seq_with_cursor.py

gnuradio软件无线电源程序.现在的手机多基于软件无线电

#
# Copyright 2003,2004 Free Software Foundation, Inc.
# 
# This file is part of GNU Radio
# 
# GNU Radio is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2, or (at your option)
# any later version.
# 
# GNU Radio is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
# 
# You should have received a copy of the GNU General Public License
# along with GNU Radio; see the file COPYING.  If not, write to
# the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
# Boston, MA 02111-1307, USA.
# 

# misc utilities

import types
import exceptions

class seq_with_cursor (object):
    __slots__ = [ 'items', 'index' ]

    def __init__ (self, items, initial_index = None):
        assert len (items) > 0, "seq_with_cursor: len (items) == 0"
        self.items = items
        self.set_index (initial_index)

    def set_index (self, initial_index):
        if initial_index is None:
            self.index = len (self.items) / 2
        elif initial_index >= 0 and initial_index < len (self.items):
            self.index = initial_index
        else:
            raise exceptions.ValueError
        
    def next (self):
        new_index = self.index + 1
        if new_index < len (self.items):
            self.index = new_index
            return self.items[new_index], True
        else:
            return self.items[self.index], False

    def prev (self):
        new_index = self.index - 1
        if new_index >= 0:
            self.index = new_index
            return self.items[new_index], True
        else:
            return self.items[self.index], False

    def current (self):
        return self.items[self.index]

    def get_seq (self):
        return self.items[:]            # copy of items