pyx/helper.py

   1 #!/usr/bin/env python
   2 # -*- coding: ISO-8859-1 -*-
   3 #
   4 #
   5 # Copyright (C) 2002-2004 Jörg Lehmann <joergl@users.sourceforge.net>
   6 # Copyright (C) 2002-2004 André Wobst <wobsta@users.sourceforge.net>
   7 #
   8 # This file is part of PyX (http://pyx.sourceforge.net/).
   9 #
  10 # PyX is free software; you can redistribute it and/or modify
  11 # it under the terms of the GNU General Public License as published by
  12 # the Free Software Foundation; either version 2 of the License, or
  13 # (at your option) any later version.
  14 #
  15 # PyX is distributed in the hope that it will be useful,
  16 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18 # GNU General Public License for more details.
  19 #
  20 # You should have received a copy of the GNU General Public License
  21 # along with PyX; if not, write to the Free Software
  22 # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  23
  24
  25 import base
  26
  27
  28 class nodefault: pass
  29
  30
  31 def isstring(arg):
  32     "arg is string-like (cf. python cookbook 3.2)"
  33     try: arg + ''
  34     except: return 0
  35     return 1
  36
  37
  38 def isnumber(arg):
  39     "arg is number-like"
  40     try: arg + 0
  41     except: return 0
  42     return 1
  43
  44
  45 def isinteger(arg):
  46     "arg is integer-like"
  47     try:
  48         if type(arg + 0.0) is type(arg):
  49             return 0
  50         return 1
  51     except: return 0
  52
  53
  54 def issequence(arg):
  55     """arg is sequence-like (e.g. has a len)
  56        a string is *not* considered to be a sequence"""
  57     if isstring(arg): return 0
  58     try: len(arg)
  59     except: return 0
  60     return 1
  61
  62
  63 def ensuresequence(arg):
  64     """return arg or (arg,) depending on the result of issequence,
  65        None is converted to ()"""
  66     if isstring(arg): return (arg,)
  67     if arg is None: return ()
  68     if issequence(arg): return arg
  69     return (arg,)
  70
  71
  72 def ensurelist(arg):
  73     """return list(arg) or [arg] depending on the result of isequence,
  74        None is converted to []"""
  75     if isstring(arg): return [arg]
  76     if arg is None: return []
  77     if issequence(arg): return list(arg)
  78     return [arg]
  79
  80 def getitemno(arg, n):
  81     """get item number n if arg is a sequence (when the sequence
  82        is not long enough, None is returned), otherweise arg is
  83        returned"""
  84     if issequence(arg):
  85         try: return arg[n]
  86         except: return None
  87     else:
  88         return arg
  89
  90
  91 def issequenceofsequences(arg):
  92     """check if arg has a sequence or None as it's first entry"""
  93     return issequence(arg) and len(arg) and (issequence(arg[0]) or arg[0] is None)
  94
  95
  96 def getsequenceno(arg, n):
  97     """get sequence number n if arg is a sequence of sequences (when
  98        the sequence is not long enough, None is returned), otherwise
  99        arg is returned"""
 100     if issequenceofsequences(arg):
 101         try: return arg[n]
 102         except: return None
 103     else:
 104         return arg