr):
 137         if not os.environ.has_key('PATH') or os.environ['PATH']=='':
 138             p = os.defpath
 139         else:
 140             p = os.environ['PATH']
 141
 142         pathlist = p.split (os.pathsep)
 143         for path in pathlist:
 144             f = os.path.join(path, programstr)
 145             if os.access(f, os.X_OK):
 146                 return True
 147         return False
 148
 149     def _read_config(self):
 150         doc = libxml2.parseFile(self._get_config_path())
 151         cmd_xmllist = doc.xpathEval( '//command')
 152
 153         # read all commands from XML description
 154         for cmdnode in cmd_xmllist:
 155             if cmdnode.type == "element" and cmdnode.name == "command":
 156
 157                 var_list = {}
 158                 optset_list = {}
 159
 160                 if cmdnode.children:
 161                     for varsetnode in cmdnode.children:
 162                         if varsetnode.type == "element" and varsetnode.name == "variable":
 163                             props =  self._read_properties(varsetnode.properties, ["name", "expr"], ["default"])
 164                             defprop = None
 165                             if "default" in props:
 166                                 defprop = props["default"]
 167                             var_list[props["name"]] = Variable(props["name"], defprop, props["expr"])
 168
 169                         elif varsetnode.type == "element" and varsetnode.name == "optionalsetting":
 170                             props = self._read_properties(varsetnode.properties, ["name", "expr"])
 171                             optset_list[props["name"]] = OptionalSetting(props["name"], props["expr"])
 172
 173                         elif varsetnode.name != "text":
 174                             raise Error("Error parsing XML: only variable and optionalsetting elements allowed in command")
 175
 176                 props = self._read_properties(cmdnode.properties, ["name", "call", "ext"])
 177
 178                 if self._cmd_program_found_in_path( props["call"].split()[0] ):
 179                     self.cmdcall_dict[props["name"]] = Command(props["name"], props["call"], props["ext"], var_list, optset_list)
 180
 181             else:
 182                 raise Error("Error parsing XML: only command elements are supported")
 183
 184     def __iter__(self):
 185         return self.cmdcall_dict.values().__iter__()
 186
 187     def __len__(self):
 188         return len(self.cmdcall_dict)
 189
 190     def __getitem__(self, name):
 191         return self.cmdcall_dict[name]