Issue 5142 - Convert Element Hiding to C++

lib/elemHide.js

Index: lib/elemHide.js
===================================================================
--- a/lib/elemHide.js
+++ b/lib/elemHide.js
@@ -12,385 +12,16 @@
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
  */
 
 "use strict";
 
-/**
- * @fileOverview Element hiding implementation.
- */
-
-const {ElemHideException} = require("filterClasses");
-const {FilterNotifier} = require("filterNotifier");
-
-/**
- * Lookup table, filters by their associated key
- * @type {Object}
- */
-let filterByKey = [];
-
-/**
- * Lookup table, keys of the filters by filter text
- * @type {Object}
- */
-let keyByFilter = Object.create(null);
-
-/**
- * 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}
- */
-let filtersByDomain = Object.create(null);
-
-/**
- * Lookup table, filter key by selector. (Only used for selectors that are
- * unconditionally matched for all domains.)
- */
-let filterKeyBySelector = Object.create(null);
-
-/**
- * This array caches the keys of filterKeyBySelector table (selectors which
- * unconditionally apply on all domains). It will be null if the cache needs to
- * be rebuilt.
- */
-let unconditionalSelectors = null;
-
-/**
- * This array caches the values of filterKeyBySelector table (filterIds for
- * selectors which unconditionally apply on all domains). It will be null if the
- * cache needs to be rebuilt.
- */
-let unconditionalFilterKeys = null;
-
-/**
- * Object to be used instead when a filter has a blank domains property.
- */
-let defaultDomains = Object.create(null);
-defaultDomains[""] = true;
-
-/**
- * Lookup table, keys are known element hiding exceptions
- * @type {Object}
- */
-let knownExceptions = Object.create(null);
-
-/**
- * Lookup table, lists of element hiding exceptions by selector
- * @type {Object}
- */
-let exceptions = Object.create(null);
-
-/**
- * Container for element hiding filters
- * @class
- */
-let ElemHide = exports.ElemHide = {
-  /**
-   * Removes all known filters
-   */
-  clear()
-  {
-    filterByKey = [];
-    keyByFilter = Object.create(null);
-    filtersByDomain = Object.create(null);
-    filterKeyBySelector = Object.create(null);
-    unconditionalSelectors = unconditionalFilterKeys = null;
-    knownExceptions = Object.create(null);
-    exceptions = Object.create(null);
-    FilterNotifier.emit("elemhideupdate");
-  },
-
-  _addToFiltersByDomain(key, filter)
-  {
-    let domains = filter.domains || defaultDomains;
-    for (let domain in domains)
-    {
-      let filters = filtersByDomain[domain];
-      if (!filters)
-        filters = filtersByDomain[domain] = Object.create(null);
-
-      if (domains[domain])
-        filters[key] = filter;
-      else
-        filters[key] = false;
-    }
-  },
-
-  /**
-   * Add a new element hiding filter
-   * @param {ElemHideFilter} filter
-   */
-  add(filter)
-  {
-    if (filter instanceof ElemHideException)
-    {
-      if (filter.text in knownExceptions)
-        return;
-
-      let {selector} = filter;
-      if (!(selector in exceptions))
-        exceptions[selector] = [];
-      exceptions[selector].push(filter);
-
-      // If this is the first exception for a previously unconditionally
-      // applied element hiding selector we need to take care to update the
-      // lookups.
-      let filterKey = filterKeyBySelector[selector];
-      if (typeof filterKey != "undefined")
-      {
-        this._addToFiltersByDomain(filterKey, filterByKey[filterKey]);
-        delete filterKeyBySelector[selector];
-        unconditionalSelectors = unconditionalFilterKeys = null;
-      }
-
-      knownExceptions[filter.text] = true;
-    }
-    else
-    {
-      if (filter.text in keyByFilter)
-        return;
-
-      let key = filterByKey.push(filter) - 1;
-      keyByFilter[filter.text] = key;
-
-      if (!(filter.domains || filter.selector in exceptions))
-      {
-        // The new filter's selector is unconditionally applied to all domains
-        filterKeyBySelector[filter.selector] = key;
-        unconditionalSelectors = unconditionalFilterKeys = null;
-      }
-      else
-      {
-        // The new filter's selector only applies to some domains
-        this._addToFiltersByDomain(key, filter);
-      }
-    }
-
-    FilterNotifier.emit("elemhideupdate");
-  },
-
-  _removeFilterKey(key, filter)
-  {
-    if (filterKeyBySelector[filter.selector] == key)
-    {
-      delete filterKeyBySelector[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(filter)
-  {
-    if (filter instanceof ElemHideException)
-    {
-      if (!(filter.text in knownExceptions))
-        return;
+const {ElemHide} = require("compiled");
 
-      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];
-      this._removeFilterKey(key, filter);
-    }
-
-    FilterNotifier.emit("elemhideupdate");
-  },
-
-  /**
-   * Checks whether an exception rule is registered for a filter on a particular
-   * domain.
-   * @param {Filter} filter
-   * @param {string} docDomain
-   * @return {ElemHideException}
-   */
-  getException(filter, docDomain)
-  {
-    if (!(filter.selector in exceptions))
-      return null;
-
-    let list = exceptions[filter.selector];
-    for (let i = list.length - 1; i >= 0; i--)
-    {
-      if (list[i].isActiveOnDomain(docDomain))
-        return list[i];
-    }
-
-    return null;
-  },
-
-  /**
-   * Retrieves an element hiding filter by the corresponding protocol key
-   * @param {number} key
-   * @return {Filter}
-   */
-  getFilterByKey(key)
-  {
-    return (key in filterByKey ? filterByKey[key] : null);
-  },
-
-  /**
-   * Returns a list of all selectors as a nested map. On first level, the keys
-   * are all values of `ElemHideBase.selectorDomain` (domains on which these
-   * selectors should apply, ignoring exceptions). The values are maps again,
-   * with the keys being selectors and values the corresponding filter keys.
-   * @returns {Map.<String,Map<String,String>>}
-   */
-  getSelectors()
-  {
-    let domains = new Map();
-    for (let key in filterByKey)
-    {
-      let filter = filterByKey[key];
-      if (!filter.selector)
-        continue;
-
-      let domain = filter.selectorDomain || "";
-
-      if (!domains.has(domain))
-        domains.set(domain, new Map());
-      domains.get(domain).set(filter.selector, key);
-    }
-
-    return domains;
-  },
-
-  /**
-   * Returns a list of selectors that apply on each website unconditionally.
-   * @returns {string[]}
-   */
-  getUnconditionalSelectors()
-  {
-    if (!unconditionalSelectors)
-      unconditionalSelectors = Object.keys(filterKeyBySelector);
-    return unconditionalSelectors.slice();
-  },
+// Keep in sync with ElemHide.h
+ElemHide.ALL_MATCHING = 0;
+ElemHide.NO_UNCONDITIONAL = 1;
+ElemHide.SPECIFIC_ONLY = 2;
 
-  /**
-   * Returns a list of filter keys for selectors which apply to all websites
-   * without exception.
-   * @returns {number[]}
-   */
-  getUnconditionalFilterKeys()
-  {
-    if (!unconditionalFilterKeys)
-    {
-      let selectors = this.getUnconditionalSelectors();
-      unconditionalFilterKeys = [];
-      for (let selector of selectors)
-        unconditionalFilterKeys.push(filterKeyBySelector[selector]);
-    }
-    return unconditionalFilterKeys.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.
-   */
-  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(domain, criteria, provideFilterKeys)
-  {
-    let filterKeys = [];
-    let selectors = [];
-
-    if (typeof criteria == "undefined")
-      criteria = ElemHide.ALL_MATCHING;
-    if (criteria < ElemHide.NO_UNCONDITIONAL)
-    {
-      selectors = this.getUnconditionalSelectors();
-      if (provideFilterKeys)
-        filterKeys = this.getUnconditionalFilterKeys();
-    }
-
-    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)
-      {
-        for (let filterKey in filters)
-        {
-          if (filterKey in seenFilters)
-            continue;
-          seenFilters[filterKey] = true;
-
-          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);
-          }
-        }
-      }
-
-      if (currentDomain == "")
-        break;
-
-      let nextDot = currentDomain.indexOf(".");
-      currentDomain = nextDot == -1 ? "" : currentDomain.substr(nextDot + 1);
-    }
-
-    if (provideFilterKeys)
-      return [selectors, filterKeys];
-    return selectors;
-  }
-};
+exports.ElemHide = ElemHide;