hooke/playlist.py

   1 # Copyright (C) 2010 W. Trevor King <wking@drexel.edu>
   2 #
   3 # This file is part of Hooke.
   4 #
   5 # Hooke is free software: you can redistribute it and/or
   6 # modify it under the terms of the GNU Lesser General Public
   7 # License as published by the Free Software Foundation, either
   8 # version 3 of the License, or (at your option) any later version.
   9 #
  10 # Hooke is distributed in the hope that it will be useful,
  11 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 # GNU Lesser General Public License for more details.
  14 #
  15 # You should have received a copy of the GNU Lesser General Public
  16 # License along with Hooke.  If not, see
  17 # <http://www.gnu.org/licenses/>.
  18
  19 """The `playlist` module provides a :class:`Playlist` and its subclass
  20 :class:`FilePlaylist` for manipulating lists of
  21 :class:`hooke.curve.Curve`\s.
  22 """
  23
  24 import copy
  25 import hashlib
  26 import os.path
  27 import xml.dom.minidom
  28
  29 from . import curve as curve
  30
  31
  32 class NoteIndexList (list):
  33     """A list that keeps track of a "current" item and additional notes.
  34
  35     :attr:`index` (i.e. "bookmark") is the index of the currently
  36     current curve.  Also keep a :class:`dict` of additional information
  37     (:attr:`info`).
  38     """
  39     def __init__(self, name=None):
  40         super(NoteIndexList, self).__init__()
  41         self.name = name
  42         self.info = {}
  43         self._index = 0
  44
  45     def __str__(self):
  46         return '<%s %s>' % (self.__class__.__name__, self.name)
  47
  48     def current(self):
  49         if len(self) == 0:
  50             return None
  51         return self[self._index]
  52
  53     def jump(self, index):
  54         if len(self) == 0:
  55             self._index = 0
  56         else:
  57             self._index = index % len(self)
  58
  59     def next(self):
  60         self.jump(self._index + 1)
  61
  62     def previous(self):
  63         self.jump(self._index - 1)
  64
  65     def filter(self, keeper_fn=lambda item:True):
  66         c = copy.deepcopy(self)
  67         for item in reversed(c):
  68             if keeper_fn(item) != True:
  69                 c.remove(item)
  70         try: # attempt to maintain the same current item
  71             c._index = c.index(self.current())
  72         except ValueError:
  73             c._index = 0
  74         return c
  75
  76 class Playlist (NoteIndexList):
  77     """A :class:`NoteIndexList` of :class:`hooke.curve.Curve`\s.
  78
  79     Keeps a list of :attr:`drivers` for loading curves.
  80     """
  81     def __init__(self, drivers, name=None):
  82         super(Playlist, self).__init__(name=name)
  83         self.drivers = drivers
  84
  85     def append_curve_by_path(self, path, info=None, identify=True):
  86         if self.path != None:
  87             path = os.path.join(self.path, path)
  88         path = os.path.normpath(path)
  89         c = curve.Curve(path, info=info)
  90         if identify == True:
  91             c.identify(self.drivers)
  92         self.append(c)
  93         return c
  94
  95 class FilePlaylist (Playlist):
  96     version = '0.1'
  97
  98     def __init__(self, drivers, name=None, path=None):
  99         super(FilePlaylist, self).__init__(drivers, name)
 100         self.set_path(path)
 101         self._digest = None
 102
 103     def set_path(self, path):
 104         if path != None:
 105             if not path.endswith('.hkp'):
 106                 path += '.hkp'
 107             self.path = path
 108             if self.name == None:
 109                 self.name = os.path.basename(path)
 110
 111     def is_saved(self):
 112         return self.digest() == self._digest
 113
 114     def digest(self):
 115         r"""Compute the sha1 digest of the flattened playlist
 116         representation.
 117
 118         Examples
 119         --------
 120
 121         >>> root_path = os.path.sep + 'path'
 122         >>> p = FilePlaylist(drivers=[],
 123         ...                  path=os.path.join(root_path, 'to','playlist'))
 124         >>> p.info['note'] = 'An example playlist'
 125         >>> c = curve.Curve(os.path.join(root_path, 'to', 'curve', 'one'))
 126         >>> c.info['note'] = 'The first curve'
 127         >>> p.append(c)
 128         >>> c = curve.Curve(os.path.join(root_path, 'to', 'curve', 'two'))
 129         >>> c.info['note'] = 'The second curve'
 130         >>> p.append(c)
 131         >>> p.digest()
 132         "\xa1\x99\x8a\x99\xed\xad\x13'\xa7w\x12\x00\x07Z\xb3\xd0zN\xa2\xe1"
 133         """
 134         string = self.flatten()
 135         return hashlib.sha1(string).digest()
 136
 137     def flatten(self, absolute_paths=False):
 138         """Create a string representation of the playlist.
 139
 140         A playlist is an XML document with the following syntax::
 141
 142             <?xml version="1.0" encoding="utf-8"?>
 143             <playlist attribute="value">
 144               <curve path="/my/file/path/"/ attribute="value" ...>
 145               <curve path="...">
 146             </playlist>
 147
 148         Relative paths are interpreted relative to the location of the
 149         playlist file.
 150
 151         Examples
 152         --------
 153
 154         >>> root_path = os.path.sep + 'path'
 155         >>> p = FilePlaylist(drivers=[],
 156         ...                  path=os.path.join(root_path, 'to','playlist'))
 157         >>> p.info['note'] = 'An example playlist'
 158         >>> c = curve.Curve(os.path.join(root_path, 'to', 'curve', 'one'))
 159         >>> c.info['note'] = 'The first curve'
 160         >>> p.append(c)
 161         >>> c = curve.Curve(os.path.join(root_path, 'to', 'curve', 'two'))
 162         >>> c.info['note'] = 'The second curve'
 163         >>> p.append(c)
 164         >>> print p.flatten() # doctest: +NORMALIZE_WHITESPACE +REPORT_UDIFF
 165         <?xml version="1.0" encoding="utf-8"?>
 166         <playlist index="0" note="An example playlist" version="0.1">
 167             <curve note="The first curve" path="../curve/one"/>
 168             <curve note="The second curve" path="../curve/two"/>
 169         </playlist>
 170         <BLANKLINE>
 171         >>> print p.flatten(absolute_paths=True) # doctest: +NORMALIZE_WHITESPACE +REPORT_UDIFF
 172         <?xml version="1.0" encoding="utf-8"?>
 173         <playlist index="0" note="An example playlist" version="0.1">
 174             <curve note="The first curve" path="/path/to/curve/one"/>
 175             <curve note="The second curve" path="/path/to/curve/two"/>
 176         </playlist>
 177         <BLANKLINE>
 178         """
 179         implementation = xml.dom.minidom.getDOMImplementation()
 180         # create the document DOM object and the root element
 181         doc = implementation.createDocument(None, 'playlist', None)
 182         root = doc.documentElement
 183         root.setAttribute('version', self.version) # store playlist version
 184         root.setAttribute('index', str(self._index))
 185         for key,value in self.info.items(): # save info variables
 186             root.setAttribute(key, str(value))
 187         for curve in self: # save curves and their attributes
 188             curve_element = doc.createElement('curve')
 189             root.appendChild(curve_element)
 190             path = os.path.abspath(os.path.expanduser(curve.path))
 191             if absolute_paths == False:
 192                 path = os.path.relpath(
 193                     path,
 194                     os.path.abspath(os.path.expanduser(self.path)))
 195             curve_element.setAttribute('path', path)
 196             for key,value in curve.info.items():
 197                 curve_element.setAttribute(key, str(value))
 198         string = doc.toprettyxml(encoding='utf-8')
 199         root.unlink() # break circular references for garbage collection
 200         return string
 201
 202     def _from_xml_doc(self, doc):
 203         """Load a playlist from an :class:`xml.dom.minidom.Document`
 204         instance.
 205         """
 206         root = doc.documentElement
 207         for attribute,value in root.attributes.items():
 208             if attribute == 'version':
 209                 assert value == self.version, \
 210                     'Cannot read v%s playlist with a v%s reader' \
 211                     % (value, self.version)
 212             elif attribute == 'index':
 213                 self._index = int(value)
 214             else:
 215                 self.info[attribute] = value
 216         for curve_element in doc.getElementsByTagName('curve'):
 217             path = curve_element.getAttribute('path')
 218             info = dict(curve_element.attributes.items())
 219             info.pop('path')
 220             self.append_curve_by_path(path, info, identify=False)
 221         self.jump(self._index) # ensure valid index
 222
 223     def from_string(self, string):
 224         """Load a playlist from a string.
 225
 226         Examples
 227         --------
 228
 229         >>> string = '''<?xml version="1.0" encoding="utf-8"?>
 230         ... <playlist index="1" note="An example playlist" version="0.1">
 231         ...     <curve note="The first curve" path="../curve/one"/>
 232         ...     <curve note="The second curve" path="../curve/two"/>
 233         ... </playlist>
 234         ... '''
 235         >>> p = FilePlaylist(drivers=[],
 236         ...                  path=os.path.join('path', 'to','playlist'))
 237         >>> p.from_string(string)
 238         >>> p._index
 239         1
 240         >>> p.info
 241         {u'note': u'An example playlist'}
 242         >>> for curve in p:
 243         ...     print curve.path
 244         path/to/curve/one
 245         path/to/curve/two
 246         """
 247         doc = xml.dom.minidom.parseString(string)
 248         self._from_xml_doc(doc)
 249
 250     def load(self, path=None):
 251         """Load a playlist from a file.
 252         """
 253         self.set_path(path)
 254         doc = xml.dom.minidom.parse(self.path)
 255         self._from_xml_doc(doc)
 256         self._digest = self.digest()
 257
 258     def save(self, path=None):
 259         """Saves the playlist in a XML file.
 260         """
 261         self.set_path(path)
 262         f = file(self.path, 'w')
 263         f.write(self.flatten())
 264         f.close()