Source Code for Module osh.command.tail

 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{tail N} 
19   
20  The last N items of the input sequence are passed on as output. All other input 
21  is ignored. N must be an integer. 
22   
23  """ 
24   
25  import osh.core 
26   
27  # CLI 
28 -def _tail(): 
29      return _Tail() 
30   
31  # API 
32 -def tail(n): 
33      """The last N items of the input sequence are passed on as output. All other input 
34      is ignored. N must be an integer. 
35      """ 
36      return _Tail().process_args(n) 
37   
38 -class _Tail(osh.core.Op): 
39   
40      _n = None 
41      _tail = None 
42      _p = None 
43      _full = None 
44   
45   
46      # object interface 
47   
48 -    def __init__(self): 
49          osh.core.Op.__init__(self, '', (1, 1)) 
50   
51   
52      # BaseOp interface 
53       
54 -    def doc(self): 
55          return __doc__ 
56   
57 -    def setup(self): 
58          args = self.args() 
59          self._n = args.next_int() 
60          self._tail = [None for i in xrange(self._n)] 
61          self._p = 0 
62          self._full = False 
63   
64 -    def receive(self, object): 
65          if self._n > 0: 
66              self._tail[self._p] = object 
67              self._p += 1 
68              if self._p == self._n: 
69                  self._full = True 
70                  self._p = 0 
71   
72 -    def receive_complete(self): 
73          tail = self._tail 
74          if self._full: 
75              for i in xrange(self._p, self._n): 
76                  self.send(tail[i]) 
77          for i in xrange(self._p): 
78              self.send(tail[i]) 
79          self.send_complete() 
80