public function __construct()
{
#
# Constructor function. Initialize appropriate member variables.
#
$this->_initDetab();
$this->prepareItalicsAndBold();
$this->nested_brackets_re = str_repeat('(?>[^\\[\\]]+|\\[', $this->nested_brackets_depth) . str_repeat('\\])*', $this->nested_brackets_depth);
$this->nested_url_parenthesis_re = str_repeat('(?>[^()\\s]+|\\(', $this->nested_url_parenthesis_depth) . str_repeat('(?>\\)))*', $this->nested_url_parenthesis_depth);
$this->escape_chars_re = '[' . preg_quote($this->escape_chars) . ']';
# Sort document, block, and span gamut in ascendent priority order.
asort($this->document_gamut);
asort($this->block_gamut);
asort($this->span_gamut);
}