Gettext_Translations

class Gettext_Translations extends Translations {
	/**
	 * The gettext implementation of select_plural_form.
	 *
	 * It lives in this class, because there are more than one descendand, which will use it and
	 * they can't share it effectively.
	 *
	 * @param int $count
	 */
	function gettext_select_plural_form($count) {
		if (!isset($this->_gettext_select_plural_form) || is_null($this->_gettext_select_plural_form)) {
			list( $nplurals, $expression ) = $this->nplurals_and_expression_from_header($this->get_header('Plural-Forms'));
			$this->_nplurals = $nplurals;
			$this->_gettext_select_plural_form = $this->make_plural_form_function($nplurals, $expression);
		}
		return call_user_func($this->_gettext_select_plural_form, $count);
	}

	/**
	 * @param string $header
	 * @return array
	 */
	function nplurals_and_expression_from_header($header) {
		if (preg_match('/^\s*nplurals\s*=\s*(\d+)\s*;\s+plural\s*=\s*(.+)$/', $header, $matches)) {
			$nplurals = (int)$matches[1];
			$expression = trim( $matches[2] );
			return array($nplurals, $expression);
		} else {
			return array(2, 'n != 1');
		}
	}

	/**
	 * Makes a function, which will return the right translation index, according to the
	 * plural forms header
	 * @param int    $nplurals
	 * @param string $expression
	 */
	function make_plural_form_function($nplurals, $expression) {
		try {
			$handler = new Plural_Forms( rtrim( $expression, ';' ) );
			return array( $handler, 'get' );
		} catch ( Exception $e ) {
			// Fall back to default plural-form function.
			return $this->make_plural_form_function( 2, 'n != 1' );
		}
	}

	/**
	 * Adds parentheses to the inner parts of ternary operators in
	 * plural expressions, because PHP evaluates ternary oerators from left to right
	 *
	 * @param string $expression the expression without parentheses
	 * @return string the expression with parentheses added
	 */
	function parenthesize_plural_exression($expression) {
		$expression .= ';';
		$res = '';
		$depth = 0;
		for ($i = 0; $i < strlen($expression); ++$i) {
			$char = $expression[$i];
			switch ($char) {
				case '?':
					$res .= ' ? (';
					$depth++;
					break;
				case ':':
					$res .= ') : (';
					break;
				case ';':
					$res .= str_repeat(')', $depth) . ';';
					$depth= 0;
					break;
				default:
					$res .= $char;
			}
		}
		return rtrim($res, ';');
	}

	/**
	 * @param string $translation
	 * @return array
	 */
	function make_headers($translation) {
		$headers = array();
		// sometimes \ns are used instead of real new lines
		$translation = str_replace('\n', "\n", $translation);
		$lines = explode("\n", $translation);
		foreach($lines as $line) {
			$parts = explode(':', $line, 2);
			if (!isset($parts[1])) continue;
			$headers[trim($parts[0])] = trim($parts[1]);
		}
		return $headers;
	}

	/**
	 * @param string $header
	 * @param string $value
	 */
	function set_header($header, $value) {
		parent::set_header($header, $value);
		if ('Plural-Forms' == $header) {
			list( $nplurals, $expression ) = $this->nplurals_and_expression_from_header($this->get_header('Plural-Forms'));
			$this->_nplurals = $nplurals;
			$this->_gettext_select_plural_form = $this->make_plural_form_function($nplurals, $expression);
		}
	}
}