1 files changed, 119 insertions, 0 deletions
diff --git a/etherpad/src/static/js/broadcast_revisions.js b/etherpad/src/static/js/broadcast_revisions.js
new file mode 100644
index 0000000..7e99003
--- /dev/null
+++ b/etherpad/src/static/js/broadcast_revisions.js
@@ -0,0 +1,119 @@
+/**
+ * Copyright 2009 Google Inc.
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS-IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// revision info is a skip list whos entries represent a particular revision
+// of the document.  These revisions are connected together by various
+// changesets,  or deltas, between any two revisions.
+function Revision(revNum) {
+  this.rev = revNum;
+  this.changesets = [];
+}
+
+Revision.prototype.addChangeset = function(destIndex, changeset, timeDelta) {
+  var changesetWrapper = {
+    deltaRev: destIndex-this.rev,
+    deltaTime: timeDelta,
+    getValue: function() {
+      return changeset;
+    }
+  };
+  this.changesets.push(changesetWrapper);
+  this.changesets.sort(function(a, b) {
+    return (b.deltaRev - a.deltaRev)
+  });
+}
+
+revisionInfo = {};
+revisionInfo.addChangeset = function(fromIndex, toIndex, changeset, backChangeset, timeDelta) {
+  var startRevision = revisionInfo[fromIndex] || revisionInfo.createNew(fromIndex);
+  var endRevision = revisionInfo[toIndex] || revisionInfo.createNew(toIndex);
+  startRevision.addChangeset(toIndex, changeset, timeDelta);
+  endRevision.addChangeset(fromIndex, backChangeset, -1 * timeDelta);
+}
+
+revisionInfo.latest = clientVars.totalRevs || -1;
+
+revisionInfo.createNew = function(index) {
+  revisionInfo[index] = new Revision(index);
+  if(index > revisionInfo.latest) {
+    revisionInfo.latest = index;
+  }
+
+  return revisionInfo[index];
+}
+
+// assuming that there is a path from fromIndex to toIndex, and that the links
+// are laid out in a skip-list format
+revisionInfo.getPath = function(fromIndex, toIndex) {
+  var changesets = [];
+  var spans = [];
+  var times = [];
+  var elem = revisionInfo[fromIndex] || revisionInfo.createNew(fromIndex);
+  if(elem.changesets.length != 0 && fromIndex != toIndex) {
+    var reverse = !(fromIndex < toIndex)
+    while(((elem.rev < toIndex) && !reverse) ||
+          ((elem.rev > toIndex) && reverse)) {
+      var couldNotContinue = false;
+      var oldRev = elem.rev;
+
+      for(var i = reverse ? elem.changesets.length - 1 : 0;
+          reverse?i>=0:i<elem.changesets.length;
+          i += reverse ? -1 : 1) {
+        if(((elem.changesets[i].deltaRev < 0) && !reverse) ||
+           ((elem.changesets[i].deltaRev > 0) && reverse)) {
+          couldNotContinue = true;
+          break;
+        }
+
+        if(((elem.rev + elem.changesets[i].deltaRev <= toIndex) && !reverse) ||
+           ((elem.rev + elem.changesets[i].deltaRev >= toIndex) && reverse)) {
+          var topush = elem.changesets[i];
+          changesets.push(topush.getValue());
+          spans.push(elem.changesets[i].deltaRev);
+          times.push(topush.deltaTime);
+          elem = revisionInfo[elem.rev + elem.changesets[i].deltaRev];
+          break;
+        }
+      }
+
+      if(couldNotContinue || oldRev == elem.rev) break;
+    }
+  }
+
+  var status = 'partial';
+  if(elem.rev == toIndex)
+    status = 'complete';
+
+  return {
+    'fromRev':fromIndex,
+    'rev': elem.rev,
+    'status': status,
+    'changesets': changesets,
+    'spans' : spans,
+    'times' : times
+  };
+}
+
+// revisionInfo.addChangeset(0, 5, "abcde")
+// revisionInfo.addChangeset(5, 10, "fghij")
+// revisionInfo.addChangeset(10, 11, "k")
+// revisionInfo.addChangeset(11, 12, "l")
+// revisionInfo.addChangeset(12, 13, "m")
+// revisionInfo.addChangeset(13, 14, "n")
+// revisionInfo.addChangeset(14, 15, "o")
+// revisionInfo.addChangeset(15, 20, "pqrst")
+//
+// print (revisionInfo.getPath(15, 0))