Issue 6296 - Handle relative prefix in :-abp-has()

lib/content/elemHideEmulation.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-present 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 104 matching lines @@
     let priority = rule.style.getPropertyPriority(property);
     styles.push(`${property}: ${value}${priority ? " !" + priority : ""};`);
   }
   styles.sort();
   return {
     style: styles.join(" "),
     subSelectors: splitSelector(rule.selectorText)
   };
 }
 
+let scopeSupported = null;
+
+function tryQuerySelector(subtree, selector, all)
+{
+  let elements = null;
+  try
+  {
+    elements = all ? subtree.querySelectorAll(selector) :
+      subtree.querySelector(selector);
+    scopeSupported = true;
+  }
+  catch (e)
+  {
+    // Edge doesn't support ":scope"
+    scopeSupported = false;
+  }
+  return elements;
+}
+
+/**
+ * Query selector. If it is relative, will try :scope.
+ * @param {Node} subtree the element to query selector
+ * @param {string} selector the selector to query
+ * @param {bool} [all=false] true to perform querySelectorAll()
+ * @returns {?(Node|NodeList)} result of the query. null in case of error.
+ */
+function scopedQuerySelector(subtree, selector, all)
+{
+  if (selector[0] == ">")
+  {
+    selector = ":scope" + selector;
+    if (scopeSupported)
+    {
+      return all ? subtree.querySelectorAll(selector) :
+        subtree.querySelector(selector);
+    }
+    if (scopeSupported == null)
+      return tryQuerySelector(subtree, selector, all);
+    return null;
+  }
+  return all ? subtree.querySelectorAll(selector) :
+    subtree.querySelector(selector);
+}
+
+function scopedQuerySelectorAll(subtree, selector)
+{
+  return scopedQuerySelector(subtree, selector, true);
+}
+
 function* evaluate(chain, index, prefix, subtree, styles)
 {
   if (index >= chain.length)
   {
     yield prefix;
     return;
   }
   for (let [selector, element] of
        chain[index].getSelectors(prefix, subtree, styles))
   {
@@ skipping 20 matching lines @@
    * @param {string} prefix the prefix for the selector.
    * @param {Node} subtree the subtree we work on.
    * @param {StringifiedStyle[]} styles the stringified style objects.
    */
   *getSelectors(prefix, subtree, styles)
   {
     yield [prefix + this._selector, subtree];
   }
 };
 
 const incompletePrefixRegexp = /[\s>+~]$/;

[lainverse, 2018/01/30 18:07:28]

Since that other regexp were replaced with string comparison it might be a good
idea to replace this one too:

{
  let u = [];
  let n = 10000000;
  let c = 0;
  let r = /[\s>+~]$/;
  let incomplete = [' ','>','+','~'];
  let isIncompleteArr = c => incomplete.includes(c);
  let isIncompleteStr = c => c == ' ' || c == '>' || c == '+' || c == '~';
  for (let i = 0; i < n; i++)
  {
    if (Math.random() < .1)
      u.push("foo bar" + incomplete[Math.floor(Math.random()*4)]);
    else
      u.push("foo bar");
  }
  let s = performance.now();
  for (let i = 0; i < n; i++)
  {
    //if (r.test(u[i]))
    // if (isIncompleteArr(u[i][u[i].length-1]))
    if (isIncompleteStr(u[i][u[i].length-1]))
      c++;
  }
  let t = (performance.now() - s) | 0;
  console.log(c + " matches found in " + t + "ms");
}

In my tests function isIncompleteArr performs on par with regexp and
isIncompleteStr ~50ms faster both in Firefox and Chrome. Downside: I only check
for normal space character in both functions instead of \s as in the original
regexp. This should work fine if ABP normalize spaces in filters during import.

[Manish Jethani, 2018/01/30 20:23:20]

If we do this then I think that it should be a separate patch.

-const relativeSelectorRegexp = /^[>+~]/;
 
 function HasSelector(selectors)
 {
   this._innerSelectors = selectors;
 }
 
 HasSelector.prototype = {
   requiresHiding: true,
 
   get dependsOnStyles()
@@ skipping 10 matching lines @@
   /**
    * Generator function returning selected elements.
    * @param {string} prefix the prefix for the selector.
    * @param {Node} subtree the subtree we work on.
    * @param {StringifiedStyle[]} styles the stringified style objects.
    */
   *getElements(prefix, subtree, styles)
   {
     let actualPrefix = (!prefix || incompletePrefixRegexp.test(prefix)) ?
         prefix + "*" : prefix;
-    let elements = subtree.querySelectorAll(actualPrefix);
-    for (let element of elements)
+    let elements = scopedQuerySelectorAll(subtree, actualPrefix);
+    if (elements)
     {
-      let iter = evaluate(this._innerSelectors, 0, "", element, styles);
-      for (let selector of iter)
+      for (let element of elements)
       {
-        if (selector == null)
+        let iter = evaluate(this._innerSelectors, 0, "", element, styles);
+        for (let selector of iter)
         {
-          yield null;
-          continue;
-        }
-        if (relativeSelectorRegexp.test(selector))
-          selector = ":scope" + selector;
-        try
-        {
-          if (element.querySelector(selector))
+          if (selector == null)
+            yield null;
+          else if (scopedQuerySelector(element, selector))
             yield element;
         }
-        catch (e)
-        {
-          // :scope isn't supported on Edge, ignore error caused by it.
-        }
+        yield null;
       }
-      yield null;
     }
   }
 };
 
 function ContainsSelector(textContent)
 {
   this._text = textContent;
 }
 
 ContainsSelector.prototype = {
   requiresHiding: true,
 
   *getSelectors(prefix, subtree, stylesheet)
   {
     for (let element of this.getElements(prefix, subtree, stylesheet))
       yield [makeSelector(element, ""), subtree];
   },
 
   *getElements(prefix, subtree, stylesheet)
   {
     let actualPrefix = (!prefix || incompletePrefixRegexp.test(prefix)) ?
         prefix + "*" : prefix;
-    let elements = subtree.querySelectorAll(actualPrefix);
 
-    for (let element of elements)
+    let elements = scopedQuerySelectorAll(subtree, actualPrefix);
+    if (elements)
     {
-      if (element.textContent.includes(this._text))
-        yield element;
-      else
-        yield null;
+      for (let element of elements)
+      {
+        if (element.textContent.includes(this._text))
+          yield element;
+        else
+          yield null;
+      }
     }
   }
 };
 
 function PropsSelector(propertyExpression)
 {
   let regexpString;
   if (propertyExpression.length >= 2 && propertyExpression[0] == "/" &&
       propertyExpression[propertyExpression.length - 1] == "/")
   {
@@ skipping 343 matching lines @@
           characterData: true,
           subtree: true
         }
       );
       this.document.addEventListener("load", this.onLoad.bind(this), true);
     }
   }
 };
 
 exports.ElemHideEmulation = ElemHideEmulation;