Issue 6652 - Do not push to unconditional selectors array

lib/elemHide.js

Index: lib/elemHide.js
===================================================================
--- a/lib/elemHide.js
+++ b/lib/elemHide.js
@@ -58,16 +58,27 @@
 
 /**
  * Lookup table, lists of element hiding exceptions by selector
  * @type {Map.<string,Filter>}
  */
 let exceptions = new Map();
 
 /**
+ * Returns a list of selectors that apply on each website unconditionally.
+ * @returns {string[]}
+ */
+function getUnconditionalSelectors()
+{
+  if (!unconditionalSelectors)
+    unconditionalSelectors = [...filterBySelector.keys()];
+  return unconditionalSelectors;

[Manish Jethani, 2018/05/08 17:15:15]

Note that now that's this function is private to the module there's no need to
create a copy. The caller can decide what's best. For example in the current
patch the caller is using Array.concat, which creates a copy anyway.

+}
+
+/**
  * Container for element hiding filters
  * @class
  */
 let ElemHide = exports.ElemHide = {
   /**
    * Removes all known filters
    */
   clear()
@@ -199,27 +210,16 @@
       if (list[i].isActiveOnDomain(docDomain))
         return list[i];
     }
 
     return null;
   },
 
   /**
-   * Returns a list of selectors that apply on each website unconditionally.
-   * @returns {string[]}
-   */
-  getUnconditionalSelectors()
-  {
-    if (!unconditionalSelectors)
-      unconditionalSelectors = [...filterBySelector.keys()];
-    return unconditionalSelectors.slice();
-  },
-
-  /**
    * Constant used by getSelectorsForDomain to return all selectors applying to
    * a particular hostname.
    */
   ALL_MATCHING: 0,
 
   /**
    * Constant used by getSelectorsForDomain to exclude selectors which apply to
    * all websites without exception.
@@ -241,20 +241,22 @@
    *                         ElemHide.SPECIFIC_ONLY.
    * @returns {string[]}
    *   List of selectors.
    */
   getSelectorsForDomain(domain, criteria)
   {
     let selectors = [];
 
+    let unconditionalSelectors = null;
+
     if (typeof criteria == "undefined")
       criteria = ElemHide.ALL_MATCHING;
     if (criteria < ElemHide.NO_UNCONDITIONAL)
-      selectors = this.getUnconditionalSelectors();
+      unconditionalSelectors = getUnconditionalSelectors();
 
     let specificOnly = (criteria >= ElemHide.SPECIFIC_ONLY);
     let excluded = new Set();
     let currentDomain = domain ? domain.toUpperCase() : "";
 
     // This code is a performance hot-spot, which is why we've made certain
     // micro-optimisations. Please be careful before making changes.
     while (true)
@@ -281,11 +283,14 @@
 
       if (currentDomain == "")
         break;
 
       let nextDot = currentDomain.indexOf(".");
       currentDomain = nextDot == -1 ? "" : currentDomain.substr(nextDot + 1);
     }
 
+    if (unconditionalSelectors)
+      selectors = unconditionalSelectors.concat(selectors);
+
     return selectors;
   }
 };