hooke/playlist.py

   1 """The playlist module provides :class:`Playlist` its subclass
   2 :class:`FilePlaylist` for manipulating lists of
   3 :class:`hooke.curve.Curve`\s.
   4 """
   5
   6 import copy
   7 import hashlib
   8 import os.path
   9 import xml.dom.minidom
  10
  11 from . import curve as curve
  12
  13 class Playlist (list):
  14     """A list of :class:`hooke.curve.Curve`\s.
  15
  16     Keeps a list of :attr:`drivers` for loading curves, the
  17     :attr:`index` (i.e. "bookmark") of the currently active curve, and
  18     a :class:`dict` of additional informtion (:attr:`info`).
  19     """
  20     def __init__(self, drivers, name=None):
  21         super(Playlist, self).__init__()
  22         self.drivers = drivers
  23         self.name = name
  24         self.info = {}
  25         self._index = 0
  26
  27     def append_curve_by_path(self, path, info=None, identify=True):
  28         if self.path != None:
  29             path = os.path.join(self.path, path)
  30         path = os.path.normpath(path)
  31         c = curve.Curve(path, info=info)
  32         if identify == True:
  33             c.identify(self.drivers)
  34         self.append(c)
  35         return c
  36
  37     def active_curve(self):
  38         return self[self._index]
  39
  40     def has_curves(self):
  41         return len(self) > 0
  42
  43     def jump(self, index):
  44         if len(self) == 0:
  45             self._index = 0
  46         else:
  47             self._index = index % len(self)
  48
  49     def next(self):
  50         self.jump(self._index + 1)
  51
  52     def previous(self):
  53         self.jump(self._index - 1)
  54
  55     def filter(self, keeper_fn=lambda curve:True):
  56         playlist = copy.deepcopy(self)
  57         for curve in reversed(playlist.curves):
  58             if keeper_fn(curve) != True:
  59                 playlist.curves.remove(curve)
  60         try: # attempt to maintain the same active curve
  61             playlist._index = playlist.index(self.active_curve())
  62         except ValueError:
  63             playlist._index = 0
  64         return playlist
  65
  66 class FilePlaylist (Playlist):
  67     version = '0.1'
  68
  69     def __init__(self, drivers, name=None, path=None):
  70         if name == None and path != None:
  71             name = os.path.basename(path)
  72         super(FilePlaylist, self).__init__(drivers, name)
  73         self.path = path
  74         self._digest = None
  75
  76     def is_saved(self):
  77         return self.digest() == self._digest
  78
  79     def digest(self):
  80         r"""Compute the sha1 digest of the flattened playlist
  81         representation.
  82
  83         Examples
  84         --------
  85
  86         >>> root_path = os.path.sep + 'path'
  87         >>> p = FilePlaylist(drivers=[],
  88         ...                  path=os.path.join(root_path, 'to','playlist'))
  89         >>> p.info['note'] = 'An example playlist'
  90         >>> c = curve.Curve(os.path.join(root_path, 'to', 'curve', 'one'))
  91         >>> c.info['note'] = 'The first curve'
  92         >>> p.append(c)
  93         >>> c = curve.Curve(os.path.join(root_path, 'to', 'curve', 'two'))
  94         >>> c.info['note'] = 'The second curve'
  95         >>> p.append(c)
  96         >>> p.digest()
  97         "\xa1\x99\x8a\x99\xed\xad\x13'\xa7w\x12\x00\x07Z\xb3\xd0zN\xa2\xe1"
  98         """
  99         string = self.flatten()
 100         return hashlib.sha1(string).digest()
 101
 102     def flatten(self, absolute_paths=False):
 103         """Create a string representation of the playlist.
 104
 105         A playlist is an XML document with the following syntax::
 106
 107             <?xml version="1.0" encoding="utf-8"?>
 108             <playlist attribute="value">
 109               <curve path="/my/file/path/"/ attribute="value" ...>
 110               <curve path="...">
 111             </playlist>
 112
 113         Relative paths are interpreted relative to the location of the
 114         playlist file.
 115
 116         Examples
 117         --------
 118
 119         >>> root_path = os.path.sep + 'path'
 120         >>> p = FilePlaylist(drivers=[],
 121         ...                  path=os.path.join(root_path, 'to','playlist'))
 122         >>> p.info['note'] = 'An example playlist'
 123         >>> c = curve.Curve(os.path.join(root_path, 'to', 'curve', 'one'))
 124         >>> c.info['note'] = 'The first curve'
 125         >>> p.append(c)
 126         >>> c = curve.Curve(os.path.join(root_path, 'to', 'curve', 'two'))
 127         >>> c.info['note'] = 'The second curve'
 128         >>> p.append(c)
 129         >>> print p.flatten() # doctest: +NORMALIZE_WHITESPACE +REPORT_UDIFF
 130         <?xml version="1.0" encoding="utf-8"?>
 131         <playlist index="0" note="An example playlist" version="0.1">
 132             <curve note="The first curve" path="../curve/one"/>
 133             <curve note="The second curve" path="../curve/two"/>
 134         </playlist>
 135         <BLANKLINE>
 136         >>> print p.flatten(absolute_paths=True) # doctest: +NORMALIZE_WHITESPACE +REPORT_UDIFF
 137         <?xml version="1.0" encoding="utf-8"?>
 138         <playlist index="0" note="An example playlist" version="0.1">
 139             <curve note="The first curve" path="/path/to/curve/one"/>
 140             <curve note="The second curve" path="/path/to/curve/two"/>
 141         </playlist>
 142         <BLANKLINE>
 143         """
 144         implementation = xml.dom.minidom.getDOMImplementation()
 145         # create the document DOM object and the root element
 146         doc = implementation.createDocument(None, 'playlist', None)
 147         root = doc.documentElement
 148         root.setAttribute('version', self.version) # store playlist version
 149         root.setAttribute('index', str(self._index))
 150         for key,value in self.info.items(): # save info variables
 151             root.setAttribute(key, str(value))
 152         for curve in self: # save curves and their attributes
 153             curve_element = doc.createElement('curve')
 154             root.appendChild(curve_element)
 155             path = os.path.abspath(os.path.expanduser(curve.path))
 156             if absolute_paths == False:
 157                 path = os.path.relpath(
 158                     path,
 159                     os.path.abspath(os.path.expanduser(self.path)))
 160             curve_element.setAttribute('path', path)
 161             for key,value in curve.info.items():
 162                 curve_element.setAttribute(key, str(value))
 163         string = doc.toprettyxml(encoding='utf-8')
 164         root.unlink() # break circular references for garbage collection
 165         return string
 166
 167     def _from_xml_doc(self, doc):
 168         """Load a playlist from an :class:`xml.dom.minidom.Document`
 169         instance.
 170         """
 171         root = doc.documentElement
 172         for attribute,value in root.attributes.items():
 173             if attribute == 'version':
 174                 assert value == self.version, \
 175                     'Cannot read v%s playlist with a v%s reader' \
 176                     % (value, self.version)
 177             elif attribute == 'index':
 178                 self._index = int(value)
 179             else:
 180                 self.info[attribute] = value
 181         for curve_element in doc.getElementsByTagName('curve'):
 182             path = curve_element.getAttribute('path')
 183             info = dict(curve_element.attributes.items())
 184             info.pop('path')
 185             self.append_curve_by_path(path, info, identify=False)
 186         self.jump(self._index) # ensure valid index
 187
 188     def from_string(self, string):
 189         """Load a playlist from a string.
 190
 191         Examples
 192         --------
 193
 194         >>> string = '''<?xml version="1.0" encoding="utf-8"?>
 195         ... <playlist index="1" note="An example playlist" version="0.1">
 196         ...     <curve note="The first curve" path="../curve/one"/>
 197         ...     <curve note="The second curve" path="../curve/two"/>
 198         ... </playlist>
 199         ... '''
 200         >>> p = FilePlaylist(drivers=[],
 201         ...                  path=os.path.join('path', 'to','playlist'))
 202         >>> p.from_string(string)
 203         >>> p._index
 204         1
 205         >>> p.info
 206         {u'note': u'An example playlist'}
 207         >>> for curve in p:
 208         ...     print curve.path
 209         path/to/curve/one
 210         path/to/curve/two
 211         """
 212         doc = xml.dom.minidom.parseString(string)
 213         return self._from_xml_doc(doc)
 214
 215     def load(self, path=None):
 216         """Load a playlist from a file.
 217         """
 218         if path != None:
 219             self.path = path
 220         if self.name == None:
 221             self.name = os.path.basename(self.path)
 222         doc = xml.dom.minidom.parse(path)
 223         return self._from_xml_doc(doc)
 224
 225     def save(self, path):
 226         """Saves the playlist in a XML file.
 227         """
 228         f = file(path, 'w')
 229         f.write(self.flatten())
 230         f.close()