apps/dvcs/models.py

   1 from datetime import datetime
   2
   3 from django.db import models
   4 from django.contrib.auth.models import User
   5 from django.utils.translation import ugettext_lazy as _
   6 from mercurial import mdiff, simplemerge
   7 import pickle
   8
   9 class Change(models.Model):
  10     """
  11         Single document change related to previous change. The "parent"
  12         argument points to the version against which this change has been
  13         recorded. Initial text will have a null parent.
  14
  15         Data contains a pickled diff needed to reproduce the initial document.
  16     """
  17     author = models.ForeignKey(User, null=True, blank=True)
  18     patch = models.TextField(blank=True)
  19     tree = models.ForeignKey('Document')
  20     revision = models.IntegerField(db_index=True)
  21
  22     parent = models.ForeignKey('self',
  23                         null=True, blank=True, default=None,
  24                         related_name="children")
  25
  26     merge_parent = models.ForeignKey('self',
  27                         null=True, blank=True, default=None,
  28                         related_name="merge_children")
  29
  30     description = models.TextField(blank=True, default='')
  31     created_at = models.DateTimeField(editable=False, db_index=True,
  32                         default=datetime.now)
  33
  34     class Meta:
  35         ordering = ('created_at',)
  36         unique_together = ['tree', 'revision']
  37
  38     def __unicode__(self):
  39         return u"Id: %r, Tree %r, Parent %r, Patch '''\n%s'''" % (self.id, self.tree_id, self.parent_id, self.patch)
  40
  41     def save(self, *args, **kwargs):
  42         """
  43             take the next available revision number if none yet
  44         """
  45         if self.revision is None:
  46             self.revision = self.tree.revision() + 1
  47         return super(Change, self).save(*args, **kwargs)
  48
  49     @staticmethod
  50     def make_patch(src, dst):
  51         if isinstance(src, unicode):
  52             src = src.encode('utf-8')
  53         if isinstance(dst, unicode):
  54             dst = dst.encode('utf-8')
  55         return pickle.dumps(mdiff.textdiff(src, dst))
  56
  57     def materialize(self):
  58         # special care for merged nodes
  59         if self.parent is None and self.merge_parent is not None:
  60             return self.apply_to(self.merge_parent.materialize())
  61
  62         changes = Change.objects.exclude(parent=None).filter(
  63                         tree=self.tree,
  64                         revision__lte=self.revision).order_by('revision')
  65         text = u''
  66         for change in changes:
  67             text = change.apply_to(text)
  68         return text
  69
  70     def make_child(self, patch, author, description):
  71         return self.children.create(patch=patch,
  72                         tree=self.tree, author=author,
  73                         description=description)
  74
  75     def make_merge_child(self, patch, author, description):
  76         return self.merge_children.create(patch=patch,
  77                         tree=self.tree, author=author,
  78                         description=description)
  79
  80     def apply_to(self, text):
  81         return mdiff.patch(text, pickle.loads(self.patch.encode('ascii')))
  82
  83     def merge_with(self, other, author, description=u"Automatic merge."):
  84         assert self.tree_id == other.tree_id  # same tree
  85         if other.parent_id == self.pk:
  86             # immediate child
  87             return other
  88
  89         local = self.materialize()
  90         base = other.merge_parent.materialize()
  91         remote = other.apply_to(base)
  92
  93         merge = simplemerge.Merge3Text(base, local, remote)
  94         result = ''.join(merge.merge_lines())
  95         patch = self.make_patch(local, result)
  96         return self.children.create(
  97                     patch=patch, merge_parent=other, tree=self.tree,
  98                     author=author, description=description)
  99
 100     def revert(self, **kwargs):
 101         """ commit this version of a doc as new head """
 102         self.tree.commit(text=self.materialize(), **kwargs)
 103
 104
 105 class Document(models.Model):
 106     """
 107         File in repository.
 108     """
 109     creator = models.ForeignKey(User, null=True, blank=True)
 110     head = models.ForeignKey(Change,
 111                     null=True, blank=True, default=None,
 112                     help_text=_("This document's current head."))
 113
 114     def __unicode__(self):
 115         return u"{0}, HEAD: {1}".format(self.id, self.head_id)
 116
 117     @models.permalink
 118     def get_absolute_url(self):
 119         return ('dvcs.views.document_data', (), {
 120                         'document_id': self.id,
 121                         'version': self.head_id,
 122         })
 123
 124     def materialize(self, change=None):
 125         if self.head is None:
 126             return u''
 127         if change is None:
 128             change = self.head
 129         elif not isinstance(change, Change):
 130             change = self.change_set.get(pk=change)
 131         return change.materialize()
 132
 133     def commit(self, **kwargs):
 134         if 'parent' not in kwargs:
 135             parent = self.head
 136         else:
 137             parent = kwargs['parent']
 138             if not isinstance(parent, Change):
 139                 parent = Change.objects.get(pk=kwargs['parent'])
 140
 141         if 'patch' not in kwargs:
 142             if 'text' not in kwargs:
 143                 raise ValueError("You must provide either patch or target document.")
 144             patch = Change.make_patch(self.materialize(change=parent), kwargs['text'])
 145         else:
 146             if 'text' in kwargs:
 147                 raise ValueError("You can provide only text or patch - not both")
 148             patch = kwargs['patch']
 149
 150         author = kwargs.get('author', None)
 151
 152         old_head = self.head
 153         if parent != old_head:
 154             change = parent.make_merge_child(patch, author, kwargs.get('description', ''))
 155             # not Fast-Forward - perform a merge
 156             self.head = old_head.merge_with(change, author=author)
 157         else:
 158             self.head = parent.make_child(patch, author, kwargs.get('description', ''))
 159
 160         self.save()
 161         return self.head
 162
 163     def history(self):
 164         return self.change_set.filter(revision__gt=-1)
 165
 166     def revision(self):
 167         rev = self.change_set.aggregate(
 168                 models.Max('revision'))['revision__max']
 169         return rev if rev is not None else -1
 170
 171     def at_revision(self, rev):
 172         if rev:
 173             return self.change_set.get(revision=rev)
 174         else:
 175             return self.head
 176
 177     @staticmethod
 178     def listener_initial_commit(sender, instance, created, **kwargs):
 179         # run for Document and its subclasses
 180         if not isinstance(instance, Document):
 181             return
 182         if created:
 183             instance.head = Change.objects.create(
 184                     revision=-1,
 185                     author=instance.creator,
 186                     patch=Change.make_patch('', ''),
 187                     tree=instance)
 188             instance.save()
 189
 190 models.signals.post_save.connect(Document.listener_initial_commit)