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         changes = Change.objects.exclude(parent=None).filter(
  46                         tree=self.tree,
  47                         created_at__lte=self.created_at).order_by('created_at')
  48         text = u''
  49         for change in changes:
  50             text = change.apply_to(text)
  51         return text
  52
  53     def make_child(self, patch, author, description):
  54         return self.children.create(patch=patch,
  55                         tree=self.tree, author=author,
  56                         description=description)
  57
  58     def make_merge_child(self, patch, author, description):
  59         return self.merge_children.create(patch=patch,
  60                         tree=self.tree, author=author,
  61                         description=description)
  62
  63     def apply_to(self, text):
  64         return mdiff.patch(text, pickle.loads(self.patch.encode('ascii')))
  65
  66     def merge_with(self, other, author, description=u"Automatic merge."):
  67         assert self.tree_id == other.tree_id  # same tree
  68         if other.parent_id == self.pk:
  69             # immediate child
  70             return other
  71
  72         local = self.materialize()
  73         base = other.merge_parent.materialize()
  74         remote = other.apply_to(base)
  75
  76         merge = simplemerge.Merge3Text(base, local, remote)
  77         result = ''.join(merge.merge_lines())
  78         patch = self.make_patch(local, result)
  79         return self.children.create(
  80                     patch=patch, merge_parent=other, tree=self.tree,
  81                     author=author, description=description)
  82
  83
  84 class Document(models.Model):
  85     """
  86         File in repository.
  87     """
  88     creator = models.ForeignKey(User, null=True, blank=True)
  89     head = models.ForeignKey(Change,
  90                     null=True, blank=True, default=None,
  91                     help_text=_("This document's current head."))
  92
  93     def __unicode__(self):
  94         return u"{0}, HEAD: {1}".format(self.id, self.head_id)
  95
  96     @models.permalink
  97     def get_absolute_url(self):
  98         return ('dvcs.views.document_data', (), {
  99                         'document_id': self.id,
 100                         'version': self.head_id,
 101         })
 102
 103     def materialize(self, version=None):
 104         if self.head is None:
 105             return u''
 106         if version is None:
 107             version = self.head
 108         elif not isinstance(version, Change):
 109             version = self.change_set.get(pk=version)
 110         return version.materialize()
 111
 112     def commit(self, **kwargs):
 113         if 'parent' not in kwargs:
 114             parent = self.head
 115         else:
 116             parent = kwargs['parent']
 117             if not isinstance(parent, Change):
 118                 parent = Change.objects.get(pk=kwargs['parent'])
 119
 120         if 'patch' not in kwargs:
 121             if 'text' not in kwargs:
 122                 raise ValueError("You must provide either patch or target document.")
 123             patch = Change.make_patch(self.materialize(version=parent), kwargs['text'])
 124         else:
 125             if 'text' in kwargs:
 126                 raise ValueError("You can provide only text or patch - not both")
 127             patch = kwargs['patch']
 128
 129         old_head = self.head
 130         if parent != old_head:
 131             change = parent.make_merge_child(patch, kwargs['author'], kwargs.get('description', ''))
 132             # not Fast-Forward - perform a merge
 133             self.head = old_head.merge_with(change, author=kwargs['author'])
 134         else:
 135             self.head = parent.make_child(patch, kwargs['author'], kwargs.get('description', ''))
 136         self.save()
 137         return self.head
 138
 139     def history(self):
 140         return self.changes.all()
 141
 142     @staticmethod
 143     def listener_initial_commit(sender, instance, created, **kwargs):
 144         if created:
 145             instance.head = Change.objects.create(
 146                     author=instance.creator,
 147                     patch=pickle.dumps(mdiff.textdiff('', '')),
 148                     tree=instance)
 149             instance.save()
 150
 151 models.signals.post_save.connect(Document.listener_initial_commit, sender=Document)