--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/piecrust/baking/records.py	Sun Aug 10 23:43:16 2014 -0700
@@ -0,0 +1,113 @@
+import logging
+from piecrust.records import Record
+
+
+logger = logging.getLogger(__name__)
+
+
+def _get_transition_key(source_name, rel_path, taxonomy_name=None,
+        taxonomy_term=None):
+    key = '%s:%s' % (source_name, rel_path)
+    if taxonomy_name and taxonomy_term:
+        key += ';%s:' % taxonomy_name
+        if isinstance(taxonomy_term, tuple):
+            key += '/'.join(taxonomy_term)
+        else:
+            key += taxonomy_term
+    return key
+
+
+class BakeRecord(Record):
+    VERSION = 1
+
+    def __init__(self):
+        super(BakeRecord, self).__init__()
+        self.out_dir = None
+        self.bake_time = None
+
+
+class BakeRecordPageEntry(object):
+    def __init__(self, page):
+        self.path = page.path
+        self.rel_path = page.rel_path
+        self.source_name = page.source.name
+        self.config = page.config.get()
+        self.taxonomy_name = None
+        self.taxonomy_term = None
+        self.out_uris = []
+        self.out_paths = []
+        self.used_source_names = set()
+        self.used_taxonomy_terms = set()
+
+    @property
+    def was_baked(self):
+        return len(self.out_paths) > 0
+
+    @property
+    def num_subs(self):
+        return len(self.out_paths)
+
+    @property
+    def transition_key(self):
+        return _get_transition_key(self.source_name, self.rel_path,
+                self.taxonomy_name, self.taxonomy_term)
+
+class TransitionalBakeRecord(object):
+    DELETION_MISSING = 1
+    DELETION_CHANGED = 2
+
+    def __init__(self, previous_path=None):
+        self.previous = BakeRecord()
+        self.current = BakeRecord()
+        self.transitions = {}
+        if previous_path:
+            self.loadPrevious(previous_path)
+        self.current.entry_added += self._onCurrentEntryAdded
+
+    def loadPrevious(self, previous_path):
+        self.previous = BakeRecord.load(previous_path)
+        for e in self.previous.entries:
+            self.transitions[e.transition_key] = (e, None)
+
+    def saveCurrent(self, current_path):
+        self.current.save(current_path)
+
+    def addEntry(self, entry):
+        self.current.addEntry(entry)
+
+    def getPreviousEntry(self, page, taxonomy_name=None, taxonomy_term=None):
+        key = _get_transition_key(page.source.name, page.rel_path,
+                taxonomy_name, taxonomy_term)
+        pair = self.transitions.get(key)
+        if pair is not None:
+            return pair[0]
+        return None
+
+    def collapseRecords(self):
+        for pair in self.transitions.itervalues():
+            prev = pair[0]
+            cur = pair[1]
+
+            if prev and cur and not cur.was_baked:
+                # This page wasn't baked, so the information from last
+                # time is still valid (we didn't get any information
+                # since we didn't bake).
+                cur.out_uris = list(prev.out_uris)
+                cur.out_paths = list(prev.out_paths)
+                cur.used_source_names = set(prev.used_source_names)
+                cur.used_taxonomy_terms = set(prev.used_taxonomy_terms)
+
+    def _onCurrentEntryAdded(self, entry):
+        key = entry.transition_key
+        te = self.transitions.get(key)
+        if te is None:
+            logger.debug("Adding new record entry: %s" % key)
+            self.transitions[key] = (None, entry)
+            return
+
+        if te[1] is not None:
+            raise Exception("A current entry already exists for: %s" %
+                    key)
+        logger.debug("Setting current record entry: %s" % key)
+        self.transitions[key] = (te[0], entry)
+