hooke/playlist.py

   1 """The `playlist` module provides a :class:`Playlist` and 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
  14 class NoteIndexList (list):
  15     """A list that keeps track of a "current" item and additional notes.
  16
  17     :attr:`index` (i.e. "bookmark") is the index of the currently
  18     current curve.  Also keep a :class:`dict` of additional information
  19     (:attr:`info`).
  20     """
  21     def __init__(self, name=None):
  22         super(NoteIndexList, self).__init__()
  23         self.name = name
  24         self.info = {}
  25         self._index = 0
  26
  27     def current(self):
  28         if len(self) == 0:
  29             return None
  30         return self[self._index]
  31
  32     def jump(self, index):
  33         if len(self) == 0:
  34             self._index = 0
  35         else:
  36             self._index = index % len(self)
  37
  38     def next(self):
  39         self.jump(self._index + 1)
  40
  41     def previous(self):
  42         self.jump(self._index - 1)
  43
  44     def filter(self, keeper_fn=lambda item:True):
  45         c = copy.deepcopy(self)
  46         for item in reversed(c):
  47             if keeper_fn(item) != True:
  48                 c.remove(item)
  49         try: # attempt to maintain the same current item
  50             c._index = c.index(self.current())
  51         except ValueError:
  52             c._index = 0
  53         return c
  54
  55 class Playlist (NoteIndexList):
  56     """A :class:`NoteIndexList` of :class:`hooke.curve.Curve`\s.
  57
  58     Keeps a list of :attr:`drivers` for loading curves.
  59     """
  60     def __init__(self, drivers, name=None):
  61         super(Playlist, self).__init__(name=name)
  62         self.drivers = drivers
  63
  64     def append_curve_by_path(self, path, info=None, identify=True):
  65         if self.path != None:
  66             path = os.path.join(self.path, path)
  67         path = os.path.normpath(path)
  68         c = curve.Curve(path, info=info)
  69         if identify == True:
  70             c.identify(self.drivers)
  71         self.append(c)
  72         return c
  73
  74 class FilePlaylist (Playlist):
  75     version = '0.1'
  76
  77     def __init__(self, drivers, name=None, path=None):
  78         super(FilePlaylist, self).__init__(drivers, name)
  79         self.set_path(path)
  80         self._digest = None
  81
  82     def set_path(self, path):
  83         if path != None:
  84             if not path.endswith('.hkp'):
  85                 path += '.hkp'
  86             if self.name == None:
  87                 name = os.path.basename(path)
  88
  89     def is_saved(self):
  90         return self.digest() == self._digest
  91
  92     def digest(self):
  93         r"""Compute the sha1 digest of the flattened playlist
  94         representation.
  95
  96         Examples
  97         --------
  98
  99         >>> root_path = os.path.sep + 'path'
 100         >>> p = FilePlaylist(drivers=[],
 101         ...                  path=os.path.join(root_path, 'to','playlist'))
 102         >>> p.info['note'] = 'An example playlist'
 103         >>> c = curve.Curve(os.path.join(root_path, 'to', 'curve', 'one'))
 104         >>> c.info['note'] = 'The first curve'
 105         >>> p.append(c)
 106         >>> c = curve.Curve(os.path.join(root_path, 'to', 'curve', 'two'))
 107         >>> c.info['note'] = 'The second curve'
 108         >>> p.append(c)
 109         >>> p.digest()
 110         "\xa1\x99\x8a\x99\xed\xad\x13'\xa7w\x12\x00\x07Z\xb3\xd0zN\xa2\xe1"
 111         """
 112         string = self.flatten()
 113         return hashlib.sha1(string).digest()
 114
 115     def flatten(self, absolute_paths=False):
 116         """Create a string representation of the playlist.
 117
 118         A playlist is an XML document with the following syntax::
 119
 120             <?xml version="1.0" encoding="utf-8"?>
 121             <playlist attribute="value">
 122               <curve path="/my/file/path/"/ attribute="value" ...>
 123               <curve path="...">
 124             </playlist>
 125
 126         Relative paths are interpreted relative to the location of the
 127         playlist file.
 128
 129         Examples
 130         --------
 131
 132         >>> root_path = os.path.sep + 'path'
 133         >>> p = FilePlaylist(drivers=[],
 134         ...                  path=os.path.join(root_path, 'to','playlist'))
 135         >>> p.info['note'] = 'An example playlist'
 136         >>> c = curve.Curve(os.path.join(root_path, 'to', 'curve', 'one'))
 137         >>> c.info['note'] = 'The first curve'
 138         >>> p.append(c)
 139         >>> c = curve.Curve(os.path.join(root_path, 'to', 'curve', 'two'))
 140         >>> c.info['note'] = 'The second curve'
 141         >>> p.append(c)
 142         >>> print p.flatten() # doctest: +NORMALIZE_WHITESPACE +REPORT_UDIFF
 143         <?xml version="1.0" encoding="utf-8"?>
 144         <playlist index="0" note="An example playlist" version="0.1">
 145             <curve note="The first curve" path="../curve/one"/>
 146             <curve note="The second curve" path="../curve/two"/>
 147         </playlist>
 148         <BLANKLINE>
 149         >>> print p.flatten(absolute_paths=True) # doctest: +NORMALIZE_WHITESPACE +REPORT_UDIFF
 150         <?xml version="1.0" encoding="utf-8"?>
 151         <playlist index="0" note="An example playlist" version="0.1">
 152             <curve note="The first curve" path="/path/to/curve/one"/>
 153             <curve note="The second curve" path="/path/to/curve/two"/>
 154         </playlist>
 155         <BLANKLINE>
 156         """
 157         implementation = xml.dom.minidom.getDOMImplementation()
 158         # create the document DOM object and the root element
 159         doc = implementation.createDocument(None, 'playlist', None)
 160         root = doc.documentElement
 161         root.setAttribute('version', self.version) # store playlist version
 162         root.setAttribute('index', str(self._index))
 163         for key,value in self.info.items(): # save info variables
 164             root.setAttribute(key, str(value))
 165         for curve in self: # save curves and their attributes
 166             curve_element = doc.createElement('curve')
 167             root.appendChild(curve_element)
 168             path = os.path.abspath(os.path.expanduser(curve.path))
 169             if absolute_paths == False:
 170                 path = os.path.relpath(
 171                     path,
 172                     os.path.abspath(os.path.expanduser(self.path)))
 173             curve_element.setAttribute('path', path)
 174             for key,value in curve.info.items():
 175                 curve_element.setAttribute(key, str(value))
 176         string = doc.toprettyxml(encoding='utf-8')
 177         root.unlink() # break circular references for garbage collection
 178         return string
 179
 180     def _from_xml_doc(self, doc):
 181         """Load a playlist from an :class:`xml.dom.minidom.Document`
 182         instance.
 183         """
 184         root = doc.documentElement
 185         for attribute,value in root.attributes.items():
 186             if attribute == 'version':
 187                 assert value == self.version, \
 188                     'Cannot read v%s playlist with a v%s reader' \
 189                     % (value, self.version)
 190             elif attribute == 'index':
 191                 self._index = int(value)
 192             else:
 193                 self.info[attribute] = value
 194         for curve_element in doc.getElementsByTagName('curve'):
 195             path = curve_element.getAttribute('path')
 196             info = dict(curve_element.attributes.items())
 197             info.pop('path')
 198             self.append_curve_by_path(path, info, identify=False)
 199         self.jump(self._index) # ensure valid index
 200
 201     def from_string(self, string):
 202         """Load a playlist from a string.
 203
 204         Examples
 205         --------
 206
 207         >>> string = '''<?xml version="1.0" encoding="utf-8"?>
 208         ... <playlist index="1" note="An example playlist" version="0.1">
 209         ...     <curve note="The first curve" path="../curve/one"/>
 210         ...     <curve note="The second curve" path="../curve/two"/>
 211         ... </playlist>
 212         ... '''
 213         >>> p = FilePlaylist(drivers=[],
 214         ...                  path=os.path.join('path', 'to','playlist'))
 215         >>> p.from_string(string)
 216         >>> p._index
 217         1
 218         >>> p.info
 219         {u'note': u'An example playlist'}
 220         >>> for curve in p:
 221         ...     print curve.path
 222         path/to/curve/one
 223         path/to/curve/two
 224         """
 225         doc = xml.dom.minidom.parseString(string)
 226         return self._from_xml_doc(doc)
 227
 228     def load(self, path=None):
 229         """Load a playlist from a file.
 230         """
 231         self.set_path(path)
 232         doc = xml.dom.minidom.parse(self.path)
 233         return self._from_xml_doc(doc)
 234
 235     def save(self, path=None):
 236         """Saves the playlist in a XML file.
 237         """
 238         self.set_path(path)
 239         f = file(self.path, 'w')
 240         f.write(self.flatten())
 241         f.close()