Practical Error Recovery in LR Parsing

Abstract

An automatic syntax error handling technique applicable to LR parsing is presented and analyzed. The technique includes a "phrase-level" error recovery strategy augmented with certain additional features such as "local correction". Attention has also been paid to diagnostic aspects, i.e. the automatic generation of error message texts. The technique has been implemented in the compiler writing system HLP (Helsinki Language Processor), and some promising experimental results have been obtained by testing the technique with erroneous student-written Algol and Pascal programs.