1 #!/usr/bin/python2.5

     2 #

     3 # Copyright 2009 the Melange authors.

     4 #

     5 # Licensed under the Apache License, Version 2.0 (the "License");

     6 # you may not use this file except in compliance with the License.

     7 # You may obtain a copy of the License at

     8 #

     9 #   http://www.apache.org/licenses/LICENSE-2.0

    10 #

    11 # Unless required by applicable law or agreed to in writing, software

    12 # distributed under the License is distributed on an "AS IS" BASIS,

    13 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

    14 # See the License for the specific language governing permissions and

    15 # limitations under the License.

    16 

    17 """RankerRoot (Model) query functions.

    18 """

    19 

    20 __authors__ = [

    21   '"Lennard de Rijk" <ljvderijk@gmail.com>',

    22   ]

    23 

    24 from google.appengine.api import datastore

    25 

    26 from ranklist.ranker import Ranker

    27 

    28 from soc.logic.models import base

    29 

    30 import soc.models.rankerroot

    31 

    32 

    33 class Logic(base.Logic):

    34   """Logic methods for the RankerRoot model.

    35   """

    36 

    37   def __init__(self, model=soc.models.rankerroot.RankerRoot, 

    38                base_model=None, scope_logic=None):

    39     """Defines the name, key_name and model for this entity.

    40     """

    41 

    42     super(Logic, self).__init__(model=model, base_model=base_model,

    43                                 scope_logic=scope_logic)

    44 

    45   def create(self, name, scope, scores, branching_factor):

    46     """Creates a new RankerRoot with a new Ranker.

    47 

    48     Args:

    49       name: the Link ID of the ranker root

    50       scope: the entity owning the ranker

    51       score_range: A list showing the range of valid scores, in the form:

    52           [most_significant_score_min, most_significant_score_max,

    53           less_significant_score_min, less_significant_score_max, ...]

    54           Ranges are [inclusive, exclusive)

    55       branching_factor: The branching factor of the tree.  The number of

    56           datastore Gets is Theta(1/log(branching_factor)), and the amount of data

    57           returned by each Get is Theta(branching_factor). 

    58 

    59     """

    60     ranker = Ranker.Create(scores, branching_factor)

    61 

    62     fields = {'link_id': name,

    63         'scope': scope,

    64         'scope_path': scope.key().name(),

    65         'root': ranker.rootkey}

    66 

    67     key_name = self.getKeyNameFromFields(fields)

    68     self.updateOrCreateFromKeyName(fields, key_name)

    69 

    70   def getRootFromEntity(self, entity):

    71     """Returns a Ranker object created from a RankerRoot entity.

    72 

    73     Args:

    74       entity: A RankerRoot entity which the root should be retrieved of

    75     """

    76 

    77     return Ranker(datastore.Get(entity.key())['root'])

    78 

    79 

    80 logic = Logic()