// If errh is nil, Parse will terminate immediately upon encountering the first
// error, and the returned syntax tree is nil.
//
// If pragh != nil, it is called with each pragma encountered.
func Parse(base *PosBase, src io.Reader, errh ErrorHandler, pragh PragmaHandler, mode Mode) (_ *File, first error) {
	defer func() {
		if p := recover(); p != nil {
			if err, ok := p.(Error); ok {
				first = err
				return