Added DVCS application - mercurial on database.

[redakcja.git] / apps / dvcs / models.py

diff --git a/apps/dvcs/models.py b/apps/dvcs/models.py
new file mode 100644 (file)
index 0000000..01ab038
--- /dev/null
+++ b/apps/dvcs/models.py
@@ -0,0 +1,146 @@
+from django.db import models
+from django.contrib.auth.models import User
+from django.utils.translation import ugettext_lazy as _
+from mercurial import mdiff, simplemerge
+import pickle
+
+class Change(models.Model):
+    """
+        Single document change related to previous change. The "parent"
+        argument points to the version against which this change has been 
+        recorded. Initial text will have a null parent.
+        
+        Data contains a reverse diff needed to reproduce the initial document.
+    """
+    author = models.ForeignKey(User)
+    patch = models.TextField(blank=True)
+    tree = models.ForeignKey('Document')
+
+    parent = models.ForeignKey('self',
+                        null=True, blank=True, default=None,
+                        related_name="children")
+
+    merge_parent = models.ForeignKey('self',
+                        null=True, blank=True, default=None,
+                        related_name="merge_children")
+
+    description = models.TextField(blank=True, default='')
+    created_at = models.DateTimeField(auto_now_add=True)
+
+    class Meta:
+        ordering = ('created_at',)
+
+    def __unicode__(self):
+        return "Id: %r, Tree %r, Parent %r, Patch '''\n%s'''" % (self.id, self.tree_id, self.parent_id, self.patch)
+
+    @staticmethod
+    def make_patch(src, dst):
+        return pickle.dumps(mdiff.textdiff(src, dst))
+
+    def materialize(self):
+        changes = Change.objects.exclude(parent=None).filter(
+                        tree=self.tree,
+                        created_at__lte=self.created_at).order_by('created_at')
+        text = ''
+        for change in changes:
+            text = change.apply_to(text)
+        return text
+
+    def make_child(self, patch, description):
+        return self.children.create(patch=patch,
+                        tree=self.tree,
+                        description=description)
+
+    def make_merge_child(self, patch, description):
+        return self.merge_children.create(patch=patch,
+                        tree=self.tree,
+                        description=description)
+
+    def apply_to(self, text):
+        return mdiff.patch(text, pickle.loads(self.patch.encode('ascii')))
+
+
+    def merge_with(self, other):
+        assert self.tree_id == other.tree_id  # same tree
+        if other.parent_id == self.pk:
+            # immediate child 
+            return other
+
+        local = self.materialize()
+        base = other.merge_parent.materialize()
+        remote = other.apply_to(base)
+
+        merge = simplemerge.Merge3Text(base, local, remote)
+        result = ''.join(merge.merge_lines())
+        patch = self.make_patch(local, result)
+        return self.children.create(
+                    patch=patch,
+                    merge_parent=other, tree=self.tree, description=u"Automatic merge")
+
+
+class Document(models.Model):
+    """
+        File in repository.
+        
+    """
+    creator = models.ForeignKey(User)
+    head = models.ForeignKey(Change,
+                    null=True, blank=True, default=None,
+                    help_text=_("This document's current head."))
+
+    # Some meta-data
+    name = models.CharField(max_length=200,
+                help_text=_("Name for this file to display."))
+
+    def __unicode__(self):
+        return "{0}, HEAD: {1}".format(self.name, self.head_id)
+
+    def materialize(self, version=None):
+        if self.head is None:
+            return u''
+        if version is None:
+            version = self.head
+        elif not isinstance(version, Change):
+            version = self.change_set.get(pk=version)
+        return version.materialize()
+
+    def commit(self, **kwargs):
+        if 'parent' not in kwargs:
+            parent = self.head
+        else:
+            parent = kwargs['parent']
+            if not isinstance(parent, Change):
+                parent = Change.objects.get(pk=kwargs['parent'])
+
+        if 'patch' not in kwargs:
+            if 'text' not in kwargs:
+                raise ValueError("You must provide either patch or target document.")
+            patch = Change.make_patch(self.materialize(version=parent), kwargs['text'])
+        else:
+            if 'text' in kwargs:
+                raise ValueError("You can provide only text or patch - not both")
+            patch = kwargs['patch']
+
+        old_head = self.head
+        if parent != old_head:
+            change = parent.make_merge_child(patch, kwargs.get('description', ''))
+            # not Fast-Forward - perform a merge
+            self.head = old_head.merge_with(change)
+        else:
+            self.head = parent.make_child(patch, kwargs.get('description', ''))
+        self.save()
+        return self.head
+
+    def history(self):
+        return self.changes.all()
+
+    @staticmethod
+    def listener_initial_commit(sender, instance, created, **kwargs):
+        if created:
+            instance.head = Change.objects.create(
+                    author=instance.creator,
+                    patch=pickle.dumps(mdiff.textdiff('', '')),
+                    tree=instance)
+            instance.save()
+
+models.signals.post_save.connect(Document.listener_initial_commit, sender=Document)