Resume warming up a partially warmed up index cache

Instead of recomputing the earlier ones

Author: Joris-van-der-Wel

lib/SymbolTree.js

@@ -497,6 +497,12 @@ class SymbolTree {
                 index = 0;
                 let object = parentNode.first;
 
+                if (parentNode.childIndexCachedUpTo) {
+                        const cachedUpToNode = this._node(parentNode.childIndexCachedUpTo);
+                        object = cachedUpToNode.next;
+                        index = cachedUpToNode.getCachedIndex(parentNode) + 1;
+                }
+
                 while (object) {
                         const node = this._node(object);
                         node.setCachedIndex(parentNode, index);
@@ -509,6 +515,8 @@ class SymbolTree {
                         object = node.next;
                 }
 
+                parentNode.childIndexCachedUpTo = child;
+
                 return index;
         }
 

lib/SymbolTreeNode.js

@@ -11,6 +11,8 @@ module.exports = class SymbolTreeNode {
 
                 /** This value is incremented anytime a children is added or removed */
                 this.childrenVersion = 0;
+                /** The last child object which has a cached index */
+                this.childIndexCachedUpTo = null;
 
                 /** This value represents the cached node index, as long as
                  * cachedIndexVersion matches with the childrenVersion of the parent */
@@ -30,6 +32,7 @@ module.exports = class SymbolTreeNode {
                 /* jshint -W016 */
                 // integer wrap around
                 this.childrenVersion = (this.childrenVersion + 1) & 0xFFFFFFFF;
+                this.childIndexCachedUpTo = null;
         }
 
         getCachedIndex(parentNode) {