Issue 4167 - getSelectorsForDomain criteria + keys

lib/elemHide.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2016 Eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 162 matching lines @@
       else
       {
         // The new filter's selector only applies to some domains
         this._addToFiltersByDomain(key, filter);
       }
     }
 
     FilterNotifier.emit("elemhideupdate");
   },
 
+  _removeFilterKey: function(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);
+          if (index == 0)
+            unconditionalFilterKeys = null;
+        }
+        else
+        {
+          delete filterKeysBySelector[filter.selector];
+          unconditionalSelectors = unconditionalFilterKeys = null;
+        }
+        return;
+      }
+    }
+
+    // We haven't found this filter in unconditional filters, look in
+    // filtersByDomain.
+    let domains = filter.domains || defaultDomains;
+    for (let domain in domains)
+    {
+      let filters = filtersByDomain[domain];
+      if (filters)
+        delete filters[key];
+    }
+  },
+
   /**
    * Removes an element hiding filter
    * @param {ElemHideFilter} filter
    */
   remove: function(filter)
   {
     if (filter instanceof ElemHideException)
     {
       if (!(filter.text in knownExceptions))
         return;
 
       let list = exceptions[filter.selector];
       let index = list.indexOf(filter);
       if (index >= 0)
         list.splice(index, 1);
       delete knownExceptions[filter.text];
     }
     else
     {
       if (!(filter.text in keyByFilter))
         return;
 
       let key = keyByFilter[filter.text];
       delete filterByKey[key];
       delete keyByFilter[filter.text];
-
-      let unconditional = !(filter.domains || filter.selector in exceptions);
-      if (unconditional)
-      {
-        let filterKeys = filterKeysBySelector[filter.selector];
-        if (filterKeys)
-        {
-          if (filterKeys.length > 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 filterKeysBySelector[filter.selector];
-            unconditionalSelectors = unconditionalFilterKeys = null;
-          }
-        }
-        else
-        {
-          // 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];
-        }
-      }
+      this._removeFilterKey(key, filter);
     }
 
     FilterNotifier.emit("elemhideupdate");
   },
 
   /**
    * Checks whether an exception rule is registered for a filter on a particular
    * domain.
    */
   getException: function(/**Filter*/ filter, /**String*/ docDomain) /**ElemHideException*/
@@ skipping 66 matching lines @@
     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)
+
+  /**
+   * 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.
+   */
+  NO_UNCONDITIONAL: 1,
+
+  /**
+   * Constant used by getSelectorsForDomain to return only selectors for filters
+   * which specifically match the given host name.
+   */
+  SPECIFIC_ONLY: 2,
+
+  /**
+   * Determines from the current filter list which selectors should be applied
+   * on a particular host name. Optionally returns the corresponding filter
+   * keys.
+   * @param {String} domain
+   * @param {Number} [criteria]
+   *   One of the following: ElemHide.ALL_MATCHING, ElemHide.NO_UNCONDITIONAL or
+   *                         ElemHide.SPECIFIC_ONLY.
+   * @param {Boolean} [provideFilterKeys]
+   *   If true, the function will return a list of corresponding filter keys in
+   *   addition to selectors.
+   * @returns {string[]|Array.<string[]>}
+   *   List of selectors or an array with two elements (list of selectors and
+   *   list of corresponding keys) if provideFilterKeys is true.
+   */
+  getSelectorsForDomain: function(domain, criteria, 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.

+
+    if (typeof criteria == "undefined")
+      criteria = ElemHide.ALL_MATCHING;
+    if (criteria < ElemHide.NO_UNCONDITIONAL)
     {
       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 specificOnly = (criteria >= ElemHide.SPECIFIC_ONLY);
     let seenFilters = Object.create(null);
     let currentDomain = domain ? domain.toUpperCase() : "";
     while (true)
     {
       if (specificOnly && currentDomain == "")
         break;
 
       let filters = filtersByDomain[currentDomain];
       if (filters)
       {
@@ skipping 14 matching lines @@
       }
 
       if (currentDomain == "")
         break;
 
       let nextDot = currentDomain.indexOf(".");
       currentDomain = nextDot == -1 ? "" : currentDomain.substr(nextDot + 1);
     }
 
     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.

+      return [selectors, filterKeys];
     else
       return selectors;
   }
 };