Issue 4125 - [emscripten] Convert filter classes to C++

compiled/ElemHideBase.cpp

+#include "ElemHideBase.h"
+#include "CSSPropertyFilter.h"
+#include "StringScanner.h"
+
+namespace
+{
+  void NormalizeWhitespace(DependentString& text, String::size_type& domainsEnd,
+      String::size_type& selectorStart)
+  {
+    // For element hiding filters we only want to remove spaces preceding the
+    // selector part. The positions we've determined already have to be adjusted
+    // accordingly.
+
+    String::size_type delta = 0;
+    String::size_type len = text.length();
+
+    // The first character is guaranteed to be a non-space, the string has been
+    // trimmed earlier.
+    for (String::size_type pos = 1; pos < len; pos++)
+    {
+      if (pos == domainsEnd)
+        domainsEnd -= delta;
+
+      // Only spaces before selectorStart position should be removed.
+      if (pos < selectorStart && text[pos] == ' ')
+        delta++;
+      else
+        text[pos - delta] = text[pos];
+    }
+    selectorStart -= delta;
+
+    text.reset(text, 0, len - delta);
+  }
+}
+
+ElemHideBase::ElemHideBase(Type type, const String& text, const ElemHideBaseData& data)
+    : ActiveFilter(type, text, false), mData(data)
+{
+  if (mData.HasDomains())
+    ParseDomains(mData.GetDomainsSource(mText), u',');
+}
+
+Filter::Type ElemHideBase::Parse(DependentString& text, ElemHideData& data)
+{
+  StringScanner scanner(text);
+
+  // Domains part
+  bool seenSpaces = false;
+  while (!scanner.done())
+  {
+    String::value_type next = scanner.next();
+    if (next == u'#')
+    {
+      data.mDomainsEnd = scanner.position();
+      break;
+    }
+
+    switch (next)
+    {
+      case u'/':
+      case u'*':
+      case u'|':
+      case u'@':
+      case u'"':
+      case u'!':
+        return Type::UNKNOWN;
+      case u' ':
+        seenSpaces = true;
+        break;
+    }
+  }
+
+  seenSpaces |= scanner.skip(u' ');
+  bool exception = scanner.skipOne(u'@');
+  if (exception)
+    seenSpaces |= scanner.skip(u' ');
+
+  String::value_type next = scanner.next();
+  if (next != u'#')
+    return Type::UNKNOWN;
+
+  // Selector part
+
+  // Selector shouldn't be empty
+  seenSpaces |= scanner.skip(u' ');
+  if (scanner.done())
+    return Type::UNKNOWN;
+
+  data.mSelectorStart = scanner.position() + 1;
+  while (!scanner.done())
+  {
+    switch (scanner.next())
+    {
+      case u'{':
+      case u'}':
+        return Type::UNKNOWN;
+    }
+  }
+
+  // We are done validating, now we can normalize whitespace and the domain part
+  if (seenSpaces)
+    NormalizeWhitespace(text, data.mDomainsEnd, data.mSelectorStart);
+  DependentString(text, 0, data.mDomainsEnd).tolower();
+
+  if (exception)
+    return Type::ELEMHIDEEXCEPTION;
+
+  do
+  {
+    // Is this a CSS property rule maybe?
+    DependentString searchString(u"[-abp-properties="_str);
+    data.mPrefixEnd = text.find(searchString, data.mSelectorStart);
+    if (data.mPrefixEnd == text.npos ||
+        data.mPrefixEnd + searchString.length() + 1 >= text.length())
+    {
+      break;
+    }
+
+    data.mRegexpStart = data.mPrefixEnd + searchString.length() + 1;
+    char16_t quotation = text[data.mRegexpStart - 1];
+    if (quotation != u'\'' && quotation != u'"')
+      break;
+
+    data.mRegexpEnd = text.find(quotation, data.mRegexpStart);
+    if (data.mRegexpEnd == text.npos || data.mRegexpEnd + 1 >= text.length() ||
+      text[data.mRegexpEnd + 1] != u']')
+    {
+      break;

[sergei, 2017/01/10 15:57:38]

Should not we rather return Type::UNKNOWN if the filter is in a broken format,
like the end is absent?

[Wladimir Palant, 2017/03/13 17:41:58]

No, a CSS property filter is an element hiding filter containing
[-abp-properties="..."]. If it doesn't contain that or only part of it then it
is just a regular element hiding filter and we leave it up to the browser to
validate its selector.

+    }
+
+    data.mSuffixStart = data.mRegexpEnd + 2;
+    return Type::CSSPROPERTY;

[sergei, 2017/01/10 15:57:40]

Just in case, do we plan to add any information about -abp-properties to
https://adblockplus.org/filters?

[Wladimir Palant, 2017/03/13 17:41:56]

We do, once we don't consider them experimental any more. Right now they come
with big warnings and we don't want to encourage their use.

+  } while (false);
+
+  return Type::ELEMHIDE;
+}
+
+OwnedString ElemHideBase::GetSelectorDomain() const
+{
+  /* TODO this is inefficient */
+  OwnedString result;
+  if (mDomains)
+  {
+    for (auto it = mDomains->begin(); it != mDomains->end(); ++it)
+    {
+      if (it->second && !it->first.empty())
+      {
+        if (!result.empty())
+          result.append(u',');
+        result.append(it->first);
+      }
+    }
+  }
+  return result;
+}