apps/dvcs/models.py

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