Source Code for Module osh.command.select

 1  # osh 
 2  # Copyright (C) Jack Orenstein <jao@geophile.com> 
 3  # 
 4  # This program is free software; you can redistribute it and/or modify 
 5  # it under the terms of the GNU General Public License as published by 
 6  # the Free Software Foundation; either version 2 of the License, or 
 7  # (at your option) any later version. 
 8  # 
 9  # This program is distributed in the hope that it will be useful, 
10  # but WITHOUT ANY WARRANTY; without even the implied warranty of 
11  # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
12  # GNU General Public License for more details. 
13  # 
14  # You should have received a copy of the GNU General Public License 
15  # along with this program; if not, write to the Free Software 
16  # Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 
17   
18  """C{select FUNCTION} 
19   
20  C{FUNCTION} is applied to input objects. Objects for which C{FUNCTION} 
21  evaluates to true are sent to the output stream. 
22   
23  B{Example}: For the input C{(1,), (2,), (3,), (4,)}, this command:: 
24   
25      select 'x: (x % 2) == 0' 
26   
27  generates the output C{(2,), (4,)}. 
28  """ 
29   
30  import osh.function 
31  import osh.core 
32   
33  # CLI 
34 -def _select(): 
35      return _Select() 
36   
37  # API 
38 -def select(function): 
39      """Input objects for which C{function} evaluates to true are sent to the output stream. 
40      """ 
41      return _Select().process_args(function) 
42   
43 -class _Select(osh.core.Op): 
44   
45      _function = None 
46   
47   
48      # object interface 
49   
50 -    def __init__(self): 
51          osh.core.Op.__init__(self, '', (1, 1)) 
52   
53   
54      # OshCommand interface 
55       
56 -    def doc(self): 
57          return __doc__ 
58   
59 -    def setup(self): 
60          args = self.args() 
61          self._function = args.next_function() 
62          if self._function is None or args.has_next(): 
63              self.usage() 
64   
65   
66      # Receiver interface 
67       
68 -    def receive(self, object): 
69          # core ensures that we get a tuple (see wrap_if_necessary) 
70          if self._function(*object): 
71              self.send(object) 
72