original_string: function whereMatch ($regexp, $preg_flags = 0, $useKeys = false)
    {
      $this->setIterator (new RegexIterator ($this->getIterator (), $regexp, RegexIterator::MATCH,
        $useKeys ? RegexIterator::USE_KEY : 0, $preg_flags));
      return $this;
    }
code: function whereMatch ($regexp, $preg_flags = 0, $useKeys = false)
    {
      $this->setIterator (new RegexIterator ($this->getIterator (), $regexp, RegexIterator::MATCH,
        $useKeys ? RegexIterator::USE_KEY : 0, $preg_flags));
      return $this;
    }
code_tokens: function whereMatch ( $ regexp , $ preg_flags = 0 , $ useKeys = false ) { $ this -> setIterator ( new RegexIterator ( $ this -> getIterator ( ) , $ regexp , RegexIterator :: MATCH , $ useKeys ? RegexIterator :: USE_KEY : 0 , $ preg_flags ) ) ; return $ this ; }
docstring: Filters data using a regular expression test.
  
  @param string $regexp     The regular expression to match.
  @param int    $preg_flags The regular expression flags. Can be 0 or PREG_OFFSET_CAPTURE.
  @param bool   $useKeys    When `true`, the iterated keys will be used instead of the corresponding values.
  @return $this
docstring_tokens: Filters data using a regular expression test .