added lineMarkerAttribute + more comments

src/static/js/AttributeManager.js

@@ -2,6 +2,23 @@ var Changeset = require('./Changeset');
 var ChangesetUtils = require('./ChangesetUtils');
 var _ = require('./underscore');
 
+var lineMarkerAttribute = 'lmkr';
+
+// If one of these attributes are set to the first character of a 
+// line it is considered as a line attribute marker i.e. attributes
+// set on this marker are applied to the whole line. 
+// The list attribute is only maintained for compatibility reasons
+var lineAttributes = [lineMarkerAttribute,'list'];
+
+/*
+  The Attribute manager builds changesets based on a SkipList
+  for setting and removing range or line-based Attributes.
+  
+  @param rep the SkipList to be used
+  @param applyChangesetCallback this callback will be called 
+    once a changeset has been built.
+*/
+
 var AttributeManager = function(rep, applyChangesetCallback)
 {
   this.rep = rep;
@@ -10,30 +27,39 @@ var AttributeManager = function(rep, applyChangesetCallback)
   
   // If the first char in a line has one of the following attributes
   // it will be considered as a line marker
-  this.lineAttributes = ['list'];
 };
 
 AttributeManager.prototype = _(AttributeManager.prototype).extend({
   
   applyChangeset: function(changeset){
+    if(!this.applyChangesetCallback) return changeset;
+    
     var cs = changeset.toString();
     if (!Changeset.isIdentity(cs))
     {
       this.applyChangesetCallback(cs);
     }
+    
+    return changeset;
   },
   
+  /* 
+    Returns if the line already has a line marker
+    @param lineNum: the number of the line
+  */
   lineHasMarker: function(lineNum){
-    // get "list" attribute of first char of line
     var that = this;
     
-    return _.find(this.lineAttributes, function(attribute){
+    return _.find(lineAttributes, function(attribute){
       return that.getAttributeOnLine(lineNum, attribute) != ''; 
     }) !== undefined;
-    
-    
   },
   
+  /*
+    Gets a specified attribute on a line
+    @param lineNum: the number of the line to set the attribute for
+    @param attributeKey: the name of the attribute to get, e.g. list  
+  */
   getAttributeOnLine: function(lineNum, attributeName){
     // get  `attributeName` attribute of first char of line
     var aline = this.rep.alines[lineNum];
@@ -71,6 +97,7 @@ AttributeManager.prototype = _(AttributeManager.prototype).extend({
         builder.insert('*', [
           ['author', this.author],
           ['insertorder', 'first'],
+          [lineMarkerAttribute, '1'],
           [attributeName, attributeValue]
         ], this.rep.apool);
     }

src/static/js/AttributePool.js

@@ -22,6 +22,12 @@
  * limitations under the License.
  */
 
+/*
+  An AttributePool maintains a mapping from [key,value] Pairs called
+  Attributes to Numbers (unsigened integers) and vice versa. These numbers are
+  used to reference Attributes in Changesets.
+*/
+
 var AttributePool = function () {
   this.numToAttrib = {}; // e.g. {0: ['foo','bar']}
   this.attribToNum = {}; // e.g. {'foo,bar': 0}