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     author_desc = models.CharField(max_length=128, null=True, blank=True)
  19     patch = models.TextField(blank=True)
  20     tree = models.ForeignKey('Document')
  21     revision = models.IntegerField(db_index=True)
  22
  23     parent = models.ForeignKey('self',
  24                         null=True, blank=True, default=None,
  25                         related_name="children")
  26
  27     merge_parent = models.ForeignKey('self',
  28                         null=True, blank=True, default=None,
  29                         related_name="merge_children")
  30
  31     description = models.TextField(blank=True, default='')
  32     created_at = models.DateTimeField(editable=False, db_index=True,
  33                         default=datetime.now)
  34
  35     class Meta:
  36         ordering = ('created_at',)
  37         unique_together = ['tree', 'revision']
  38
  39     def __unicode__(self):
  40         return u"Id: %r, Tree %r, Parent %r, Patch '''\n%s'''" % (self.id, self.tree_id, self.parent_id, self.patch)
  41
  42     def author_str(self):
  43         if self.author:
  44             return "%s %s <%s>" % (
  45                 self.author.first_name,
  46                 self.author.last_name,
  47                 self.author.email)
  48         else:
  49             return self.author_desc
  50
  51
  52     def save(self, *args, **kwargs):
  53         """
  54             take the next available revision number if none yet
  55         """
  56         if self.revision is None:
  57             self.revision = self.tree.revision() + 1
  58         return super(Change, self).save(*args, **kwargs)
  59
  60     @staticmethod
  61     def make_patch(src, dst):
  62         if isinstance(src, unicode):
  63             src = src.encode('utf-8')
  64         if isinstance(dst, unicode):
  65             dst = dst.encode('utf-8')
  66         return pickle.dumps(mdiff.textdiff(src, dst))
  67
  68     def materialize(self):
  69         # special care for merged nodes
  70         if self.parent is None and self.merge_parent is not None:
  71             return self.apply_to(self.merge_parent.materialize())
  72
  73         changes = Change.objects.exclude(parent=None).filter(
  74                         tree=self.tree,
  75                         revision__lte=self.revision).order_by('revision')
  76         text = u''
  77         for change in changes:
  78             text = change.apply_to(text)
  79         return text
  80
  81     def make_child(self, patch, description, author=None, author_desc=None):
  82         return self.children.create(patch=patch,
  83                         tree=self.tree, author=author,
  84                         author_desc=author_desc,
  85                         description=description)
  86
  87     def make_merge_child(self, patch, description, author=None,
  88             author_desc=None):
  89         return self.merge_children.create(patch=patch,
  90                         tree=self.tree, author=author,
  91                         author_desc=author_desc,
  92                         description=description)
  93
  94     def apply_to(self, text):
  95         return mdiff.patch(text, pickle.loads(self.patch.encode('ascii')))
  96
  97     def merge_with(self, other, author=None, author_desc=None,
  98             description=u"Automatic merge."):
  99         assert self.tree_id == other.tree_id  # same tree
 100         if other.parent_id == self.pk:
 101             # immediate child
 102             return other
 103
 104         local = self.materialize()
 105         base = other.merge_parent.materialize()
 106         remote = other.apply_to(base)
 107
 108         merge = simplemerge.Merge3Text(base, local, remote)
 109         result = ''.join(merge.merge_lines())
 110         patch = self.make_patch(local, result)
 111         return self.children.create(
 112                     patch=patch, merge_parent=other, tree=self.tree,
 113                     author=author, author_desc=author_desc,
 114                     description=description)
 115
 116     def revert(self, **kwargs):
 117         """ commit this version of a doc as new head """
 118         self.tree.commit(text=self.materialize(), **kwargs)
 119
 120
 121 class Document(models.Model):
 122     """
 123         File in repository.
 124     """
 125     creator = models.ForeignKey(User, null=True, blank=True)
 126     head = models.ForeignKey(Change,
 127                     null=True, blank=True, default=None,
 128                     help_text=_("This document's current head."))
 129
 130     def __unicode__(self):
 131         return u"{0}, HEAD: {1}".format(self.id, self.head_id)
 132
 133     @models.permalink
 134     def get_absolute_url(self):
 135         return ('dvcs.views.document_data', (), {
 136                         'document_id': self.id,
 137                         'version': self.head_id,
 138         })
 139
 140     def materialize(self, change=None):
 141         if self.head is None:
 142             return u''
 143         if change is None:
 144             change = self.head
 145         elif not isinstance(change, Change):
 146             change = self.change_set.get(pk=change)
 147         return change.materialize()
 148
 149     def commit(self, **kwargs):
 150         if 'parent' not in kwargs:
 151             parent = self.head
 152         else:
 153             parent = kwargs['parent']
 154             if not isinstance(parent, Change):
 155                 parent = Change.objects.get(pk=kwargs['parent'])
 156
 157         if 'patch' not in kwargs:
 158             if 'text' not in kwargs:
 159                 raise ValueError("You must provide either patch or target document.")
 160             patch = Change.make_patch(self.materialize(change=parent), kwargs['text'])
 161         else:
 162             if 'text' in kwargs:
 163                 raise ValueError("You can provide only text or patch - not both")
 164             patch = kwargs['patch']
 165
 166         author = kwargs.get('author', None)
 167         author_desc = kwargs.get('author_desc', None)
 168
 169         old_head = self.head
 170         if parent != old_head:
 171             change = parent.make_merge_child(patch, author=author,
 172                     author_desc=author_desc,
 173                     description=kwargs.get('description', ''))
 174             # not Fast-Forward - perform a merge
 175             self.head = old_head.merge_with(change, author=author,
 176                     author_desc=author_desc)
 177         else:
 178             self.head = parent.make_child(patch, author=author,
 179                     author_desc=author_desc,
 180                     description=kwargs.get('description', ''))
 181
 182         self.save()
 183         return self.head
 184
 185     def history(self):
 186         return self.change_set.filter(revision__gt=-1)
 187
 188     def revision(self):
 189         rev = self.change_set.aggregate(
 190                 models.Max('revision'))['revision__max']
 191         return rev if rev is not None else -1
 192
 193     def at_revision(self, rev):
 194         if rev:
 195             return self.change_set.get(revision=rev)
 196         else:
 197             return self.head
 198
 199     @staticmethod
 200     def listener_initial_commit(sender, instance, created, **kwargs):
 201         # run for Document and its subclasses
 202         if not isinstance(instance, Document):
 203             return
 204         if created:
 205             instance.head = Change.objects.create(
 206                     revision=-1,
 207                     author=instance.creator,
 208                     patch=Change.make_patch('', ''),
 209                     tree=instance)
 210             instance.save()
 211
 212 models.signals.post_save.connect(Document.listener_initial_commit)