LR-parsing of extended context free grammars

Summary To improve the readability of a grammar it is common to use extended context free grammars (ECFGs) which are context free grammars (CFGs) extended with the repetition operator (^*), the alternation operator (¦) and parentheses to express the right hand sides of the productions. The topic treated here is LR-parsing of ECFGs. The LR(k) concept is generalized to ECFGs, a set of LR-preserving transformations from ECFGs to CFGs is given and finally it is shown how to construct LR-parsers directly from ECFGs.