Source code for core.graph.id_generator

# -*- python -*-
#
#       OpenAlea.Core
#
#       Copyright 2006-2009 INRIA - CIRAD - INRA
#
#       File author(s): Jerome Chopard <jerome.chopard@sophia.inria.fr>
#                       Fred Theveny <theveny@cirad.fr>
#
#       Distributed under the Cecill-C License.
#       See accompanying file LICENSE.txt or copy at
#           http://www.cecill.info/licences/Licence_CeCILL-C_V1-en.html
#
#       OpenAlea WebSite : http://openalea.gforge.inria.fr
#
###############################################################################

__doc__="""
This module provide a generator for id numbers
"""

__license__= "Cecill-C"
__revision__=" $Id$ "


class IdGenerator(object):

    def __init__(self):
        self._id_max=0
        self._id_list=[]

    def get_id(self, id=None):
        if id is None:
            if len(self._id_list)==0:
                ret=self._id_max
                self._id_max+=1
                return ret
            else:
                return self._id_list.pop()
        else:
            if id>=self._id_max:
                self._id_list.extend(range(self._id_max, id))
                self._id_max=id+1
                return id
            else:
                try:
                    ind=self._id_list.index(id)
                    del self._id_list[ind]
                    return id
                except ValueError:
                    raise IndexError("id %d already used" % id)

    def release_id(self, id):
        if id>self._id_max:
            raise IndexError("id out of range")
        elif id in self._id_list:
            raise IndexError("id already not used")
        else:
            self._id_list.append(id)