A Robust Parser for the Web Query Language Xcerpt

This project thesis investigates error handling for the Web Query Language Xcerpt (cf. http://www.xcerpt.org). In addition, a formal definition of the Xcerpt syntax is given. After a short introduction to Xcerpt and parsing, several error management techniques known from literature are presented. They are compared regarding their usefulness for Xcerpt, and one technique is recommended as most suitable for Xcerpt. Unfortunately, the technology to produce a fast and easy to maintain parser for Xcerpt allows only a very limited error management. We discuss some extensions of this technology to improve its error management potentials. We also discuss the error management, possible with the available technology, which has been implemented for the Xcerpt parser. In the last section we present a new error handling technique weakening some problems of traditional error management techniques.