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 not path.endswith('.hkp'):
  84             path += '.hkp'
  85         if name == None and path != None:
  86             name = os.path.basename(path)
  87
  88     def is_saved(self):
  89         return self.digest() == self._digest
  90
  91     def digest(self):
  92         r"""Compute the sha1 digest of the flattened playlist
  93         representation.
  94
  95         Examples
  96         --------
  97
  98         >>> root_path = os.path.sep + 'path'
  99         >>> p = FilePlaylist(drivers=[],
 100         ...                  path=os.path.join(root_path, 'to','playlist'))
 101         >>> p.info['note'] = 'An example playlist'
 102         >>> c = curve.Curve(os.path.join(root_path, 'to', 'curve', 'one'))
 103         >>> c.info['note'] = 'The first curve'
 104         >>> p.append(c)
 105         >>> c = curve.Curve(os.path.join(root_path, 'to', 'curve', 'two'))
 106         >>> c.info['note'] = 'The second curve'
 107         >>> p.append(c)
 108         >>> p.digest()
 109         "\xa1\x99\x8a\x99\xed\xad\x13'\xa7w\x12\x00\x07Z\xb3\xd0zN\xa2\xe1"
 110         """
 111         string = self.flatten()
 112         return hashlib.sha1(string).digest()
 113
 114     def flatten(self, absolute_paths=False):
 115         """Create a string representation of the playlist.
 116
 117         A playlist is an XML document with the following syntax::
 118
 119             <?xml version="1.0" encoding="utf-8"?>
 120             <playlist attribute="value">
 121               <curve path="/my/file/path/"/ attribute="value" ...>
 122               <curve path="...">
 123             </playlist>
 124
 125         Relative paths are interpreted relative to the location of the
 126         playlist file.
 127
 128         Examples
 129         --------
 130
 131         >>> root_path = os.path.sep + 'path'
 132         >>> p = FilePlaylist(drivers=[],
 133         ...                  path=os.path.join(root_path, 'to','playlist'))
 134         >>> p.info['note'] = 'An example playlist'
 135         >>> c = curve.Curve(os.path.join(root_path, 'to', 'curve', 'one'))
 136         >>> c.info['note'] = 'The first curve'
 137         >>> p.append(c)
 138         >>> c = curve.Curve(os.path.join(root_path, 'to', 'curve', 'two'))
 139         >>> c.info['note'] = 'The second curve'
 140         >>> p.append(c)
 141         >>> print p.flatten() # doctest: +NORMALIZE_WHITESPACE +REPORT_UDIFF
 142         <?xml version="1.0" encoding="utf-8"?>
 143         <playlist index="0" note="An example playlist" version="0.1">
 144             <curve note="The first curve" path="../curve/one"/>
 145             <curve note="The second curve" path="../curve/two"/>
 146         </playlist>
 147         <BLANKLINE>
 148         >>> print p.flatten(absolute_paths=True) # doctest: +NORMALIZE_WHITESPACE +REPORT_UDIFF
 149         <?xml version="1.0" encoding="utf-8"?>
 150         <playlist index="0" note="An example playlist" version="0.1">
 151             <curve note="The first curve" path="/path/to/curve/one"/>
 152             <curve note="The second curve" path="/path/to/curve/two"/>
 153         </playlist>
 154         <BLANKLINE>
 155         """
 156         implementation = xml.dom.minidom.getDOMImplementation()
 157         # create the document DOM object and the root element
 158         doc = implementation.createDocument(None, 'playlist', None)
 159         root = doc.documentElement
 160         root.setAttribute('version', self.version) # store playlist version
 161         root.setAttribute('index', str(self._index))
 162         for key,value in self.info.items(): # save info variables
 163             root.setAttribute(key, str(value))
 164         for curve in self: # save curves and their attributes
 165             curve_element = doc.createElement('curve')
 166             root.appendChild(curve_element)
 167             path = os.path.abspath(os.path.expanduser(curve.path))
 168             if absolute_paths == False:
 169                 path = os.path.relpath(
 170                     path,
 171                     os.path.abspath(os.path.expanduser(self.path)))
 172             curve_element.setAttribute('path', path)
 173             for key,value in curve.info.items():
 174                 curve_element.setAttribute(key, str(value))
 175         string = doc.toprettyxml(encoding='utf-8')
 176         root.unlink() # break circular references for garbage collection
 177         return string
 178
 179     def _from_xml_doc(self, doc):
 180         """Load a playlist from an :class:`xml.dom.minidom.Document`
 181         instance.
 182         """
 183         root = doc.documentElement
 184         for attribute,value in root.attributes.items():
 185             if attribute == 'version':
 186                 assert value == self.version, \
 187                     'Cannot read v%s playlist with a v%s reader' \
 188                     % (value, self.version)
 189             elif attribute == 'index':
 190                 self._index = int(value)
 191             else:
 192                 self.info[attribute] = value
 193         for curve_element in doc.getElementsByTagName('curve'):
 194             path = curve_element.getAttribute('path')
 195             info = dict(curve_element.attributes.items())
 196             info.pop('path')
 197             self.append_curve_by_path(path, info, identify=False)
 198         self.jump(self._index) # ensure valid index
 199
 200     def from_string(self, string):
 201         """Load a playlist from a string.
 202
 203         Examples
 204         --------
 205
 206         >>> string = '''<?xml version="1.0" encoding="utf-8"?>
 207         ... <playlist index="1" note="An example playlist" version="0.1">
 208         ...     <curve note="The first curve" path="../curve/one"/>
 209         ...     <curve note="The second curve" path="../curve/two"/>
 210         ... </playlist>
 211         ... '''
 212         >>> p = FilePlaylist(drivers=[],
 213         ...                  path=os.path.join('path', 'to','playlist'))
 214         >>> p.from_string(string)
 215         >>> p._index
 216         1
 217         >>> p.info
 218         {u'note': u'An example playlist'}
 219         >>> for curve in p:
 220         ...     print curve.path
 221         path/to/curve/one
 222         path/to/curve/two
 223         """
 224         doc = xml.dom.minidom.parseString(string)
 225         return self._from_xml_doc(doc)
 226
 227     def load(self, path=None):
 228         """Load a playlist from a file.
 229         """
 230         self.set_path(path)
 231         doc = xml.dom.minidom.parse(self.path)
 232         return self._from_xml_doc(doc)
 233
 234     def save(self, path=None):
 235         """Saves the playlist in a XML file.
 236         """
 237         self.set_path(path)
 238         f = file(self.path, 'w')
 239         f.write(self.flatten())
 240         f.close()