Issue 4167 - getSelectorsForDomain criteria + keys

lib/elemHide.js

Index: lib/elemHide.js
diff --git a/lib/elemHide.js b/lib/elemHide.js
index 2c81a2324f579247d53eca5eeb6ac459210a937a..1ca6f7910a2d3cd8953a05c4bebb0e0af001c5ef 100644
--- a/lib/elemHide.js
+++ b/lib/elemHide.js
@@ -36,14 +36,6 @@ var filterByKey = [];
 var keyByFilter = Object.create(null);
 
 /**
- * Indicates whether we are using the getSelectorsForDomain function and
- * therefore mainting the required filtersByDomain, filtersBySelector and
- * unconditionalSelectors lookups. (Will be false for Firefox)
- * @type Boolean
- */
-var usingGetSelectorsForDomain = !("nsIStyleSheetService" in Ci);
-
-/**
  * Nested lookup table, filter (or false if inactive) by filter key by domain.
  * (Only contains filters that aren't unconditionally matched for all domains.)
  * @type Object
@@ -51,19 +43,27 @@ var usingGetSelectorsForDomain = !("nsIStyleSheetService" in Ci);
 var filtersByDomain = Object.create(null);
 
 /**
- * Lookup table, filters by selector. (Only contains filters that have a
+ * Lookup table, filter keys by selector. (Only contains filters that have a
  * selector that is unconditionally matched for all domains.)
  */
-var filtersBySelector = Object.create(null);
+var filterKeysBySelector = Object.create(null);
 
 /**
- * This array caches the keys of filtersBySelector table (selectors which
+ * This array caches the keys of filterKeysBySelector table (selectors which
  * unconditionally apply on all domains). It will be null if the cache needs to
  * be rebuilt.
  */
 var unconditionalSelectors = null;
 
 /**
+ * This array caches the values of filterKeysBySelector table (filterIds for
+ * selectors which unconditionally apply on all domains). It will be null if the
+ * cache needs to be rebuilt. Note: Only the first filter key for each selector
+ * is cached.
+ */
+var unconditionalFilterKeys = null;
+
+/**
  * Object to be used instead when a filter has a blank domains property.
  */
 var defaultDomains = Object.create(null);
@@ -95,16 +95,15 @@ var ElemHide = exports.ElemHide =
     filterByKey = [];
     keyByFilter = Object.create(null);
     filtersByDomain = Object.create(null);
-    filtersBySelector = Object.create(null);
-    unconditionalSelectors = null;
+    filterKeysBySelector = Object.create(null);
+    unconditionalSelectors = unconditionalFilterKeys = null;
     knownExceptions = Object.create(null);
     exceptions = Object.create(null);
     FilterNotifier.emit("elemhideupdate");
   },
 
-  _addToFiltersByDomain: function(filter)
+  _addToFiltersByDomain: function(key, filter)
   {
-    let key = keyByFilter[filter.text];
     let domains = filter.domains || defaultDomains;
     for (let domain in domains)
     {
@@ -135,19 +134,16 @@ var ElemHide = exports.ElemHide =
         exceptions[selector] = [];
       exceptions[selector].push(filter);
 
-      if (usingGetSelectorsForDomain)
+      // If this is the first exception for a previously unconditionally
+      // applied element hiding selector we need to take care to update the
+      // lookups.
+      let filterKeys = filterKeysBySelector[selector];
+      if (filterKeys)
       {
-        // If this is the first exception for a previously unconditionally
-        // applied element hiding selector we need to take care to update the
-        // lookups.
-        let unconditionalFilters = filtersBySelector[selector];
-        if (unconditionalFilters)
-        {
-          for (let f of unconditionalFilters)
-            this._addToFiltersByDomain(f);
-          delete filtersBySelector[selector];
-          unconditionalSelectors = null;
-        }
+        for (let filterKey of filterKeys)
+          this._addToFiltersByDomain(filterKey, filterByKey[filterKey]);
+        delete filterKeysBySelector[selector];
+        unconditionalSelectors = unconditionalFilterKeys = null;
       }
 
       knownExceptions[filter.text] = true;
@@ -160,28 +156,25 @@ var ElemHide = exports.ElemHide =
       let key = filterByKey.push(filter) - 1;
       keyByFilter[filter.text] = key;
 
-      if (usingGetSelectorsForDomain)
+      if (!(filter.domains || filter.selector in exceptions))
       {
-        if (!(filter.domains || filter.selector in exceptions))
+        // The new filter's selector is unconditionally applied to all domains
+        let filterKeys = filterKeysBySelector[filter.selector];
+        if (filterKeys)
         {
-          // The new filter's selector is unconditionally applied to all domains
-          let filters = filtersBySelector[filter.selector];
-          if (filters)
-          {
-            filters.push(filter);
-          }
-          else
-          {
-            filtersBySelector[filter.selector] = [filter];
-            unconditionalSelectors = null;
-          }
+          filterKeys.push(key);
         }
         else
         {
-          // The new filter's selector only applies to some domains
-          this._addToFiltersByDomain(filter);
+          filterKeysBySelector[filter.selector] = [key];
+          unconditionalSelectors = unconditionalFilterKeys = null;
         }
       }
+      else
+      {
+        // The new filter's selector only applies to some domains
+        this._addToFiltersByDomain(key, filter);
+      }
     }
 
     FilterNotifier.emit("elemhideupdate");
@@ -213,31 +206,42 @@ var ElemHide = exports.ElemHide =
       delete filterByKey[key];
       delete keyByFilter[filter.text];
 
-      if (usingGetSelectorsForDomain)
+      let unconditional = !(filter.domains || filter.selector in exceptions);
+      if (unconditional)
       {
-        let filters = filtersBySelector[filter.selector];
-        if (filters)
+        let filterKeys = filterKeysBySelector[filter.selector];
+        if (filterKeys)
         {
-          if (filters.length > 1)
+          if (filterKeys.length > 1)
           {
-            let index = filters.indexOf(filter);
-            filters.splice(index, 1);
+            let index = filterKeys.indexOf(key);
+            filterKeys.splice(index, 1);

[Wladimir Palant, 2016/09/20 16:31:14]

index should be positive but if we ever have a bug and it is -1 bad things will
happen. Should we check maybe, just in case?

In fact, maybe this entire code is better off like this:

  function _removeFilterKey(key, filter)
  {
    let filterKeys = filterKeysBySelector[filter.selector];
    if (filterKeys)
    {
      let index = filterKeys.indexOf(key);
      if (index >= 0)
      {
        if (filterKeys.length > 1)
        {
          filterKeys.splice(index, 1);
          ...
        }
        else
        {
          delete filterKeysBySelector[filter.selector];
          ...
        }
        return;
      }
    }

    // We haven't found this filter in unconditional filters, look
    // in filtersByDomain.
    let domains = filter.domains || defaultDomains;
    ...
  }

[kzar, 2016/09/20 18:37:35]

Done.

+            if (index == 0)
+              unconditionalFilterKeys = null;
           }
           else
           {
-            delete filtersBySelector[filter.selector];
-            unconditionalSelectors = null;
+            delete filterKeysBySelector[filter.selector];
+            unconditionalSelectors = unconditionalFilterKeys = null;
           }
         }
         else
         {
-          let domains = filter.domains || defaultDomains;
-          for (let domain in domains)
-          {
-            let filters = filtersByDomain[domain];
-            if (filters)
-              delete filters[key];
-          }
+          // Even if this filter appears unconditional its selector might not
+          // be. In that case we need to take care to remove it from
+          // filtersByDomain instead.

[Wladimir Palant, 2016/09/20 16:31:14]

This comment makes little sense, should really be something like "Even
unconditional filters will end up in filtersByDomain after an exception applying
to them is removed"

[kzar, 2016/09/20 18:37:35]

Done.

+          unconditional = false;
+        }
+      }
+
+      if (!unconditional)
+      {
+        let domains = filter.domains || defaultDomains;
+        for (let domain in domains)
+        {
+          let filters = filtersByDomain[domain];
+          if (filters)
+            delete filters[key];
         }
       }
     }
@@ -265,7 +269,7 @@ var ElemHide = exports.ElemHide =
   /**
    * Retrieves an element hiding filter by the corresponding protocol key
    */
-  getFilterByKey: function(/**String*/ key) /**Filter*/
+  getFilterByKey: function(/**Number*/ key) /**Filter*/
   {
     return (key in filterByKey ? filterByKey[key] : null);
   },
@@ -298,18 +302,56 @@ var ElemHide = exports.ElemHide =
   },
 
   /**
-   * Returns a list of all selectors active on a particular domain, must not be
-   * used in Firefox (when usingGetSelectorsForDomain is false).
+   * Returns a list of selectors that apply on each website unconditionally.
+   * @returns {String[]}
    */
-  getSelectorsForDomain: function(/**String*/ domain, /**Boolean*/ specificOnly)
+  getUnconditionalSelectors: function()
   {
-    if (!usingGetSelectorsForDomain)
-      throw new Error("getSelectorsForDomain can not be used in Firefox!");
-
     if (!unconditionalSelectors)
-      unconditionalSelectors = Object.keys(filtersBySelector);
-    let selectors = specificOnly ? [] : unconditionalSelectors.slice();
+      unconditionalSelectors = Object.keys(filterKeysBySelector);
+    return unconditionalSelectors.slice();
+  },
 
+  /**
+   * Returns a list of all selectors active on a particular domain.
+   * Returns a list of filterKeys for selectors that apply on each website
+   * unconditionally.
+   * @returns {Number[]}
+   */
+  getUnconditionalFilterKeys: function()
+  {
+    if (!unconditionalFilterKeys)
+    {
+      let selectors = this.getUnconditionalSelectors();
+      unconditionalFilterKeys = [];
+      for (let selector of selectors)
+        unconditionalFilterKeys.push(filterKeysBySelector[selector][0]);
+    }
+    return unconditionalFilterKeys.slice();
+  },
+
+  /**
+   * Returns a list of all selectors active on a particular domain. Optionally
+   * a list of corresponding filter keys for the selectors can be returned too.
+   * The optional criteria parameter restricts the results as follows:
+   *   0 - All selectors allowed (default)
+   *   1 - No unconditionally matching selectors allowed
+   *   2 - Only specifically matching selectors allowed

[Wladimir Palant, 2016/09/20 16:31:14]

No magic numbers please, these should be exposed as constants.

[kzar, 2016/09/20 18:37:35]

Done.

+   */
+  getSelectorsForDomain: function(/**String*/ domain,
+                                  /**Number*/ criteria,
+                                  /**Boolean*/ provideFilterKeys)
+  {
+    let filterKeys = [];
+    let selectors = [];
+    if (!criteria)

[Wladimir Palant, 2016/09/20 16:31:14]

Should be something like:

  if (typeof criteria == "undefined")
    criteria = Elemhide.ALL_MATCHING;
  if (criteria < ElemHide.NO_UNCONDITIONAL)

[kzar, 2016/09/20 18:37:35]

Done.

+    {
+      selectors = this.getUnconditionalSelectors();
+      if (provideFilterKeys)
+        filterKeys = this.getUnconditionalFilterKeys();
+    }
+
+    let specificOnly = criteria == 2;

[Wladimir Palant, 2016/09/20 16:31:14]

Should be something like:

  let specificOnly = (criteria >= ElemHide.SPECIFIC_ONLY);

[kzar, 2016/09/20 18:37:35]

Done.

     let seenFilters = Object.create(null);
     let currentDomain = domain ? domain.toUpperCase() : "";
     while (true)
@@ -328,7 +370,11 @@ var ElemHide = exports.ElemHide =
 
           let filter = filters[filterKey];
           if (filter && !this.getException(filter, domain))
+          {
             selectors.push(filter.selector);
+            // It is faster to always push the key, even if not required.
+            filterKeys.push(filterKey);
+          }
         }
       }
 
@@ -339,6 +385,9 @@ var ElemHide = exports.ElemHide =
       currentDomain = nextDot == -1 ? "" : currentDomain.substr(nextDot + 1);
     }
 
-    return selectors;
+    if (provideFilterKeys)
+      return [selectors, filterKeys.map(key => parseInt(key, 10))];

[Wladimir Palant, 2016/09/20 16:31:14]

Keys are opaque to the caller, we used to have strings here and the caller
doesn't need to know that they are numeric now. Converting them to numbers is
pointless.

[kzar, 2016/09/20 18:37:35]

Done.

+    else
+      return selectors;
   }
 };