private function _checkIndentation($token) {
		$whitespaceString = $token->text;

		if ($this->_isActive('indentation')) {
			$indentationType = $this->_config->getTestProperty('indentation', 'type');

			// If indentation type is space, we look for tabs in the string
			if (strtolower($indentationType) === 'space' || strtolower($indentationType) === 'spaces') {
				$tabfound = preg_match("/\t/", $whitespaceString);
				if ($tabfound) {
					$this->_writeError('indentation', $this->_getMessage('INDENTATION_TAB'), $token->line);
				}

				// for spaces, we check the indentation level
				$this->_checkIndentationLevel($token);
			} else if (strtolower($indentationType) === 'tab' || strtolower($indentationType) === 'tabs') {
				// If indentation type is tabs, we look for whitespace in the string
				$whitespacefound = preg_match("/[ ]/", $whitespaceString);
				if ($whitespacefound) {
					$this->_writeError('indentation', $this->_getMessage('INDENTATION_WHITESPACE'), $token->line);
				}
			}
		}
	}